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Orlando Cazalet-Hyams 4f09faa3f6 [DebugInfo@O2][LoopVectorize] pr39024: Vectorized code linenos step through loop even after completion
Summary:
Bug: https://bugs.llvm.org/show_bug.cgi?id=39024

The bug reports that a vectorized loop is stepped through 4 times and each step through the loop seemed to show a different path. I found two problems here:

A) An incorrect line number on a preheader block (for.body.preheader) instruction causes a step into the loop before it begins.
B) Instructions in the middle block have different line numbers which give the impression of another iteration.

In this patch I give all of the middle block instructions the line number of the scalar loop latch terminator branch. This seems to provide the smoothest debugging experience because the vectorized loops will always end on this line before dropping into the scalar loop. To solve problem A I have altered llvm::SplitBlockPredecessors to accommodate loop header blocks.

I have set up a separate review D61933 for a fix which is required for this patch.

Reviewers: samsonov, vsk, aprantl, probinson, anemet, hfinkel, jmorse

Reviewed By: hfinkel, jmorse

Subscribers: jmorse, javed.absar, eraman, kcc, bjope, jmellorcrummey, hfinkel, gbedwell, hiraditya, zzheng, llvm-commits

Tags: #llvm, #debug-info

Differential Revision: https://reviews.llvm.org/D60831

> llvm-svn: 363046

llvm-svn: 363786
2019-06-19 10:50:47 +00:00

93 lines
5.1 KiB
LLVM

; RUN: opt -S < %s -loop-vectorize -force-vector-interleave=1 -force-vector-width=2 | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
; Make sure we are preserving debug info in the vectorized code.
; CHECK: for.body.lr.ph
; CHECK: min.iters.check = icmp ult i64 {{.*}}, 2, !dbg !{{[0-9]+}}
; CHECK: vector.body
; CHECK: index {{.*}}, !dbg ![[LOC:[0-9]+]]
; CHECK: getelementptr inbounds i32, i32* %a, {{.*}}, !dbg ![[LOC]]
; CHECK: load <2 x i32>, <2 x i32>* {{.*}}, !dbg ![[LOC]]
; CHECK: add <2 x i32> {{.*}}, !dbg ![[LOC]]
; CHECK: add i64 %index, 2, !dbg ![[LOC]]
; CHECK: icmp eq i64 %index.next, %n.vec, !dbg ![[LOC]]
; CHECK: middle.block
; CHECK: add <2 x i32> %{{.*}}, %rdx.shuf, !dbg ![[BR_LOC:[0-9]+]]
; CHECK: extractelement <2 x i32> %bin.rdx, i32 0, !dbg ![[BR_LOC]]
; CHECK: for.body
; CHECK br i1{{.*}}, label %for.body,{{.*}}, !dbg ![[BR_LOC]],
; CHECK: ![[BR_LOC]] = !DILocation(line: 5,
define i32 @f(i32* nocapture %a, i32 %size) #0 !dbg !4 {
entry:
call void @llvm.dbg.value(metadata i32* %a, metadata !13, metadata !DIExpression()), !dbg !19
call void @llvm.dbg.value(metadata i32 %size, metadata !14, metadata !DIExpression()), !dbg !19
call void @llvm.dbg.value(metadata i32 0, metadata !15, metadata !DIExpression()), !dbg !20
call void @llvm.dbg.value(metadata i32 0, metadata !16, metadata !DIExpression()), !dbg !21
%cmp4 = icmp eq i32 %size, 0, !dbg !21
br i1 %cmp4, label %for.end, label %for.body.lr.ph, !dbg !21
for.body.lr.ph: ; preds = %entry
br label %for.body, !dbg !21
for.body: ; preds = %for.body.lr.ph, %for.body
%indvars.iv = phi i64 [ 0, %for.body.lr.ph ], [ %indvars.iv.next, %for.body ]
%sum.05 = phi i32 [ 0, %for.body.lr.ph ], [ %add, %for.body ]
%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv, !dbg !22
%0 = load i32, i32* %arrayidx, align 4, !dbg !22
%add = add i32 %0, %sum.05, !dbg !22
%indvars.iv.next = add i64 %indvars.iv, 1, !dbg !22
call void @llvm.dbg.value(metadata !{null}, metadata !16, metadata !DIExpression()), !dbg !22
%lftr.wideiv = trunc i64 %indvars.iv.next to i32, !dbg !22
%exitcond = icmp ne i32 %lftr.wideiv, %size, !dbg !21
br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge, !dbg !21
for.cond.for.end_crit_edge: ; preds = %for.body
%add.lcssa = phi i32 [ %add, %for.body ]
call void @llvm.dbg.value(metadata i32 %add.lcssa, metadata !15, metadata !DIExpression()), !dbg !22
br label %for.end, !dbg !21
for.end: ; preds = %entry, %for.cond.for.end_crit_edge
%sum.0.lcssa = phi i32 [ %add.lcssa, %for.cond.for.end_crit_edge ], [ 0, %entry ]
ret i32 %sum.0.lcssa, !dbg !26
}
; Function Attrs: nounwind readnone
declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
; Function Attrs: nounwind readnone
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
attributes #0 = { nounwind readonly ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "unsafe-fp-math"="true" "use-soft-float"="false" }
attributes #1 = { nounwind readnone }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!18, !27}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "clang version 3.4 (trunk 185038) (llvm/trunk 185097)", isOptimized: true, emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
!1 = !DIFile(filename: "-", directory: "/Volumes/Data/backedup/dev/os/llvm/debug")
!2 = !{}
!4 = distinct !DISubprogram(name: "f", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 3, file: !5, scope: !6, type: !7, retainedNodes: !12)
!5 = !DIFile(filename: "<stdin>", directory: "/Volumes/Data/backedup/dev/os/llvm/debug")
!6 = !DIFile(filename: "<stdin>", directory: "/Volumes/Data/backedup/dev/os/llvm/debug")
!7 = !DISubroutineType(types: !8)
!8 = !{!9, !10, !11}
!9 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!10 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 64, align: 64, baseType: !9)
!11 = !DIBasicType(tag: DW_TAG_base_type, name: "unsigned int", size: 32, align: 32, encoding: DW_ATE_unsigned)
!12 = !{!13, !14, !15, !16}
!13 = !DILocalVariable(name: "a", line: 3, arg: 1, scope: !4, file: !6, type: !10)
!14 = !DILocalVariable(name: "size", line: 3, arg: 2, scope: !4, file: !6, type: !11)
!15 = !DILocalVariable(name: "sum", line: 4, scope: !4, file: !6, type: !11)
!16 = !DILocalVariable(name: "i", line: 5, scope: !17, file: !6, type: !11)
!17 = distinct !DILexicalBlock(line: 5, column: 0, file: !5, scope: !4)
!18 = !{i32 2, !"Dwarf Version", i32 3}
!19 = !DILocation(line: 3, scope: !4)
!20 = !DILocation(line: 4, scope: !4)
!21 = !DILocation(line: 5, scope: !17)
!22 = !DILocation(line: 6, scope: !17)
!26 = !DILocation(line: 7, scope: !4)
!27 = !{i32 1, !"Debug Info Version", i32 3}