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llvm-mirror/test/Transforms/LoopVectorize/fix-reduction-dbg.ll
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

88 lines
3.6 KiB
LLVM
Executable File

; Confirm that the line numbers for the middle.block operations are all the
; same as the start of the loop.
; RUN: opt -S -loop-vectorize -force-vector-width=4 -force-vector-interleave=4 <%s | FileCheck %s
;
; CHECK: middle.block:
; CHECK-NEXT: %{{.*}}= add <4 x i32>{{.*}}, !dbg ![[DL:[0-9]+]]
; CHECK-NEXT: %{{.*}}= add <4 x i32>{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: %{{.*}}= add <4 x i32>{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: %{{.*}}= shufflevector <4 x i32>{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: %{{.*}}= add <4 x i32>{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: %{{.*}}= shufflevector <4 x i32>{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: %{{.*}}= add <4 x i32>{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: %{{.*}}= extractelement <4 x i32>{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: %{{.*}}= icmp eq i64{{.*}}, !dbg ![[DL]]
; CHECK-NEXT: br i1 %{{.*}}, !dbg ![[DL]]
; CHECK: ![[DL]] = !DILocation(line: 5,
; This IR can be generated by running:
; clang -gmlt -S src.cpp -emit-llvm -mllvm -opt-bisect-limit=56 -O2 -o -
;
; Where src.cpp contains:
; int foo(int count, int *bar)
; {
; int ret = count;
; int tmp;
; for (int j = 0; j < count; j++) {
; tmp = bar[j];
; ret += tmp;
; }
;
; return ret;
; }
define dso_local i32 @"foo"(i32 %count, i32* nocapture readonly %bar) local_unnamed_addr !dbg !8 {
entry:
%cmp8 = icmp sgt i32 %count, 0, !dbg !10
br i1 %cmp8, label %for.body.preheader, label %for.cond.cleanup, !dbg !10
for.body.preheader: ; preds = %entry
%wide.trip.count = zext i32 %count to i64
br label %for.body, !dbg !11
for.cond.cleanup.loopexit: ; preds = %for.body
%add.lcssa = phi i32 [ %add, %for.body ], !dbg !12
br label %for.cond.cleanup, !dbg !13
for.cond.cleanup: ; preds = %for.cond.cleanup.loopexit, %entry
%ret.0.lcssa = phi i32 [ %count, %entry ], [ %add.lcssa, %for.cond.cleanup.loopexit ], !dbg !14
ret i32 %ret.0.lcssa, !dbg !13
for.body: ; preds = %for.body, %for.body.preheader
%indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %for.body ]
%ret.09 = phi i32 [ %count, %for.body.preheader ], [ %add, %for.body ]
%arrayidx = getelementptr inbounds i32, i32* %bar, i64 %indvars.iv, !dbg !11
%0 = load i32, i32* %arrayidx, align 4, !dbg !11, !tbaa !15
%add = add nsw i32 %0, %ret.09, !dbg !12
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1, !dbg !10
%exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count, !dbg !10
br i1 %exitcond, label %for.cond.cleanup.loopexit, label %for.body, !dbg !10, !llvm.loop !19
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6}
!llvm.ident = !{!7}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "src.cpp", directory: "")
!2 = !{}
!3 = !{i32 2, !"CodeView", i32 1}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 2}
!6 = !{i32 7, !"PIC Level", i32 2}
!7 = !{!""}
!8 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !9, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
!9 = !DISubroutineType(types: !2)
!10 = !DILocation(line: 5, scope: !8)
!11 = !DILocation(line: 6, scope: !8)
!12 = !DILocation(line: 7, scope: !8)
!13 = !DILocation(line: 10, scope: !8)
!14 = !DILocation(line: 0, scope: !8)
!15 = !{!16, !16, i64 0}
!16 = !{!"int", !17, i64 0}
!17 = !{!"omnipotent char", !18, i64 0}
!18 = !{!"Simple C++ TBAA"}
!19 = distinct !{!19, !10, !20}
!20 = !DILocation(line: 8, scope: !8)