instcombine: Migrate strcat and strncat optimizations
This patch migrates the strcat and strncat optimizations from the
simplify-libcalls pass into the instcombine library call simplifier.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165874 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 73f53b7..22a01fc 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -133,105 +133,7 @@
// 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.
- FunctionType *FT = Callee->getFunctionType();
- if (FT->getNumParams() != 2 ||
- FT->getReturnType() != B.getInt8PtrTy() ||
- FT->getParamType(0) != FT->getReturnType() ||
- FT->getParamType(1) != FT->getReturnType())
- return 0;
-
- // Extract some information from the instruction
- Value *Dst = CI->getArgOperand(0);
- Value *Src = CI->getArgOperand(1);
-
- // 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 DataLayout.
- if (!TD) return 0;
-
- return EmitStrLenMemCpy(Src, Dst, Len, B);
- }
-
- Value *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, TD, TLI);
- if (!DstLen)
- return 0;
-
- // 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.
- B.CreateMemCpy(CpyDst, Src,
- ConstantInt::get(TD->getIntPtrType(*Context), Len + 1), 1);
- return Dst;
- }
-};
-
-//===---------------------------------------===//
-// 'strncat' Optimizations
-
-struct StrNCatOpt : public StrCatOpt {
- virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
- // Verify the "strncat" function prototype.
- FunctionType *FT = Callee->getFunctionType();
- if (FT->getNumParams() != 3 ||
- FT->getReturnType() != B.getInt8PtrTy() ||
- FT->getParamType(0) != FT->getReturnType() ||
- FT->getParamType(1) != FT->getReturnType() ||
- !FT->getParamType(2)->isIntegerTy())
- return 0;
-
- // Extract some information from the instruction
- Value *Dst = CI->getArgOperand(0);
- Value *Src = CI->getArgOperand(1);
- uint64_t Len;
-
- // We don't do anything if length is not constant
- if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getArgOperand(2)))
- 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 DataLayout.
- 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
- return EmitStrLenMemCpy(Src, Dst, SrcLen, B);
- }
-};
-
//===---------------------------------------===//
// 'strchr' Optimizations
@@ -1564,7 +1466,7 @@
StringMap<LibCallOptimization*> Optimizations;
// String and Memory LibCall Optimizations
- StrCatOpt StrCat; StrNCatOpt StrNCat; StrChrOpt StrChr; StrRChrOpt StrRChr;
+ StrChrOpt StrChr; StrRChrOpt StrRChr;
StrCmpOpt StrCmp; StrNCmpOpt StrNCmp;
StrCpyOpt StrCpy; StrCpyOpt StrCpyChk;
StpCpyOpt StpCpy; StpCpyOpt StpCpyChk;
@@ -1639,8 +1541,6 @@
/// we know.
void SimplifyLibCalls::InitOptimizations() {
// String and Memory LibCall Optimizations
- Optimizations["strcat"] = &StrCat;
- Optimizations["strncat"] = &StrNCat;
Optimizations["strchr"] = &StrChr;
Optimizations["strrchr"] = &StrRChr;
Optimizations["strcmp"] = &StrCmp;