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authorEvgeniy Stepanov <eugeni.stepanov@gmail.com>2013-01-25 15:35:29 +0000
committerEvgeniy Stepanov <eugeni.stepanov@gmail.com>2013-01-25 15:35:29 +0000
commit94d1f5b10cbc65d12fc8eb46fd36a2f407cf4a35 (patch)
tree578d11dd096602b196047d3bbb250b230cff9c3a /lib
parent351f65d9723c075af86466c07a0a3dc28be272cd (diff)
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[msan] A comment on ICmp handling logic.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173453 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r--lib/Transforms/Instrumentation/MemorySanitizer.cpp3
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 64882c284b..a329dcc6be 100644
--- a/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -1211,6 +1211,9 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
A = IRB.CreatePointerCast(A, Sa->getType());
B = IRB.CreatePointerCast(B, Sb->getType());
+ // Let [a0, a1] be the interval of possible values of A, taking into account
+ // its undefined bits. Let [b0, b1] be the interval of possible values of B.
+ // Then (A cmp B) is defined iff (a0 cmp b1) == (a1 cmp b0).
bool IsSigned = I.isSigned();
Value *S1 = IRB.CreateICmp(I.getPredicate(),
getLowestPossibleValue(IRB, A, Sa, IsSigned),