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clang-p2996/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
Michael Kruse 7244852557 [Unroll/UnrollAndJam/Vectorizer/Distribute] Add followup loop attributes. 
When multiple loop transformation are defined in a loop's metadata, their order of execution is defined by the order of their respective passes in the pass pipeline. For instance, e.g.

    #pragma clang loop unroll_and_jam(enable)
    #pragma clang loop distribute(enable)

is the same as

    #pragma clang loop distribute(enable)
    #pragma clang loop unroll_and_jam(enable)

and will try to loop-distribute before Unroll-And-Jam because the LoopDistribute pass is scheduled after UnrollAndJam pass. UnrollAndJamPass only supports one inner loop, i.e. it will necessarily fail after loop distribution. It is not possible to specify another execution order. Also,t the order of passes in the pipeline is subject to change between versions of LLVM, optimization options and which pass manager is used.

This patch adds 'followup' attributes to various loop transformation passes. These attributes define which attributes the resulting loop of a transformation should have. For instance,

    !0 = !{!0, !1, !2}
    !1 = !{!"llvm.loop.unroll_and_jam.enable"}
    !2 = !{!"llvm.loop.unroll_and_jam.followup_inner", !3}
    !3 = !{!"llvm.loop.distribute.enable"}

defines a loop ID (!0) to be unrolled-and-jammed (!1) and then the attribute !3 to be added to the jammed inner loop, which contains the instruction to distribute the inner loop.

Currently, in both pass managers, pass execution is in a fixed order and UnrollAndJamPass will not execute again after LoopDistribute. We hope to fix this in the future by allowing pass managers to run passes until a fixpoint is reached, use Polly to perform these transformations, or add a loop transformation pass which takes the order issue into account.

For mandatory/forced transformations (e.g. by having been declared by #pragma omp simd), the user must be notified when a transformation could not be performed. It is not possible that the responsible pass emits such a warning because the transformation might be 'hidden' in a followup attribute when it is executed, or it is not present in the pipeline at all. For this reason, this patche introduces a WarnMissedTransformations pass, to warn about orphaned transformations.

Since this changes the user-visible diagnostic message when a transformation is applied, two test cases in the clang repository need to be updated.

To ensure that no other transformation is executed before the intended one, the attribute `llvm.loop.disable_nonforced` can be added which should disable transformation heuristics before the intended transformation is applied. E.g. it would be surprising if a loop is distributed before a #pragma unroll_and_jam is applied.

With more supported code transformations (loop fusion, interchange, stripmining, offloading, etc.), transformations can be used as building blocks for more complex transformations (e.g. stripmining+stripmining+interchange -> tiling).

Reviewed By: hfinkel, dmgreen

Differential Revision: https://reviews.llvm.org/D49281
Differential Revision: https://reviews.llvm.org/D55288

llvm-svn: 348944
2018-12-12 17:32:52 +00:00

314 lines
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; RUN: opt < %s -loop-vectorize -transform-warning -S -pass-remarks-missed='loop-vectorize' -pass-remarks-analysis='loop-vectorize' 2>&1 | FileCheck %s
; RUN: opt < %s -loop-vectorize -transform-warning -o /dev/null -pass-remarks-output=%t.yaml
; RUN: cat %t.yaml | FileCheck -check-prefix=YAML %s
; 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:4:5: loop not vectorized: could not determine number of loop iterations
; CHECK: remark: source.cpp:4:5: 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:13:5: 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:19:5: loop not vectorized
; CHECK: warning: source.cpp:19:5: 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: CantComputeNumberOfIterations
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 4, Column: 5 }
; YAML-NEXT: Function: _Z4testPii
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
; YAML-NEXT: - String: could not determine number of loop iterations
; YAML-NEXT: ...
; YAML-NEXT: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
; YAML-NEXT: Name: MissedDetails
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 4, Column: 5 }
; 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: 13, Column: 5 }
; 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: 19, Column: 5 }
; 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: 19, Column: 5 }
; 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: CantComputeNumberOfIterations
; 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: could not determine number of loop iterations
; YAML-NEXT: ...
; YAML-NEXT: --- !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(i32* 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, i32* %A, i64 %indvars.iv, !dbg !16
%0 = trunc i64 %indvars.iv to i32, !dbg !16
%ld = load i32, i32* %arrayidx, align 4
store i32 %0, i32* %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(i32* 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, i32* %A, i64 %indvars.iv, !dbg !30
%0 = trunc i64 %indvars.iv to i32, !dbg !30
store i32 %0, i32* %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(i32* nocapture %A, i32* 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 !35
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, i32* %B, i64 %indvars.iv, !dbg !35
%0 = load i32, i32* %arrayidx, align 4, !dbg !35, !tbaa !18
%idxprom1 = sext i32 %0 to i64, !dbg !35
%arrayidx2 = getelementptr inbounds i32, i32* %A, i64 %idxprom1, !dbg !35
%1 = load i32, i32* %arrayidx2, align 4, !dbg !35, !tbaa !18
%arrayidx4 = getelementptr inbounds i32, i32* %A, i64 %indvars.iv, !dbg !35
store i32 %1, i32* %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(i32* 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, i32* %A, i32 %i.09, !dbg !40
%0 = load i32, i32* %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, i32* %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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