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[BranchFolding] Update debug location along with the update of branch instruction.

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Summary:
Currently, BranchFolder drops DebugLoc for branch instructions in some places. For example, for the test code attached, the branch instruction of 'entry' block has a DILocation of

```
!12 = !DILocation(line: 6, column: 3, scope: !11)
```

, but this information is gone when then block is lowered because BranchFolder misses it. This patch is a fix for this issue.

Reviewers: qcolombet, aprantl, craig.topper, MatzeB

Reviewed By: aprantl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29902

llvm-svn: 295684
This commit is contained in:
Taewook Oh 2017-02-21 00:12:38 +00:00
parent 3ff799a5b9
commit ff35f1dcd3
2 changed files with 86 additions and 3 deletions
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6
lib/CodeGen/BranchFolding.cpp
View File

@ -389,7 +389,7 @@ MachineBasicBlock *BranchFolder::SplitMBBAt(MachineBasicBlock &CurMBB,
NewMBB->splice(NewMBB->end(), &CurMBB, BBI1, CurMBB.end());
// NewMBB belongs to the same loop as CurMBB.
if (MLI)
if (MLI)
if (MachineLoop *ML = MLI->getLoopFor(&CurMBB))
ML->addBasicBlockToLoop(NewMBB, MLI->getBase());
@ -437,7 +437,7 @@ static void FixTail(MachineBasicBlock *CurMBB, MachineBasicBlock *SuccBB,
MachineFunction::iterator I = std::next(MachineFunction::iterator(CurMBB));
MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
SmallVector<MachineOperand, 4> Cond;
DebugLoc dl; // FIXME: this is nowhere
DebugLoc dl = CurMBB->findBranchDebugLoc();
if (I != MF->end() && !TII->analyzeBranch(*CurMBB, TBB, FBB, Cond, true)) {
MachineBasicBlock *NextBB = &*I;
if (TBB == NextBB && !Cond.empty() && !FBB) {
@ -1073,7 +1073,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
// Remove the unconditional branch at the end, if any.
if (TBB && (Cond.empty() || FBB)) {
DebugLoc dl; // FIXME: this is nowhere
DebugLoc dl = PBB->findBranchDebugLoc();
TII->removeBranch(*PBB);
if (!Cond.empty())
// reinsert conditional branch only, for now

83
test/CodeGen/X86/branchfolding-debugloc.ll Normal file
View File

@ -0,0 +1,83 @@
; RUN: llc < %s | FileCheck %s
;
; The test code is generated from the following source 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 }
;
; CHECK: # %entry
; CHECK-NOT: # %for.body
; CHECK: .loc 1 6 3
; CHECK-NEXT: je [[BB:.LBB[^ ]+]]
; CHECK: [[BB]]:{{.}}# %for.end
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, emissionKind: FullDebug)
!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)