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llvm-project/llvm/test/Transforms/IndVarSimplify/invalidate-modified-lcssa-phi.ll
Yingwei Zheng 0b9f1cc024
[SCEV] Disallow simplifying phi(undef, X) to X (#115109) 
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.
2024-11-07 15:53:51 +08:00

212 lines
6.7 KiB
LLVM
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -passes='loop(indvars,loop-deletion)' -verify-scev -S %s | FileCheck %s
; Make sure indvarsimplify properly forgets the exit value %p.2.lcssa phi after
; modifying it. Loop deletion is required to show the incorrect use of the cached
; SCEV value.
define void @test(i1 %c) {
; CHECK-LABEL: @test(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[HEADER_1:%.*]]
; CHECK: header.1.loopexit:
; CHECK-NEXT: br label [[HEADER_1_BACKEDGE:%.*]]
; CHECK: header.1:
; CHECK-NEXT: br label [[HEADER_2:%.*]]
; CHECK: header.2:
; CHECK-NEXT: br i1 [[C:%.*]], label [[LATCH_1:%.*]], label [[LATCH_2:%.*]]
; CHECK: latch.1:
; CHECK-NEXT: br label [[HEADER_1_LOOPEXIT:%.*]]
; CHECK: latch.2:
; CHECK-NEXT: br label [[HEADER_1_BACKEDGE]]
; CHECK: header.1.backedge:
; CHECK-NEXT: br label [[HEADER_1]]
;
entry:
br label %header.1
header.1:
%p.1 = phi i32 [ 0, %entry ], [ %p.2.lcssa, %latch.2 ], [ 0, %latch.1 ]
br label %header.2
header.2:
%p.2 = phi i32 [ %p.1, %header.1 ], [ %p.2.next, %latch.1 ]
br i1 %c, label %latch.1, label %latch.2
latch.1:
%p.2.next = add i32 %p.2, 1
br i1 false, label %header.2, label %header.1
latch.2:
%p.2.lcssa = phi i32 [ %p.2, %header.2 ]
br label %header.1
}
define i8 @test_pr52023(i1 %c.1, i1 %c.2) {
; CHECK-LABEL: @test_pr52023(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LOOP_1:%.*]]
; CHECK: loop.1:
; CHECK-NEXT: [[INC79:%.*]] = phi i8 [ [[TMP0:%.*]], [[LOOP_1_LATCH:%.*]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: [[TMP1:%.*]] = add i8 [[INC79]], 1
; CHECK-NEXT: br label [[LOOP_2:%.*]]
; CHECK: loop.2:
; CHECK-NEXT: br i1 [[C_1:%.*]], label [[LOOP_2_LATCH:%.*]], label [[LOOP_1_LATCH]]
; CHECK: loop.2.latch:
; CHECK-NEXT: br label [[LOOP_1_LATCH]]
; CHECK: loop.1.latch:
; CHECK-NEXT: [[TMP0]] = phi i8 [ [[TMP1]], [[LOOP_2_LATCH]] ], [ undef, [[LOOP_2]] ]
; CHECK-NEXT: br i1 [[C_2:%.*]], label [[EXIT:%.*]], label [[LOOP_1]]
; CHECK: exit:
; CHECK-NEXT: [[INC_LCSSA_LCSSA:%.*]] = phi i8 [ [[TMP0]], [[LOOP_1_LATCH]] ]
; CHECK-NEXT: ret i8 [[INC_LCSSA_LCSSA]]
;
entry:
br label %loop.1
loop.1:
%inc79 = phi i8 [ %inc.lcssa, %loop.1.latch ], [ 0, %entry ]
br label %loop.2
loop.2:
%inc6 = phi i8 [ %inc79, %loop.1 ], [ %inc, %loop.2.latch ]
%inc = add i8 %inc6, 1
br i1 %c.1, label %loop.2.latch , label %loop.1.latch
loop.2.latch:
br i1 false, label %loop.2, label %loop.1.latch
loop.1.latch:
%inc.lcssa = phi i8 [ %inc, %loop.2.latch ], [ undef, %loop.2 ]
br i1 %c.2, label %exit, label %loop.1
exit:
%inc.lcssa.lcssa = phi i8 [ %inc.lcssa, %loop.1.latch ]
ret i8 %inc.lcssa.lcssa
}
define i32 @test_pr58440(i1 %c.0) {
; CHECK-LABEL: @test_pr58440(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = or i32 0, 1
; CHECK-NEXT: br label [[LOOP_1_HEADER:%.*]]
; CHECK: loop.1.header.loopexit:
; CHECK-NEXT: br label [[LOOP_1_HEADER]]
; CHECK: loop.1.header:
; CHECK-NEXT: br label [[LOOP_2_HEADER:%.*]]
; CHECK: loop.2.header:
; CHECK-NEXT: br i1 [[C_0:%.*]], label [[LOOP_2_LATCH:%.*]], label [[LOOP_1_HEADER_LOOPEXIT:%.*]]
; CHECK: loop.2.latch:
; CHECK-NEXT: br i1 false, label [[EXIT:%.*]], label [[LOOP_2_HEADER]]
