0b9f1cc024
See the following case:
```
@GlobIntONE = global i32 0, align 4
define ptr @src() {
entry:
br label %for.body.peel.begin
for.body.peel.begin: ; preds = %entry
br label %for.body.peel
for.body.peel: ; preds = %for.body.peel.begin
br i1 true, label %cleanup.peel, label %cleanup.loopexit.peel
cleanup.loopexit.peel: ; preds = %for.body.peel
br label %cleanup.peel
cleanup.peel: ; preds = %cleanup.loopexit.peel, %for.body.peel
%retval.2.peel = phi ptr [ undef, %for.body.peel ], [ @GlobIntONE, %cleanup.loopexit.peel ]
br i1 true, label %for.body.peel.next, label %cleanup7
for.body.peel.next: ; preds = %cleanup.peel
br label %for.body.peel.next1
for.body.peel.next1: ; preds = %for.body.peel.next
br label %entry.peel.newph
entry.peel.newph: ; preds = %for.body.peel.next1
br label %for.body
for.body: ; preds = %cleanup, %entry.peel.newph
%retval.0 = phi ptr [ %retval.2.peel, %entry.peel.newph ], [ %retval.2, %cleanup ]
br i1 false, label %cleanup, label %cleanup.loopexit
cleanup.loopexit: ; preds = %for.body
br label %cleanup
cleanup: ; preds = %cleanup.loopexit, %for.body
%retval.2 = phi ptr [ %retval.0, %for.body ], [ @GlobIntONE, %cleanup.loopexit ]
br i1 false, label %for.body, label %cleanup7.loopexit
cleanup7.loopexit: ; preds = %cleanup
%retval.2.lcssa.ph = phi ptr [ %retval.2, %cleanup ]
br label %cleanup7
cleanup7: ; preds = %cleanup7.loopexit, %cleanup.peel
%retval.2.lcssa = phi ptr [ %retval.2.peel, %cleanup.peel ], [ %retval.2.lcssa.ph, %cleanup7.loopexit ]
ret ptr %retval.2.lcssa
}
define ptr @tgt() {
entry:
br label %for.body.peel.begin
for.body.peel.begin: ; preds = %entry
br label %for.body.peel
for.body.peel: ; preds = %for.body.peel.begin
br i1 true, label %cleanup.peel, label %cleanup.loopexit.peel
cleanup.loopexit.peel: ; preds = %for.body.peel
br label %cleanup.peel
cleanup.peel: ; preds = %cleanup.loopexit.peel, %for.body.peel
%retval.2.peel = phi ptr [ undef, %for.body.peel ], [ @GlobIntONE, %cleanup.loopexit.peel ]
br i1 true, label %for.body.peel.next, label %cleanup7
for.body.peel.next: ; preds = %cleanup.peel
br label %for.body.peel.next1
for.body.peel.next1: ; preds = %for.body.peel.next
br label %entry.peel.newph
entry.peel.newph: ; preds = %for.body.peel.next1
br label %for.body
for.body: ; preds = %cleanup, %entry.peel.newph
br i1 false, label %cleanup, label %cleanup.loopexit
cleanup.loopexit: ; preds = %for.body
br label %cleanup
cleanup: ; preds = %cleanup.loopexit, %for.body
br i1 false, label %for.body, label %cleanup7.loopexit
cleanup7.loopexit: ; preds = %cleanup
%retval.2.lcssa.ph = phi ptr [ %retval.2.peel, %cleanup ]
br label %cleanup7
cleanup7: ; preds = %cleanup7.loopexit, %cleanup.peel
%retval.2.lcssa = phi ptr [ %retval.2.peel, %cleanup.peel ], [ %retval.2.lcssa.ph, %cleanup7.loopexit ]
ret ptr %retval.2.lcssa
}
```
1. `simplifyInstruction(%retval.2.peel)` returns `@GlobIntONE`. Thus,
`ScalarEvolution::createNodeForPHI` returns SCEV expr `@GlobIntONE` for
`%retval.2.peel`.
2. `SimplifyIndvar::replaceIVUserWithLoopInvariant` tries to replace the
use of `%retval.2.peel` in `%retval.2.lcssa.ph` with `@GlobIntONE`.
3. `simplifyLoopAfterUnroll -> simplifyLoopIVs -> SCEVExpander::expand`
reuses `%retval.2.peel = phi ptr [ undef, %for.body.peel ], [
@GlobIntONE, %cleanup.loopexit.peel ]` to generate code for
`@GlobIntONE`. It is incorrect.
