instcombine: Migrate stpcpy optimizations
This patch migrates the stpcpy optimizations from the simplify-libcalls
pass into the instcombine library call simplifier. Note that the
__stpcpy_chk simplifications were migrated in a previous commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167083 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 5984a96..bc36001 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -592,6 +592,42 @@
}
};
+struct StpCpyOpt: public LibCallOptimization {
+ virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+ // Verify the "stpcpy" function prototype.
+ FunctionType *FT = Callee->getFunctionType();
+ if (FT->getNumParams() != 2 ||
+ FT->getReturnType() != FT->getParamType(0) ||
+ FT->getParamType(0) != FT->getParamType(1) ||
+ FT->getParamType(0) != B.getInt8PtrTy())
+ return 0;
+
+ // These optimizations require DataLayout.
+ if (!TD) return 0;
+
+ Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
+ if (Dst == Src) { // stpcpy(x,x) -> x+strlen(x)
+ Value *StrLen = EmitStrLen(Src, B, TD, TLI);
+ return StrLen ? B.CreateInBoundsGEP(Dst, StrLen) : 0;
+ }
+
+ // See if we can get the length of the input string.
+ uint64_t Len = GetStringLength(Src);
+ if (Len == 0) return 0;
+
+ Type *PT = FT->getParamType(0);
+ Value *LenV = ConstantInt::get(TD->getIntPtrType(PT), Len);
+ Value *DstEnd = B.CreateGEP(Dst,
+ ConstantInt::get(TD->getIntPtrType(PT),
+ Len - 1));
+
+ // We have enough information to now generate the memcpy call to do the
+ // copy for us. Make a memcpy to copy the nul byte with align = 1.
+ B.CreateMemCpy(Dst, Src, LenV, 1);
+ return DstEnd;
+ }
+};
+
} // End anonymous namespace.
namespace llvm {
@@ -617,6 +653,7 @@
StrCmpOpt StrCmp;
StrNCmpOpt StrNCmp;
StrCpyOpt StrCpy;
+ StpCpyOpt StpCpy;
void initOptimizations();
public:
@@ -646,6 +683,7 @@
Optimizations["strcmp"] = &StrCmp;
Optimizations["strncmp"] = &StrNCmp;
Optimizations["strcpy"] = &StrCpy;
+ Optimizations["stpcpy"] = &StpCpy;
}
Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {