[PATCH] D50966: Fix an undefined behavior when storing an empty StringRef.

[Haojian Wu via Phabricator via cfe-commits]

hokein created this revision.
hokein added a reviewer: ioeric.
Herald added a subscriber: llvm-commits.

Passing a nullptr to memcpy is UB.


Repository:
  rL LLVM

https://reviews.llvm.org/D50966

Files:
  lib/Support/StringSaver.cpp


Index: lib/Support/StringSaver.cpp
===================================================================
--- lib/Support/StringSaver.cpp
+++ lib/Support/StringSaver.cpp
@@ -12,6 +12,8 @@
 using namespace llvm;
 
 StringRef StringSaver::save(StringRef S) {
+  if (S.empty())
+    return StringRef();
   char *P = Alloc.Allocate<char>(S.size() + 1);
   memcpy(P, S.data(), S.size());
   P[S.size()] = '\0';



Index: lib/Support/StringSaver.cpp
===================================================================
--- lib/Support/StringSaver.cpp
+++ lib/Support/StringSaver.cpp
@@ -12,6 +12,8 @@
 using namespace llvm;
 
 StringRef StringSaver::save(StringRef S) {
+  if (S.empty())
+    return StringRef();
   char *P = Alloc.Allocate<char>(S.size() + 1);
   memcpy(P, S.data(), S.size());
   P[S.size()] = '\0';

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