RegAllocFast: Add extra DBG_VALUE for live out spills

This allows LiveDebugValues to insert the proper DBG_VALUEs in live out blocks if a spill is inserted before the use of a register. Previously, this would see the register use as the last DBG_VALUE, even though the stack slot should be treated as the live out value. This avoids an lldb test regression when D52010 is re-applied.
2020-09-28 13:42:17 -04:00 · 2020-09-28 13:42:17 -04:00 · a66fca44ac
parent 89baeaef2f
commit a66fca44ac
7 changed files with 249 additions and 13 deletions
--- a/llvm/lib/CodeGen/RegAllocFast.cpp
+++ b/llvm/lib/CodeGen/RegAllocFast.cpp
@ -255,7 +255,7 @@ namespace {

    int getStackSpaceFor(Register VirtReg);
    void spill(MachineBasicBlock::iterator Before, Register VirtReg,
-               MCPhysReg AssignedReg, bool Kill);
+               MCPhysReg AssignedReg, bool Kill, bool LiveOut);
    void reload(MachineBasicBlock::iterator Before, Register VirtReg,
                MCPhysReg PhysReg);

@ -384,7 +384,7 @@ bool RegAllocFast::mayLiveIn(Register VirtReg) {
 /// Insert spill instruction for \p AssignedReg before \p Before. Update
 /// DBG_VALUEs with \p VirtReg operands with the stack slot.
 void RegAllocFast::spill(MachineBasicBlock::iterator Before, Register VirtReg,
-                         MCPhysReg AssignedReg, bool Kill) {
+                         MCPhysReg AssignedReg, bool Kill, bool LiveOut) {
  LLVM_DEBUG(dbgs() << "Spilling " << printReg(VirtReg, TRI)
                    << " in " << printReg(AssignedReg, TRI));
  int FI = getStackSpaceFor(VirtReg);
@ -394,6 +394,8 @@ void RegAllocFast::spill(MachineBasicBlock::iterator Before, Register VirtReg,
  TII->storeRegToStackSlot(*MBB, Before, AssignedReg, Kill, FI, &RC, TRI);
  ++NumStores;

