instcombine: Migrate strspn optimizations
This patch migrates the strspn optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167568 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 581b8d3..64c7011 100644
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -772,6 +772,35 @@
}
};
+struct StrSpnOpt : public LibCallOptimization {
+ virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+ FunctionType *FT = Callee->getFunctionType();
+ if (FT->getNumParams() != 2 ||
+ FT->getParamType(0) != B.getInt8PtrTy() ||
+ FT->getParamType(1) != FT->getParamType(0) ||
+ !FT->getReturnType()->isIntegerTy())
+ return 0;
+
+ StringRef S1, S2;
+ bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1);
+ bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2);
+
+ // strspn(s, "") -> 0
+ // strspn("", s) -> 0
+ if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
+ return Constant::getNullValue(CI->getType());
+
+ // Constant folding.
+ if (HasS1 && HasS2) {
+ size_t Pos = S1.find_first_not_of(S2);
+ if (Pos == StringRef::npos) Pos = S1.size();
+ return ConstantInt::get(CI->getType(), Pos);
+ }
+
+ return 0;
+ }
+};
+
} // End anonymous namespace.
namespace llvm {
@@ -802,6 +831,7 @@
StrLenOpt StrLen;
StrPBrkOpt StrPBrk;
StrToOpt StrTo;
+ StrSpnOpt StrSpn;
void initOptimizations();
public:
@@ -842,6 +872,7 @@
Optimizations["strtoll"] = &StrTo;
Optimizations["strtold"] = &StrTo;
Optimizations["strtoull"] = &StrTo;
+ Optimizations["strspn"] = &StrSpn;
}
Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {