[msan] Use explicitely aligned stores and loads with function argument shadow.

Use explicitely aligned store and load instructions to deal with argument and
retval shadow. This matters when an argument's alignment is higher than
__msan_param_tls alignment (which is the case with __m128i).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169859 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 8 deletions

diff --git a/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 947a2e3..d03e300 100644
--- a/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -76,6 +76,7 @@ static const uint64_t kShadowMask32 = 1ULL << 31;
 static const uint64_t kShadowMask64 = 1ULL << 46;
 static const uint64_t kOriginOffset32 = 1ULL << 30;
 static const uint64_t kOriginOffset64 = 1ULL << 45;
+static const uint64_t kShadowTLSAlignment = 8;
 
 // This is an important flag that makes the reports much more
 // informative at the cost of greater slowdown. Not fully implemented
@@ -1226,11 +1227,13 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
                                  Size, Alignment);
       } else {
         Size = MS.TD->getTypeAllocSize(A->getType());
-        Store = IRB.CreateStore(ArgShadow, ArgShadowBase);
+        Store = IRB.CreateAlignedStore(ArgShadow, ArgShadowBase,
+                                       kShadowTLSAlignment);
       }
       if (ClTrackOrigins)
-        IRB.CreateStore(getOrigin(A),
-                        getOriginPtrForArgument(A, IRB, ArgOffset));
+        IRB.CreateAlignedStore(getOrigin(A),
+                               getOriginPtrForArgument(A, IRB, ArgOffset),
+                               kShadowTLSAlignment);
       assert(Size != 0 && Store != 0);
       DEBUG(dbgs() << "  Param:" << *Store << "\n");
       ArgOffset += DataLayout::RoundUpAlignment(Size, 8);
@@ -1248,7 +1251,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     IRBuilder<> IRBBefore(&I);
     // Untill we have full dynamic coverage, make sure the retval shadow is 0.
     Value *Base = getShadowPtrForRetval(&I, IRBBefore);
-    IRBBefore.CreateStore(getCleanShadow(&I), Base);
+    IRBBefore.CreateAlignedStore(getCleanShadow(&I), Base, kShadowTLSAlignment);
     Instruction *NextInsn = 0;
     if (CS.isCall()) {
       NextInsn = I.getNextNode();
@@ -1267,8 +1270,10 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
              "Could not find insertion point for retval shadow load");
     }
     IRBuilder<> IRBAfter(NextInsn);
-    setShadow(&I, IRBAfter.CreateLoad(getShadowPtrForRetval(&I, IRBAfter),
-                                      "_msret"));
+    Value *RetvalShadow =
+      IRBAfter.CreateAlignedLoad(getShadowPtrForRetval(&I, IRBAfter),
+                                 kShadowTLSAlignment, "_msret");
+    setShadow(&I, RetvalShadow);
     if (ClTrackOrigins)
       setOrigin(&I, IRBAfter.CreateLoad(getOriginPtrForRetval(IRBAfter)));
   }
@@ -1280,7 +1285,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
       Value *Shadow = getShadow(RetVal);
       Value *ShadowPtr = getShadowPtrForRetval(RetVal, IRB);
       DEBUG(dbgs() << "Return: " << *Shadow << "\n" << *ShadowPtr << "\n");
-      IRB.CreateStore(Shadow, ShadowPtr);
+      IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment);
       if (ClTrackOrigins)
         IRB.CreateStore(getOrigin(RetVal), getOriginPtrForRetval(IRB));
     }
@@ -1471,7 +1476,7 @@ struct VarArgAMD64Helper : public VarArgHelper {
         Base = getShadowPtrForVAArgument(A, IRB, OverflowOffset);
         OverflowOffset += DataLayout::RoundUpAlignment(ArgSize, 8);
       }
-      IRB.CreateStore(MSV.getShadow(A), Base);
+      IRB.CreateAlignedStore(MSV.getShadow(A), Base, kShadowTLSAlignment);
     }
     Constant *OverflowSize =
       ConstantInt::get(IRB.getInt64Ty(), OverflowOffset - AMD64FpEndOffset);