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[NaryReassociate] Fix crash from pointer width / index width confusion #125923

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Merged
merged 3 commits into from
Feb 6, 2025
Merged

[NaryReassociate] Fix crash from pointer width / index width confusion #125923

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68c9124
[NaryReassociate] Fix crash from pointer width / index width confusion
krzysz00 Feb 5, 2025
cf2867a
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krzysz00 Feb 5, 2025
1c279a6
Make the test less trivial
krzysz00 Feb 6, 2025
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14 changes: 9 additions & 5 deletions llvm/lib/Transforms/Scalar/NaryReassociate.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -402,16 +402,20 @@ NaryReassociatePass::tryReassociateGEPAtIndex(GetElementPtrInst *GEP,
IndexExprs.push_back(SE->getSCEV(Index));
// Replace the I-th index with LHS.
IndexExprs[I] = SE->getSCEV(LHS);
Type *GEPArgType = GEP->getOperand(I)->getType();
Type *LHSType = LHS->getType();
size_t LHSSize = DL->getTypeSizeInBits(LHSType).getFixedValue();
size_t GEPArgSize = DL->getTypeSizeInBits(GEPArgType).getFixedValue();
// For pointers, we need to look at the index size, not the total type size.
if (isa<PointerType>(GEPArgType))
GEPArgSize = DL->getIndexTypeSizeInBits(GEPArgType);
if (isKnownNonNegative(LHS, SimplifyQuery(*DL, DT, AC, GEP)) &&
DL->getTypeSizeInBits(LHS->getType()).getFixedValue() <
DL->getTypeSizeInBits(GEP->getOperand(I)->getType())
.getFixedValue()) {
LHSSize < GEPArgSize) {
// Zero-extend LHS if it is non-negative. InstCombine canonicalizes sext to
// zext if the source operand is proved non-negative. We should do that
// consistently so that CandidateExpr more likely appears before. See
// @reassociate_gep_assume for an example of this canonicalization.
IndexExprs[I] =
SE->getZeroExtendExpr(IndexExprs[I], GEP->getOperand(I)->getType());
IndexExprs[I] = SE->getZeroExtendExpr(IndexExprs[I], GEPArgType);
}
const SCEV *CandidateExpr = SE->getGEPExpr(cast<GEPOperator>(GEP),
IndexExprs);
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11 changes: 11 additions & 0 deletions llvm/test/Transforms/NaryReassociate/nary-gep.ll
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Expand Up @@ -21,6 +21,17 @@ define void @no_sext_fat_pointer(ptr addrspace(2) %a, i32 %i, i32 %j) {
ret void
}

define ptr addrspace(2) @zext_fat_pointer_crash() {
; CHECK-LABEL: @zext_fat_pointer_crash(
; CHECK-NEXT: [[C:%.*]] = add i32 0, 0
; CHECK-NEXT: [[Q:%.*]] = getelementptr double, ptr addrspace(2) null, i32 [[C]]
; CHECK-NEXT: ret ptr addrspace(2) [[Q]]
;
%c = add i32 0, 0
%q = getelementptr double, ptr addrspace(2) null, i32 %c
ret ptr addrspace(2) %q
}

define void @or_disjoint(ptr addrspace(2) %a, i32 %i, i32 %j, i32 %k) {
; CHECK-LABEL: @or_disjoint(
; CHECK-NEXT: [[OR:%.*]] = or disjoint i32 [[I:%.*]], [[J:%.*]]
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