r334417 - [MS] Use mangled names and comdats for string merging with ASan

[Reid Kleckner via cfe-commits]

Author: rnk
Date: Mon Jun 11 09:49:43 2018
New Revision: 334417

URL: http://llvm.org/viewvc/llvm-project?rev=334417&view=rev
Log:
[MS] Use mangled names and comdats for string merging with ASan

This should reduce the binary size penalty of ASan on Windows. After
r334313, ASan will add red zones to globals in comdats, so we will still
find OOB accesses to string literals.

Modified:
    cfe/trunk/lib/CodeGen/CodeGenModule.cpp

Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=334417&r1=334416&r2=334417&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Mon Jun 11 09:49:43 2018
@@ -4114,15 +4114,13 @@ CodeGenModule::GetAddrOfConstantStringFr
   StringRef GlobalVariableName;
   llvm::GlobalValue::LinkageTypes LT;
 
-  // Mangle the string literal if the ABI allows for it.  However, we cannot
-  // do this if  we are compiling with ASan or -fwritable-strings because they
-  // rely on strings having normal linkage.
-  if (!LangOpts.WritableStrings &&
-      !LangOpts.Sanitize.has(SanitizerKind::Address) &&
-      getCXXABI().getMangleContext().shouldMangleStringLiteral(S)) {
+  // Mangle the string literal if that's how the ABI merges duplicate strings.
+  // Don't do it if they are writable, since we don't want writes in one TU to
+  // affect strings in another.
+  if (getCXXABI().getMangleContext().shouldMangleStringLiteral(S) &&
+      !LangOpts.WritableStrings) {
     llvm::raw_svector_ostream Out(MangledNameBuffer);
     getCXXABI().getMangleContext().mangleStringLiteral(S, Out);
-
     LT = llvm::GlobalValue::LinkOnceODRLinkage;
     GlobalVariableName = MangledNameBuffer;
   } else {