forked from OSchip/llvm-project
Fix out-of-order stepping behavior in programs with sunk instructions.
MachineSink attempts to place instructions near the basic blocks where they are needed. Once an instruction has been sunk, its location relative to other instructions no longer is consistent with the original source code. In order to ensure correct stepping in the debugger, the debug location for sunk instructions is either merged with the insertion point or erased if the target successor block is empty. Originally submitted as r318679, revised to fix sanitizer failure and improve testing. Patch by Matthew Voss! Differential Revision: https://reviews.llvm.org/D39933 llvm-svn: 320216
This commit is contained in:
Paul Robinson
parent
502775a2ee
commit
8bd9d6ad83
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@ -38,6 +38,7 @@
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#include "llvm/CodeGen/TargetSubtargetInfo.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/DebugInfoMetadata.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/BranchProbability.h"
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#include "llvm/Support/CommandLine.h"
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@ -868,11 +869,20 @@ bool MachineSinking::SinkInstruction(MachineInstr &MI, bool &SawStore,
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SmallVector<MachineInstr *, 2> DbgValuesToSink;
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collectDebugValues(MI, DbgValuesToSink);
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// Merge or erase debug location to ensure consistent stepping in profilers
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// and debuggers.
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if (!SuccToSinkTo->empty() && InsertPos != SuccToSinkTo->end())
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MI.setDebugLoc(DILocation::getMergedLocation(MI.getDebugLoc(),
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InsertPos->getDebugLoc()));
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else
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MI.setDebugLoc(DebugLoc());
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// Move the instruction.
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SuccToSinkTo->splice(InsertPos, ParentBlock, MI,
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++MachineBasicBlock::iterator(MI));
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// Move debug values.
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// Move previously adjacent debug value instructions to the insert position.
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for (SmallVectorImpl<MachineInstr *>::iterator DBI = DbgValuesToSink.begin(),
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DBE = DbgValuesToSink.end(); DBI != DBE; ++DBI) {
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MachineInstr *DbgMI = *DBI;
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@ -0,0 +1,56 @@
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; RUN: llc -simplify-mir -stop-after=machine-sink < %s -o - | FileCheck %s
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; ModuleID = 'test-sink-debug.cpp'
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source_filename = "test-sink-debug.cpp"
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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; Function Attrs: nounwind readnone uwtable
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define double @_Z3fooddb(double %x, double %y, i1 zeroext %c) local_unnamed_addr !dbg !7 {
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tail call void @llvm.dbg.value(metadata double %x, metadata !13, metadata !DIExpression()), !dbg !16
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tail call void @llvm.dbg.value(metadata double %y, metadata !14, metadata !DIExpression()), !dbg !16
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tail call void @llvm.dbg.value(metadata i1 %c, metadata !15, metadata !DIExpression()), !dbg !16
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%a = fdiv double %x, 3.000000e+00
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%b = fdiv double %y, 5.000000e+00, !dbg !17
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br i1 %c, label %first, label %second
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first:
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%e = fadd double %a, 1.000000e+00
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br label %final
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second:
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%f = fadd double %b, 1.000000e+00, !dbg !17
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; CHECK: debug-location !17
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; CHECK: debug-location !17
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br label %final
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final:
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%cond = phi double [%e, %first], [%f, %second]
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%d = fadd double %cond, 1.000000e+00
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ret double %d
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}
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.value(metadata, metadata, metadata) #1
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attributes #1 = { nounwind readnone speculatable }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 6.0.0 (trunk 313291)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
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!1 = !DIFile(filename: "test-sink-debug.cpp", directory: "/tmp")
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!2 = !{}
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!3 = !{i32 2, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"wchar_size", i32 4}
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!6 = !{!"clang version 6.0.0 (trunk 313291)"}
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!7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3fooddb", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !12)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10, !10, !10, !11}
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!10 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
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!11 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
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!12 = !{!13, !14, !15}
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!13 = !DILocalVariable(name: "x", arg: 1, scope: !7, file: !1, line: 1, type: !10)
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!14 = !DILocalVariable(name: "y", arg: 2, scope: !7, file: !1, line: 1, type: !10)
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!15 = !DILocalVariable(name: "c", arg: 3, scope: !7, file: !1, line: 1, type: !11)
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!16 = !DILocation(line: 1, column: 19, scope: !7)
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!17 = !DILocation(line: 2, column: 26, scope: !7)
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@ -0,0 +1,49 @@
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; RUN: llc -simplify-mir -stop-after=machine-sink < %s -o - | FileCheck %s
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; ModuleID = 'test-sink-debug.cpp'
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source_filename = "test-sink-debug.cpp"
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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; Function Attrs: nounwind readnone uwtable
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define double @_Z3fooddb(double %x, double %y, i1 zeroext %c) local_unnamed_addr !dbg !7 {
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tail call void @llvm.dbg.value(metadata double %x, metadata !13, metadata !DIExpression()), !dbg !16
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tail call void @llvm.dbg.value(metadata double %y, metadata !14, metadata !DIExpression()), !dbg !17
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tail call void @llvm.dbg.value(metadata i1 %c, metadata !15, metadata !DIExpression()), !dbg !18
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%a = fdiv double %x, 3.000000e+00
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%b = fdiv double %y, 5.000000e+00, !dbg !21
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%cond = select i1 %c, double %a, double %b
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; CHECK-NOT: debug-location !21
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ret double %cond, !dbg !22
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}
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.value(metadata, metadata, metadata) #1
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attributes #1 = { nounwind readnone speculatable }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 6.0.0 (trunk 313291)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
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!1 = !DIFile(filename: "test-sink-debug.cpp", directory: "/tmp")
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!2 = !{}
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!3 = !{i32 2, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"wchar_size", i32 4}
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!6 = !{!"clang version 6.0.0 (trunk 313291)"}
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!7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3fooddb", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !12)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10, !10, !10, !11}
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!10 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
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!11 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
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!12 = !{!13, !14, !15}
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!13 = !DILocalVariable(name: "x", arg: 1, scope: !7, file: !1, line: 1, type: !10)
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!14 = !DILocalVariable(name: "y", arg: 2, scope: !7, file: !1, line: 1, type: !10)
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!15 = !DILocalVariable(name: "c", arg: 3, scope: !7, file: !1, line: 1, type: !11)
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!16 = !DILocation(line: 1, column: 19, scope: !7)
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!17 = !DILocation(line: 1, column: 29, scope: !7)
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!18 = !DILocation(line: 1, column: 37, scope: !7)
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!21 = !DILocation(line: 2, column: 26, scope: !7)
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!22 = !DILocation(line: 2, column: 3, scope: !7)
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