This patch disallows simplifying `phi(undef, X)` to `X` by setting
`CanUseUndef` to false.
Closes https://github.com/llvm/llvm-project/issues/114879.
63 lines
2.5 KiB
LLVM
63 lines
2.5 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt -S -passes=loop-unroll-full -unroll-full-max-count=1 %s | FileCheck %s
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@GlobIntONE = global i32 0, align 4
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; Make sure we don't reuse the phi (undef, X) for X.
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define ptr @test() {
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; CHECK-LABEL: define ptr @test() {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: br label %[[FOR_BODY_PEEL_BEGIN:.*]]
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; CHECK: [[FOR_BODY_PEEL_BEGIN]]:
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; CHECK-NEXT: br label %[[FOR_BODY_PEEL:.*]]
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; CHECK: [[FOR_BODY_PEEL]]:
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; CHECK-NEXT: br i1 true, label %[[CLEANUP_PEEL:.*]], label %[[CLEANUP_LOOPEXIT_PEEL:.*]]
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; CHECK: [[CLEANUP_LOOPEXIT_PEEL]]:
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; CHECK-NEXT: br label %[[CLEANUP_PEEL]]
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; CHECK: [[CLEANUP_PEEL]]:
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; CHECK-NEXT: [[RETVAL_2_PEEL:%.*]] = phi ptr [ undef, %[[FOR_BODY_PEEL]] ], [ @GlobIntONE, %[[CLEANUP_LOOPEXIT_PEEL]] ]
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; CHECK-NEXT: br i1 true, label %[[FOR_BODY_PEEL_NEXT:.*]], label %[[CLEANUP2:.*]]
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; CHECK: [[FOR_BODY_PEEL_NEXT]]:
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; CHECK-NEXT: br label %[[FOR_BODY_PEEL_NEXT1:.*]]
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; CHECK: [[FOR_BODY_PEEL_NEXT1]]:
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; CHECK-NEXT: br label %[[ENTRY_PEEL_NEWPH:.*]]
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; CHECK: [[ENTRY_PEEL_NEWPH]]:
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; CHECK-NEXT: br label %[[FOR_BODY:.*]]
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; CHECK: [[FOR_BODY]]:
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; CHECK-NEXT: br i1 false, label %[[CLEANUP:.*]], label %[[CLEANUP_LOOPEXIT:.*]]
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; CHECK: [[CLEANUP_LOOPEXIT]]:
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; CHECK-NEXT: br label %[[CLEANUP]]
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; CHECK: [[CLEANUP]]:
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; CHECK-NEXT: br i1 false, label %[[FOR_BODY]], label %[[CLEANUP2_LOOPEXIT:.*]], !llvm.loop [[LOOP0:![0-9]+]]
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; CHECK: [[CLEANUP2_LOOPEXIT]]:
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; CHECK-NEXT: [[RETVAL_2_LCSSA_PH:%.*]] = phi ptr [ @GlobIntONE, %[[CLEANUP]] ]
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; CHECK-NEXT: br label %[[CLEANUP2]]
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; CHECK: [[CLEANUP2]]:
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; CHECK-NEXT: [[RETVAL_2_LCSSA:%.*]] = phi ptr [ [[RETVAL_2_PEEL]], %[[CLEANUP_PEEL]] ], [ [[RETVAL_2_LCSSA_PH]], %[[CLEANUP2_LOOPEXIT]] ]
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; CHECK-NEXT: ret ptr [[RETVAL_2_LCSSA]]
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;
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entry:
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br label %for.body
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for.body:
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%retval.0 = phi ptr [ undef, %entry ], [ %retval.2, %cleanup ]
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%cmp1.not = phi i1 [ true, %entry ], [ false, %cleanup ]
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br i1 %cmp1.not, label %cleanup, label %cleanup.loopexit
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cleanup.loopexit:
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br label %cleanup
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cleanup:
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%retval.2 = phi ptr [ %retval.0, %for.body ], [ @GlobIntONE, %cleanup.loopexit ]
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br i1 %cmp1.not, label %for.body, label %cleanup2
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cleanup2:
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%retval.2.lcssa = phi ptr [ %retval.2, %cleanup ]
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ret ptr %retval.2.lcssa
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}
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;.
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; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]]}
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; CHECK: [[META1]] = !{!"llvm.loop.peeled.count", i32 1}
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;.
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