test/DebugInfo/X86/instr-ref-track-clobbers.mir

# RUN: llc --run-pass=livedebugvalues %s -o - -experimental-debug-variable-locations | FileCheck %s --check-prefixes=CHECK

# Test that we accurately track variables through transfers and clobbers.

# In this test case, the value of "b" is found in $rax. From there it is moved
# to $r15, $rax is killed, the value is moved back from $r15 into $rax again,
# and then $r15 is killed. Throughout this, we should track "b" and end up with
# DBG_VALUEs pointing to $rax, then $r15, then $rax again.

# CHECK-LABEL: bb.0.entry:
# CHECK: DBG_VALUE $rax,
# CHECK: $r15 = MOV64rr

## Technically it's correct to insert the DBG_VALUE for $r15 either immediately
## after the move to $r15 or immediately after $rax is clobbered, but no later.
# CHECK: DBG_VALUE $r15,
# CHECK: $rax = LEA64r
# CHECK: $rax = MOV64rr

## Again, the DBG_VALUE can come either after the copy to $rax or the kill of
## $r15, but no later.
# CHECK: $r15 = LEA64r
# CHECK: DBG_VALUE $rax,
# CHECK: RET64

--- |
  ; ModuleID = 'test.cpp'
  source_filename = "test.cpp"
  target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
  target triple = "x86_64-unknown-linux-gnu"
  
  ; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone willreturn uwtable
  define dso_local noundef i64 @_Z3fooxx(i64 noundef %a, i64 noundef %b) local_unnamed_addr !dbg !7 {
  entry:
    call void @llvm.dbg.value(metadata i64 %a, metadata !12, metadata !DIExpression()), !dbg !16
    call void @llvm.dbg.value(metadata i64 %b, metadata !13, metadata !DIExpression()), !dbg !16
    %add = add nsw i64 %b, %a, !dbg !17
    call void @llvm.dbg.value(metadata i64 %add, metadata !14, metadata !DIExpression()), !dbg !16
    %mul17 = sub i64 %a, %b, !dbg !18
    %sub = mul i64 %add, %mul17, !dbg !18
    call void @llvm.dbg.value(metadata i64 %sub, metadata !15, metadata !DIExpression()), !dbg !16
    %add2 = add nsw i64 %sub, %add, !dbg !19
    ret i64 %add2, !dbg !20
  }
  
  ; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
  declare void @llvm.dbg.value(metadata, metadata, metadata)
  
  !llvm.dbg.cu = !{!0}
  !llvm.module.flags = !{!2, !3, !4, !5}
  !llvm.ident = !{!6}
  
  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 15.0.0 (https://github.com/llvm/llvm-project.git 44673278e029d7a6f56c8a3177247026b831720f)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
  !1 = !DIFile(filename: "test.cpp", directory: "/home/stozer/dev/llvm-project-build", checksumkind: CSK_MD5, checksum: "1e1c19354b0e967af705e204e8740d56")
  !2 = !{i32 7, !"Dwarf Version", i32 5}
  !3 = !{i32 2, !"Debug Info Version", i32 3}
  !4 = !{i32 1, !"wchar_size", i32 4}
  !5 = !{i32 7, !"uwtable", i32 2}
  !6 = !{!"clang version 15.0.0 (https://github.com/llvm/llvm-project.git 44673278e029d7a6f56c8a3177247026b831720f)"}
  !7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3fooxx", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
  !8 = !DISubroutineType(types: !9)
  !9 = !{!10, !10, !10}
  !10 = !DIBasicType(name: "long long", size: 64, encoding: DW_ATE_signed)
  !11 = !{!12, !13, !14, !15}
  !12 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !1, line: 1, type: !10)
  !13 = !DILocalVariable(name: "b", arg: 2, scope: !7, file: !1, line: 1, type: !10)
  !14 = !DILocalVariable(name: "c", scope: !7, file: !1, line: 2, type: !10)
  !15 = !DILocalVariable(name: "d", scope: !7, file: !1, line: 3, type: !10)
  !16 = !DILocation(line: 0, scope: !7)
  !17 = !DILocation(line: 2, column: 19, scope: !7)
  !18 = !DILocation(line: 3, column: 23, scope: !7)
  !19 = !DILocation(line: 4, column: 12, scope: !7)
  !20 = !DILocation(line: 4, column: 3, scope: !7)

...
---
name:            _Z3fooxx
alignment:       16
exposesReturnsTwice: false
legalized:       false
regBankSelected: false
selected:        false
failedISel:      false
tracksRegLiveness: true
hasWinCFI:       false
callsEHReturn:   false
callsUnwindInit: false
hasEHCatchret:   false
hasEHScopes:     false
hasEHFunclets:   false
failsVerification: false
tracksDebugUserValues: true
debugInstrRef: true
registers:       []
liveins:
  - { reg: '$rdi', virtual-reg: '' }
  - { reg: '$rsi', virtual-reg: '' }
frameInfo:
  isFrameAddressTaken: false
  isReturnAddressTaken: false
  hasStackMap:     false
  hasPatchPoint:   false
  stackSize:       0
  offsetAdjustment: 0
  maxAlignment:    1
  adjustsStack:    false
  hasCalls:        false
  stackProtector:  ''
  functionContext: ''
  maxCallFrameSize: 0
  cvBytesOfCalleeSavedRegisters: 0
  hasOpaqueSPAdjustment: false
  hasVAStart:      false
  hasMustTailInVarArgFunc: false
  hasTailCall:     false
  localFrameSize:  0
  savePoint:       ''
  restorePoint:    ''
fixedStack:
- { id: 0, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default, 
    callee-saved-register: '$r15', callee-saved-restored: true, debug-info-variable: '', 
    debug-info-expression: '', debug-info-location: '' }
stack:           []
callSites:       []
debugValueSubstitutions:
  - { srcinst: 1, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }
constants:       []
machineFunctionInfo: {}
body:             |
  bb.0.entry:
    liveins: $rdi, $rsi
  
    renamable $rax = LEA64r renamable $rsi, 1, renamable $rdi, 0, $noreg, debug-instr-number 3, debug-location !17
    DBG_VALUE $rax, $noreg, !13, !DIExpression(), debug-location !17
    $r15 = MOV64rr killed $rax, debug-location !16
    renamable $rax = LEA64r renamable $rdi, 1, $noreg, 12, $noreg, debug-location !16
    $rax = MOV64rr killed $r15, debug-location !16
    renamable $r15 = LEA64r renamable $rdi, 1, $noreg, 12, $noreg, debug-location !16
    RET64 $r15, debug-location !20

...