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[IndVarSimplify] Handle the case where both operands are the same when widening IV #135207

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Merged
merged 2 commits into from
Apr 11, 2025
Merged

[IndVarSimplify] Handle the case where both operands are the same when widening IV #135207

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9207e62
[IndVarSimplify] Add pre-commit tests. NFC.
dtcxzyw Apr 10, 2025
dc3c046
[IndVarSimplify] Handle the case where both operands are the same whe…
dtcxzyw Apr 10, 2025
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3 changes: 3 additions & 0 deletions llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1743,6 +1743,9 @@ bool WidenIV::widenWithVariantUse(WidenIV::NarrowIVDefUse DU) {
// TODO: Support case for NarrowDef = NarrowUse->getOperand(1).
if (NarrowUse->getOperand(0) != NarrowDef)
return false;
// We cannot use a different extend kind for the same operand.
if (NarrowUse->getOperand(1) == NarrowDef)
return false;
if (!SE->isKnownNegative(RHS))
return false;
bool ProvedSubNUW = SE->isKnownPredicateAt(ICmpInst::ICMP_UGE, LHS,
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27 changes: 27 additions & 0 deletions llvm/test/Transforms/IndVarSimplify/pr135182.ll
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@@ -0,0 +1,27 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -S -passes=indvars < %s | FileCheck %s

target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"

define i32 @pr135182() {
; CHECK-LABEL: define i32 @pr135182() {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br label %[[FOR_BODY:.*]]
; CHECK: [[FOR_BODY]]:
; CHECK-NEXT: br i1 false, label %[[FOR_BODY]], label %[[FOR_END:.*]]
; CHECK: [[FOR_END]]:
; CHECK-NEXT: ret i32 65512
;
entry:
br label %for.body

for.body:
%indvar = phi i16 [ -12, %entry ], [ %indvar.next, %for.body ]
%add = add i16 %indvar, %indvar
%ext = zext i16 %add to i32
%indvar.next = add i16 %indvar, 1
br i1 false, label %for.body, label %for.end

for.end:
ret i32 %ext
}
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