2017-08-02 08:28:10 +08:00
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; RUN: llc -stop-after=machine-sink < %s | FileCheck %s
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Make MachineBasicBlock::updateTerminator to update DebugLoc as well
Summary:
Currently MachineBasicBlock::updateTerminator simply drops DebugLoc for newly created branch instructions, which may cause incorrect stepping and/or imprecise sample profile data. Below is an example:
```
1 extern int bar(int x);
2
3 int foo(int *begin, int *end) {
4 int *i;
5 int ret = 0;
6 for (
7 i = begin ;
8 i != end ;
9 i++)
10 {
11 ret += bar(*i);
12 }
13 return ret;
14 }
```
Below is a bitcode of 'foo' at the end of LLVM-IR level optimizations with -O3:
```
define i32 @foo(i32* readonly %begin, i32* readnone %end) !dbg !4 {
entry:
%cmp6 = icmp eq i32* %begin, %end, !dbg !9
br i1 %cmp6, label %for.end, label %for.body.preheader, !dbg !12
for.body.preheader: ; preds = %entry
br label %for.body, !dbg !13
for.body: ; preds = %for.body.preheader, %for.body
%ret.08 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
%i.07 = phi i32* [ %incdec.ptr, %for.body ], [ %begin, %for.body.preheader ]
%0 = load i32, i32* %i.07, align 4, !dbg !13, !tbaa !15
%call = tail call i32 @bar(i32 %0), !dbg !19
%add = add nsw i32 %call, %ret.08, !dbg !20
%incdec.ptr = getelementptr inbounds i32, i32* %i.07, i64 1, !dbg !21
%cmp = icmp eq i32* %incdec.ptr, %end, !dbg !9
br i1 %cmp, label %for.end.loopexit, label %for.body, !dbg !12, !llvm.loop !22
for.end.loopexit: ; preds = %for.body
br label %for.end, !dbg !24
for.end: ; preds = %for.end.loopexit, %entry
%ret.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.end.loopexit ]
ret i32 %ret.0.lcssa, !dbg !24
}
```
where
```
!12 = !DILocation(line: 6, column: 3, scope: !11)
```
. As you can see, the terminator of 'entry' block, which is a loop control branch, has a DebugLoc of line 6, column 3. Howerver, after the execution of 'MachineBlock::updateTerminator' function, which is triggered by MachineSinking pass, the DebugLoc info is dropped as below (see there's no debug-location for JNE_1):
```
bb.0.entry:
successors: %bb.4(0x30000000), %bb.1.for.body.preheader(0x50000000)
liveins: %rdi, %rsi
%6 = COPY %rsi
%5 = COPY %rdi
%8 = SUB64rr %5, %6, implicit-def %eflags, debug-location !9
JNE_1 %bb.1.for.body.preheader, implicit %eflags
```
This patch addresses this issue and make newly created branch instructions to keep debug-location info.
Reviewers: aprantl, MatzeB, craig.topper, qcolombet
Reviewed By: qcolombet
Subscribers: qcolombet, llvm-commits
Differential Revision: https://reviews.llvm.org/D29596
llvm-svn: 294976
2017-02-14 02:15:31 +08:00
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;
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; test code:
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; 1 extern int bar(int x);
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; 2
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; 3 int foo(int *begin, int *end) {
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; 4 int *i;
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; 5 int ret = 0;
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; 6 for (
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; 7 i = begin ;
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; 8 i != end ;
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; 9 i++)
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; 10 {
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; 11 ret += bar(*i);
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; 12 }
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; 13 return ret;
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; 14 }
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;
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; With the test code, LLVM-IR below shows that loop-control branches have a
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; debug location of line 6 (branches in entry and for.body block). Make sure that
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; these debug locations are propaged correctly to lowered instructions.
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;
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; CHECK: [[DLOC:![0-9]+]] = !DILocation(line: 6
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; CHECK-DAG: [[VREG1:%[^ ]+]] = COPY %rsi
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; CHECK-DAG: [[VREG2:%[^ ]+]] = COPY %rdi
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; CHECK: SUB64rr [[VREG2]], [[VREG1]]
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; CHECK-NEXT: JNE_1 {{.*}}, debug-location [[DLOC]]{{$}}
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; CHECK: [[VREG3:%[^ ]+]] = PHI [[VREG2]]
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; CHECK: [[VREG4:%[^ ]+]] = ADD64ri8 [[VREG3]], 4
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; CHECK: SUB64rr [[VREG1]], [[VREG4]]
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; CHECK-NEXT: JNE_1 {{.*}}, debug-location [[DLOC]]{{$}}
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; CHECK-NEXT: JMP_1 {{.*}}, debug-location [[DLOC]]{{$}}
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target triple = "x86_64-unknown-linux-gnu"
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define i32 @foo(i32* readonly %begin, i32* readnone %end) !dbg !4 {
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entry:
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%cmp6 = icmp eq i32* %begin, %end, !dbg !9
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br i1 %cmp6, label %for.end, label %for.body.preheader, !dbg !12
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for.body.preheader: ; preds = %entry
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br label %for.body, !dbg !13
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for.body: ; preds = %for.body.preheader, %for.body
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%ret.08 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
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%i.07 = phi i32* [ %incdec.ptr, %for.body ], [ %begin, %for.body.preheader ]
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%0 = load i32, i32* %i.07, align 4, !dbg !13, !tbaa !15
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%call = tail call i32 @bar(i32 %0), !dbg !19
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%add = add nsw i32 %call, %ret.08, !dbg !20
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%incdec.ptr = getelementptr inbounds i32, i32* %i.07, i64 1, !dbg !21
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%cmp = icmp eq i32* %incdec.ptr, %end, !dbg !9
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br i1 %cmp, label %for.end.loopexit, label %for.body, !dbg !12, !llvm.loop !22
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for.end.loopexit: ; preds = %for.body
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br label %for.end, !dbg !24
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for.end: ; preds = %for.end.loopexit, %entry
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%ret.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.end.loopexit ]
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ret i32 %ret.0.lcssa, !dbg !24
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}
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declare i32 @bar(i32)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1)
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!1 = !DIFile(filename: "foo.c", directory: "b/")
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!2 = !{i32 2, !"Dwarf Version", i32 4}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, unit: !0)
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!5 = !DISubroutineType(types: !6)
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!6 = !{!7, !8, !8}
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!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!8 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !7, size: 64)
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!9 = !DILocation(line: 8, column: 9, scope: !10)
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!10 = distinct !DILexicalBlock(scope: !11, file: !1, line: 6, column: 3)
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!11 = distinct !DILexicalBlock(scope: !4, file: !1, line: 6, column: 3)
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!12 = !DILocation(line: 6, column: 3, scope: !11)
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!13 = !DILocation(line: 11, column: 18, scope: !14)
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!14 = distinct !DILexicalBlock(scope: !10, file: !1, line: 10, column: 3)
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!15 = !{!16, !16, i64 0}
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!16 = !{!"int", !17, i64 0}
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!17 = !{!"omnipotent char", !18, i64 0}
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!18 = !{!"Simple C/C++ TBAA"}
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!19 = !DILocation(line: 11, column: 14, scope: !14)
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!20 = !DILocation(line: 11, column: 11, scope: !14)
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!21 = !DILocation(line: 9, column: 8, scope: !10)
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!22 = distinct !{!22, !12, !23}
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!23 = !DILocation(line: 12, column: 3, scope: !11)
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!24 = !DILocation(line: 13, column: 3, scope: !4)
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