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[SCEV] Fix potentially empty set for unsigned ranges

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The following commit enabled the analysis of ranges for heap allocations:
22ca38da25e19a7c5fcfeb3f22159aba92ec381e

The range turns out to be empty in cases such as the one in test (which
is [1,1)), leading to an assertion failure. This patch fixes for the
same case.

Fixes https://github.com/llvm/llvm-project/issues/63856

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D159160
This commit is contained in:
Tejas Joshi 2023-09-04 10:46:52 +01:00 committed by Florian Hahn
parent fdb6e8b792
commit 0609b65aaf
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GPG Key ID: 9E54DEA47A8F4434
2 changed files with 12 additions and 1 deletions
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2
llvm/lib/Analysis/ScalarEvolution.cpp
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@ -6843,7 +6843,7 @@ const ConstantRange &ScalarEvolution::getRangeRef(
if (llvm::isKnownNonZero(V, DL))
MinVal = Align;
ConservativeResult = ConservativeResult.intersectWith(
{MinVal, MaxVal + 1}, RangeType);
ConstantRange::getNonEmpty(MinVal, MaxVal + 1), RangeType);
}
}

11
llvm/test/Analysis/ScalarEvolution/malloc.ll
View File

@ -23,4 +23,15 @@ define ptr @f2() {
ret ptr %alloc
}
define ptr @undefined_max() {
; CHECK-LABEL: 'undefined_max'
; CHECK-NEXT: Classifying expressions for: @undefined_max
; CHECK-NEXT: %alloc = call nonnull ptr @malloc(i64 -1)
; CHECK-NEXT: --> %alloc U: full-set S: full-set
; CHECK-NEXT: Determining loop execution counts for: @undefined_max
;
%alloc = call nonnull ptr @malloc(i64 -1)
ret ptr %alloc
}
declare noalias noundef ptr @malloc(i64 noundef) allockind("alloc,uninitialized") allocsize(0)