Check result of emitStrLen before passing it to CreateGEP
Summary:
This fixes PR43081, where the transformation of `strchr(p, 0) -> p +
strlen(p)` can cause a segfault, if `-fno-builtin-strlen` is used. In
that case, `emitStrLen` returns nullptr, which CreateGEP is not designed
to handle. Also add the minimized code from the PR as a test case.
Reviewers: xbolva00, spatel, jdoerfert, efriedma
Reviewed By: efriedma
Subscribers: lebedev.ri, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D70143
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 0324993..18a1711 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -364,8 +364,8 @@
StringRef Str;
if (!getConstantStringInfo(SrcStr, Str)) {
if (CharC->isZero()) // strchr(p, 0) -> p + strlen(p)
- return B.CreateGEP(B.getInt8Ty(), SrcStr, emitStrLen(SrcStr, B, DL, TLI),
- "strchr");
+ if (Value *StrLen = emitStrLen(SrcStr, B, DL, TLI))
+ return B.CreateGEP(B.getInt8Ty(), SrcStr, StrLen, "strchr");
return nullptr;
}