simplify-libcalls: fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106047 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/BuildLibCalls.cpp b/lib/Transforms/Utils/BuildLibCalls.cpp
index 059aeab..309a7bc5 100644
--- a/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -69,6 +69,31 @@
return CI;
}
+/// EmitStrNCmp - Emit a call to the strncmp function to the builder.
+Value *llvm::EmitStrNCmp(Value *Ptr1, Value *Ptr2, Value *Len,
+ IRBuilder<> &B, const TargetData *TD) {
+ Module *M = B.GetInsertBlock()->getParent()->getParent();
+ AttributeWithIndex AWI[3];
+ AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
+ AWI[1] = AttributeWithIndex::get(2, Attribute::NoCapture);
+ AWI[2] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
+ Attribute::NoUnwind);
+
+ LLVMContext &Context = B.GetInsertBlock()->getContext();
+ Value *StrNCmp = M->getOrInsertFunction("strncmp", AttrListPtr::get(AWI, 3),
+ B.getInt32Ty(),
+ B.getInt8PtrTy(),
+ B.getInt8PtrTy(),
+ TD->getIntPtrType(Context), NULL);
+ CallInst *CI = B.CreateCall3(StrNCmp, CastToCStr(Ptr1, B),
+ CastToCStr(Ptr2, B), Len, "strncmp");
+
+ if (const Function *F = dyn_cast<Function>(StrNCmp->stripPointerCasts()))
+ CI->setCallingConv(F->getCallingConv());
+
+ return CI;
+}
+
/// EmitStrCpy - Emit a call to the strcpy function to the builder, for the
/// specified pointer arguments.
Value *llvm::EmitStrCpy(Value *Dst, Value *Src, IRBuilder<> &B,