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clang-p2996/llvm/test/Transforms/LoopVectorize/uniform-blend.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

223 lines
11 KiB
LLVM
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes=loop-vectorize -force-vector-width=4 -S %s | FileCheck %s
@dst = external global [32 x i16], align 1
define void @blend_uniform_iv_trunc(i1 %c) {
; CHECK-LABEL: define void @blend_uniform_iv_trunc(
; CHECK-SAME: i1 [[C:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = trunc i64 [[INDEX]] to i16
; CHECK-NEXT: [[TMP1:%.*]] = add i16 [[TMP0]], 0
; CHECK-NEXT: [[TMP6:%.*]] = select i1 [[C]], i16 [[TMP1]], i16 poison
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[TMP6]]
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds i16, ptr [[TMP7]], i32 0
; CHECK-NEXT: store <4 x i16> zeroinitializer, ptr [[TMP3]], align 2
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP4:%.*]] = icmp eq i64 [[INDEX_NEXT]], 32
; CHECK-NEXT: br i1 [[TMP4]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: br i1 true, label %[[EXIT:.*]], label %[[SCALAR_PH]]
; CHECK: [[SCALAR_PH]]:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 32, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[LOOP_HEADER:.*]]
; CHECK: [[LOOP_HEADER]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ]
; CHECK-NEXT: [[IV_TRUNC_2:%.*]] = trunc i64 [[IV]] to i16
; CHECK-NEXT: br i1 [[C]], label %[[LOOP_NEXT:.*]], label %[[LOOP_LATCH]]
; CHECK: [[LOOP_NEXT]]:
; CHECK-NEXT: br label %[[LOOP_LATCH]]
; CHECK: [[LOOP_LATCH]]:
; CHECK-NEXT: [[BLEND:%.*]] = phi i16 [ poison, %[[LOOP_HEADER]] ], [ [[IV_TRUNC_2]], %[[LOOP_NEXT]] ]
; CHECK-NEXT: [[DST_PTR:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 [[BLEND]]
; CHECK-NEXT: store i16 0, ptr [[DST_PTR]], align 2
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[CMP439:%.*]] = icmp ult i64 [[IV]], 31
; CHECK-NEXT: br i1 [[CMP439]], label %[[LOOP_HEADER]], label %[[EXIT]], !llvm.loop [[LOOP3:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
entry:
br label %loop.header
loop.header: ; preds = %loop.latch, %entry
%iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
%iv.trunc.2 = trunc i64 %iv to i16
br i1 %c, label %loop.next, label %loop.latch
loop.next: ; preds = %loop.header
br label %loop.latch
loop.latch: ; preds = %loop.next, %loop.header
%blend = phi i16 [ poison, %loop.header ], [ %iv.trunc.2, %loop.next ]
%dst.ptr = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i16 %blend
store i16 0, ptr %dst.ptr
%iv.next = add nuw nsw i64 %iv, 1
%cmp439 = icmp ult i64 %iv, 31
br i1 %cmp439, label %loop.header, label %exit
exit: ; preds = %loop.latch
ret void
}
define void @blend_uniform_iv(i1 %c) {
; CHECK-LABEL: define void @blend_uniform_iv(
; CHECK-SAME: i1 [[C:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[TMP6:%.*]] = select i1 [[C]], i64 [[TMP0]], i64 poison
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP6]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i16, ptr [[TMP7]], i32 0
; CHECK-NEXT: store <4 x i16> zeroinitializer, ptr [[TMP2]], align 2
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP3:%.*]] = icmp eq i64 [[INDEX_NEXT]], 32
; CHECK-NEXT: br i1 [[TMP3]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: br i1 true, label %[[EXIT:.*]], label %[[SCALAR_PH]]
; CHECK: [[SCALAR_PH]]:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 32, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[LOOP_HEADER:.*]]
; CHECK: [[LOOP_HEADER]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ]
; CHECK-NEXT: br i1 [[C]], label %[[LOOP_NEXT:.*]], label %[[LOOP_LATCH]]
; CHECK: [[LOOP_NEXT]]:
; CHECK-NEXT: br label %[[LOOP_LATCH]]
; CHECK: [[LOOP_LATCH]]:
; CHECK-NEXT: [[BLEND:%.*]] = phi i64 [ poison, %[[LOOP_HEADER]] ], [ [[IV]], %[[LOOP_NEXT]] ]
; CHECK-NEXT: [[DST_PTR:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[BLEND]]
; CHECK-NEXT: store i16 0, ptr [[DST_PTR]], align 2
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[CMP439:%.*]] = icmp ult i64 [[IV]], 31
; CHECK-NEXT: br i1 [[CMP439]], label %[[LOOP_HEADER]], label %[[EXIT]], !llvm.loop [[LOOP5:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
entry:
br label %loop.header
loop.header: ; preds = %loop.latch, %entry
%iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
br i1 %c, label %loop.next, label %loop.latch
loop.next: ; preds = %loop.header
br label %loop.latch
loop.latch: ; preds = %loop.next, %loop.header
%blend = phi i64 [ poison, %loop.header ], [ %iv, %loop.next ]
