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llvm-mirror/lib/Transforms/Scalar/SimplifyLibCalls.cpp

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//===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a simple pass that applies a variety of small
// optimizations for calls to specific well-known function calls (e.g. runtime
// library functions). Any optimization that takes the very simple form
// "replace call to library function with simpler code that provides the same
// result" belongs in this file.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "simplify-libcalls"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Intrinsics.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Config/config.h"
using namespace llvm;
STATISTIC(NumSimplified, "Number of library calls simplified");
STATISTIC(NumAnnotated, "Number of attributes added to library functions");
//===----------------------------------------------------------------------===//
// Optimizer Base Class
//===----------------------------------------------------------------------===//
/// This class is the abstract base class for the set of optimizations that
/// corresponds to one library call.
namespace {
class LibCallOptimization {
protected:
Function *Caller;
const TargetData *TD;
LLVMContext* Context;
public:
LibCallOptimization() { }
virtual ~LibCallOptimization() {}
/// CallOptimizer - This pure virtual method is implemented by base classes to
/// do various optimizations. If this returns null then no transformation was
/// performed. If it returns CI, then it transformed the call and CI is to be
/// deleted. If it returns something else, replace CI with the new value and
/// delete CI.
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B)
=0;
Value *OptimizeCall(CallInst *CI, const TargetData *TD, IRBuilder<> &B) {
Caller = CI->getParent()->getParent();
this->TD = TD;
if (CI->getCalledFunction())
Context = &CI->getCalledFunction()->getContext();
return CallOptimizer(CI->getCalledFunction(), CI, B);
}
/// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
Value *CastToCStr(Value *V, IRBuilder<> &B);
/// EmitStrLen - Emit a call to the strlen function to the builder, for the
/// specified pointer. Ptr is required to be some pointer type, and the
/// return value has 'intptr_t' type.
Value *EmitStrLen(Value *Ptr, IRBuilder<> &B);
/// EmitMemCpy - Emit a call to the memcpy function to the builder. This
/// always expects that the size has type 'intptr_t' and Dst/Src are pointers.
Value *EmitMemCpy(Value *Dst, Value *Src, Value *Len,
unsigned Align, IRBuilder<> &B);
/// EmitMemMove - Emit a call to the memmove function to the builder. This
/// always expects that the size has type 'intptr_t' and Dst/Src are pointers.
Value *EmitMemMove(Value *Dst, Value *Src, Value *Len,
unsigned Align, IRBuilder<> &B);
/// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
/// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
Value *EmitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilder<> &B);
/// EmitMemCmp - Emit a call to the memcmp function.
Value *EmitMemCmp(Value *Ptr1, Value *Ptr2, Value *Len, IRBuilder<> &B);
/// EmitMemSet - Emit a call to the memset function
Value *EmitMemSet(Value *Dst, Value *Val, Value *Len, IRBuilder<> &B);
/// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
/// 'floor'). This function is known to take a single of type matching 'Op'
/// and returns one value with the same type. If 'Op' is a long double, 'l'
/// is added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
Value *EmitUnaryFloatFnCall(Value *Op, const char *Name, IRBuilder<> &B,
const AttrListPtr &Attrs);
/// EmitPutChar - Emit a call to the putchar function. This assumes that Char
/// is an integer.
Value *EmitPutChar(Value *Char, IRBuilder<> &B);
/// EmitPutS - Emit a call to the puts function. This assumes that Str is
/// some pointer.
void EmitPutS(Value *Str, IRBuilder<> &B);
/// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
/// an i32, and File is a pointer to FILE.
void EmitFPutC(Value *Char, Value *File, IRBuilder<> &B);
/// EmitFPutS - Emit a call to the puts function. Str is required to be a
/// pointer and File is a pointer to FILE.
void EmitFPutS(Value *Str, Value *File, IRBuilder<> &B);
/// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is
/// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
void EmitFWrite(Value *Ptr, Value *Size, Value *File, IRBuilder<> &B);
};
} // End anonymous namespace.
/// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
Value *LibCallOptimization::CastToCStr(Value *V, IRBuilder<> &B) {
return B.CreateBitCast(V, Type::getInt8PtrTy(*Context), "cstr");
}
/// EmitStrLen - Emit a call to the strlen function to the builder, for the
/// specified pointer. This always returns an integer value of size intptr_t.
Value *LibCallOptimization::EmitStrLen(Value *Ptr, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[2];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
Attribute::NoUnwind);
Constant *StrLen =M->getOrInsertFunction("strlen", AttrListPtr::get(AWI, 2),
TD->getIntPtrType(*Context),
Type::getInt8PtrTy(*Context),
NULL);
CallInst *CI = B.CreateCall(StrLen, CastToCStr(Ptr, B), "strlen");
if (const Function *F = dyn_cast<Function>(StrLen->stripPointerCasts()))
CI->setCallingConv(F->getCallingConv());
return CI;
}
/// EmitMemCpy - Emit a call to the memcpy function to the builder. This always
/// expects that the size has type 'intptr_t' and Dst/Src are pointers.
Value *LibCallOptimization::EmitMemCpy(Value *Dst, Value *Src, Value *Len,
unsigned Align, IRBuilder<> &B) {
Module *M = Caller->getParent();
const Type *Ty = Len->getType();
Value *MemCpy = Intrinsic::getDeclaration(M, Intrinsic::memcpy, &Ty, 1);
Dst = CastToCStr(Dst, B);
Src = CastToCStr(Src, B);
return B.CreateCall4(MemCpy, Dst, Src, Len,
ConstantInt::get(Type::getInt32Ty(*Context), Align));
}
/// EmitMemMove - Emit a call to the memmove function to the builder. This
/// always expects that the size has type 'intptr_t' and Dst/Src are pointers.
Value *LibCallOptimization::EmitMemMove(Value *Dst, Value *Src, Value *Len,
unsigned Align, IRBuilder<> &B) {
Module *M = Caller->getParent();
const Type *Ty = TD->getIntPtrType(*Context);
Value *MemMove = Intrinsic::getDeclaration(M, Intrinsic::memmove, &Ty, 1);
Dst = CastToCStr(Dst, B);
Src = CastToCStr(Src, B);
Value *A = ConstantInt::get(Type::getInt32Ty(*Context), Align);
return B.CreateCall4(MemMove, Dst, Src, Len, A);
}
/// EmitMemChr - Emit a call to the memchr function. This assumes that Ptr is
/// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
Value *LibCallOptimization::EmitMemChr(Value *Ptr, Value *Val,
Value *Len, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI;
AWI = AttributeWithIndex::get(~0u, Attribute::ReadOnly | Attribute::NoUnwind);
Value *MemChr = M->getOrInsertFunction("memchr", AttrListPtr::get(&AWI, 1),
Type::getInt8PtrTy(*Context),
Type::getInt8PtrTy(*Context),
Type::getInt32Ty(*Context),
TD->getIntPtrType(*Context),
NULL);
CallInst *CI = B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr");
if (const Function *F = dyn_cast<Function>(MemChr->stripPointerCasts()))
CI->setCallingConv(F->getCallingConv());
return CI;
}
/// EmitMemCmp - Emit a call to the memcmp function.
Value *LibCallOptimization::EmitMemCmp(Value *Ptr1, Value *Ptr2,
Value *Len, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[3];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(2, Attribute::NoCapture);
AWI[2] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
Attribute::NoUnwind);
Value *MemCmp = M->getOrInsertFunction("memcmp", AttrListPtr::get(AWI, 3),
Type::getInt32Ty(*Context),
Type::getInt8PtrTy(*Context),
Type::getInt8PtrTy(*Context),
TD->getIntPtrType(*Context), NULL);
CallInst *CI = B.CreateCall3(MemCmp, CastToCStr(Ptr1, B), CastToCStr(Ptr2, B),
Len, "memcmp");
if (const Function *F = dyn_cast<Function>(MemCmp->stripPointerCasts()))
CI->setCallingConv(F->getCallingConv());
return CI;
}
/// EmitMemSet - Emit a call to the memset function
Value *LibCallOptimization::EmitMemSet(Value *Dst, Value *Val,
Value *Len, IRBuilder<> &B) {
Module *M = Caller->getParent();
Intrinsic::ID IID = Intrinsic::memset;
const Type *Tys[1];
Tys[0] = Len->getType();
Value *MemSet = Intrinsic::getDeclaration(M, IID, Tys, 1);
Value *Align = ConstantInt::get(Type::getInt32Ty(*Context), 1);
return B.CreateCall4(MemSet, CastToCStr(Dst, B), Val, Len, Align);
}
/// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
/// 'floor'). This function is known to take a single of type matching 'Op' and
/// returns one value with the same type. If 'Op' is a long double, 'l' is
/// added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
Value *LibCallOptimization::EmitUnaryFloatFnCall(Value *Op, const char *Name,
IRBuilder<> &B,
const AttrListPtr &Attrs) {
char NameBuffer[20];
if (!Op->getType()->isDoubleTy()) {
// If we need to add a suffix, copy into NameBuffer.
unsigned NameLen = strlen(Name);
assert(NameLen < sizeof(NameBuffer)-2);
memcpy(NameBuffer, Name, NameLen);
if (Op->getType()->isFloatTy())
NameBuffer[NameLen] = 'f'; // floorf
else
NameBuffer[NameLen] = 'l'; // floorl
NameBuffer[NameLen+1] = 0;
Name = NameBuffer;
}
Module *M = Caller->getParent();
Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
Op->getType(), NULL);
CallInst *CI = B.CreateCall(Callee, Op, Name);
CI->setAttributes(Attrs);
if (const Function *F = dyn_cast<Function>(Callee->stripPointerCasts()))
CI->setCallingConv(F->getCallingConv());
return CI;
}
/// EmitPutChar - Emit a call to the putchar function. This assumes that Char
/// is an integer.
Value *LibCallOptimization::EmitPutChar(Value *Char, IRBuilder<> &B) {
Module *M = Caller->getParent();
Value *PutChar = M->getOrInsertFunction("putchar", Type::getInt32Ty(*Context),
Type::getInt32Ty(*Context), NULL);
CallInst *CI = B.CreateCall(PutChar,
B.CreateIntCast(Char,
Type::getInt32Ty(*Context),
/*isSigned*/true,
"chari"),
"putchar");
if (const Function *F = dyn_cast<Function>(PutChar->stripPointerCasts()))
CI->setCallingConv(F->getCallingConv());
return CI;
}
/// EmitPutS - Emit a call to the puts function. This assumes that Str is
/// some pointer.
void LibCallOptimization::EmitPutS(Value *Str, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[2];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Value *PutS = M->getOrInsertFunction("puts", AttrListPtr::get(AWI, 2),
Type::getInt32Ty(*Context),
Type::getInt8PtrTy(*Context),
NULL);
CallInst *CI = B.CreateCall(PutS, CastToCStr(Str, B), "puts");
if (const Function *F = dyn_cast<Function>(PutS->stripPointerCasts()))
CI->setCallingConv(F->getCallingConv());
}
/// EmitFPutC - Emit a call to the fputc function. This assumes that Char is
/// an integer and File is a pointer to FILE.
void LibCallOptimization::EmitFPutC(Value *Char, Value *File, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[2];
AWI[0] = AttributeWithIndex::get(2, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Constant *F;
if (isa<PointerType>(File->getType()))
F = M->getOrInsertFunction("fputc", AttrListPtr::get(AWI, 2),
Type::getInt32Ty(*Context),
Type::getInt32Ty(*Context), File->getType(),
NULL);
else
F = M->getOrInsertFunction("fputc",
Type::getInt32Ty(*Context),
Type::getInt32Ty(*Context),
File->getType(), NULL);
Char = B.CreateIntCast(Char, Type::getInt32Ty(*Context), /*isSigned*/true,
"chari");
CallInst *CI = B.CreateCall2(F, Char, File, "fputc");
if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
CI->setCallingConv(Fn->getCallingConv());
}
/// EmitFPutS - Emit a call to the puts function. Str is required to be a
/// pointer and File is a pointer to FILE.
void LibCallOptimization::EmitFPutS(Value *Str, Value *File, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[3];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(2, Attribute::NoCapture);
AWI[2] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Constant *F;
if (isa<PointerType>(File->getType()))
F = M->getOrInsertFunction("fputs", AttrListPtr::get(AWI, 3),
Type::getInt32Ty(*Context),
Type::getInt8PtrTy(*Context),
File->getType(), NULL);
else
F = M->getOrInsertFunction("fputs", Type::getInt32Ty(*Context),
Type::getInt8PtrTy(*Context),
File->getType(), NULL);
CallInst *CI = B.CreateCall2(F, CastToCStr(Str, B), File, "fputs");
if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
CI->setCallingConv(Fn->getCallingConv());
}
/// EmitFWrite - Emit a call to the fwrite function. This assumes that Ptr is
/// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
void LibCallOptimization::EmitFWrite(Value *Ptr, Value *Size, Value *File,
IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI[3];
AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
AWI[1] = AttributeWithIndex::get(4, Attribute::NoCapture);
AWI[2] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
Constant *F;
if (isa<PointerType>(File->getType()))
F = M->getOrInsertFunction("fwrite", AttrListPtr::get(AWI, 3),
TD->getIntPtrType(*Context),
Type::getInt8PtrTy(*Context),
TD->getIntPtrType(*Context),
TD->getIntPtrType(*Context),
File->getType(), NULL);
else
F = M->getOrInsertFunction("fwrite", TD->getIntPtrType(*Context),
Type::getInt8PtrTy(*Context),
TD->getIntPtrType(*Context),
TD->getIntPtrType(*Context),
File->getType(), NULL);
CallInst *CI = B.CreateCall4(F, CastToCStr(Ptr, B), Size,
ConstantInt::get(TD->getIntPtrType(*Context), 1), File);
if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
CI->setCallingConv(Fn->getCallingConv());
}
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
/// GetStringLengthH - If we can compute the length of the string pointed to by
/// the specified pointer, return 'len+1'. If we can't, return 0.
static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
// Look through noop bitcast instructions.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
return GetStringLengthH(BCI->getOperand(0), PHIs);
// If this is a PHI node, there are two cases: either we have already seen it
// or we haven't.
if (PHINode *PN = dyn_cast<PHINode>(V)) {
if (!PHIs.insert(PN))
return ~0ULL; // already in the set.
// If it was new, see if all the input strings are the same length.
uint64_t LenSoFar = ~0ULL;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
if (Len == 0) return 0; // Unknown length -> unknown.
if (Len == ~0ULL) continue;
if (Len != LenSoFar && LenSoFar != ~0ULL)
return 0; // Disagree -> unknown.
LenSoFar = Len;
}
// Success, all agree.
return LenSoFar;
}
// strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
if (Len1 == 0) return 0;
uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
if (Len2 == 0) return 0;
if (Len1 == ~0ULL) return Len2;
if (Len2 == ~0ULL) return Len1;
if (Len1 != Len2) return 0;
return Len1;
}
// If the value is not a GEP instruction nor a constant expression with a
// GEP instruction, then return unknown.
User *GEP = 0;
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
GEP = GEPI;
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() != Instruction::GetElementPtr)
return 0;
GEP = CE;
} else {
return 0;
}
// Make sure the GEP has exactly three arguments.
if (GEP->getNumOperands() != 3)
return 0;
// Check to make sure that the first operand of the GEP is an integer and
// has value 0 so that we are sure we're indexing into the initializer.
if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
if (!Idx->isZero())
return 0;
} else
return 0;
// If the second index isn't a ConstantInt, then this is a variable index
// into the array. If this occurs, we can't say anything meaningful about
// the string.
uint64_t StartIdx = 0;
if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
StartIdx = CI->getZExtValue();
else
return 0;
// The GEP instruction, constant or instruction, must reference a global
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
GV->mayBeOverridden())
return 0;
Constant *GlobalInit = GV->getInitializer();
// Handle the ConstantAggregateZero case, which is a degenerate case. The
// initializer is constant zero so the length of the string must be zero.
if (isa<ConstantAggregateZero>(GlobalInit))
return 1; // Len = 0 offset by 1.
// Must be a Constant Array
ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
if (!Array ||
Array->getType()->getElementType() != Type::getInt8Ty(V->getContext()))
return false;
// Get the number of elements in the array
uint64_t NumElts = Array->getType()->getNumElements();
// Traverse the constant array from StartIdx (derived above) which is
// the place the GEP refers to in the array.
for (unsigned i = StartIdx; i != NumElts; ++i) {
Constant *Elt = Array->getOperand(i);
ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
if (!CI) // This array isn't suitable, non-int initializer.
return 0;
if (CI->isZero())
return i-StartIdx+1; // We found end of string, success!
