llvm/llvm/test/DebugInfo/MIR/X86/backup-entry-values-usage.mir

# RUN: llc -run-pass=livedebugvalues -emit-call-site-info -march=x86-64 -o - \
# RUN:    %s  -experimental-debug-variable-locations=false | FileCheck %s

## Test from PR47628.
## Compiled from source:
##  extern void bar(int);
##  extern int side_effect, value;
##  int foo(int param) {
##    side_effect = param;
##    param = value;
##    bar(param);
##    return 0;
##  }
## Using command:
## $ clang m.c -O1 -g -c -mllvm -stop-before=livedebugvalues

## Confirm that Backup Entry Value is not used for modified parameter "param".

# CHECK: ![[PARAM:.*]] = !DILocalVariable(name: "param"
# CHECK: renamable $edi = MOV32rm $rip, 1, $noreg
# CHECK-NOT: DBG_VALUE $edi, $noreg, ![[PARAM]], !DIExpression(DW_OP_LLVM_entry_value, 1)
# CHECK-NEXT: DBG_VALUE $edi, $noreg, ![[PARAM]], !DIExpression()
# CHECK-NEXT: CALL64pcrel32 @bar
# CHECK-NOT: DBG_VALUE $edi, $noreg, ![[PARAM]], !DIExpression(DW_OP_LLVM_entry_value, 1)

--- |
  ; ModuleID = 'm.c'
  source_filename = "m.c"
  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"
  
  @side_effect = external dso_local local_unnamed_addr global i32, align 4
  @value = external dso_local local_unnamed_addr global i32, align 4
  
  ; Function Attrs: nounwind uwtable
  define dso_local i32 @foo(i32 %param) local_unnamed_addr !dbg !8 {
  entry:
    call void @llvm.dbg.value(metadata i32 %param, metadata !13, metadata !DIExpression()), !dbg !14
    store i32 %param, ptr @side_effect, align 4, !dbg !15, !tbaa !16
    %0 = load i32, ptr @value, align 4, !dbg !20, !tbaa !16
    call void @llvm.dbg.value(metadata i32 %0, metadata !13, metadata !DIExpression()), !dbg !14
    call void @bar(i32 %0), !dbg !21
    ret i32 0, !dbg !22
  }
  
  declare !dbg !23 dso_local void @bar(i32) local_unnamed_addr
  
  ; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
  declare void @llvm.dbg.value(metadata, metadata, metadata)
  
  !llvm.dbg.cu = !{!0}
  !llvm.module.flags = !{!3, !4, !5, !6}
  !llvm.ident = !{!7}
  
  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 13.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
  !1 = !DIFile(filename: "m.c", directory: "/dir")
  !2 = !{}
  !3 = !{i32 7, !"Dwarf Version", i32 4}
  !4 = !{i32 2, !"Debug Info Version", i32 3}
  !5 = !{i32 1, !"wchar_size", i32 4}
  !6 = !{i32 7, !"uwtable", i32 1}
  !7 = !{!"clang version 13.0.0"}
  !8 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 4, type: !9, scopeLine: 4, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
  !9 = !DISubroutineType(types: !10)
  !10 = !{!11, !11}
  !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
  !12 = !{!13}
  !13 = !DILocalVariable(name: "param", arg: 1, scope: !8, file: !1, line: 4, type: !11)
  !14 = !DILocation(line: 0, scope: !8)
  !15 = !DILocation(line: 5, column: 17, scope: !8)
  !16 = !{!17, !17, i64 0}
  !17 = !{!"int", !18, i64 0}
  !18 = !{!"omnipotent char", !19, i64 0}
  !19 = !{!"Simple C/C++ TBAA"}
  !20 = !DILocation(line: 6, column: 13, scope: !8)
  !21 = !DILocation(line: 7, column: 5, scope: !8)
  !22 = !DILocation(line: 8, column: 5, scope: !8)
  !23 = !DISubprogram(name: "bar", scope: !1, file: !1, line: 1, type: !24, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
  !24 = !DISubroutineType(types: !25)
  !25 = !{null, !11}

...
---
name:            foo
alignment:       16
liveins:
  - { reg: '$edi', virtual-reg: '' }
callSites:
  - { bb: 0, offset: 6, fwdArgRegs: 
      - { arg: 0, reg: '$edi' } }
body:             |
  bb.0.entry:
    liveins: $edi
  
    DBG_VALUE $edi, $noreg, !13, !DIExpression(), debug-location !14
    frame-setup PUSH64r undef $rax, implicit-def $rsp, implicit $rsp
    CFI_INSTRUCTION def_cfa_offset 16
    MOV32mr $rip, 1, $noreg, @side_effect, $noreg, killed renamable $edi, debug-location !15 :: (store 4 into @side_effect, !tbaa !16)
    renamable $edi = MOV32rm $rip, 1, $noreg, @value, $noreg, debug-location !20 :: (dereferenceable load 4 from @value, !tbaa !16)
    DBG_VALUE $edi, $noreg, !13, !DIExpression(), debug-location !14
    CALL64pcrel32 @bar, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $rsp, implicit-def $ssp, debug-location !21
    $eax = XOR32rr undef $eax, undef $eax, implicit-def dead $eflags, debug-location !22
    $rcx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !22
    CFI_INSTRUCTION def_cfa_offset 8, debug-location !22
    RET64 killed $eax, debug-location !22

...