[llvm] r320216 - Fix out-of-order stepping behavior in programs with sunk instructions.
Paul Robinson via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 8 16:17:01 PST 2017
Author: probinson
Date: Fri Dec 8 16:17:01 2017
New Revision: 320216
URL: http://llvm.org/viewvc/llvm-project?rev=320216&view=rev
Log:
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
Added:
llvm/trunk/test/CodeGen/X86/machinesink-merge-debuginfo.ll
llvm/trunk/test/CodeGen/X86/machinesink-null-debuginfo.ll
Modified:
llvm/trunk/lib/CodeGen/MachineSink.cpp
Modified: llvm/trunk/lib/CodeGen/MachineSink.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineSink.cpp?rev=320216&r1=320215&r2=320216&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineSink.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineSink.cpp Fri Dec 8 16:17:01 2017
@@ -38,6 +38,7 @@
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/Pass.h"
#include "llvm/Support/BranchProbability.h"
#include "llvm/Support/CommandLine.h"
@@ -868,11 +869,20 @@ bool MachineSinking::SinkInstruction(Mac
SmallVector<MachineInstr *, 2> DbgValuesToSink;
collectDebugValues(MI, DbgValuesToSink);
+ // Merge or erase debug location to ensure consistent stepping in profilers
+ // and debuggers.
+ if (!SuccToSinkTo->empty() && InsertPos != SuccToSinkTo->end())
+ MI.setDebugLoc(DILocation::getMergedLocation(MI.getDebugLoc(),
+ InsertPos->getDebugLoc()));
+ else
+ MI.setDebugLoc(DebugLoc());
+
+
// Move the instruction.
SuccToSinkTo->splice(InsertPos, ParentBlock, MI,
++MachineBasicBlock::iterator(MI));
- // Move debug values.
+ // Move previously adjacent debug value instructions to the insert position.
for (SmallVectorImpl<MachineInstr *>::iterator DBI = DbgValuesToSink.begin(),
DBE = DbgValuesToSink.end(); DBI != DBE; ++DBI) {
MachineInstr *DbgMI = *DBI;
Added: llvm/trunk/test/CodeGen/X86/machinesink-merge-debuginfo.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/machinesink-merge-debuginfo.ll?rev=320216&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/machinesink-merge-debuginfo.ll (added)
+++ llvm/trunk/test/CodeGen/X86/machinesink-merge-debuginfo.ll Fri Dec 8 16:17:01 2017
@@ -0,0 +1,56 @@
+; RUN: llc -simplify-mir -stop-after=machine-sink < %s -o - | FileCheck %s
+
+; ModuleID = 'test-sink-debug.cpp'
+source_filename = "test-sink-debug.cpp"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind readnone uwtable
+define double @_Z3fooddb(double %x, double %y, i1 zeroext %c) local_unnamed_addr !dbg !7 {
+ tail call void @llvm.dbg.value(metadata double %x, metadata !13, metadata !DIExpression()), !dbg !16
+ tail call void @llvm.dbg.value(metadata double %y, metadata !14, metadata !DIExpression()), !dbg !16
+ tail call void @llvm.dbg.value(metadata i1 %c, metadata !15, metadata !DIExpression()), !dbg !16
+ %a = fdiv double %x, 3.000000e+00
+ %b = fdiv double %y, 5.000000e+00, !dbg !17
+ br i1 %c, label %first, label %second
+first:
+ %e = fadd double %a, 1.000000e+00
+ br label %final
+second:
+ %f = fadd double %b, 1.000000e+00, !dbg !17
+; CHECK: debug-location !17
+; CHECK: debug-location !17
+ br label %final
+final:
+ %cond = phi double [%e, %first], [%f, %second]
+ %d = fadd double %cond, 1.000000e+00
+ ret double %d
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+attributes #1 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!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)
+!1 = !DIFile(filename: "test-sink-debug.cpp", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 6.0.0 (trunk 313291)"}
+!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)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !10, !10, !11}
+!10 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
+!11 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
+!12 = !{!13, !14, !15}
+!13 = !DILocalVariable(name: "x", arg: 1, scope: !7, file: !1, line: 1, type: !10)
+!14 = !DILocalVariable(name: "y", arg: 2, scope: !7, file: !1, line: 1, type: !10)
+!15 = !DILocalVariable(name: "c", arg: 3, scope: !7, file: !1, line: 1, type: !11)
+!16 = !DILocation(line: 1, column: 19, scope: !7)
+!17 = !DILocation(line: 2, column: 26, scope: !7)
Added: llvm/trunk/test/CodeGen/X86/machinesink-null-debuginfo.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/machinesink-null-debuginfo.ll?rev=320216&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/machinesink-null-debuginfo.ll (added)
+++ llvm/trunk/test/CodeGen/X86/machinesink-null-debuginfo.ll Fri Dec 8 16:17:01 2017
@@ -0,0 +1,49 @@
+; RUN: llc -simplify-mir -stop-after=machine-sink < %s -o - | FileCheck %s
+
+; ModuleID = 'test-sink-debug.cpp'
+source_filename = "test-sink-debug.cpp"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind readnone uwtable
+define double @_Z3fooddb(double %x, double %y, i1 zeroext %c) local_unnamed_addr !dbg !7 {
+ tail call void @llvm.dbg.value(metadata double %x, metadata !13, metadata !DIExpression()), !dbg !16
+ tail call void @llvm.dbg.value(metadata double %y, metadata !14, metadata !DIExpression()), !dbg !17
+ tail call void @llvm.dbg.value(metadata i1 %c, metadata !15, metadata !DIExpression()), !dbg !18
+ %a = fdiv double %x, 3.000000e+00
+ %b = fdiv double %y, 5.000000e+00, !dbg !21
+ %cond = select i1 %c, double %a, double %b
+; CHECK-NOT: debug-location !21
+ ret double %cond, !dbg !22
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+attributes #1 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!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)
+!1 = !DIFile(filename: "test-sink-debug.cpp", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 6.0.0 (trunk 313291)"}
+!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)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !10, !10, !11}
+!10 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
+!11 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
+!12 = !{!13, !14, !15}
+!13 = !DILocalVariable(name: "x", arg: 1, scope: !7, file: !1, line: 1, type: !10)
+!14 = !DILocalVariable(name: "y", arg: 2, scope: !7, file: !1, line: 1, type: !10)
+!15 = !DILocalVariable(name: "c", arg: 3, scope: !7, file: !1, line: 1, type: !11)
+!16 = !DILocation(line: 1, column: 19, scope: !7)
+!17 = !DILocation(line: 1, column: 29, scope: !7)
+!18 = !DILocation(line: 1, column: 37, scope: !7)
+!21 = !DILocation(line: 2, column: 26, scope: !7)
+!22 = !DILocation(line: 2, column: 3, scope: !7)
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