}
return 0; // The array isn't null terminated, conservatively return 'unknown'.
}
/// GetStringLength - If we can compute the length of the string pointed to by
/// the specified pointer, return 'len+1'. If we can't, return 0.
static uint64_t GetStringLength(Value *V) {
if (!isa<PointerType>(V->getType())) return 0;
SmallPtrSet<PHINode*, 32> PHIs;
uint64_t Len = GetStringLengthH(V, PHIs);
// If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
// an empty string as a length.
return Len == ~0ULL ? 1 : Len;
}
/// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
/// value is equal or not-equal to zero.
static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {
for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
if (IC->isEquality())
if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
if (C->isNullValue())
continue;
// Unknown instruction.
return false;
}
return true;
}
//===----------------------------------------------------------------------===//
// String and Memory LibCall Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'strcat' Optimizations
namespace {
struct StrCatOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strcat" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
FT->getReturnType() != Type::getInt8PtrTy(*Context) ||
FT->getParamType(0) != FT->getReturnType() ||
FT->getParamType(1) != FT->getReturnType())
return 0;
// Extract some information from the instruction
Value *Dst = CI->getOperand(1);
Value *Src = CI->getOperand(2);
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len == 0) return 0;
--Len; // Unbias length.
// Handle the simple, do-nothing case: strcat(x, "") -> x
if (Len == 0)
return Dst;
// These optimizations require TargetData.
if (!TD) return 0;
EmitStrLenMemCpy(Src, Dst, Len, B);
return Dst;
}
void EmitStrLenMemCpy(Value *Src, Value *Dst, uint64_t Len, IRBuilder<> &B) {
// We need to find the end of the destination string. That's where the
// memory is to be moved to. We just generate a call to strlen.
Value *DstLen = EmitStrLen(Dst, B);
// Now that we have the destination's length, we must index into the
// destination's pointer to get the actual memcpy destination (end of
// the string .. we're concatenating).
Value *CpyDst = B.CreateGEP(Dst, DstLen, "endptr");
// We have enough information to now generate the memcpy call to do the
// concatenation for us. Make a memcpy to copy the nul byte with align = 1.
EmitMemCpy(CpyDst, Src,
ConstantInt::get(TD->getIntPtrType(*Context), Len+1), 1, B);
}
};
//===---------------------------------------===//
// 'strncat' Optimizations
struct StrNCatOpt : public StrCatOpt {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strncat" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 ||
FT->getReturnType() != Type::getInt8PtrTy(*Context) ||
FT->getParamType(0) != FT->getReturnType() ||
FT->getParamType(1) != FT->getReturnType() ||
!isa<IntegerType>(FT->getParamType(2)))
return 0;
// Extract some information from the instruction
Value *Dst = CI->getOperand(1);
Value *Src = CI->getOperand(2);
uint64_t Len;
// We don't do anything if length is not constant
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3)))
Len = LengthArg->getZExtValue();
else
return 0;
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen == 0) return 0;
--SrcLen; // Unbias length.
// Handle the simple, do-nothing cases:
// strncat(x, "", c) -> x
// strncat(x, c, 0) -> x
if (SrcLen == 0 || Len == 0) return Dst;
// These optimizations require TargetData.
if (!TD) return 0;
// We don't optimize this case
if (Len < SrcLen) return 0;
// strncat(x, s, c) -> strcat(x, s)
// s is constant so the strcat can be optimized further
EmitStrLenMemCpy(Src, Dst, SrcLen, B);
return Dst;
}
};
//===---------------------------------------===//
// 'strchr' Optimizations
struct StrChrOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strchr" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
FT->getReturnType() != Type::getInt8PtrTy(*Context) ||
FT->getParamType(0) != FT->getReturnType())
return 0;
Value *SrcStr = CI->getOperand(1);
// If the second operand is non-constant, see if we can compute the length
// of the input string and turn this into memchr.
ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getOperand(2));
if (CharC == 0) {
// These optimizations require TargetData.
if (!TD) return 0;
uint64_t Len = GetStringLength(SrcStr);
if (Len == 0 ||
FT->getParamType(1) != Type::getInt32Ty(*Context)) // memchr needs i32.
return 0;
return EmitMemChr(SrcStr, CI->getOperand(2), // include nul.
ConstantInt::get(TD->getIntPtrType(*Context), Len), B);
}
// Otherwise, the character is a constant, see if the first argument is
// a string literal. If so, we can constant fold.
std::string Str;
if (!GetConstantStringInfo(SrcStr, Str))
return 0;
// strchr can find the nul character.
Str += '\0';
char CharValue = CharC->getSExtValue();
// Compute the offset.
uint64_t i = 0;
while (1) {
if (i == Str.size()) // Didn't find the char. strchr returns null.
return Constant::getNullValue(CI->getType());
// Did we find our match?
if (Str[i] == CharValue)
break;
++i;
}
// strchr(s+n,c) -> gep(s+n+i,c)
Value *Idx = ConstantInt::get(Type::getInt64Ty(*Context), i);
return B.CreateGEP(SrcStr, Idx, "strchr");
}
};
//===---------------------------------------===//
// 'strcmp' Optimizations
struct StrCmpOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strcmp" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
FT->getReturnType() != Type::getInt32Ty(*Context) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(*Context))
return 0;
Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
if (Str1P == Str2P) // strcmp(x,x) -> 0
return ConstantInt::get(CI->getType(), 0);
std::string Str1, Str2;
bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
if (HasStr1 && Str1.empty()) // strcmp("", x) -> *x
return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
// strcmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(),
strcmp(Str1.c_str(),Str2.c_str()));
// strcmp(P, "x") -> memcmp(P, "x", 2)
uint64_t Len1 = GetStringLength(Str1P);
uint64_t Len2 = GetStringLength(Str2P);
if (Len1 && Len2) {
// These optimizations require TargetData.
if (!TD) return 0;
return EmitMemCmp(Str1P, Str2P,
ConstantInt::get(TD->getIntPtrType(*Context),
std::min(Len1, Len2)), B);
}
return 0;
}
};
//===---------------------------------------===//
// 'strncmp' Optimizations
struct StrNCmpOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strncmp" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 ||
FT->getReturnType() != Type::getInt32Ty(*Context) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(*Context) ||
!isa<IntegerType>(FT->getParamType(2)))
return 0;
Value *Str1P = CI->getOperand(1), *Str2P = CI->getOperand(2);
if (Str1P == Str2P) // strncmp(x,x,n) -> 0
return ConstantInt::get(CI->getType(), 0);
// Get the length argument if it is constant.
uint64_t Length;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getOperand(3)))
Length = LengthArg->getZExtValue();
else
return 0;
if (Length == 0) // strncmp(x,y,0) -> 0
return ConstantInt::get(CI->getType(), 0);
std::string Str1, Str2;
bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> *x
return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x
return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
// strncmp(x, y) -> cnst (if both x and y are constant strings)
if (HasStr1 && HasStr2)
return ConstantInt::get(CI->getType(),
strncmp(Str1.c_str(), Str2.c_str(), Length));
return 0;
}
};
//===---------------------------------------===//
// 'strcpy' Optimizations
struct StrCpyOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Verify the "strcpy" function prototype.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(*Context))
return 0;
Value *Dst = CI->getOperand(1), *Src = CI->getOperand(2);
if (Dst == Src) // strcpy(x,x) -> x
return Src;
// These optimizations require TargetData.
if (!TD) return 0;
// See if we can get the length of the input string.
uint64_t Len = GetStringLength(Src);
if (Len == 0) return 0;
// We have enough information to now generate the memcpy call to do the
// concatenation for us. Make a memcpy to copy the nul byte with align = 1.