+  MachineBasicBlock::iterator FirstTerm = MBB->getFirstTerminator();
+
  // When we spill a virtual register, we will have spill instructions behind
  // every definition of it, meaning we can switch all the DBG_VALUEs over
  // to just reference the stack slot.
@ -403,6 +405,17 @@ void RegAllocFast::spill(MachineBasicBlock::iterator Before, Register VirtReg,
    assert(NewDV->getParent() == MBB && "dangling parent pointer");
    (void)NewDV;
    LLVM_DEBUG(dbgs() << "Inserting debug info due to spill:\n" << *NewDV);
+
+    if (LiveOut) {
+      // We need to insert a DBG_VALUE at the end of the block if the spill slot
+      // is live out, but there is another use of the value after the
+      // spill. This will allow LiveDebugValues to see the correct live out
+      // value to propagate to the successors.
+      MachineInstr *ClonedDV = MBB->getParent()->CloneMachineInstr(NewDV);
+      MBB->insert(FirstTerm, ClonedDV);
+      LLVM_DEBUG(dbgs() << "Cloning debug info due to live out spill\n");
+    }
+
    // Rewrite unassigned dbg_values to use the stack slot.
    MachineOperand &MO = DBG->getOperand(0);
    if (MO.isReg() && MO.getReg() == 0)
@ -868,7 +881,7 @@ void RegAllocFast::defineVirtReg(MachineInstr &MI, unsigned OpNum,
      LLVM_DEBUG(dbgs() << "Spill Reason: LO: " << LRI->LiveOut << " RL: "
                        << LRI->Reloaded << '\n');
      bool Kill = LRI->LastUse == nullptr;
-      spill(SpillBefore, VirtReg, PhysReg, Kill);
+      spill(SpillBefore, VirtReg, PhysReg, Kill, LRI->LiveOut);
      LRI->LastUse = nullptr;
    }
    LRI->LiveOut = false;
--- a/llvm/test/CodeGen/X86/fast-regalloc-live-out-debug-values.mir
+++ b/llvm/test/CodeGen/X86/fast-regalloc-live-out-debug-values.mir
@ -0,0 +1,222 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -O0 -mtriple=x86_64-unknown-linux-gnu -start-before=regallocfast -stop-after=livedebugvalues -verify-machineinstrs -o - %s | FileCheck %s
+# DBG_VALUEs for %0 should be present in the use blocks
+
+--- |
+  define dso_local i32 @foo(i32 %a) #0 !dbg !6 {
+  entry:
+    %a.addr = alloca i32, align 4
+    %saved_stack = alloca i8*, align 8
+    %__vla_expr0 = alloca i64, align 8
+    %i = alloca i32, align 4
+    store i32 %a, i32* %a.addr, align 4
+    call void @llvm.dbg.declare(metadata i32* %a.addr, metadata !11, metadata !DIExpression()), !dbg !12
+    %0 = load i32, i32* %a.addr, align 4, !dbg !13
+    %1 = zext i32 %0 to i64, !dbg !14
+    %2 = call i8* @llvm.stacksave(), !dbg !14
+    store i8* %2, i8** %saved_stack, align 8, !dbg !14
+    %vla = alloca i32, i64 %1, align 16, !dbg !14
+    store i64 %1, i64* %__vla_expr0, align 8, !dbg !14
+    call void @llvm.dbg.declare(metadata i64* %__vla_expr0, metadata !15, metadata !DIExpression()), !dbg !17
+    call void @llvm.dbg.declare(metadata i32* %vla, metadata !18, metadata !DIExpression()), !dbg !22
+    call void @llvm.dbg.declare(metadata i32* %i, metadata !23, metadata !DIExpression()), !dbg !25
+    store i32 0, i32* %i, align 4, !dbg !25
+    br label %for.cond, !dbg !26
+
+  for.cond:                                         ; preds = %for.inc, %entry
+    %3 = load i32, i32* %i, align 4, !dbg !27
+    %4 = load i32, i32* %a.addr, align 4, !dbg !29
+    %cmp = icmp slt i32 %3, %4, !dbg !30
+    br i1 %cmp, label %for.body, label %for.end, !dbg !31
+
+  for.body:                                         ; preds = %for.cond
+    %5 = load i32, i32* %a.addr, align 4, !dbg !32
+    %6 = load i32, i32* %i, align 4, !dbg !33
+    %sub = sub nsw i32 %5, %6, !dbg !34
+    %7 = load i32, i32* %i, align 4, !dbg !35
+    %idxprom = sext i32 %7 to i64, !dbg !36
+    %arrayidx = getelementptr inbounds i32, i32* %vla, i64 %idxprom, !dbg !36
+    store i32 %sub, i32* %arrayidx, align 4, !dbg !37
+    br label %for.inc, !dbg !36
+
+  for.inc:                                          ; preds = %for.body
+    %8 = load i32, i32* %i, align 4, !dbg !38
+    %inc = add nsw i32 %8, 1, !dbg !38
+    store i32 %inc, i32* %i, align 4, !dbg !38
+    br label %for.cond, !dbg !39, !llvm.loop !40
+
+  for.end:                                          ; preds = %for.cond
+    %9 = load i32, i32* %a.addr, align 4, !dbg !42
+    %sub1 = sub nsw i32 %9, 1, !dbg !43
+    %idxprom2 = sext i32 %sub1 to i64, !dbg !44
+    %arrayidx3 = getelementptr inbounds i32, i32* %vla, i64 %idxprom2, !dbg !44
+    %10 = load i32, i32* %arrayidx3, align 4, !dbg !44
+    %11 = load i8*, i8** %saved_stack, align 8, !dbg !45
+    call void @llvm.stackrestore(i8* %11), !dbg !45
+    ret i32 %10, !dbg !45
+  }
+
+  declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+  declare i8* @llvm.stacksave() #2
+  declare void @llvm.stackrestore(i8*) #2
+
+  attributes #0 = { noinline nounwind optnone uwtable }
+  attributes #1 = { nounwind readnone speculatable willreturn }
