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clang-p2996/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
David Sherwood e762d4dac7 [LoopVectorize] Teach LoopVectorizationLegality about more early exits (#107004) 
This patch is split off from PR #88385 and concerns only the code
related to the legality of vectorising early exit loops. It is the first
step in adding support for vectorisation of a simple class of loops that
typically involves searching for something, i.e.

  for (int i = 0; i < n; i++) {
    if (p[i] == val)
      return i;
  }
  return n;

or

  for (int i = 0; i < n; i++) {
    if (p1[i] != p2[i])
      return i;
  }
  return n;

In this initial commit LoopVectorizationLegality will only consider
early exit loops legal for vectorising if they follow these criteria:

1. There are no stores in the loop.
2. The loop must have only one early exit like those shown in the above
example. I have referred to such exits as speculative early exits, to
distinguish from existing support for early exits where the
exit-not-taken count is known exactly at compile time.
3. The early exit block dominates the latch block.
4. The latch block must have an exact exit count.
5. There are no loads after the early exit block.
6. The loop must not contain reductions or recurrences. I don't see
anything fundamental blocking vectorisation of such loops, but I just
haven't done the work to support them yet.
7. We must be able to prove at compile-time that loops will not contain
faulting loads.

Tests have been added here:

  Transforms/LoopVectorize/AArch64/simple_early_exit.ll
2024-09-19 09:41:25 +01:00

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; RUN: opt < %s -passes=loop-vectorize,transform-warning -S -pass-remarks-missed='loop-vectorize' -pass-remarks-analysis='loop-vectorize' 2>&1 | FileCheck %s
; RUN: opt < %s -passes=loop-vectorize,transform-warning -o /dev/null -pass-remarks-output=%t.yaml
; RUN: cat %t.yaml | FileCheck -check-prefix=YAML %s
; C/C++ code for tests
; void test(int *A, int Length) {
; #pragma clang loop vectorize(enable) interleave(enable)
; for (int i = 0; i < Length; i++) {
; A[i] = i;
; if (A[i] > Length)
; break;
; }
; }
; File, line, and column should match those specified in the metadata
; CHECK: remark: source.cpp:5:9: loop not vectorized: Cannot vectorize early exit loop
; CHECK: remark: source.cpp:5:9: loop not vectorized
; void test_disabled(int *A, int Length) {
; #pragma clang loop vectorize(disable) interleave(disable)
; for (int i = 0; i < Length; i++)
; A[i] = i;
; }
; CHECK: remark: source.cpp:12:8: loop not vectorized: vectorization and interleaving are explicitly disabled, or the loop has already been vectorized
; void test_array_bounds(int *A, int *B, int Length) {
; #pragma clang loop vectorize(enable)
; for (int i = 0; i < Length; i++)
; A[i] = A[B[i]];
; }
; CHECK: remark: source.cpp:19:5: loop not vectorized: cannot identify array bounds
; CHECK: remark: source.cpp:18:8: loop not vectorized (Force=true)
; CHECK: warning: source.cpp:18:8: loop not vectorized: the optimizer was unable to perform the requested transformation; the transformation might be disabled or specified as part of an unsupported transformation ordering
; int foo();
; void test_multiple_failures(int *A) {
; int k = 0;
; #pragma clang loop vectorize(enable) interleave(enable)
; for (int i = 0; i < 1000; i+=A[i]) {
; if (A[i])
; k = foo();
; }
; return k;
; }
; CHECK: remark: source.cpp:29:7: loop not vectorized: control flow cannot be substituted for a select
