[asan] Don't skip instrumentation of masked load/store unless we've seen a full load/store on that pointer.

Reviewers: kcc, RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D27625

llvm-svn: 289718

1 files changed, 12 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 633df4f3b3a..acc13aaeaf4 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2066,11 +2066,20 @@ bool AddressSanitizer::runOnFunction(Function &F) {
     int NumInsnsPerBB = 0;
     for (auto &Inst : BB) {
       if (LooksLikeCodeInBug11395(&Inst)) return false;
+      Value *MaybeMask = nullptr;
       if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
-                                                  &Alignment)) {
+                                                  &Alignment, &MaybeMask)) {
         if (ClOpt && ClOptSameTemp) {
-          if (!TempsToInstrument.insert(Addr).second)
-            continue;  // We've seen this temp in the current BB.
+          // If we have a mask, skip instrumentation if we've already
+          // instrumented the full object. But don't add to TempsToInstrument
+          // because we might get another load/store with a different mask.
+          if (MaybeMask) {
+            if (TempsToInstrument.count(Addr))
+              continue; // We've seen this (whole) temp in the current BB.
+          } else {
+            if (!TempsToInstrument.insert(Addr).second)
+              continue; // We've seen this temp in the current BB.
+          }
         }
       } else if (ClInvalidPointerPairs &&
                  isInterestingPointerComparisonOrSubtraction(&Inst)) {