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[SCEV] Reject comparision of pointers to different address spaces in SCEVWrapPredicate::implies #137935

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Merged
merged 3 commits into from
Apr 30, 2025
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[SCEV] Reject comparision of pointers to different address spaces in SCEVWrapPredicate::implies #137935

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[SCEV] reject comparision of pointers to different address spaces in …
vikramRH Apr 30, 2025
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vikramRH Apr 30, 2025
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vikramRH Apr 30, 2025
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4 changes: 4 additions & 0 deletions llvm/lib/Analysis/ScalarEvolution.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -14967,6 +14967,10 @@ bool SCEVWrapPredicate::implies(const SCEVPredicate *N,
if (Start->getType()->isPointerTy() != OpStart->getType()->isPointerTy())
return false;

// Reject pointers to different address spaces.
if (Start->getType()->isPointerTy() && Start->getType() != OpStart->getType())
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nit: might be worth adding a comment here to say that this rejects pointers in different address spaces?

return false;

const SCEV *Step = AR->getStepRecurrence(SE);
const SCEV *OpStep = Op->AR->getStepRecurrence(SE);
if (!SE.isKnownPositive(Step) || !SE.isKnownPositive(OpStep))
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36 changes: 35 additions & 1 deletion llvm/test/Analysis/LoopAccessAnalysis/nusw-predicates.ll
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@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes='print<access-info>' -disable-output %s 2>&1 | FileCheck %s

target datalayout = "p:16:16"
target datalayout = "p:16:16-p3:32:32"

define void @int_and_pointer_predicate(ptr %v, i32 %N) {
; CHECK-LABEL: 'int_and_pointer_predicate'
Expand Down Expand Up @@ -124,3 +124,37 @@ loop:
exit:
ret void
}

define void @pointers_to_different_aspace_predicates(ptr %v, ptr addrspace(3) %w, i32 %N) {
; CHECK-LABEL: 'pointers_to_different_aspace_predicates'
; CHECK-NEXT: loop:
; CHECK-NEXT: Report: cannot identify array bounds
; CHECK-NEXT: Dependences:
; CHECK-NEXT: Run-time memory checks:
; CHECK-NEXT: Grouped accesses:
; CHECK-EMPTY:
; CHECK-NEXT: Non vectorizable stores to invariant address were not found in loop.
; CHECK-NEXT: SCEV assumptions:
; CHECK-NEXT: {0,+,1}<%loop> Added Flags: <nusw>
; CHECK-NEXT: {%v,+,4}<%loop> Added Flags: <nusw>
; CHECK-NEXT: {%w,+,4}<%loop> Added Flags: <nusw>
; CHECK-EMPTY:
; CHECK-NEXT: Expressions re-written:
;
entry:
br label %loop

loop:
%iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
%gep.v = getelementptr {i16, i16}, ptr %v, i64 %iv
store i16 0, ptr %gep.v, align 1
%gep.w = getelementptr i32, ptr addrspace(3) %w, i64 %iv
store i32 0, ptr addrspace(3) %gep.w, align 1
%iv.next = add i64 %iv, 1
%iv.i32 = trunc i64 %iv to i32
%.not = icmp ult i32 %N, %iv.i32
br i1 %.not, label %exit, label %loop

exit:
ret void
}