; CHECK: remark: source.cpp:27:3: loop not vectorized
; YAML: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: EarlyExitNotLatchPredecessor
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 5, Column: 9 }
; YAML-NEXT: Function: _Z4testPii
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
; YAML-NEXT: - String: Cannot vectorize early exit loop
; YAML-NEXT: ...
; YAML-NEXT: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: MissedDetails
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 5, Column: 9 }
; YAML-NEXT: Function: _Z4testPii
; YAML-NEXT: Args:
; YAML-NEXT: - String: loop not vectorized
; YAML-NEXT: ...
; YAML-NEXT: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: AllDisabled
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 12, Column: 8 }
; YAML-NEXT: Function: _Z13test_disabledPii
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: vectorization and interleaving are explicitly disabled, or the loop has already been vectorized
; YAML-NEXT: ...
; YAML-NEXT: --- !Analysis
; YAML-NEXT: Pass: ''
; YAML-NEXT: Name: CantIdentifyArrayBounds
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 19, Column: 5 }
; YAML-NEXT: Function: _Z17test_array_boundsPiS_i
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
; YAML-NEXT: - String: cannot identify array bounds
; YAML-NEXT: ...
; YAML-NEXT: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: MissedDetails
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 18, Column: 8 }
; YAML-NEXT: Function: _Z17test_array_boundsPiS_i
; YAML-NEXT: Args:
; YAML-NEXT: - String: loop not vectorized
; YAML-NEXT: - String: ' (Force='
; YAML-NEXT: - Force: 'true'
; YAML-NEXT: - String: ')'
; YAML-NEXT: ...
; YAML-NEXT: --- !Failure
; YAML-NEXT: Pass: transform-warning
; YAML-NEXT: Name: FailedRequestedVectorization
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 18, Column: 8 }
; YAML-NEXT: Function: _Z17test_array_boundsPiS_i
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: the optimizer was unable to perform the requested transformation; the transformation might be disabled or specified as part of an unsupported transformation ordering'
; YAML-NEXT: ...
; YAML-NEXT: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: NoCFGForSelect
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 29, Column: 7 }
; YAML-NEXT: Function: test_multiple_failures
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
; YAML-NEXT: - String: control flow cannot be substituted for a select
; YAML-NEXT: ...
; YAML-NEXT: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: NonReductionValueUsedOutsideLoop
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 27, Column: 3 }
; YAML-NEXT: Function: test_multiple_failures
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
; YAML-NEXT: - String: value that could not be identified as reduction is used outside the loop
; YAML-NEXT: ...
; YAML-NEXT: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: EarlyExitNotLatchPredecessor
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 27, Column: 3 }
; YAML-NEXT: Function: test_multiple_failures
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
; YAML-NEXT: - String: Cannot vectorize early exit loop
; YAML-NEXT: ...
; YAML: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: MissedDetails
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 27, Column: 3 }
; YAML-NEXT: Function: test_multiple_failures
; YAML-NEXT: Args:
; YAML-NEXT: - String: loop not vectorized
; YAML-NEXT: ...
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
