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[BasicAA] Make sure types match in constant offset heuristic

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This can only happen if offset types that are larger than the
pointer size are involved. The previous implementation did not
assert in this case because it initialized the APInts to the
width of one of the variables -- though I strongly suspect it
did not compute correct results in this case.

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=32621
reported by fhahn.
This commit is contained in:
Nikita Popov 2021-03-28 21:20:50 +02:00
parent 99c3c72646
commit ab6e561d30
2 changed files with 9 additions and 1 deletions
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2
lib/Analysis/BasicAliasAnalysis.cpp
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@ -1725,7 +1725,7 @@ bool BasicAAResult::constantOffsetHeuristic(
const VariableGEPIndex &Var0 = VarIndices[0], &Var1 = VarIndices[1]; const VariableGEPIndex &Var0 = VarIndices[0], &Var1 = VarIndices[1];
if (Var0.ZExtBits != Var1.ZExtBits || Var0.SExtBits != Var1.SExtBits || if (Var0.ZExtBits != Var1.ZExtBits || Var0.SExtBits != Var1.SExtBits ||
Var0.Scale != -Var1.Scale) Var0.Scale != -Var1.Scale || Var0.V->getType() != Var1.V->getType())
return false; return false;
// We'll strip off the Extensions of Var0 and Var1 and do another round // We'll strip off the Extensions of Var0 and Var1 and do another round

8
test/Analysis/BasicAA/q.bad.ll
View File

@ -178,3 +178,11 @@ define void @constantOffsetHeuristic_i8_i8(i8* %mem, i8 %val) {
%c = bitcast i8* %c.8 to i32* %c = bitcast i8* %c.8 to i32*
ret void ret void
} }
; CHECK-LABEL: different_large_bitwidths
; MayAlias: i64* %p1, i64* %p2
define void @different_large_bitwidths(i8* %a, i64 %i, i128 %j) {
%p1 = getelementptr i8, i8* %a, i64 %i
%p2 = getelementptr i8, i8* %a, i128 %j
ret void
}