+  attributes #2 = { nounwind }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!3, !4, !5}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 12.0.0 (git@github.com:llvm/llvm-project.git 954995d0a45729c7935b82258c166524ee87ad3f)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+  !1 = !DIFile(filename: "/home/matt/src/llvm-project/lldb/test/API/lang/c/vla/main.c", directory: "/home/matt/src/llvm-project/build_debug_lldbg")
+  !2 = !{}
+  !3 = !{i32 7, !"Dwarf Version", i32 4}
+  !4 = !{i32 2, !"Debug Info Version", i32 3}
+  !5 = !{i32 1, !"wchar_size", i32 4}
+  !6 = distinct !DISubprogram(name: "foo", scope: !7, file: !7, line: 3, type: !8, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+  !7 = !DIFile(filename: "lldb/test/API/lang/c/vla/main.c", directory: "/home/matt/src/llvm-project")
+  !8 = !DISubroutineType(types: !9)
+  !9 = !{!10, !10}
+  !10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !11 = !DILocalVariable(name: "a", arg: 1, scope: !6, file: !7, line: 3, type: !10)
+  !12 = !DILocation(line: 3, column: 13, scope: !6)
+  !13 = !DILocation(line: 4, column: 11, scope: !6)
+  !14 = !DILocation(line: 4, column: 3, scope: !6)
+  !15 = !DILocalVariable(name: "__vla_expr0", scope: !6, type: !16, flags: DIFlagArtificial)
+  !16 = !DIBasicType(name: "long unsigned int", size: 64, encoding: DW_ATE_unsigned)
+  !17 = !DILocation(line: 0, scope: !6)
+  !18 = !DILocalVariable(name: "vla", scope: !6, file: !7, line: 4, type: !19)
+  !19 = !DICompositeType(tag: DW_TAG_array_type, baseType: !10, elements: !20)
+  !20 = !{!21}
+  !21 = !DISubrange(count: !15)
+  !22 = !DILocation(line: 4, column: 7, scope: !6)
+  !23 = !DILocalVariable(name: "i", scope: !24, file: !7, line: 6, type: !10)
+  !24 = distinct !DILexicalBlock(scope: !6, file: !7, line: 6, column: 3)
+  !25 = !DILocation(line: 6, column: 12, scope: !24)
+  !26 = !DILocation(line: 6, column: 8, scope: !24)
+  !27 = !DILocation(line: 6, column: 19, scope: !28)
+  !28 = distinct !DILexicalBlock(scope: !24, file: !7, line: 6, column: 3)
+  !29 = !DILocation(line: 6, column: 23, scope: !28)
+  !30 = !DILocation(line: 6, column: 21, scope: !28)
+  !31 = !DILocation(line: 6, column: 3, scope: !24)
+  !32 = !DILocation(line: 7, column: 14, scope: !28)
+  !33 = !DILocation(line: 7, column: 16, scope: !28)
+  !34 = !DILocation(line: 7, column: 15, scope: !28)
+  !35 = !DILocation(line: 7, column: 9, scope: !28)
+  !36 = !DILocation(line: 7, column: 5, scope: !28)
+  !37 = !DILocation(line: 7, column: 12, scope: !28)
+  !38 = !DILocation(line: 6, column: 26, scope: !28)
+  !39 = !DILocation(line: 6, column: 3, scope: !28)
+  !40 = distinct !{!40, !31, !41}
+  !41 = !DILocation(line: 7, column: 16, scope: !24)
+  !42 = !DILocation(line: 10, column: 14, scope: !6)
+  !43 = !DILocation(line: 10, column: 15, scope: !6)
+  !44 = !DILocation(line: 10, column: 10, scope: !6)
+  !45 = !DILocation(line: 11, column: 1, scope: !6)
+
+...
+---
+name:            foo
+tracksRegLiveness: true
+frameInfo:
+  hasCalls:        true
+stack:
+  - { id: 0, name: a.addr, size: 4, alignment: 4, debug-info-variable: '!11',
+      debug-info-expression: '!DIExpression()', debug-info-location: '!12' }
+  - { id: 1, name: __vla_expr0, size: 8, alignment: 8, debug-info-variable: '!15',
+      debug-info-expression: '!DIExpression()', debug-info-location: '!17' }
+  - { id: 2, name: i, size: 4, alignment: 4, debug-info-variable: '!23',
+      debug-info-expression: '!DIExpression()', debug-info-location: '!25' }
+  - { id: 3, name: vla, type: variable-sized, alignment: 1 }
+body:             |
+  ; CHECK-LABEL: name: foo
+  ; CHECK: bb.0.entry:
+  ; CHECK:   successors: %bb.1(0x80000000)
+  ; CHECK:   liveins: $edi, $rbx
+  ; CHECK:   frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
+  ; CHECK:   CFI_INSTRUCTION def_cfa_offset 16
+  ; CHECK:   CFI_INSTRUCTION offset $rbp, -16
+  ; CHECK:   $rbp = frame-setup MOV64rr $rsp
+  ; CHECK:   CFI_INSTRUCTION def_cfa_register $rbp
+  ; CHECK:   frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp, debug-location !13
+  ; CHECK:   $rsp = frame-setup SUB64ri8 $rsp, 40, implicit-def dead $eflags
+  ; CHECK:   CFI_INSTRUCTION offset $rbx, -24
+  ; CHECK:   renamable $eax = MOV32rm $rbp, 1, $noreg, -12, $noreg, debug-location !13 :: (dereferenceable load 4 from %ir.a.addr)
+  ; CHECK:   renamable $rax = KILL killed renamable $eax, debug-location !13
+  ; CHECK:   $rcx = MOV64rr $rsp, debug-location !14
+  ; CHECK:   MOV64mr $rbp, 1, $noreg, -40, $noreg, $rcx :: (store 8 into %stack.4)
+  ; CHECK:   DBG_VALUE $rbp, 0, !18, !DIExpression(DW_OP_constu, 40, DW_OP_minus, DW_OP_deref), debug-location !22
+  ; CHECK:   $rsp = MOV64rr $rcx, debug-location !14
+  ; CHECK:   MOV64mr $rbp, 1, $noreg, -24, $noreg, killed renamable $rax, debug-location !14 :: (store 8 into %ir.__vla_expr0)
+  ; CHECK:   DBG_VALUE renamable $rcx, 0, !18, !DIExpression(), debug-location !22
+  ; CHECK:   MOV32mi $rbp, 1, $noreg, -28, $noreg, 0, debug-location !25 :: (store 4 into %ir.i)
