diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 53 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll | 1 |
2 files changed, 29 insertions, 25 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 118f412d4a..649dd46c81 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -7673,41 +7673,21 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { unsigned Size = MemOpLength->getZExtValue(); unsigned Align = cast<ConstantInt>(CI.getOperand(4))->getZExtValue(); PointerType *NewPtrTy = NULL; - unsigned numBits = Size << 3; // Destination pointer type is always i8 * // If Size is 8 then use Int64Ty // If Size is 4 then use Int32Ty // If Size is 2 then use Int16Ty // If Size is 1 then use Int8Ty if (Size && Size <=8 && !(Size&(Size-1))) - NewPtrTy = PointerType::get(IntegerType::get(numBits)); + NewPtrTy = PointerType::get(IntegerType::get(Size<<3)); if (NewPtrTy) { - Value *L = NULL; - // If source is a null terminated constant c string then try to use immediate store. - if (Constant *C = dyn_cast<Constant>(CI.getOperand(2))) { - const std::string &Str = C->getStringValue(); - if (!Str.empty()) { - APInt StrVal(numBits, 0); - unsigned len = Str.length(); - APInt SingleChar(numBits, 0); - for (unsigned i = 0; i < len; i++) { - SingleChar = (uint64_t) Str[i]; - StrVal = (StrVal << 8) | SingleChar; - } - // Append NULL at the end. - SingleChar = 0; - StrVal = (StrVal << 8) | SingleChar; - L = ConstantInt::get(StrVal); - } - } - // Otherwise load source from memory. - if (L == NULL) { - Value *Src = InsertCastBefore(Instruction::BitCast, CI.getOperand(2), NewPtrTy, CI); - L = new LoadInst(Src, "tmp", false, Align, &CI); - } + Value *Src = InsertCastBefore(Instruction::BitCast, CI.getOperand(2), NewPtrTy, CI); Value *Dest = InsertCastBefore(Instruction::BitCast, CI.getOperand(1), NewPtrTy, CI); + Value *L = new LoadInst(Src, "tmp", false, Align, &CI); Value *NS = new StoreInst(L, Dest, false, Align, &CI); + AddToWorkList(cast<Instruction>(L)); + AddToWorkList(cast<Instruction>(NS)); CI.replaceAllUsesWith(NS); Changed = true; return EraseInstFromFunction(CI); @@ -9136,6 +9116,29 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { } } else if (CE->isCast()) { + // Instead of loading constant c string, use corresponding integer value + // directly if string length is small enough. + const std::string &Str = CE->getOperand(0)->getStringValue(); + if (!Str.empty()) { + unsigned len = Str.length(); + const Type *Ty = cast<PointerType>(CE->getType())->getElementType(); + unsigned numBits = Ty->getPrimitiveSizeInBits(); + if ((numBits >> 3) == len + 1) { + // Replace LI with immediate integer store. + APInt StrVal(numBits, 0); + APInt SingleChar(numBits, 0); + for (unsigned i = 0; i < len; i++) { + SingleChar = (uint64_t) Str[i]; + StrVal = (StrVal << 8) | SingleChar; + } + // Append NULL at the end. + SingleChar = 0; + StrVal = (StrVal << 8) | SingleChar; + Value *NL = ConstantInt::get(StrVal); + return ReplaceInstUsesWith(LI, NL); + } + } + if (Instruction *Res = InstCombineLoadCast(*this, LI)) return Res; } diff --git a/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll b/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll index 5cc6e3bc58..22765243bd 100644 --- a/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll +++ b/test/Transforms/InstCombine/2007-10-10-EliminateMemCpy.ll @@ -1,4 +1,5 @@ ; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep call +; RUN: llvm-as < %s | opt -std-compile-opts | llvm-dis | not grep xyz @.str = internal constant [4 x i8] c"xyz\00" ; <[4 x i8]*> [#uses=1] define void @foo(i8* %P) { |