; Function Attrs: nounwind optsize ssp uwtable
define void @_Z4testPii(ptr nocapture %A, i32 %Length) #0 !dbg !4 {
entry:
%cmp10 = icmp sgt i32 %Length, 0, !dbg !12
br i1 %cmp10, label %for.body, label %for.end, !dbg !12, !llvm.loop !14
for.body: ; preds = %entry, %for.body
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, ptr %A, i64 %indvars.iv, !dbg !16
%0 = trunc i64 %indvars.iv to i32, !dbg !16
%ld = load i32, ptr %arrayidx, align 4
store i32 %0, ptr %arrayidx, align 4, !dbg !16, !tbaa !18
%cmp3 = icmp sle i32 %ld, %Length, !dbg !22
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1, !dbg !12
%1 = trunc i64 %indvars.iv.next to i32
%cmp = icmp slt i32 %1, %Length, !dbg !12
%or.cond = and i1 %cmp3, %cmp, !dbg !22
br i1 %or.cond, label %for.body, label %for.end, !dbg !22
for.end: ; preds = %for.body, %entry
ret void, !dbg !24
}
; CHECK: _Z4testPii
; CHECK-NOT: x i32>
; CHECK: ret
; Function Attrs: nounwind optsize ssp uwtable
define void @_Z13test_disabledPii(ptr nocapture %A, i32 %Length) #0 !dbg !7 {
entry:
%cmp4 = icmp sgt i32 %Length, 0, !dbg !25
br i1 %cmp4, label %for.body, label %for.end, !dbg !25, !llvm.loop !27
for.body: ; preds = %entry, %for.body
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, ptr %A, i64 %indvars.iv, !dbg !30
%0 = trunc i64 %indvars.iv to i32, !dbg !30
store i32 %0, ptr %arrayidx, align 4, !dbg !30, !tbaa !18
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1, !dbg !25
%lftr.wideiv = trunc i64 %indvars.iv.next to i32, !dbg !25
%exitcond = icmp eq i32 %lftr.wideiv, %Length, !dbg !25
br i1 %exitcond, label %for.end, label %for.body, !dbg !25, !llvm.loop !27
for.end: ; preds = %for.body, %entry
ret void, !dbg !31
}
; CHECK: _Z13test_disabledPii
; CHECK-NOT: x i32>
; CHECK: ret
; Function Attrs: nounwind optsize ssp uwtable
define void @_Z17test_array_boundsPiS_i(ptr nocapture %A, ptr nocapture readonly %B, i32 %Length) #0 !dbg !8 {
entry:
%cmp9 = icmp sgt i32 %Length, 0, !dbg !32
br i1 %cmp9, label %for.body.preheader, label %for.end, !dbg !32, !llvm.loop !34
for.body.preheader: ; preds = %entry
br label %for.body, !dbg !32
for.body: ; preds = %for.body.preheader, %for.body
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
%arrayidx = getelementptr inbounds i32, ptr %B, i64 %indvars.iv, !dbg !35
%0 = load i32, ptr %arrayidx, align 4, !dbg !35, !tbaa !18
%idxprom1 = sext i32 %0 to i64, !dbg !35
%arrayidx2 = getelementptr inbounds i32, ptr %A, i64 %idxprom1, !dbg !35
%1 = load i32, ptr %arrayidx2, align 4, !dbg !35, !tbaa !18
%arrayidx4 = getelementptr inbounds i32, ptr %A, i64 %indvars.iv, !dbg !35
store i32 %1, ptr %arrayidx4, align 4, !dbg !35, !tbaa !18
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1, !dbg !32
%lftr.wideiv = trunc i64 %indvars.iv.next to i32, !dbg !32
%exitcond = icmp eq i32 %lftr.wideiv, %Length, !dbg !32
br i1 %exitcond, label %for.end.loopexit, label %for.body, !dbg !32, !llvm.loop !34
for.end.loopexit: ; preds = %for.body
br label %for.end
for.end: ; preds = %for.end.loopexit, %entry
ret void, !dbg !36
}
; CHECK: _Z17test_array_boundsPiS_i
; CHECK-NOT: x i32>
; CHECK: ret
; Function Attrs: nounwind uwtable
define i32 @test_multiple_failures(ptr nocapture readonly %A) #0 !dbg !46 {
entry:
br label %for.body, !dbg !38
for.body: ; preds = %entry, %for.inc
%i.09 = phi i32 [ 0, %entry ], [ %add, %for.inc ]
%k.09 = phi i32 [ 0, %entry ], [ %k.1, %for.inc ]
%arrayidx = getelementptr inbounds i32, ptr %A, i32 %i.09, !dbg !40
%0 = load i32, ptr %arrayidx, align 4, !dbg !40
%tobool = icmp eq i32 %0, 0, !dbg !40
br i1 %tobool, label %for.inc, label %if.then, !dbg !40
