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[msan] Fix "Add optional flag to improve instrumentation of disjoint OR (#145990)" #146799

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Merged
merged 3 commits into from
Jul 3, 2025
Merged

[msan] Fix "Add optional flag to improve instrumentation of disjoint OR (#145990)" #146799

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7a7aeb0
[msan] Fix "Add optional flag to improve instrumentation of disjoint …
thurstond Jul 2, 2025
86a1df3
Recast operands as ints instead, per Florian2
thurstond Jul 2, 2025
7eb398e
Refactor to NotV1 / NotV2
thurstond Jul 2, 2025
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17 changes: 11 additions & 6 deletions llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2512,20 +2512,25 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
// S = S | (V1 & V2)
Value *S1 = getShadow(&I, 0);
Value *S2 = getShadow(&I, 1);
Value *V1 = IRB.CreateNot(I.getOperand(0));
Value *V2 = IRB.CreateNot(I.getOperand(1));
Value *V1 = I.getOperand(0);
Value *V2 = I.getOperand(1);
if (V1->getType() != S1->getType()) {
V1 = IRB.CreateIntCast(V1, S1->getType(), false);
V2 = IRB.CreateIntCast(V2, S2->getType(), false);
}

Value *NotV1 = IRB.CreateNot(V1);
Value *NotV2 = IRB.CreateNot(V2);

Value *S1S2 = IRB.CreateAnd(S1, S2);
Value *V1S2 = IRB.CreateAnd(V1, S2);
Value *S1V2 = IRB.CreateAnd(S1, V2);
Value *S2NotV1 = IRB.CreateAnd(NotV1, S2);
Value *S1NotV2 = IRB.CreateAnd(S1, NotV2);

Value *S = IRB.CreateOr({S1S2, S2NotV1, S1NotV2});

Value *S = IRB.CreateOr({S1S2, V1S2, S1V2});
if (ClPreciseDisjointOr && cast<PossiblyDisjointInst>(&I)->isDisjoint()) {
Value *V1V2 = IRB.CreateAnd(V1, V2);
S = IRB.CreateOr({S, V1V2});
S = IRB.CreateOr(S, V1V2, "_ms_disjoint");
}

setShadow(&I, S);
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2 changes: 1 addition & 1 deletion llvm/test/Instrumentation/MemorySanitizer/or.ll
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Expand Up @@ -45,7 +45,7 @@ define i8 @test_disjoint_or(i8 %a, i8 %b) sanitize_memory {
; CHECK-IMPRECISE: [[C:%.*]] = or disjoint i8 [[A]], [[B]]
; CHECK-IMPRECISE-NEXT: store i8 [[TMP11]], ptr @__msan_retval_tls, align 8
;
; CHECK-PRECISE: [[TMP10:%.*]] = and i8 [[TMP3]], [[TMP4]]
; CHECK-PRECISE: [[TMP10:%.*]] = and i8 [[A]], [[B]]
; CHECK-PRECISE-NEXT: [[TMP12:%.*]] = or i8 [[TMP11]], [[TMP10]]
; CHECK-PRECISE-NEXT: [[C:%.*]] = or disjoint i8 [[A]], [[B]]
; CHECK-PRECISE-NEXT: store i8 [[TMP12]], ptr @__msan_retval_tls, align 8
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