%dst.ptr = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 %blend
store i16 0, ptr %dst.ptr
%iv.next = add nuw nsw i64 %iv, 1
%cmp439 = icmp ult i64 %iv, 31
br i1 %cmp439, label %loop.header, label %exit
exit: ; preds = %loop.latch
ret void
}
define void @blend_chain_iv(i1 %c) {
; CHECK-LABEL: define void @blend_chain_iv(
; CHECK-SAME: i1 [[C:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i1> poison, i1 [[C]], i64 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i1> [[BROADCAST_SPLATINSERT]], <4 x i1> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 0, i64 1, i64 2, i64 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = select <4 x i1> [[BROADCAST_SPLAT]], <4 x i1> [[BROADCAST_SPLAT]], <4 x i1> zeroinitializer
; CHECK-NEXT: [[PREDPHI:%.*]] = select <4 x i1> [[TMP0]], <4 x i64> [[VEC_IND]], <4 x i64> undef
; CHECK-NEXT: [[PREDPHI1:%.*]] = select <4 x i1> [[BROADCAST_SPLAT]], <4 x i64> [[PREDPHI]], <4 x i64> undef
; CHECK-NEXT: [[TMP1:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 0
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP1]]
; CHECK-NEXT: [[TMP3:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 1
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP3]]
; CHECK-NEXT: [[TMP5:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 2
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP5]]
; CHECK-NEXT: [[TMP7:%.*]] = extractelement <4 x i64> [[PREDPHI1]], i32 3
; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[TMP7]]
; CHECK-NEXT: store i16 0, ptr [[TMP2]], align 2
; CHECK-NEXT: store i16 0, ptr [[TMP4]], align 2
; CHECK-NEXT: store i16 0, ptr [[TMP6]], align 2
; CHECK-NEXT: store i16 0, ptr [[TMP8]], align 2
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[VEC_IND_NEXT]] = add <4 x i64> [[VEC_IND]], splat (i64 4)
; CHECK-NEXT: [[TMP9:%.*]] = icmp eq i64 [[INDEX_NEXT]], 32
; CHECK-NEXT: br i1 [[TMP9]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
; CHECK: [[MIDDLE_BLOCK]]:
; CHECK-NEXT: br i1 true, label %[[EXIT:.*]], label %[[SCALAR_PH]]
; CHECK: [[SCALAR_PH]]:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ 32, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
; CHECK-NEXT: br label %[[LOOP_HEADER:.*]]
; CHECK: [[LOOP_HEADER]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ]
; CHECK-NEXT: br i1 [[C]], label %[[LOOP_NEXT:.*]], label %[[LOOP_LATCH]]
; CHECK: [[LOOP_NEXT]]:
; CHECK-NEXT: br i1 [[C]], label %[[LOOP_NEXT_2:.*]], label %[[LOOP_NEXT_3:.*]]
; CHECK: [[LOOP_NEXT_2]]:
; CHECK-NEXT: br label %[[LOOP_NEXT_3]]
; CHECK: [[LOOP_NEXT_3]]:
; CHECK-NEXT: [[BLEND_1:%.*]] = phi i64 [ undef, %[[LOOP_NEXT]] ], [ [[IV]], %[[LOOP_NEXT_2]] ]
; CHECK-NEXT: br label %[[LOOP_LATCH]]
; CHECK: [[LOOP_LATCH]]:
; CHECK-NEXT: [[BLEND:%.*]] = phi i64 [ undef, %[[LOOP_HEADER]] ], [ [[BLEND_1]], %[[LOOP_NEXT_3]] ]
; CHECK-NEXT: [[DST_PTR:%.*]] = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 [[BLEND]]
; CHECK-NEXT: store i16 0, ptr [[DST_PTR]], align 2
; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
; CHECK-NEXT: [[CMP439:%.*]] = icmp ult i64 [[IV]], 31
; CHECK-NEXT: br i1 [[CMP439]], label %[[LOOP_HEADER]], label %[[EXIT]], !llvm.loop [[LOOP7:![0-9]+]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
entry:
br label %loop.header
loop.header: ; preds = %loop.latch, %entry
%iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
br i1 %c, label %loop.next, label %loop.latch
loop.next: ; preds = %loop.header
br i1 %c, label %loop.next.2, label %loop.next.3
loop.next.2:
br label %loop.next.3
loop.next.3:
%blend.1 = phi i64 [ undef, %loop.next ], [ %iv, %loop.next.2 ]
br label %loop.latch
loop.latch: ; preds = %loop.next, %loop.header
%blend = phi i64 [ undef, %loop.header ], [ %blend.1, %loop.next.3 ]
%dst.ptr = getelementptr inbounds [32 x i16], ptr @dst, i16 0, i64 %blend
store i16 0, ptr %dst.ptr
%iv.next = add nuw nsw i64 %iv, 1
%cmp439 = icmp ult i64 %iv, 31
br i1 %cmp439, label %loop.header, label %exit
exit: ; preds = %loop.latch
ret void
}
;.
; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]}
; CHECK: [[META1]] = !{!"llvm.loop.isvectorized", i32 1}
; CHECK: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"}
; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META2]], [[META1]]}
; CHECK: [[LOOP4]] = distinct !{[[LOOP4]], [[META1]], [[META2]]}
; CHECK: [[LOOP5]] = distinct !{[[LOOP5]], [[META2]], [[META1]]}
; CHECK: [[LOOP6]] = distinct !{[[LOOP6]], [[META1]], [[META2]]}
; CHECK: [[LOOP7]] = distinct !{[[LOOP7]], [[META2]], [[META1]]}
;.
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