llvm-project/llvm/test/CodeGen/X86/update-terminator-debugloc.ll

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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
; RUN: llc -stop-after=machine-sink -march=x86-64 < %s | FileCheck %s
;
; test code:
; 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 }
;
; With the test code, LLVM-IR below shows that loop-control branches have a
; debug location of line 6 (branches in entry and for.body block). Make sure that
; these debug locations are propaged correctly to lowered instructions.
;
; CHECK: [[DLOC:![0-9]+]] = !DILocation(line: 6
; CHECK-DAG: [[VREG1:%[^ ]+]] = COPY %rsi
; CHECK-DAG: [[VREG2:%[^ ]+]] = COPY %rdi
; CHECK: SUB64rr [[VREG2]], [[VREG1]]
; CHECK-NEXT: JNE_1 {{.*}}, debug-location [[DLOC]]{{$}}
; CHECK: [[VREG3:%[^ ]+]] = PHI [[VREG2]]
; CHECK: [[VREG4:%[^ ]+]] = ADD64ri8 [[VREG3]], 4
; CHECK: SUB64rr [[VREG1]], [[VREG4]]
; CHECK-NEXT: JNE_1 {{.*}}, debug-location [[DLOC]]{{$}}
; CHECK-NEXT: JMP_1 {{.*}}, debug-location [[DLOC]]{{$}}
target triple = "x86_64-unknown-linux-gnu"
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
}
declare i32 @bar(i32)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1)
!1 = !DIFile(filename: "foo.c", directory: "b/")
!2 = !{i32 2, !"Dwarf Version", i32 4}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!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)
!5 = !DISubroutineType(types: !6)
!6 = !{!7, !8, !8}
!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!8 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !7, size: 64)
!9 = !DILocation(line: 8, column: 9, scope: !10)
!10 = distinct !DILexicalBlock(scope: !11, file: !1, line: 6, column: 3)
!11 = distinct !DILexicalBlock(scope: !4, file: !1, line: 6, column: 3)
!12 = !DILocation(line: 6, column: 3, scope: !11)
!13 = !DILocation(line: 11, column: 18, scope: !14)
!14 = distinct !DILexicalBlock(scope: !10, file: !1, line: 10, column: 3)
!15 = !{!16, !16, i64 0}
!16 = !{!"int", !17, i64 0}
!17 = !{!"omnipotent char", !18, i64 0}
!18 = !{!"Simple C/C++ TBAA"}
!19 = !DILocation(line: 11, column: 14, scope: !14)
!20 = !DILocation(line: 11, column: 11, scope: !14)
!21 = !DILocation(line: 9, column: 8, scope: !10)
!22 = distinct !{!22, !12, !23}
!23 = !DILocation(line: 12, column: 3, scope: !11)
!24 = !DILocation(line: 13, column: 3, scope: !4)