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optimize strstr, PR5783

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llvm-svn: 91438
This commit is contained in:
Chris Lattner 2009-12-15 19:14:40 +00:00
parent 8ef481b5d7
commit fa960751b1
2 changed files with 123 additions and 9 deletions
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84
lib/Transforms/Scalar/SimplifyLibCalls.cpp
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@ -76,6 +76,11 @@ public:
/// return value has 'intptr_t' type.
Value *EmitStrLen(Value *Ptr, IRBuilder<> &B);
/// EmitStrChr - Emit a call to the strchr function to the builder, for the
/// specified pointer and character. Ptr is required to be some pointer type,
/// and the return value has 'i8*' type.
Value *EmitStrChr(Value *Ptr, char C, 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,
@ -151,6 +156,26 @@ Value *LibCallOptimization::EmitStrLen(Value *Ptr, IRBuilder<> &B) {
return CI;
}
/// EmitStrChr - Emit a call to the strchr function to the builder, for the
/// specified pointer and character. Ptr is required to be some pointer type,
/// and the return value has 'i8*' type.
Value *LibCallOptimization::EmitStrChr(Value *Ptr, char C, IRBuilder<> &B) {
Module *M = Caller->getParent();
AttributeWithIndex AWI =
AttributeWithIndex::get(~0u, Attribute::ReadOnly | Attribute::NoUnwind);
const Type *I8Ptr = Type::getInt8PtrTy(*Context);
const Type *I32Ty = Type::getInt32Ty(*Context);
Constant *StrChr = M->getOrInsertFunction("strchr", AttrListPtr::get(&AWI, 1),
I8Ptr, I8Ptr, I32Ty, NULL);
CallInst *CI = B.CreateCall2(StrChr, CastToCStr(Ptr, B),
ConstantInt::get(I32Ty, C), "strchr");
if (const Function *F = dyn_cast<Function>(StrChr->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,
@ -890,7 +915,7 @@ struct StrLenOpt : public LibCallOptimization {
};
//===---------------------------------------===//
// 'strto*' Optimizations
// 'strto*' Optimizations. This handles strtol, strtod, strtof, strtoul, etc.
struct StrToOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
@ -910,6 +935,52 @@ struct StrToOpt : public LibCallOptimization {
}
};
//===---------------------------------------===//
// 'strstr' Optimizations
struct StrStrOpt : public LibCallOptimization {
virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
const FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 2 ||
!isa<PointerType>(FT->getParamType(0)) ||
!isa<PointerType>(FT->getParamType(1)) ||
!isa<PointerType>(FT->getReturnType()))
return 0;
// fold strstr(x, x) -> x.
if (CI->getOperand(1) == CI->getOperand(2))
return CI->getOperand(1);
// See if either input string is a constant string.
std::string SearchStr, ToFindStr;
bool HasStr1 = GetConstantStringInfo(CI->getOperand(1), SearchStr);
bool HasStr2 = GetConstantStringInfo(CI->getOperand(2), ToFindStr);
// fold strstr(x, "") -> x.
if (HasStr2 && ToFindStr.empty())
return B.CreateBitCast(CI->getOperand(1), CI->getType());
// If both strings are known, constant fold it.
if (HasStr1 && HasStr2) {
std::string::size_type Offset = SearchStr.find(ToFindStr);
if (Offset == std::string::npos) // strstr("foo", "bar") -> null
return Constant::getNullValue(CI->getType());
// strstr("abcd", "bc") -> gep((char*)"abcd", 2)
Value *Result = CastToCStr(CI->getOperand(1), B);
Result = B.CreateConstInBoundsGEP1_64(Result, Offset, "strstr");
return B.CreateBitCast(Result, CI->getType());
}
// fold strstr(x, "y") -> strchr(x, 'y').
if (HasStr2 && ToFindStr.size() == 1)
return B.CreateBitCast(EmitStrChr(CI->getOperand(1), ToFindStr[0], B),
CI->getType());
return 0;
}
};
//===---------------------------------------===//
// 'memcmp' Optimizations
@ -1675,8 +1746,8 @@ namespace {
// 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;
StrToOpt StrTo; StrStrOpt StrStr;
MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
// Math Library Optimizations
PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
// Integer Optimizations
@ -1738,6 +1809,7 @@ void SimplifyLibCalls::InitOptimizations() {
Optimizations["strtoll"] = &StrTo;
Optimizations["strtold"] = &StrTo;
Optimizations["strtoull"] = &StrTo;
Optimizations["strstr"] = &StrStr;
Optimizations["memcmp"] = &MemCmp;
Optimizations["memcpy"] = &MemCpy;
Optimizations["memmove"] = &MemMove;
@ -2644,12 +2716,6 @@ bool SimplifyLibCalls::doInitialization(Module &M) {
// * strcspn("",a) -> 0
// * strcspn(s,"") -> strlen(a)
//
// strstr: (PR5783)
// * strstr(x,x) -> x
// * strstr(x, "") -> x
// * strstr(x, "a") -> strchr(x, 'a')
// * strstr(s1,s2) -> result (if s1 and s2 are constant strings)
//
// tan, tanf, tanl:
// * tan(atan(x)) -> x
//

48
test/Transforms/SimplifyLibCalls/StrStr.ll Normal file
View File

@ -0,0 +1,48 @@
; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
; PR5783
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
target triple = "i386-apple-darwin9.0"
@.str = private constant [1 x i8] zeroinitializer ; <[1 x i8]*> [#uses=1]
@.str1 = private constant [2 x i8] c"a\00" ; <[2 x i8]*> [#uses=1]
@.str2 = private constant [6 x i8] c"abcde\00" ; <[6 x i8]*> [#uses=1]
@.str3 = private constant [4 x i8] c"bcd\00" ; <[4 x i8]*> [#uses=1]
define i8* @test1(i8* %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([1 x i8]* @.str, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr(P, "") -> P
; CHECK: @test1
; CHECK: ret i8* %P
}
declare i8* @strstr(i8*, i8* nocapture) nounwind readonly
define i8* @test2(i8* %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* %P, i8* getelementptr inbounds ([2 x i8]* @.str1, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr(P, "a") -> strchr(P, 'a')
; CHECK: @test2
; CHECK: @strchr(i8* %P, i32 97)
}
define i8* @test3(i8* nocapture %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* getelementptr inbounds ([6 x i8]* @.str2, i32 0, i32 0), i8* getelementptr inbounds ([4 x i8]* @.str3, i32 0, i32 0)) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr("abcde", "bcd") -> "abcde"+1
; CHECK: @test3
; CHECK: getelementptr inbounds ([6 x i8]* @.str2, i32 0, i64 1)
}
define i8* @test4(i8* %P) nounwind readonly {
entry:
%call = tail call i8* @strstr(i8* %P, i8* %P) nounwind ; <i8*> [#uses=1]
ret i8* %call
; strstr(P, P) -> P
; CHECK: @test4
; CHECK: ret i8* %P
}