[PATCH] D23354: [asan] Support dynamic shadow address instrumentation

[Anna Zaks via llvm-commits]

zaks.anna added a comment.

When testing with this patch on the Mac, I ran into a problem using -asan-force-dynamic-shadow. Specifically, Mapping.OrShadowOffset was not inferred correctly because it relies on checking kDynamicShadowSentinel and not the ClForceDynamicShadow. How about using ClForceDynamicShadow when setting the Mapping.Offset and gating the maybeInsertDynamicShadowAtFunctionEntry solely on the value of the Mapping.Offset?

  @@ -434,13 +434,19 @@ static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
  ...
       else
         Mapping.Offset = kDefaultShadowOffset64;
     }
   
  +  if (ClForceDynamicShadow) {
  +    Mapping.Offset = kDynamicShadowSentinel;
  +  }
  +
     Mapping.Scale = kDefaultShadowScale;
     if (ClMappingScale.getNumOccurrences() > 0) {
       Mapping.Scale = ClMappingScale;
  @@ -1802,7 +1808,7 @@ bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
   
   void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
     // Generate code only when dynamic addressing is needed.
  -  if (!ClForceDynamicShadow && Mapping.Offset != kDynamicShadowSentinel)
  +  if (Mapping.Offset != kDynamicShadowSentinel)
       return;
   
     IRBuilder<> IRB(&F.front().front());

If you'd like, I can commit this as a separate patch.


https://reviews.llvm.org/D23354