+  ; CHECK:   DBG_VALUE $rbp, 0, !18, !DIExpression(DW_OP_constu, 40, DW_OP_minus, DW_OP_deref), debug-location !22
+  ; CHECK: bb.1.for.cond:
+  ; CHECK:   successors: %bb.4(0x40000000), %bb.2(0x40000000)
+  ; CHECK:   DBG_VALUE $rbp, 0, !18, !DIExpression(DW_OP_constu, 40, DW_OP_minus, DW_OP_deref), debug-location !22
+  ; CHECK:   renamable $eax = MOV32rm $rbp, 1, $noreg, -28, $noreg, debug-location !27 :: (load 4 from %ir.i)
+  ; CHECK:   CMP32rm killed renamable $eax, $rbp, 1, $noreg, -12, $noreg, implicit-def $eflags, debug-location !30 :: (load 4 from %ir.a.addr)
+  ; CHECK:   JCC_1 %bb.4, 13, implicit killed $eflags, debug-location !31
+  ; CHECK: bb.2.for.body:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK:   DBG_VALUE $rbp, 0, !18, !DIExpression(DW_OP_constu, 40, DW_OP_minus, DW_OP_deref), debug-location !22
+  ; CHECK:   $rax = MOV64rm $rbp, 1, $noreg, -40, $noreg :: (load 8 from %stack.4)
+  ; CHECK:   renamable $edx = MOV32rm $rbp, 1, $noreg, -12, $noreg, debug-location !32 :: (load 4 from %ir.a.addr)
+  ; CHECK:   renamable $rcx = MOVSX64rm32 $rbp, 1, $noreg, -28, $noreg, debug-location !36 :: (load 4 from %ir.i)
+  ; CHECK:   MOV32mr renamable $rax, 4, killed renamable $rcx, 0, $noreg, killed renamable $edx, debug-location !37 :: (store 4 into %ir.arrayidx)
+  ; CHECK: bb.3.for.inc:
+  ; CHECK:   successors: %bb.1(0x80000000)
+  ; CHECK:   DBG_VALUE $rbp, 0, !18, !DIExpression(DW_OP_constu, 40, DW_OP_minus, DW_OP_deref), debug-location !22
+  ; CHECK:   JMP_1 %bb.1, debug-location !39
+  ; CHECK: bb.4.for.end:
+  ; CHECK:   DBG_VALUE $rbp, 0, !18, !DIExpression(DW_OP_constu, 40, DW_OP_minus, DW_OP_deref), debug-location !22
+  ; CHECK:   $rax = IMPLICIT_DEF
+  ; CHECK:   $rax = MOV64rm $rbp, 1, $noreg, -40, $noreg :: (load 8 from %stack.4)
+  ; CHECK:   dead $rbx = IMPLICIT_DEF
+  ; CHECK:   dead $rcx = IMPLICIT_DEF
+  ; CHECK:   dead $rdx = IMPLICIT_DEF
+  ; CHECK:   renamable $rcx = IMPLICIT_DEF
+  ; CHECK:   renamable $eax = MOV32rm killed renamable $rax, 4, killed renamable $rcx, 0, $noreg, debug-location !44 :: (load 4 from %ir.arrayidx3)
+  ; CHECK:   $rsp = LEA64r $rbp, 1, $noreg, -8, $noreg, debug-location !45
+  ; CHECK:   $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !45
+  ; CHECK:   $rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !45
+  ; CHECK:   CFI_INSTRUCTION def_cfa $rsp, 8, debug-location !45
+  ; CHECK:   RETQ implicit killed $eax, debug-location !45
+  bb.0.entry:
+    liveins: $edi
+
+    %0:gr32 = COPY $edi
+    %1:gr32 = MOV32rm %stack.0.a.addr, 1, $noreg, 0, $noreg, debug-location !13 :: (dereferenceable load 4 from %ir.a.addr)
+    %2:gr64_nosp = SUBREG_TO_REG 0, killed %1, %subreg.sub_32bit, debug-location !13
+    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !14
+    %3:gr64 = COPY $rsp, debug-location !14
+    $rsp = COPY %3, debug-location !14
+    ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !14
+    MOV64mr %stack.1.__vla_expr0, 1, $noreg, 0, $noreg, %2, debug-location !14 :: (store 8 into %ir.__vla_expr0)
+    DBG_VALUE %3, 0, !18, !DIExpression(), debug-location !22
+    MOV32mi %stack.2.i, 1, $noreg, 0, $noreg, 0, debug-location !25 :: (store 4 into %ir.i)
+
+  bb.1.for.cond:
+    %4:gr32 = MOV32rm %stack.2.i, 1, $noreg, 0, $noreg, debug-location !27 :: (load 4 from %ir.i)
+    CMP32rm %4, %stack.0.a.addr, 1, $noreg, 0, $noreg, implicit-def $eflags, debug-location !30 :: (load 4 from %ir.a.addr)
+    JCC_1 %bb.4, 13, implicit $eflags, debug-location !31
+
+  bb.2.for.body:
+    %5:gr32 = MOV32rm %stack.0.a.addr, 1, $noreg, 0, $noreg, debug-location !32 :: (load 4 from %ir.a.addr)
+    %6:gr64_nosp = MOVSX64rm32 %stack.2.i, 1, $noreg, 0, $noreg, debug-location !36 :: (load 4 from %ir.i)
+    MOV32mr %3, 4, %6, 0, $noreg, killed %5, debug-location !37 :: (store 4 into %ir.arrayidx)
+
+  bb.3.for.inc:
+    JMP_1 %bb.1, debug-location !39
+
+  bb.4.for.end:
+    $rax = IMPLICIT_DEF
+    $rbx = IMPLICIT_DEF
+    $rcx = IMPLICIT_DEF
+    $rdx = IMPLICIT_DEF
+    %7:gr64_nosp = IMPLICIT_DEF
+    %8:gr32 = MOV32rm %3, 4, %7, 0, $noreg, debug-location !44 :: (load 4 from %ir.arrayidx3)
+    $eax = COPY %8, debug-location !45
+    RETQ implicit $eax, debug-location !45
+
+...
--- a/llvm/test/DebugInfo/X86/fission-ranges.ll
+++ b/llvm/test/DebugInfo/X86/fission-ranges.ll
@ -51,7 +51,7 @@
 ; CHECK-NEXT:   DW_LLE_end_of_list   ()
 ; CHECK:      [[E]]:
 ; CHECK-NEXT:   DW_LLE_startx_length (0x00000005, 0x0000000b): DW_OP_reg0 RAX
-; CHECK-NEXT:   DW_LLE_startx_length (0x00000006, 0x0000005a): DW_OP_breg7 RSP-36
+; CHECK-NEXT:   DW_LLE_startx_length (0x00000006, 0x0000005a): DW_OP_breg7 RSP-48
 ; CHECK-NEXT:   DW_LLE_end_of_list   ()
 ; CHECK:      [[B]]:
 ; CHECK-NEXT:   DW_LLE_startx_length (0x00000007, 0x0000000b): DW_OP_reg0 RAX
--- a/llvm/test/DebugInfo/X86/op_deref.ll
+++ b/llvm/test/DebugInfo/X86/op_deref.ll
@ -7,7 +7,8 @@

 ; DWARF4: DW_AT_location [DW_FORM_sec_offset]                      (0x00000000
 ; DWARF4-NEXT:  {{.*}}: DW_OP_breg6 RBP-40, DW_OP_deref, DW_OP_deref
-; DWARF4-NEXT:  {{.*}}: DW_OP_breg0 RAX+0, DW_OP_deref)
+; DWARF4-NEXT:  {{.*}}: DW_OP_breg0 RAX+0, DW_OP_deref
+; DWARF4-NEXT:  {{.*}}: DW_OP_breg6 RBP-40, DW_OP_deref, DW_OP_deref)

 ; DWARF3: DW_AT_location [DW_FORM_data4]                      (0x00000000
 ; DWARF3-NEXT:  {{.*}}: DW_OP_breg6 RBP-40, DW_OP_deref, DW_OP_deref
--- a/llvm/test/DebugInfo/X86/parameters.ll
+++ b/llvm/test/DebugInfo/X86/parameters.ll
@ -38,7 +38,8 @@
 ; CHECK: DW_TAG_formal_parameter
 ; CHECK: DW_AT_location{{.*}}(
 ; CHECK-NEXT: {{.*}}: DW_OP_breg7 RSP+8, DW_OP_deref, DW_OP_deref
-; CHECK-NEXT: {{.*}}: DW_OP_breg4 RSI+0, DW_OP_deref)
+; CHECK-NEXT: {{.*}}: DW_OP_breg4 RSI+0, DW_OP_deref
+; CHECK-NEXT: {{.*}}: DW_OP_breg7 RSP+8, DW_OP_deref, DW_OP_deref)
 ; CHECK-NOT: DW_TAG
 ; CHECK: DW_AT_name{{.*}} = "g"