EmitMemCpy(Dst, Src,
ConstantInt::get(TD->getIntPtrType(*Context), Len), 1, B);
return Dst;
}
};
//===---------------------------------------===//
// 'strncpy' Optimizations
struct StrNCpyOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
FT->getParamType(0) != Type::getInt8PtrTy(*Context) ||
!isa<IntegerType>(FT->getParamType(2)))
return 0;
Value *Dst = CI->getOperand(1);
Value *Src = CI->getOperand(2);
Value *LenOp = CI->getOperand(3);
// See if we can get the length of the input string.
uint64_t SrcLen = GetStringLength(Src);
if (SrcLen == 0) return 0;
--SrcLen;
if (SrcLen == 0) {
// strncpy(x, "", y) -> memset(x, '\0', y, 1)
EmitMemSet(Dst, ConstantInt::get(Type::getInt8Ty(*Context), '\0'), LenOp,
B);
return Dst;
}
uint64_t Len;
if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(LenOp))
Len = LengthArg->getZExtValue();
else
return 0;
if (Len == 0) return Dst; // strncpy(x, y, 0) -> x
// These optimizations require TargetData.
if (!TD) return 0;
// Let strncpy handle the zero padding
if (Len > SrcLen+1) return 0;
// strncpy(x, s, c) -> memcpy(x, s, c, 1) [s and c are constant]
EmitMemCpy(Dst, Src,
ConstantInt::get(TD->getIntPtrType(*Context), Len), 1, B);
return Dst;
}
};
//===---------------------------------------===//
// 'strlen' Optimizations
struct StrLenOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 1 ||
FT->getParamType(0) != Type::getInt8PtrTy(*Context) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
Value *Src = CI->getOperand(1);
// Constant folding: strlen("xyz") -> 3
if (uint64_t Len = GetStringLength(Src))
return ConstantInt::get(CI->getType(), Len-1);
// Handle strlen(p) != 0.
if (!IsOnlyUsedInZeroEqualityComparison(CI)) return 0;
// strlen(x) != 0 --> *x != 0
// strlen(x) == 0 --> *x == 0
return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType());
}
};
//===---------------------------------------===//
// 'strto*' Optimizations
struct StrToOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if ((FT->getNumParams() != 2 && FT->getNumParams() != 3) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)))
return 0;
Value *EndPtr = CI->getOperand(2);
if (isa<ConstantPointerNull>(EndPtr)) {
CI->setOnlyReadsMemory();
CI->addAttribute(1, Attribute::NoCapture);
}
return 0;
}
};
//===---------------------------------------===//
// 'memcmp' Optimizations
struct MemCmpOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
FT->getReturnType() != Type::getInt32Ty(*Context))
return 0;
Value *LHS = CI->getOperand(1), *RHS = CI->getOperand(2);
if (LHS == RHS) // memcmp(s,s,x) -> 0
return Constant::getNullValue(CI->getType());
// Make sure we have a constant length.
ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getOperand(3));
if (!LenC) return 0;
uint64_t Len = LenC->getZExtValue();
if (Len == 0) // memcmp(s1,s2,0) -> 0
return Constant::getNullValue(CI->getType());
if (Len == 1) { // memcmp(S1,S2,1) -> *LHS - *RHS
Value *LHSV = B.CreateLoad(CastToCStr(LHS, B), "lhsv");
Value *RHSV = B.CreateLoad(CastToCStr(RHS, B), "rhsv");
return B.CreateSExt(B.CreateSub(LHSV, RHSV, "chardiff"), CI->getType());
}
// memcmp(S1,S2,2) != 0 -> (*(short*)LHS ^ *(short*)RHS) != 0
// memcmp(S1,S2,4) != 0 -> (*(int*)LHS ^ *(int*)RHS) != 0
if ((Len == 2 || Len == 4) && IsOnlyUsedInZeroEqualityComparison(CI)) {
const Type *PTy = PointerType::getUnqual(Len == 2 ?
Type::getInt16Ty(*Context) : Type::getInt32Ty(*Context));
LHS = B.CreateBitCast(LHS, PTy, "tmp");
RHS = B.CreateBitCast(RHS, PTy, "tmp");
LoadInst *LHSV = B.CreateLoad(LHS, "lhsv");
LoadInst *RHSV = B.CreateLoad(RHS, "rhsv");
LHSV->setAlignment(1); RHSV->setAlignment(1); // Unaligned loads.
return B.CreateZExt(B.CreateXor(LHSV, RHSV, "shortdiff"), CI->getType());
}
// Constant folding: memcmp(x, y, l) -> cnst (all arguments are constant)
std::string LHSStr, RHSStr;
if (GetConstantStringInfo(LHS, LHSStr) &&
GetConstantStringInfo(RHS, RHSStr)) {
// Make sure we're not reading out-of-bounds memory.
if (Len > LHSStr.length() || Len > RHSStr.length())
return 0;
uint64_t Ret = memcmp(LHSStr.data(), RHSStr.data(), Len);
return ConstantInt::get(CI->getType(), Ret);
}
return 0;
}
};
//===---------------------------------------===//
// 'memcpy' Optimizations
struct MemCpyOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
FT->getParamType(2) != TD->getIntPtrType(*Context))
return 0;
// memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1)
EmitMemCpy(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), 1, B);
return CI->getOperand(1);
}
};
//===---------------------------------------===//
// 'memmove' Optimizations
struct MemMoveOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
FT->getParamType(2) != TD->getIntPtrType(*Context))
return 0;
// memmove(x, y, n) -> llvm.memmove(x, y, n, 1)
EmitMemMove(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), 1, B);
return CI->getOperand(1);
}
};
//===---------------------------------------===//
// 'memset' Optimizations
struct MemSetOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<IntegerType>(FT->getParamType(1)) ||
FT->getParamType(2) != TD->getIntPtrType(*Context))
return 0;
// memset(p, v, n) -> llvm.memset(p, v, n, 1)
Value *Val = B.CreateIntCast(CI->getOperand(2), Type::getInt8Ty(*Context),
false);
EmitMemSet(CI->getOperand(1), Val, CI->getOperand(3), B);
return CI->getOperand(1);
}
};
//===----------------------------------------------------------------------===//
// Object Size Checking Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'object size'
namespace {
struct SizeOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// TODO: We can do more with this, but delaying to here should be no change
// in behavior.
ConstantInt *Const = dyn_cast<ConstantInt>(CI->getOperand(2));
if (!Const) return 0;
const Type *Ty = Callee->getFunctionType()->getReturnType();
if (Const->getZExtValue() < 2)
return Constant::getAllOnesValue(Ty);
else
return ConstantInt::get(Ty, 0);
}
};
}
//===---------------------------------------===//
// 'memcpy_chk' Optimizations
struct MemCpyChkOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getParamType(3)) ||
FT->getParamType(2) != TD->getIntPtrType(*Context))
return 0;
ConstantInt *SizeCI = dyn_cast<ConstantInt>(CI->getOperand(4));
if (!SizeCI)
return 0;
if (SizeCI->isAllOnesValue()) {
EmitMemCpy(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3), 1, B);
return CI->getOperand(1);
}
return 0;
}
};
//===---------------------------------------===//
// 'memset_chk' Optimizations
struct MemSetChkOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<IntegerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getParamType(3)) ||
FT->getParamType(2) != TD->getIntPtrType(*Context))
return 0;
ConstantInt *SizeCI = dyn_cast<ConstantInt>(CI->getOperand(4));
if (!SizeCI)
return 0;
if (SizeCI->isAllOnesValue()) {
Value *Val = B.CreateIntCast(CI->getOperand(2), Type::getInt8Ty(*Context),
false);
EmitMemSet(CI->getOperand(1), Val, CI->getOperand(3), B);
return CI->getOperand(1);
}
return 0;
}
};
//===---------------------------------------===//
// 'memmove_chk' Optimizations
struct MemMoveChkOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getParamType(3)) ||
FT->getParamType(2) != TD->getIntPtrType(*Context))
return 0;
ConstantInt *SizeCI = dyn_cast<ConstantInt>(CI->getOperand(4));
if (!SizeCI)
return 0;
if (SizeCI->isAllOnesValue()) {
EmitMemMove(CI->getOperand(1), CI->getOperand(2), CI->getOperand(3),
1, B);
return CI->getOperand(1);
}
return 0;
}
};
//===----------------------------------------------------------------------===//
// Math Library Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'pow*' Optimizations
struct PowOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// Just make sure this has 2 arguments of the same FP type, which match the
// result type.
if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != FT->getParamType(1) ||
!FT->getParamType(0)->isFloatingPoint())
return 0;
Value *Op1 = CI->getOperand(1), *Op2 = CI->getOperand(2);
if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
if (Op1C->isExactlyValue(1.0)) // pow(1.0, x) -> 1.0
return Op1C;
if (Op1C->isExactlyValue(2.0)) // pow(2.0, x) -> exp2(x)
return EmitUnaryFloatFnCall(Op2, "exp2", B, Callee->getAttributes());
}
ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2);
if (Op2C == 0) return 0;
if (Op2C->getValueAPF().isZero()) // pow(x, 0.0) -> 1.0
return ConstantFP::get(CI->getType(), 1.0);
if (Op2C->isExactlyValue(0.5)) {
// Expand pow(x, 0.5) to (x == -infinity ? +infinity : fabs(sqrt(x))).
