Revert "Fix out-of-order stepping behavior in programs with sunk instructions."

This reverts commit 30419e150cd940893a13b345e85f96053850208f.
aka r318679.  It caused "sanitizer-windows" bot to fail.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318684 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MachineSink.cpp

@@ -38,7 +38,6 @@
 #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"
@@ -869,16 +868,6 @@ bool MachineSinking::SinkInstruction(MachineInstr &MI, bool &SawStore,
   SmallVector<MachineInstr *, 2> DbgValuesToSink;
   collectDebugValues(MI, DbgValuesToSink);
 
-  // Merge or erase debug location to ensure consistent stepping in profilers
-  // and debuggers.
-  if (!SuccToSinkTo->empty()) {
-    MI.setDebugLoc(DILocation::getMergedLocation(MI.getDebugLoc(),
-                                                 InsertPos->getDebugLoc()));
-  } else {
-    MI.setDebugLoc(DebugLoc());
-  }
-
-
   // Move the instruction.
   SuccToSinkTo->splice(InsertPos, ParentBlock, MI,
                        ++MachineBasicBlock::iterator(MI));

test/CodeGen/X86/machinesink-debuginfo.ll

@@ -1,49 +0,0 @@
-; RUN: llc -O2 -o - < %s | 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: .loc 1 2 26
-  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)