instcombine: Split out the __stpcpy_chk simplifications from StrCpyChkOpt
r166198 migrated the strcpy optimization to instcombine. The strcpy
simplifier that was migrated from Transforms/Scalar/SimplifyLibCalls.cpp
was also doing some __strcpy_chk simplifications. Those fortified
simplifications were migrated as well, but introduced a bug in the
__stpcpy_chk simplifier in the process. This happened because the
__strcpy_chk and __stpcpy_chk simplifiers were both mapped to StrCpyChkOpt
which was updated with simplifications that worked for __strcpy_chk, but
not __stpcpy_chk.
This patch fixes the problem by adding proper test coverage and creating a
new simplifier for __stpcpy_chk (instead of sharing one with __strcpy_chk).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167082 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 162b29e..5984a96 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -185,8 +185,8 @@
return Src;
// If a) we don't have any length information, or b) we know this will
- // fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our
- // st[rp]cpy_chk call which may fail at runtime if the size is too long.
+ // fit then just lower to a plain strcpy. Otherwise we'll keep our
+ // strcpy_chk call which may fail at runtime if the size is too long.
// TODO: It might be nice to get a maximum length out of the possible
// string lengths for varying.
if (isFoldable(2, 1, true)) {
@@ -210,6 +210,56 @@
}
};
+struct StpCpyChkOpt : public InstFortifiedLibCallOptimization {
+ virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+ this->CI = CI;
+ StringRef Name = Callee->getName();
+ FunctionType *FT = Callee->getFunctionType();
+ LLVMContext &Context = CI->getParent()->getContext();
+
+ // Check if this has the right signature.
+ if (FT->getNumParams() != 3 ||
+ FT->getReturnType() != FT->getParamType(0) ||
+ FT->getParamType(0) != FT->getParamType(1) ||
+ FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
+ FT->getParamType(2) != TD->getIntPtrType(FT->getParamType(0)))
+ 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;
+ }
+
+ // If a) we don't have any length information, or b) we know this will
+ // fit then just lower to a plain stpcpy. Otherwise we'll keep our
+ // stpcpy_chk call which may fail at runtime if the size is too long.
+ // TODO: It might be nice to get a maximum length out of the possible
+ // string lengths for varying.
+ if (isFoldable(2, 1, true)) {
+ Value *Ret = EmitStrCpy(Dst, Src, B, TD, TLI, Name.substr(2, 6));
+ return Ret;
+ } else {
+ // Maybe we can stil fold __stpcpy_chk to __memcpy_chk.
+ uint64_t Len = GetStringLength(Src);
+ if (Len == 0) return 0;
+
+ // This optimization require DataLayout.
+ if (!TD) 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));
+ if (!EmitMemCpyChk(Dst, Src, LenV, CI->getArgOperand(2), B, TD, TLI))
+ return 0;
+ return DstEnd;
+ }
+ return 0;
+ }
+};
+
struct StrNCpyChkOpt : public InstFortifiedLibCallOptimization {
virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
this->CI = CI;
@@ -556,6 +606,7 @@
MemMoveChkOpt MemMoveChk;
MemSetChkOpt MemSetChk;
StrCpyChkOpt StrCpyChk;
+ StpCpyChkOpt StpCpyChk;
StrNCpyChkOpt StrNCpyChk;
// String and memory library call optimizations.
@@ -583,7 +634,7 @@
Optimizations["__memmove_chk"] = &MemMoveChk;
Optimizations["__memset_chk"] = &MemSetChk;
Optimizations["__strcpy_chk"] = &StrCpyChk;
- Optimizations["__stpcpy_chk"] = &StrCpyChk;
+ Optimizations["__stpcpy_chk"] = &StpCpyChk;
Optimizations["__strncpy_chk"] = &StrNCpyChk;
Optimizations["__stpncpy_chk"] = &StrNCpyChk;