Changes in directory llvm/lib/Transforms/IPO:
SimplifyLibCalls.cpp updated: 1.96 -> 1.97 --- Log message: Fix several nasty bugs in the strchr optimizer, this fixes SimplifyLibCalls/2007-04-06-strchr-miscompile.ll and PR1307: http://llvm.org/PR1307 --- Diffs of the changes: (+53 -47) SimplifyLibCalls.cpp | 100 +++++++++++++++++++++++++++------------------------ 1 files changed, 53 insertions(+), 47 deletions(-) Index: llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp diff -u llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp:1.96 llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp:1.97 --- llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp:1.96 Fri Apr 6 17:59:33 2007 +++ llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp Fri Apr 6 18:38:55 2007 @@ -532,74 +532,80 @@ "Number of 'strchr' calls simplified") {} /// @brief Make sure that the "strchr" function has the right prototype - virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC){ - if (f->getReturnType() == PointerType::get(Type::Int8Ty) && - f->arg_size() == 2) - return true; - return false; + virtual bool ValidateCalledFunction(const Function *F, SimplifyLibCalls &SLC){ + const FunctionType *FT = F->getFunctionType(); + return FT->getNumParams() == 2 && + FT->getReturnType() == PointerType::get(Type::Int8Ty) && + FT->getParamType(0) == FT->getReturnType() && + isa<IntegerType>(FT->getParamType(1)); } /// @brief Perform the strchr optimizations - virtual bool OptimizeCall(CallInst *ci, SimplifyLibCalls &SLC) { - // If there aren't three operands, bail - if (ci->getNumOperands() != 3) - return false; - + virtual bool OptimizeCall(CallInst *CI, SimplifyLibCalls &SLC) { // Check that the first argument to strchr is a constant array of sbyte. // If it is, get the length and data, otherwise return false. - uint64_t len, StartIdx; - ConstantArray* CA = 0; - if (!GetConstantStringInfo(ci->getOperand(1), CA, len, StartIdx)) + uint64_t StrLength, StartIdx; + ConstantArray *CA = 0; + if (!GetConstantStringInfo(CI->getOperand(1), CA, StrLength, StartIdx)) return false; - // Check that the second argument to strchr is a constant int. If it isn't - // a constant integer, we can try an alternate optimization - ConstantInt* CSI = dyn_cast<ConstantInt>(ci->getOperand(2)); + // If the second operand is not constant, just lower this to memchr since we + // know the length of the input string. + ConstantInt *CSI = dyn_cast<ConstantInt>(CI->getOperand(2)); if (!CSI) { - // The second operand is not constant just lower this to - // memchr since we know the length of the string since it is constant. - Constant *f = SLC.get_memchr(); - Value* args[3] = { - ci->getOperand(1), - ci->getOperand(2), - ConstantInt::get(SLC.getIntPtrType(), len) + Value *Args[3] = { + CI->getOperand(1), + CI->getOperand(2), + ConstantInt::get(SLC.getIntPtrType(), StrLength+1) }; - ci->replaceAllUsesWith(new CallInst(f, args, 3, ci->getName(), ci)); - ci->eraseFromParent(); + CI->replaceAllUsesWith(new CallInst(SLC.get_memchr(), Args, 3, + CI->getName(), CI)); + CI->eraseFromParent(); return true; } // Get the character we're looking for - int64_t chr = CSI->getSExtValue(); + int64_t CharValue = CSI->getSExtValue(); + if (StrLength == 0) { + // If the length of the string is zero, and we are searching for zero, + // return the input pointer. + if (CharValue == 0) { + CI->replaceAllUsesWith(CI->getOperand(1)); + } else { + // Otherwise, char wasn't found. + CI->replaceAllUsesWith(Constant::getNullValue(CI->getType())); + } + CI->eraseFromParent(); + return true; + } + // Compute the offset - uint64_t offset = 0; - bool char_found = false; - for (uint64_t i = 0; i < len; ++i) { - if (ConstantInt* CI = dyn_cast<ConstantInt>(CA->getOperand(i))) { - // Check for the null terminator - if (CI->isZero()) - break; // we found end of string - else if (CI->getSExtValue() == chr) { - char_found = true; - offset = i; + uint64_t i = 0; + while (1) { + assert(i <= StrLength && "Didn't find null terminator?"); + if (ConstantInt *C = dyn_cast<ConstantInt>(CA->getOperand(i+StartIdx))) { + // Did we find our match? + if (C->getSExtValue() == CharValue) break; + if (C->isZero()) { + // We found the end of the string. strchr returns null. + CI->replaceAllUsesWith(Constant::getNullValue(CI->getType())); + CI->eraseFromParent(); + return true; } } + ++i; } - // strchr(s,c) -> offset_of_in(c,s) + // strchr(s+n,c) -> gep(s+n+i,c) // (if c is a constant integer and s is a constant string) - if (char_found) { - Value* Idx = ConstantInt::get(Type::Int64Ty,offset); - GetElementPtrInst* GEP = new GetElementPtrInst(ci->getOperand(1), Idx, - ci->getOperand(1)->getName()+".strchr",ci); - ci->replaceAllUsesWith(GEP); - } else { - ci->replaceAllUsesWith( - ConstantPointerNull::get(PointerType::get(Type::Int8Ty))); - } - ci->eraseFromParent(); + Value *Idx = ConstantInt::get(Type::Int64Ty, i); + Value *GEP = new GetElementPtrInst(CI->getOperand(1), Idx, + CI->getOperand(1)->getName() + + ".strchr", CI); + CI->replaceAllUsesWith(GEP); + CI->eraseFromParent(); return true; } } StrChrOptimizer; _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
