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.
60 lines
2.5 KiB
LLVM
60 lines
2.5 KiB
LLVM
; RUN: opt %loadNPMPolly -pass-remarks-analysis="polly-scops" '-passes=print<polly-function-scops>' \
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; RUN: -disable-output < %s 2>&1 | FileCheck %s
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;
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; CHECK: Low complexity assumption: { : false }
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;
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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%struct.bc_struct.0.2.4.6.13.20.27.43.44.46.50.52.58.60.81.89.90.99.107.108.109.111.116.118.149 = type { i32, i32, i32, i32, [1024 x i8] }
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; Function Attrs: nounwind uwtable
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define void @bc_multiply(ptr readonly %n1, i32 %scale) #0 {
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entry:
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%0 = load i32, ptr undef, align 4
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%1 = load i32, ptr undef, align 4
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%2 = load i32, ptr undef, align 4
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%add3 = add nsw i32 %2, %1
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%cmp = icmp sgt i32 %0, %2
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%. = select i1 %cmp, i32 %0, i32 %2
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%cmp12 = icmp slt i32 %., %scale
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%scale.. = select i1 %cmp12, i32 %scale, i32 %.
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%cmp26 = icmp sgt i32 0, %scale..
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%scale...add7 = select i1 %cmp26, i32 %scale.., i32 0
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%sub = sub nsw i32 0, %scale...add7
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%add.ptr = getelementptr inbounds %struct.bc_struct.0.2.4.6.13.20.27.43.44.46.50.52.58.60.81.89.90.99.107.108.109.111.116.118.149, ptr %n1, i64 0, i32 4, i64 0
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%add.ptr59 = getelementptr inbounds i8, ptr %add.ptr, i64 -1
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%idx.ext62 = sext i32 %add3 to i64
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%cmp70140 = icmp sgt i32 %sub, 0
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br label %for.body104.lr.ph
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for.body104.lr.ph: ; preds = %entry
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%3 = add i32 0, -1
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%4 = sub i32 %3, %scale...add7
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%5 = add i32 %4, 1
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%6 = sext i32 %5 to i64
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br label %for.body104
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for.body104: ; preds = %while.end146, %for.body104.lr.ph
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%indvars.iv = phi i64 [ %6, %for.body104.lr.ph ], [ poison, %while.end146 ]
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%7 = sub nsw i64 %indvars.iv, %idx.ext62
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%cmp107 = icmp slt i64 %7, -1
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%.op = xor i64 %7, -1
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%idx.neg116 = select i1 %cmp107, i64 0, i64 %.op
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%add.ptr117 = getelementptr inbounds i8, ptr %add.ptr59, i64 %idx.neg116
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br label %while.body138
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while.body138: ; preds = %while.body138, %for.body104
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%n1ptr.1126 = phi ptr [ %incdec.ptr139, %while.body138 ], [ %add.ptr117, %for.body104 ]
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%incdec.ptr139 = getelementptr inbounds i8, ptr %n1ptr.1126, i64 -1
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%cmp132 = icmp uge ptr %incdec.ptr139, null
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%cmp135 = icmp slt i64 0, -1
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%or.cond99 = and i1 %cmp135, %cmp132
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br i1 %or.cond99, label %while.body138, label %while.end146
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while.end146: ; preds = %while.body138
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br i1 undef, label %free_num.exit, label %for.body104
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free_num.exit: ; preds = %while.end146
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ret void
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}
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