; CHECK: exit:
; CHECK-NEXT: [[LCSSA:%.*]] = phi i32 [ [[TMP0]], [[LOOP_2_LATCH]] ]
; CHECK-NEXT: ret i32 [[LCSSA]]
;
entry:
br label %loop.1.header
loop.1.header:
%p.1 = phi i32 [ 0, %entry ], [ %p.2, %loop.2.header ]
br label %loop.2.header
loop.2.header:
%p.2 = phi i32 [ %p.1, %loop.1.header ], [ %0, %loop.2.latch ]
br i1 %c.0, label %loop.2.latch, label %loop.1.header
loop.2.latch:
%0 = or i32 %p.1, 1
br i1 false, label %exit, label %loop.2.header
exit:
%lcssa = phi i32 [ %0, %loop.2.latch ]
ret i32 %lcssa
}
define i16 @test_pr58515_invalidate_loop_disposition(ptr %a) {
; CHECK-LABEL: @test_pr58515_invalidate_loop_disposition(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SEL:%.*]] = select i1 true, i16 2, i16 0
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i16 [ 1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
; CHECK-NEXT: [[SUM:%.*]] = phi i16 [ 0, [[ENTRY]] ], [ [[SUM_NEXT:%.*]], [[LOOP]] ]
; CHECK-NEXT: [[SUM_NEXT]] = add i16 [[SEL]], [[SUM]]
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i16 [[IV]], 1
; CHECK-NEXT: [[C_2:%.*]] = icmp ult i16 [[IV]], 9
; CHECK-NEXT: br i1 [[C_2]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: [[LCSSA:%.*]] = phi i16 [ [[SUM_NEXT]], [[LOOP]] ]
; CHECK-NEXT: ret i16 0
;
entry:
br label %loop
loop:
%iv = phi i16 [ 1, %entry ], [ %iv.next, %loop ]
%sum = phi i16 [ 0, %entry ], [ %sum.next, %loop ]
%gep = getelementptr inbounds i16, ptr %a, i16 %iv
%c.1 = icmp ne ptr %a, %gep
%sel = select i1 %c.1, i16 2, i16 0
%sum.next = add i16 %sel, %sum
%iv.next = add nuw nsw i16 %iv, 1
%c.2 = icmp ult i16 %iv, 9
br i1 %c.2, label %loop, label %exit
exit:
%lcssa = phi i16 [ %sum.next, %loop ]
ret i16 0
}
define i32 @pr58750(i16 %a, ptr %dst, i1 %c.0) {
; CHECK-LABEL: @pr58750(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP186_NOT:%.*]] = icmp eq i16 [[A:%.*]], 0
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP186_NOT]])
; CHECK-NEXT: br label [[OUTER_HEADER:%.*]]
; CHECK: outer.header:
; CHECK-NEXT: [[P_0:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[LCSSA:%.*]], [[OUTER_LATCH:%.*]] ]
; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[P_0]], 0
; CHECK-NEXT: br label [[INNER:%.*]]
; CHECK: inner:
; CHECK-NEXT: store i16 0, ptr [[DST:%.*]], align 1
; CHECK-NEXT: br i1 false, label [[INNER]], label [[OUTER_LATCH]]
; CHECK: outer.latch:
; CHECK-NEXT: [[LCSSA]] = phi i32 [ [[XOR]], [[INNER]] ]
; CHECK-NEXT: br i1 [[C_0:%.*]], label [[OUTER_HEADER]], label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: [[LCSSA_LCSSA:%.*]] = phi i32 [ [[LCSSA]], [[OUTER_LATCH]] ]
; CHECK-NEXT: ret i32 [[LCSSA_LCSSA]]
;
entry:
%cmp186.not = icmp eq i16 %a, 0
call void @llvm.assume(i1 %cmp186.not)
br label %outer.header
outer.header:
%p.0 = phi i32 [ 0, %entry ], [ %lcssa, %outer.latch ]
br label %inner
inner:
%inner.iv = phi i16 [ 0, %outer.header ], [ %inner.iv.next, %inner ]
%p.1 = phi i32 [ %p.0, %outer.header ], [ %xor, %inner ]
store i16 %inner.iv, ptr %dst, align 1
%conv = sext i16 %inner.iv to i32
%xor = xor i32 %p.1, %conv
%inner.iv.next = add nuw i16 %inner.iv, 1
%c.1 = icmp ult i16 %inner.iv.next, %a
br i1 %c.1, label %inner, label %outer.latch
outer.latch:
%lcssa = phi i32 [ %xor, %inner ]
br i1 %c.0, label %outer.header, label %exit
exit:
ret i32 %lcssa
}
; Function Attrs: inaccessiblememonly nocallback nofree nosync nounwind willreturn
declare void @llvm.assume(i1 noundef) #1
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