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add some optimizations for strncpy/strncat and factor some

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code.  Patch by Benjamin Kramer!

llvm-svn: 68885
This commit is contained in:
Chris Lattner 2009-04-12 05:06:39 +00:00
parent ac11c8d30f
commit f03202e76d
3 changed files with 166 additions and 22 deletions
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136
lib/Transforms/Scalar/SimplifyLibCalls.cpp
View File

@ -85,6 +85,9 @@ public:
/// 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'
@ -183,6 +186,18 @@ Value *LibCallOptimization::EmitMemCmp(Value *Ptr1, Value *Ptr2,
Len, "memcmp");
}
/// 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::Int32Ty, 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
@ -507,6 +522,11 @@ struct VISIBILITY_HIDDEN StrCatOpt : public LibCallOptimization {
if (Len == 0)
return Dst;
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);
@ -519,6 +539,50 @@ struct VISIBILITY_HIDDEN StrCatOpt : public LibCallOptimization {
// 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(), Len+1), 1, B);
}
};
//===---------------------------------------===//
// 'strncat' Optimizations
struct VISIBILITY_HIDDEN 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() != PointerType::getUnqual(Type::Int8Ty) ||
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;
// 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, Len, B);
return Dst;
}
};
@ -694,7 +758,50 @@ struct VISIBILITY_HIDDEN StrCpyOpt : public LibCallOptimization {
}
};
//===---------------------------------------===//
// 'strncpy' Optimizations
struct VISIBILITY_HIDDEN 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) != PointerType::getUnqual(Type::Int8Ty) ||
!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::Int8Ty, '\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
// 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(), Len), 1, B);
return Dst;
}
};
//===---------------------------------------===//
// 'strlen' Optimizations
@ -849,16 +956,8 @@ struct VISIBILITY_HIDDEN MemSetOpt : public LibCallOptimization {
return 0;
// memset(p, v, n) -> llvm.memset(p, v, n, 1)
Module *M = Caller->getParent();
Intrinsic::ID IID = Intrinsic::memset;
const Type *Tys[1];
Tys[0] = TD->getIntPtrType();
Value *MemSet = Intrinsic::getDeclaration(M, IID, Tys, 1);
Value *Dst = CastToCStr(CI->getOperand(1), B);
Value *Val = B.CreateTrunc(CI->getOperand(2), Type::Int8Ty);
Value *Size = CI->getOperand(3);
Value *Align = ConstantInt::get(Type::Int32Ty, 1);
B.CreateCall4(MemSet, Dst, Val, Size, Align);
EmitMemSet(CI->getOperand(1), Val, CI->getOperand(3), B);
return CI->getOperand(1);
}
};
@ -1351,9 +1450,10 @@ namespace {
// Miscellaneous LibCall Optimizations
ExitOpt Exit;
// String and Memory LibCall Optimizations
StrCatOpt StrCat; StrChrOpt StrChr; StrCmpOpt StrCmp; StrNCmpOpt StrNCmp;
StrCpyOpt StrCpy; StrLenOpt StrLen; StrToOpt StrTo; MemCmpOpt MemCmp;
MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
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
@ -1401,10 +1501,12 @@ 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;
@ -2299,16 +2401,6 @@ bool SimplifyLibCalls::doInitialization(Module &M) {
// (if c is a constant integer and s is a constant string)
// * strrchr(s1,0) -> strchr(s1,0)
//
// strncat:
// * strncat(x,y,0) -> x
// * strncat(x,y,0) -> x (if strlen(y) = 0)
// * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
//
// strncpy:
// * strncpy(d,s,0) -> d
// * strncpy(d,s,l) -> memcpy(d,s,l,1)
// (if s and l are constants)
//
// strpbrk:
// * strpbrk(s,a) -> offset_in_for(s,a)
// (if s and a are both constant strings)

27
test/Transforms/SimplifyLibCalls/StrNCat.ll Normal file
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@ -0,0 +1,27 @@
; Test that the StrNCatOptimizer works correctly
; RUN: llvm-as < %s | opt -simplify-libcalls | llvm-dis | \
; RUN: not grep {call.*strncat}
; RUN: llvm-as < %s | opt -simplify-libcalls | llvm-dis | \
; RUN: grep {puts.*%arg1}
@hello = constant [6 x i8] c"hello\00" ; <[6 x i8]*> [#uses=1]
@null = constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
@null_hello = constant [7 x i8] c"\00hello\00" ; <[7 x i8]*> [#uses=1]
declare i8* @strncat(i8*, i8*, i32)
declare i32 @puts(i8*)
define i32 @main() {
%target = alloca [1024 x i8] ; <[1024 x i8]*> [#uses=1]
%arg1 = getelementptr [1024 x i8]* %target, i32 0, i32 0 ; <i8*> [#uses=2]
store i8 0, i8* %arg1
%arg2 = getelementptr [6 x i8]* @hello, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt1 = call i8* @strncat( i8* %arg1, i8* %arg2, i32 6 ) ; <i8*> [#uses=1]
%arg3 = getelementptr [1 x i8]* @null, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt2 = call i8* @strncat( i8* %rslt1, i8* %arg3, i32 42 ) ; <i8*> [#uses=1]
%arg4 = getelementptr [7 x i8]* @null_hello, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt3 = call i8* @strncat( i8* %rslt2, i8* %arg4, i32 42 ) ; <i8*> [#uses=1]
call i32 @puts( i8* %rslt3 ) ; <i32>:1 [#uses=0]
ret i32 0
}

25
test/Transforms/SimplifyLibCalls/StrNCpy.ll Normal file
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@ -0,0 +1,25 @@
; Test that the StrNCpyOptimizer works correctly
; RUN: llvm-as < %s | opt -simplify-libcalls | llvm-dis | \
; RUN: not grep {call.*strncpy}
@hello = constant [6 x i8] c"hello\00" ; <[6 x i8]*> [#uses=1]
@null = constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
@null_hello = constant [7 x i8] c"\00hello\00" ; <[7 x i8]*> [#uses=1]
declare i8* @strncpy(i8*, i8*, i32)
declare i32 @puts(i8*)
define i32 @main() {
%target = alloca [1024 x i8] ; <[1024 x i8]*> [#uses=1]
%arg1 = getelementptr [1024 x i8]* %target, i32 0, i32 0 ; <i8*> [#uses=2]
store i8 0, i8* %arg1
%arg2 = getelementptr [6 x i8]* @hello, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt1 = call i8* @strncpy( i8* %arg1, i8* %arg2, i32 6 ) ; <i8*> [#uses=1]
%arg3 = getelementptr [1 x i8]* @null, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt2 = call i8* @strncpy( i8* %rslt1, i8* %arg3, i32 42 ) ; <i8*> [#uses=1]
%arg4 = getelementptr [7 x i8]* @null_hello, i32 0, i32 0 ; <i8*> [#uses=1]
%rslt3 = call i8* @strncpy( i8* %rslt2, i8* %arg4, i32 42 ) ; <i8*> [#uses=1]
call i32 @puts( i8* %rslt3 ) ; <i32>:1 [#uses=0]
ret i32 0
}