[PATCH] D97029: [msan] Set cmpxchg shadow precisely

[stephan.yichao.zhao via Phabricator via llvm-commits]

stephan.yichao.zhao created this revision.
stephan.yichao.zhao added a reviewer: eugenis.
Herald added subscribers: jfb, hiraditya.
stephan.yichao.zhao requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

In terms of https://llvm.org/docs/LangRef.html#cmpxchg-instruction,
the return type of chmpxchg is a pair {ty, i1}, while I think we
only wanted to set the shadow for the address 0th op, and it has type
ty.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D97029

Files:
  llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
  llvm/test/Instrumentation/MemorySanitizer/atomics.ll


Index: llvm/test/Instrumentation/MemorySanitizer/atomics.ll
===================================================================
--- llvm/test/Instrumentation/MemorySanitizer/atomics.ll
+++ llvm/test/Instrumentation/MemorySanitizer/atomics.ll
@@ -51,7 +51,7 @@
 }
 
 ; CHECK-LABEL: @Cmpxchg
-; CHECK: store { i32, i1 } zeroinitializer,
+; CHECK: store i32 0,
 ; CHECK: icmp
 ; CHECK: br
 ; CHECK: @__msan_warning_with_origin
@@ -70,7 +70,7 @@
 }
 
 ; CHECK-LABEL: @CmpxchgMonotonic
-; CHECK: store { i32, i1 } zeroinitializer,
+; CHECK: store i32 0,
 ; CHECK: icmp
 ; CHECK: br
 ; CHECK: @__msan_warning_with_origin
Index: llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -1948,7 +1948,8 @@
 
     IRBuilder<> IRB(&I);
     Value *Addr = I.getOperand(0);
-    Value *ShadowPtr = getShadowOriginPtr(Addr, IRB, I.getType(), Align(1),
+    Value *Val = I.getOperand(1);
+    Value *ShadowPtr = getShadowOriginPtr(Addr, IRB, Val->getType(), Align(1),
                                           /*isStore*/ true)
                            .first;
 
@@ -1959,9 +1960,9 @@
     // The other argument can potentially be uninitialized, but we can not
     // detect this situation reliably without possible false positives.
     if (isa<AtomicCmpXchgInst>(I))
-      insertShadowCheck(I.getOperand(1), &I);
+      insertShadowCheck(Val, &I);
 
-    IRB.CreateStore(getCleanShadow(&I), ShadowPtr);
+    IRB.CreateStore(getCleanShadow(Val), ShadowPtr);
 
     setShadow(&I, getCleanShadow(&I));
     setOrigin(&I, getCleanOrigin());


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D97029.324870.patch
Type: text/x-patch
Size: 1721 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20210219/d467cc4a/attachment.bin>