// This is faster than calling pow, and still handles negative zero
// and negative infinite correctly.
// TODO: In fast-math mode, this could be just sqrt(x).
// TODO: In finite-only mode, this could be just fabs(sqrt(x)).
Value *Inf = ConstantFP::getInfinity(CI->getType());
Value *NegInf = ConstantFP::getInfinity(CI->getType(), true);
Value *Sqrt = EmitUnaryFloatFnCall(Op1, "sqrt", B,
Callee->getAttributes());
Value *FAbs = EmitUnaryFloatFnCall(Sqrt, "fabs", B,
Callee->getAttributes());
Value *FCmp = B.CreateFCmpOEQ(Op1, NegInf, "tmp");
Value *Sel = B.CreateSelect(FCmp, Inf, FAbs, "tmp");
return Sel;
}
if (Op2C->isExactlyValue(1.0)) // pow(x, 1.0) -> x
return Op1;
if (Op2C->isExactlyValue(2.0)) // pow(x, 2.0) -> x*x
return B.CreateFMul(Op1, Op1, "pow2");
if (Op2C->isExactlyValue(-1.0)) // pow(x, -1.0) -> 1.0/x
return B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0),
Op1, "powrecip");
return 0;
}
};
//===---------------------------------------===//
// 'exp2' Optimizations
struct Exp2Opt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// Just make sure this has 1 argument of FP type, which matches the
// result type.
if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isFloatingPoint())
return 0;
Value *Op = CI->getOperand(1);
// Turn exp2(sitofp(x)) -> ldexp(1.0, sext(x)) if sizeof(x) <= 32
// Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < 32
Value *LdExpArg = 0;
if (SIToFPInst *OpC = dyn_cast<SIToFPInst>(Op)) {
if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() <= 32)
LdExpArg = B.CreateSExt(OpC->getOperand(0),
Type::getInt32Ty(*Context), "tmp");
} else if (UIToFPInst *OpC = dyn_cast<UIToFPInst>(Op)) {
if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() < 32)
LdExpArg = B.CreateZExt(OpC->getOperand(0),
Type::getInt32Ty(*Context), "tmp");
}
if (LdExpArg) {
const char *Name;
if (Op->getType()->isFloatTy())
Name = "ldexpf";
else if (Op->getType()->isDoubleTy())
Name = "ldexp";
else
Name = "ldexpl";
Constant *One = ConstantFP::get(*Context, APFloat(1.0f));
if (!Op->getType()->isFloatTy())
One = ConstantExpr::getFPExtend(One, Op->getType());
Module *M = Caller->getParent();
Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
Op->getType(),
Type::getInt32Ty(*Context),NULL);
CallInst *CI = B.CreateCall2(Callee, One, LdExpArg);
if (const Function *F = dyn_cast<Function>(Callee->stripPointerCasts()))
CI->setCallingConv(F->getCallingConv());
return CI;
}
return 0;
}
};
//===---------------------------------------===//
// Double -> Float Shrinking Optimizations for Unary Functions like 'floor'
struct UnaryDoubleFPOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 1 || !FT->getReturnType()->isDoubleTy() ||
!FT->getParamType(0)->isDoubleTy())
return 0;
// If this is something like 'floor((double)floatval)', convert to floorf.
FPExtInst *Cast = dyn_cast<FPExtInst>(CI->getOperand(1));
if (Cast == 0 || !Cast->getOperand(0)->getType()->isFloatTy())
return 0;
// floor((double)floatval) -> (double)floorf(floatval)
Value *V = Cast->getOperand(0);
V = EmitUnaryFloatFnCall(V, Callee->getName().data(), B,
Callee->getAttributes());
return B.CreateFPExt(V, Type::getDoubleTy(*Context));
}
};
//===----------------------------------------------------------------------===//
// Integer Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'ffs*' Optimizations
struct FFSOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// Just make sure this has 2 arguments of the same FP type, which match the
// result type.
if (FT->getNumParams() != 1 ||
FT->getReturnType() != Type::getInt32Ty(*Context) ||
!isa<IntegerType>(FT->getParamType(0)))
return 0;
Value *Op = CI->getOperand(1);
// Constant fold.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
if (CI->getValue() == 0) // ffs(0) -> 0.
return Constant::getNullValue(CI->getType());
return ConstantInt::get(Type::getInt32Ty(*Context), // ffs(c) -> cttz(c)+1
CI->getValue().countTrailingZeros()+1);
}
// ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0
const Type *ArgType = Op->getType();
Value *F = Intrinsic::getDeclaration(Callee->getParent(),
Intrinsic::cttz, &ArgType, 1);
Value *V = B.CreateCall(F, Op, "cttz");
V = B.CreateAdd(V, ConstantInt::get(V->getType(), 1), "tmp");
V = B.CreateIntCast(V, Type::getInt32Ty(*Context), false, "tmp");
Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType), "tmp");
return B.CreateSelect(Cond, V,
ConstantInt::get(Type::getInt32Ty(*Context), 0));
}
};
//===---------------------------------------===//
// 'isdigit' Optimizations
struct IsDigitOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require integer(i32)
if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
FT->getParamType(0) != Type::getInt32Ty(*Context))
return 0;
// isdigit(c) -> (c-'0') <u 10
Value *Op = CI->getOperand(1);
Op = B.CreateSub(Op, ConstantInt::get(Type::getInt32Ty(*Context), '0'),
"isdigittmp");
Op = B.CreateICmpULT(Op, ConstantInt::get(Type::getInt32Ty(*Context), 10),
"isdigit");
return B.CreateZExt(Op, CI->getType());
}
};
//===---------------------------------------===//
// 'isascii' Optimizations
struct IsAsciiOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require integer(i32)
if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
FT->getParamType(0) != Type::getInt32Ty(*Context))
return 0;
// isascii(c) -> c <u 128
Value *Op = CI->getOperand(1);
Op = B.CreateICmpULT(Op, ConstantInt::get(Type::getInt32Ty(*Context), 128),
"isascii");
return B.CreateZExt(Op, CI->getType());
}
};
//===---------------------------------------===//
// 'abs', 'labs', 'llabs' Optimizations
struct AbsOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require integer(integer) where the types agree.
if (FT->getNumParams() != 1 || !isa<IntegerType>(FT->getReturnType()) ||
FT->getParamType(0) != FT->getReturnType())
return 0;
// abs(x) -> x >s -1 ? x : -x
Value *Op = CI->getOperand(1);
Value *Pos = B.CreateICmpSGT(Op,
Constant::getAllOnesValue(Op->getType()),
"ispos");
Value *Neg = B.CreateNeg(Op, "neg");
return B.CreateSelect(Pos, Op, Neg);
}
};
//===---------------------------------------===//
// 'toascii' Optimizations
struct ToAsciiOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
// We require i32(i32)
if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
FT->getParamType(0) != Type::getInt32Ty(*Context))
return 0;
// isascii(c) -> c & 0x7f
return B.CreateAnd(CI->getOperand(1),
ConstantInt::get(CI->getType(),0x7F));
}
};
//===----------------------------------------------------------------------===//
// Formatting and IO Optimizations
//===----------------------------------------------------------------------===//
//===---------------------------------------===//
// 'printf' Optimizations
struct PrintFOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require one fixed pointer argument and an integer/void result.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() < 1 || !isa<PointerType>(FT->getParamType(0)) ||
!(isa<IntegerType>(FT->getReturnType()) ||
FT->getReturnType()->isVoidTy()))
return 0;
// Check for a fixed format string.
std::string FormatStr;
if (!GetConstantStringInfo(CI->getOperand(1), FormatStr))
return 0;
// Empty format string -> noop.
if (FormatStr.empty()) // Tolerate printf's declared void.
return CI->use_empty() ? (Value*)CI :
ConstantInt::get(CI->getType(), 0);
// printf("x") -> putchar('x'), even for '%'. Return the result of putchar
// in case there is an error writing to stdout.
if (FormatStr.size() == 1) {
Value *Res = EmitPutChar(ConstantInt::get(Type::getInt32Ty(*Context),
FormatStr[0]), B);
if (CI->use_empty()) return CI;
return B.CreateIntCast(Res, CI->getType(), true);
}
// printf("foo\n") --> puts("foo")
if (FormatStr[FormatStr.size()-1] == '\n' &&
FormatStr.find('%') == std::string::npos) { // no format characters.