--- a/llvm/test/DebugInfo/X86/sret.ll
+++ b/llvm/test/DebugInfo/X86/sret.ll
@ -3,8 +3,8 @@

 ; Based on the debuginfo-tests/sret.cpp code.

-; CHECK-DWO: DW_AT_GNU_dwo_id (0x409e35dbb641730e)
-; CHECK-DWO: DW_AT_GNU_dwo_id (0x409e35dbb641730e)
+; CHECK-DWO: DW_AT_GNU_dwo_id (0xa58a336e896549f1)
+; CHECK-DWO: DW_AT_GNU_dwo_id (0xa58a336e896549f1)

 ; RUN: llc -O0 -fast-isel=true -mtriple=x86_64-apple-darwin -filetype=obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck -check-prefixes=CHECK,FASTISEL %s
 ; RUN: llc -O0 -fast-isel=false -mtriple=x86_64-apple-darwin -filetype=obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck -check-prefixes=CHECK,SDAG %s
@ -12,8 +12,10 @@
 ; CHECK: DW_TAG_variable
 ; CHECK-NEXT:   DW_AT_location (0x00000000
 ; FASTISEL-NEXT:     [{{.*}}, {{.*}}): DW_OP_breg6 RBP-32, DW_OP_deref
-; FASTISEL-NEXT:     [{{.*}}, {{.*}}): DW_OP_breg5 RDI+0)
-; SDAG-NEXT:     [{{.*}}, {{.*}}): DW_OP_breg5 RDI+0)
+; FASTISEL-NEXT:     [{{.*}}, {{.*}}): DW_OP_breg5 RDI+0
+; FASTISEL-NEXT:     [{{.*}}, {{.*}}): DW_OP_breg6 RBP-32, DW_OP_deref)
+; SDAG-NEXT:     [{{.*}}, {{.*}}): DW_OP_breg5 RDI+0
+; SDAG-NEXT:     [{{.*}}, {{.*}}): DW_OP_breg6 RBP-32, DW_OP_deref)
 ; CHECK-NEXT:   DW_AT_name {{.*}}"a"

 %class.A = type { i32 (...)**, i32 }
--- a/llvm/test/DebugInfo/X86/subreg.ll
+++ b/llvm/test/DebugInfo/X86/subreg.ll
@ -11,9 +11,6 @@
 define i16 @f(i16 signext %zzz) nounwind !dbg !1 {
 entry:
  call void @llvm.dbg.value(metadata i16 %zzz, metadata !0, metadata !DIExpression()), !dbg !DILocation(scope: !1)
-  br label %exit
-
-exit:
  %conv = sext i16 %zzz to i32, !dbg !7
  %conv1 = trunc i32 %conv to i16
  ret i16 %conv1