if.then: ; preds = %for.body
%call = tail call i32 (...) @foo(), !dbg !41
%.pre = load i32, ptr %arrayidx, align 4
br label %for.inc, !dbg !42
for.inc: ; preds = %for.body, %if.then
%1 = phi i32 [ %.pre, %if.then ], [ 0, %for.body ], !dbg !43
%k.1 = phi i32 [ %call, %if.then ], [ %k.09, %for.body ]
%add = add nsw i32 %1, %i.09, !dbg !44
%cmp = icmp slt i32 %add, 1000, !dbg !45
br i1 %cmp, label %for.body, label %for.cond.cleanup, !dbg !38
for.cond.cleanup: ; preds = %for.inc
ret i32 %k.1, !dbg !39
}
declare i32 @foo(...)
; CHECK: test_multiple_failure
; CHECK-NOT: x i32>
; CHECK: ret
attributes #0 = { nounwind }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!9, !10}
!llvm.ident = !{!11}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5.0", isOptimized: true, runtimeVersion: 6, emissionKind: LineTablesOnly, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
!1 = !DIFile(filename: "source.cpp", directory: ".")
!2 = !{}
!4 = distinct !DISubprogram(name: "test", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 1, file: !1, scope: !5, type: !6, retainedNodes: !2)
!5 = !DIFile(filename: "source.cpp", directory: ".")
!6 = !DISubroutineType(types: !2)
!7 = distinct !DISubprogram(name: "test_disabled", line: 10, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 10, file: !1, scope: !5, type: !6, retainedNodes: !2)
!8 = distinct !DISubprogram(name: "test_array_bounds", line: 16, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 16, file: !1, scope: !5, type: !6, retainedNodes: !2)
!9 = !{i32 2, !"Dwarf Version", i32 2}
!10 = !{i32 2, !"Debug Info Version", i32 3}
!11 = !{!"clang version 3.5.0"}
!12 = !DILocation(line: 3, column: 8, scope: !13)
!13 = distinct !DILexicalBlock(line: 3, column: 3, file: !1, scope: !4)
!14 = !{!14, !15, !15}
!15 = !{!"llvm.loop.vectorize.enable", i1 true}
!16 = !DILocation(line: 4, column: 5, scope: !17)
!17 = distinct !DILexicalBlock(line: 3, column: 36, file: !1, scope: !13)
!18 = !{!19, !19, i64 0}
!19 = !{!"int", !20, i64 0}
!20 = !{!"omnipotent char", !21, i64 0}
!21 = !{!"Simple C/C++ TBAA"}
!22 = !DILocation(line: 5, column: 9, scope: !23)
!23 = distinct !DILexicalBlock(line: 5, column: 9, file: !1, scope: !17)
!24 = !DILocation(line: 8, column: 1, scope: !4)
!25 = !DILocation(line: 12, column: 8, scope: !26)
!26 = distinct !DILexicalBlock(line: 12, column: 3, file: !1, scope: !7)
!27 = !{!27, !28, !29}
!28 = !{!"llvm.loop.interleave.count", i32 1}
!29 = !{!"llvm.loop.vectorize.width", i32 1}
!30 = !DILocation(line: 13, column: 5, scope: !26)
!31 = !DILocation(line: 14, column: 1, scope: !7)
!32 = !DILocation(line: 18, column: 8, scope: !33)
!33 = distinct !DILexicalBlock(line: 18, column: 3, file: !1, scope: !8)
!34 = !{!34, !15}
!35 = !DILocation(line: 19, column: 5, scope: !33)
!36 = !DILocation(line: 20, column: 1, scope: !8)
!37 = distinct !DILexicalBlock(line: 24, column: 3, file: !1, scope: !46)
!38 = !DILocation(line: 27, column: 3, scope: !37)
!39 = !DILocation(line: 31, column: 3, scope: !37)
!40 = !DILocation(line: 28, column: 9, scope: !37)
!41 = !DILocation(line: 29, column: 11, scope: !37)
!42 = !DILocation(line: 29, column: 7, scope: !37)
!43 = !DILocation(line: 27, column: 32, scope: !37)
!44 = !DILocation(line: 27, column: 30, scope: !37)
!45 = !DILocation(line: 27, column: 21, scope: !37)
!46 = distinct !DISubprogram(name: "test_multiple_failures", line: 26, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 26, file: !1, scope: !5, type: !6, retainedNodes: !2)
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