// Create a string literal with no \n on it. We expect the constant merge
// pass to be run after this pass, to merge duplicate strings.
FormatStr.erase(FormatStr.end()-1);
Constant *C = ConstantArray::get(*Context, FormatStr, true);
C = new GlobalVariable(*Callee->getParent(), C->getType(), true,
GlobalVariable::InternalLinkage, C, "str");
EmitPutS(C, B);
return CI->use_empty() ? (Value*)CI :
ConstantInt::get(CI->getType(), FormatStr.size()+1);
}
// Optimize specific format strings.
// printf("%c", chr) --> putchar(*(i8*)dst)
if (FormatStr == "%c" && CI->getNumOperands() > 2 &&
isa<IntegerType>(CI->getOperand(2)->getType())) {
Value *Res = EmitPutChar(CI->getOperand(2), B);
if (CI->use_empty()) return CI;
return B.CreateIntCast(Res, CI->getType(), true);
}
// printf("%s\n", str) --> puts(str)
if (FormatStr == "%s\n" && CI->getNumOperands() > 2 &&
isa<PointerType>(CI->getOperand(2)->getType()) &&
CI->use_empty()) {
EmitPutS(CI->getOperand(2), B);
return CI;
}
return 0;
}
};
//===---------------------------------------===//
// 'sprintf' Optimizations
struct SPrintFOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require two fixed pointer arguments and an integer result.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
// Check for a fixed format string.
std::string FormatStr;
if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
return 0;
// If we just have a format string (nothing else crazy) transform it.
if (CI->getNumOperands() == 3) {
// Make sure there's no % in the constant array. We could try to handle
// %% -> % in the future if we cared.
for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
if (FormatStr[i] == '%')
return 0; // we found a format specifier, bail out.
// These optimizations require TargetData.
if (!TD) return 0;
// sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1)
EmitMemCpy(CI->getOperand(1), CI->getOperand(2), // Copy the nul byte.
ConstantInt::get(TD->getIntPtrType(*Context), FormatStr.size()+1),1,B);
return ConstantInt::get(CI->getType(), FormatStr.size());
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
return 0;
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
// sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
Value *V = B.CreateTrunc(CI->getOperand(3),
Type::getInt8Ty(*Context), "char");
Value *Ptr = CastToCStr(CI->getOperand(1), B);
B.CreateStore(V, Ptr);
Ptr = B.CreateGEP(Ptr, ConstantInt::get(Type::getInt32Ty(*Context), 1),
"nul");
B.CreateStore(Constant::getNullValue(Type::getInt8Ty(*Context)), Ptr);
return ConstantInt::get(CI->getType(), 1);
}
if (FormatStr[1] == 's') {
// These optimizations require TargetData.
if (!TD) return 0;
// sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
if (!isa<PointerType>(CI->getOperand(3)->getType())) return 0;
Value *Len = EmitStrLen(CI->getOperand(3), B);
Value *IncLen = B.CreateAdd(Len,
ConstantInt::get(Len->getType(), 1),
"leninc");
EmitMemCpy(CI->getOperand(1), CI->getOperand(3), IncLen, 1, B);
// The sprintf result is the unincremented number of bytes in the string.
return B.CreateIntCast(Len, CI->getType(), false);
}
return 0;
}
};
//===---------------------------------------===//
// 'fwrite' Optimizations
struct FWriteOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require a pointer, an integer, an integer, a pointer, returning integer.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 4 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<IntegerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getParamType(2)) ||
!isa<PointerType>(FT->getParamType(3)) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
// Get the element size and count.
ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getOperand(2));
ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getOperand(3));
if (!SizeC || !CountC) return 0;
uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
// If this is writing zero records, remove the call (it's a noop).
if (Bytes == 0)
return ConstantInt::get(CI->getType(), 0);
// If this is writing one byte, turn it into fputc.
if (Bytes == 1) { // fwrite(S,1,1,F) -> fputc(S[0],F)
Value *Char = B.CreateLoad(CastToCStr(CI->getOperand(1), B), "char");
EmitFPutC(Char, CI->getOperand(4), B);
return ConstantInt::get(CI->getType(), 1);
}
return 0;
}
};
//===---------------------------------------===//
// 'fputs' Optimizations
struct FPutsOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// These optimizations require TargetData.
if (!TD) return 0;
// Require two pointers. Also, we can't optimize if return value is used.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!CI->use_empty())
return 0;
// fputs(s,F) --> fwrite(s,1,strlen(s),F)
uint64_t Len = GetStringLength(CI->getOperand(1));
if (!Len) return 0;
EmitFWrite(CI->getOperand(1),
ConstantInt::get(TD->getIntPtrType(*Context), Len-1),
CI->getOperand(2), B);
return CI; // Known to have no uses (see above).
}
};
//===---------------------------------------===//
// 'fprintf' Optimizations
struct FPrintFOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
// Require two fixed paramters as pointers and integer result.
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 || !isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!isa<IntegerType>(FT->getReturnType()))
return 0;
// All the optimizations depend on the format string.
std::string FormatStr;
if (!GetConstantStringInfo(CI->getOperand(2), FormatStr))
return 0;
// fprintf(F, "foo") --> fwrite("foo", 3, 1, F)
if (CI->getNumOperands() == 3) {
for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
if (FormatStr[i] == '%') // Could handle %% -> % if we cared.
return 0; // We found a format specifier.
// These optimizations require TargetData.
if (!TD) return 0;
EmitFWrite(CI->getOperand(2), ConstantInt::get(TD->getIntPtrType(*Context),
FormatStr.size()),
CI->getOperand(1), B);
return ConstantInt::get(CI->getType(), FormatStr.size());
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() != 2 || FormatStr[0] != '%' || CI->getNumOperands() <4)
return 0;
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
// fprintf(F, "%c", chr) --> *(i8*)dst = chr
if (!isa<IntegerType>(CI->getOperand(3)->getType())) return 0;
EmitFPutC(CI->getOperand(3), CI->getOperand(1), B);
return ConstantInt::get(CI->getType(), 1);
}
if (FormatStr[1] == 's') {
// fprintf(F, "%s", str) -> fputs(str, F)
if (!isa<PointerType>(CI->getOperand(3)->getType()) || !CI->use_empty())
return 0;
EmitFPutS(CI->getOperand(3), CI->getOperand(1), B);
return CI;
}
return 0;
}
};
} // end anonymous namespace.
//===----------------------------------------------------------------------===//
// SimplifyLibCalls Pass Implementation
//===----------------------------------------------------------------------===//
namespace {
/// This pass optimizes well known library functions from libc and libm.
///
class SimplifyLibCalls : public FunctionPass {
StringMap<LibCallOptimization*> Optimizations;
// String and Memory LibCall Optimizations
StrCatOpt StrCat; StrNCatOpt StrNCat; StrChrOpt StrChr; StrCmpOpt StrCmp;
StrNCmpOpt StrNCmp; StrCpyOpt StrCpy; StrNCpyOpt StrNCpy; StrLenOpt StrLen;
StrToOpt StrTo; MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove;
MemSetOpt MemSet;
// Math Library Optimizations
PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
// Integer Optimizations
FFSOpt FFS; AbsOpt Abs; IsDigitOpt IsDigit; IsAsciiOpt IsAscii;
ToAsciiOpt ToAscii;
// Formatting and IO Optimizations
SPrintFOpt SPrintF; PrintFOpt PrintF;
FWriteOpt FWrite; FPutsOpt FPuts; FPrintFOpt FPrintF;
// Object Size Checking
SizeOpt ObjectSize;
MemCpyChkOpt MemCpyChk; MemSetChkOpt MemSetChk; MemMoveChkOpt MemMoveChk;
bool Modified; // This is only used by doInitialization.
public:
static char ID; // Pass identification
SimplifyLibCalls() : FunctionPass(&ID) {}
void InitOptimizations();
bool runOnFunction(Function &F);
void setDoesNotAccessMemory(Function &F);
void setOnlyReadsMemory(Function &F);
void setDoesNotThrow(Function &F);
void setDoesNotCapture(Function &F, unsigned n);
void setDoesNotAlias(Function &F, unsigned n);
bool doInitialization(Module &M);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
}
};
char SimplifyLibCalls::ID = 0;
} // end anonymous namespace.
static RegisterPass<SimplifyLibCalls>
X("simplify-libcalls", "Simplify well-known library calls");
// Public interface to the Simplify LibCalls pass.
