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[InstCombine] Don't check uses of constant exprs #113684

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Merged
merged 2 commits into from
Oct 28, 2024
Merged

[InstCombine] Don't check uses of constant exprs #113684

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c7c0538
[InstCombine] Don't check uses of constant exprs
dtcxzyw Oct 25, 2024
0db560f
[InstCombine] Add comments. NFC.
dtcxzyw Oct 25, 2024
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4 changes: 3 additions & 1 deletion llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3753,7 +3753,9 @@ Instruction *InstCombinerImpl::visitBranchInst(BranchInst &BI) {
}

// Replace all dominated uses of the condition with true/false
if (BI.getSuccessor(0) != BI.getSuccessor(1)) {
// Ignore constant expressions to avoid iterating over uses on other
// functions.
if (!isa<Constant>(Cond) && BI.getSuccessor(0) != BI.getSuccessor(1)) {
for (auto &U : make_early_inc_range(Cond->uses())) {
BasicBlockEdge Edge0(BI.getParent(), BI.getSuccessor(0));
if (DT.dominates(Edge0, U)) {
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43 changes: 43 additions & 0 deletions llvm/test/Transforms/InstCombine/pr105510.ll
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@@ -0,0 +1,43 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -S -passes=instcombine < %s | FileCheck %s

; Make sure we don't crash in this case.
@g = global i32 0

define i1 @foo() {
; CHECK-LABEL: define i1 @foo() {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br i1 ptrtoint (ptr @g to i1), label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
; CHECK: [[IF_THEN]]:
; CHECK-NEXT: ret i1 true
; CHECK: [[IF_ELSE]]:
; CHECK-NEXT: ret i1 false
;
entry:
br i1 ptrtoint (ptr @g to i1), label %if.then, label %if.else

if.then:
ret i1 true

if.else:
ret i1 false
}

define i1 @bar() {
; CHECK-LABEL: define i1 @bar() {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br i1 ptrtoint (ptr @g to i1), label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
; CHECK: [[IF_THEN]]:
; CHECK-NEXT: ret i1 true
; CHECK: [[IF_ELSE]]:
; CHECK-NEXT: ret i1 false
;
entry:
br i1 ptrtoint (ptr @g to i1), label %if.then, label %if.else

if.then:
ret i1 true

if.else:
ret i1 false
}
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