FunctionPass *llvm::createSimplifyLibCallsPass() {
return new SimplifyLibCalls();
}
/// Optimizations - Populate the Optimizations map with all the optimizations
/// we know.
void SimplifyLibCalls::InitOptimizations() {
// String and Memory LibCall Optimizations
Optimizations["strcat"] = &StrCat;
Optimizations["strncat"] = &StrNCat;
Optimizations["strchr"] = &StrChr;
Optimizations["strcmp"] = &StrCmp;
Optimizations["strncmp"] = &StrNCmp;
Optimizations["strcpy"] = &StrCpy;
Optimizations["strncpy"] = &StrNCpy;
Optimizations["strlen"] = &StrLen;
Optimizations["strtol"] = &StrTo;
Optimizations["strtod"] = &StrTo;
Optimizations["strtof"] = &StrTo;
Optimizations["strtoul"] = &StrTo;
Optimizations["strtoll"] = &StrTo;
Optimizations["strtold"] = &StrTo;
Optimizations["strtoull"] = &StrTo;
Optimizations["memcmp"] = &MemCmp;
Optimizations["memcpy"] = &MemCpy;
Optimizations["memmove"] = &MemMove;
Optimizations["memset"] = &MemSet;
// Math Library Optimizations
Optimizations["powf"] = &Pow;
Optimizations["pow"] = &Pow;
Optimizations["powl"] = &Pow;
Optimizations["llvm.pow.f32"] = &Pow;
Optimizations["llvm.pow.f64"] = &Pow;
Optimizations["llvm.pow.f80"] = &Pow;
Optimizations["llvm.pow.f128"] = &Pow;
Optimizations["llvm.pow.ppcf128"] = &Pow;
Optimizations["exp2l"] = &Exp2;
Optimizations["exp2"] = &Exp2;
Optimizations["exp2f"] = &Exp2;
Optimizations["llvm.exp2.ppcf128"] = &Exp2;
Optimizations["llvm.exp2.f128"] = &Exp2;
Optimizations["llvm.exp2.f80"] = &Exp2;
Optimizations["llvm.exp2.f64"] = &Exp2;
Optimizations["llvm.exp2.f32"] = &Exp2;
#ifdef HAVE_FLOORF
Optimizations["floor"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_CEILF
Optimizations["ceil"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_ROUNDF
Optimizations["round"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_RINTF
Optimizations["rint"] = &UnaryDoubleFP;
#endif
#ifdef HAVE_NEARBYINTF
Optimizations["nearbyint"] = &UnaryDoubleFP;
#endif
// Integer Optimizations
Optimizations["ffs"] = &FFS;
Optimizations["ffsl"] = &FFS;
Optimizations["ffsll"] = &FFS;
Optimizations["abs"] = &Abs;
Optimizations["labs"] = &Abs;
Optimizations["llabs"] = &Abs;
Optimizations["isdigit"] = &IsDigit;
Optimizations["isascii"] = &IsAscii;
Optimizations["toascii"] = &ToAscii;
// Formatting and IO Optimizations
Optimizations["sprintf"] = &SPrintF;
Optimizations["printf"] = &PrintF;
Optimizations["fwrite"] = &FWrite;
Optimizations["fputs"] = &FPuts;
Optimizations["fprintf"] = &FPrintF;
// Object Size Checking
Optimizations["llvm.objectsize.i32"] = &ObjectSize;
Optimizations["llvm.objectsize.i64"] = &ObjectSize;
Optimizations["__memcpy_chk"] = &MemCpyChk;
Optimizations["__memset_chk"] = &MemSetChk;
Optimizations["__memmove_chk"] = &MemMoveChk;
}
/// runOnFunction - Top level algorithm.
///
bool SimplifyLibCalls::runOnFunction(Function &F) {
if (Optimizations.empty())
InitOptimizations();
const TargetData *TD = getAnalysisIfAvailable<TargetData>();
IRBuilder<> Builder(F.getContext());
bool Changed = false;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
// Ignore non-calls.
CallInst *CI = dyn_cast<CallInst>(I++);
if (!CI) continue;
// Ignore indirect calls and calls to non-external functions.
Function *Callee = CI->getCalledFunction();
if (Callee == 0 || !Callee->isDeclaration() ||
!(Callee->hasExternalLinkage() || Callee->hasDLLImportLinkage()))
continue;
// Ignore unknown calls.
LibCallOptimization *LCO = Optimizations.lookup(Callee->getName());
if (!LCO) continue;
// Set the builder to the instruction after the call.
Builder.SetInsertPoint(BB, I);
// Try to optimize this call.
Value *Result = LCO->OptimizeCall(CI, TD, Builder);
if (Result == 0) continue;
DEBUG(errs() << "SimplifyLibCalls simplified: " << *CI;
errs() << " into: " << *Result << "\n");
// Something changed!
Changed = true;
++NumSimplified;
// Inspect the instruction after the call (which was potentially just
// added) next.
I = CI; ++I;
if (CI != Result && !CI->use_empty()) {
CI->replaceAllUsesWith(Result);
if (!Result->hasName())
Result->takeName(CI);
}
CI->eraseFromParent();
}
}
return Changed;
}
// Utility methods for doInitialization.
void SimplifyLibCalls::setDoesNotAccessMemory(Function &F) {
if (!F.doesNotAccessMemory()) {
F.setDoesNotAccessMemory();
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setOnlyReadsMemory(Function &F) {
if (!F.onlyReadsMemory()) {
F.setOnlyReadsMemory();
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setDoesNotThrow(Function &F) {
if (!F.doesNotThrow()) {
F.setDoesNotThrow();
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setDoesNotCapture(Function &F, unsigned n) {
if (!F.doesNotCapture(n)) {
F.setDoesNotCapture(n);
++NumAnnotated;
Modified = true;
}
}
void SimplifyLibCalls::setDoesNotAlias(Function &F, unsigned n) {
if (!F.doesNotAlias(n)) {
F.setDoesNotAlias(n);
++NumAnnotated;
Modified = true;
}
}
/// doInitialization - Add attributes to well-known functions.
///
bool SimplifyLibCalls::doInitialization(Module &M) {
Modified = false;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
Function &F = *I;
if (!F.isDeclaration())
continue;
if (!F.hasName())
continue;
const FunctionType *FTy = F.getFunctionType();
StringRef Name = F.getName();
switch (Name[0]) {
case 's':
if (Name == "strlen") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "strcpy" ||
Name == "stpcpy" ||
Name == "strcat" ||
Name == "strtol" ||
Name == "strtod" ||
Name == "strtof" ||
Name == "strtoul" ||
Name == "strtoll" ||
Name == "strtold" ||
Name == "strncat" ||
Name == "strncpy" ||
Name == "strtoull") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "strxfrm") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "strcmp" ||
Name == "strspn" ||
Name == "strncmp" ||
Name ==" strcspn" ||
Name == "strcoll" ||
Name == "strcasecmp" ||
Name == "strncasecmp") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "strstr" ||
Name == "strpbrk") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "strtok" ||
Name == "strtok_r") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "scanf" ||
Name == "setbuf" ||
Name == "setvbuf") {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "strdup" ||
Name == "strndup") {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
} else if (Name == "stat" ||
Name == "sscanf" ||
Name == "sprintf" ||
Name == "statvfs") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "snprintf") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(2)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 3);
} else if (Name == "setitimer") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(1)) ||
!isa<PointerType>(FTy->getParamType(2)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
setDoesNotCapture(F, 3);
} else if (Name == "system") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
// May throw; "system" is a valid pthread cancellation point.
setDoesNotCapture(F, 1);
}
break;
case 'm':
if (Name == "malloc") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
} else if (Name == "memcmp") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "memchr" ||
Name == "memrchr") {
if (FTy->getNumParams() != 3)
continue;
setOnlyReadsMemory(F);
setDoesNotThrow(F);
} else if (Name == "modf" ||
Name == "modff" ||
Name == "modfl" ||
Name == "memcpy" ||
Name == "memccpy" ||
Name == "memmove") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "memalign") {
if (!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotAlias(F, 0);
} else if (Name == "mkdir" ||
Name == "mktime") {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'r':
if (Name == "realloc") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
} else if (Name == "read") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
// May throw; "read" is a valid pthread cancellation point.
setDoesNotCapture(F, 2);
} else if (Name == "rmdir" ||
Name == "rewind" ||
Name == "remove" ||
Name == "realpath") {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "rename" ||
Name == "readlink") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
}
break;
case 'w':
if (Name == "write") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
// May throw; "write" is a valid pthread cancellation point.
setDoesNotCapture(F, 2);
}
break;
case 'b':
if (Name == "bcopy") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "bcmp") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setOnlyReadsMemory(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "bzero") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'c':
if (Name == "calloc") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
} else if (Name == "chmod" ||
Name == "chown" ||
Name == "ctermid" ||
Name == "clearerr" ||
Name == "closedir") {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'a':
if (Name == "atoi" ||
Name == "atol" ||
Name == "atof" ||
Name == "atoll") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setOnlyReadsMemory(F);
setDoesNotCapture(F, 1);
} else if (Name == "access") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'f':
if (Name == "fopen") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "fdopen") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 2);
} else if (Name == "feof" ||
Name == "free" ||
Name == "fseek" ||
Name == "ftell" ||
Name == "fgetc" ||
Name == "fseeko" ||
Name == "ftello" ||
Name == "fileno" ||
Name == "fflush" ||
Name == "fclose" ||
Name == "fsetpos" ||
Name == "flockfile" ||
Name == "funlockfile" ||
Name == "ftrylockfile") {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "ferror") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setOnlyReadsMemory(F);
} else if (Name == "fputc" ||
Name == "fstat" ||
Name == "frexp" ||
Name == "frexpf" ||
Name == "frexpl" ||
Name == "fstatvfs") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "fgets") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(2)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 3);
} else if (Name == "fread" ||
Name == "fwrite") {
if (FTy->getNumParams() != 4 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(3)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 4);
} else if (Name == "fputs" ||
Name == "fscanf" ||
Name == "fprintf" ||
Name == "fgetpos") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
}
break;
case 'g':
if (Name == "getc" ||
Name == "getlogin_r" ||
Name == "getc_unlocked") {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "getenv") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setOnlyReadsMemory(F);
setDoesNotCapture(F, 1);
} else if (Name == "gets" ||
Name == "getchar") {
setDoesNotThrow(F);
} else if (Name == "getitimer") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "getpwnam") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'u':
if (Name == "ungetc") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "uname" ||
Name == "unlink" ||
Name == "unsetenv") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "utime" ||
Name == "utimes") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
}
break;
case 'p':
if (Name == "putc") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "puts" ||
Name == "printf" ||
Name == "perror") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "pread" ||
Name == "pwrite") {
if (FTy->getNumParams() != 4 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
// May throw; these are valid pthread cancellation points.
setDoesNotCapture(F, 2);
} else if (Name == "putchar") {
setDoesNotThrow(F);
} else if (Name == "popen") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "pclose") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'v':
if (Name == "vscanf") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "vsscanf" ||
Name == "vfscanf") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(1)) ||
!isa<PointerType>(FTy->getParamType(2)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "valloc") {
if (!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
} else if (Name == "vprintf") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "vfprintf" ||
Name == "vsprintf") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "vsnprintf") {
if (FTy->getNumParams() != 4 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(2)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 3);
}
break;
case 'o':
if (Name == "open") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
// May throw; "open" is a valid pthread cancellation point.
setDoesNotCapture(F, 1);
} else if (Name == "opendir") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
}
break;
case 't':
if (Name == "tmpfile") {
if (!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
} else if (Name == "times") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'h':
if (Name == "htonl" ||
Name == "htons") {
setDoesNotThrow(F);
setDoesNotAccessMemory(F);
}
break;
case 'n':
if (Name == "ntohl" ||
Name == "ntohs") {
setDoesNotThrow(F);
setDoesNotAccessMemory(F);
}
break;
case 'l':
if (Name == "lstat") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "lchown") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
}
break;
case 'q':
if (Name == "qsort") {
if (FTy->getNumParams() != 4 ||
!isa<PointerType>(FTy->getParamType(3)))
continue;
// May throw; places call through function pointer.
setDoesNotCapture(F, 4);
}
break;
case '_':
if (Name == "__strdup" ||
Name == "__strndup") {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
} else if (Name == "__strtok_r") {
if (FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "_IO_getc") {
if (FTy->getNumParams() != 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "_IO_putc") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
}
break;
case 1:
if (Name == "\1__isoc99_scanf") {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "\1stat64" ||
Name == "\1lstat64" ||
Name == "\1statvfs64" ||
Name == "\1__isoc99_sscanf") {
if (FTy->getNumParams() < 1 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "\1fopen64") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getReturnType()) ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
setDoesNotCapture(F, 1);
setDoesNotCapture(F, 2);
} else if (Name == "\1fseeko64" ||
Name == "\1ftello64") {
if (FTy->getNumParams() == 0 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 1);
} else if (Name == "\1tmpfile64") {
if (!isa<PointerType>(FTy->getReturnType()))
continue;
setDoesNotThrow(F);
setDoesNotAlias(F, 0);
} else if (Name == "\1fstat64" ||
Name == "\1fstatvfs64") {
if (FTy->getNumParams() != 2 ||
!isa<PointerType>(FTy->getParamType(1)))
continue;
setDoesNotThrow(F);
setDoesNotCapture(F, 2);
} else if (Name == "\1open64") {
if (FTy->getNumParams() < 2 ||
!isa<PointerType>(FTy->getParamType(0)))
continue;
// May throw; "open" is a valid pthread cancellation point.
setDoesNotCapture(F, 1);
}
break;
}
}
return Modified;
}
// TODO:
// Additional cases that we need to add to this file:
//
// cbrt:
// * cbrt(expN(X)) -> expN(x/3)
// * cbrt(sqrt(x)) -> pow(x,1/6)
// * cbrt(sqrt(x)) -> pow(x,1/9)
//
// cos, cosf, cosl:
// * cos(-x) -> cos(x)
//
// exp, expf, expl:
// * exp(log(x)) -> x
//
// log, logf, logl:
// * log(exp(x)) -> x
// * log(x**y) -> y*log(x)
// * log(exp(y)) -> y*log(e)
// * log(exp2(y)) -> y*log(2)
// * log(exp10(y)) -> y*log(10)
// * log(sqrt(x)) -> 0.5*log(x)
// * log(pow(x,y)) -> y*log(x)
//
// lround, lroundf, lroundl:
// * lround(cnst) -> cnst'
//
// pow, powf, powl:
// * pow(exp(x),y) -> exp(x*y)
// * pow(sqrt(x),y) -> pow(x,y*0.5)
// * pow(pow(x,y),z)-> pow(x,y*z)
//
// puts:
// * puts("") -> putchar("\n")
//
// round, roundf, roundl:
// * round(cnst) -> cnst'
//
// signbit:
// * signbit(cnst) -> cnst'
// * signbit(nncst) -> 0 (if pstv is a non-negative constant)
//
// sqrt, sqrtf, sqrtl:
// * sqrt(expN(x)) -> expN(x*0.5)
// * sqrt(Nroot(x)) -> pow(x,1/(2*N))
// * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
//
// stpcpy:
// * stpcpy(str, "literal") ->
// llvm.memcpy(str,"literal",strlen("literal")+1,1)
// strrchr:
// * strrchr(s,c) -> reverse_offset_of_in(c,s)
// (if c is a constant integer and s is a constant string)
// * strrchr(s1,0) -> strchr(s1,0)
//
// strpbrk:
// * strpbrk(s,a) -> offset_in_for(s,a)
// (if s and a are both constant strings)
// * strpbrk(s,"") -> 0
// * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
//
// strspn, strcspn:
// * strspn(s,a) -> const_int (if both args are constant)
// * strspn("",a) -> 0
// * strspn(s,"") -> 0
// * strcspn(s,a) -> const_int (if both args are constant)
// * strcspn("",a) -> 0
// * strcspn(s,"") -> strlen(a)
//
// strstr:
// * strstr(x,x) -> x
// * strstr(s1,s2) -> offset_of_s2_in(s1)
// (if s1 and s2 are constant strings)
//
// tan, tanf, tanl:
// * tan(atan(x)) -> x
//
// trunc, truncf, truncl:
// * trunc(cnst) -> cnst'
//
//
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