llvm/test/DebugInfo/MIR/InstrRef/livedebugvalues_subreg_substitutions.mir

# RUN: llc %s -march=x86-64 -run-pass=livedebugvalues -experimental-debug-variable-locations -o - 2>&1 | FileCheck %s
#
# Test that when we have a subregister qualifiers in substitutions, that
# InstrRefBasedLDV correctly applies them to the variable location. Below, a
# call defines all of $rax, but the variable locations should only apply to
# the low order 8 bits.
--- |
  define i8 @test(i32 %bar) local_unnamed_addr !dbg !7 {
  entry:
    ret i8 0, !dbg !12
  }

  declare dso_local void @ext(i64)

  !llvm.dbg.cu = !{!0}
  !llvm.module.flags = !{!3, !4, !5, !6}
  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
  !1 = !DIFile(filename: "foo.cpp", directory: ".")
  !2 = !DIBasicType(name: "int", size: 8, encoding: DW_ATE_signed)
  !3 = !{i32 2, !"Dwarf Version", i32 4}
  !4 = !{i32 2, !"Debug Info Version", i32 3}
  !5 = !{i32 1, !"wchar_size", i32 2}
  !6 = !{i32 7, !"PIC Level", i32 2}
  !7 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: !1, file: !1, line: 6, type: !8, scopeLine: 6, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !10)
  !8 = !DISubroutineType(types: !9)
  !9 = !{!2, !2}
  !10 = !{!11}
  !11 = !DILocalVariable(name: "baz", scope: !7, file: !1, line: 7, type: !2)
  !12 = !DILocation(line: 10, scope: !7)
...
---
name: test
tracksRegLiveness: true
liveins:
  - { reg: '$rdi', virtual-reg: '' }
debugValueSubstitutions:
  - { srcinst: 1, srcop: 0, dstinst: 2, dstop: 0, subreg: 1 } # sub_8bit
  - { srcinst: 2, srcop: 0, dstinst: 3, dstop: 0, subreg: 4 } # sub_16bit
  - { srcinst: 3, srcop: 0, dstinst: 4, dstop: 5, subreg: 6 } # sub_32bit
  # Substitution involving sub_8bit_hi, should land in $ah
  - { srcinst: 5, srcop: 0, dstinst: 6, dstop: 0, subreg: 2 } # sub_8bit_hi
  - { srcinst: 6, srcop: 0, dstinst: 7, dstop: 0, subreg: 4 } # sub_16bit
  - { srcinst: 7, srcop: 0, dstinst: 4, dstop: 5, subreg: 6 } # sub_32bit
  # Several redundant substitutions, representing extractions from a small
  # register, followed by larger spurious ones, for example:
  # %0:gr64 = COPY $rax
  # %1:gr32 = COPY %0.sub_32bit
  # %2:gr16 = COPY %1.sub_16bit
  # %3:gr64 = SUBREG_TO_REG %2, sub_8bit_hi
  # %4:gr32 = COPY %3.sub_32bit
  # %5:gr16 = COPY %2.sub_16bit
  # Should still come out as ah.
  - { srcinst: 8, srcop: 0, dstinst: 9, dstop: 0, subreg: 4 } # sub_16bit
  - { srcinst: 9, srcop: 0, dstinst: 10,dstop: 0, subreg: 6 } # sub_32bit
  - { srcinst: 10,srcop: 0, dstinst: 11,dstop: 0, subreg: 2 } # sub_8bit_hi
  - { srcinst: 11,srcop: 0, dstinst: 12,dstop: 0, subreg: 4 } # sub_16bit
  - { srcinst: 12,srcop: 0, dstinst: 4, dstop: 5, subreg: 6 } # sub_32bit
  # If some kind of really mal-formed code appears that extracts the high bits
  # out of a too-small location, we should drop it. It's not clear whether this
  # scenario could ever happen; but if it did, best to not emit a known bad
  # variable location. Should generate a DBG_VALUE $noreg.
  - { srcinst: 13, srcop: 0, dstinst: 14,dstop: 0, subreg: 5 } # sub_16bit_hi
  - { srcinst: 14, srcop: 0, dstinst: 15,dstop: 0, subreg: 6 } # sub_32bit
  - { srcinst: 15, srcop: 0, dstinst: 4, dstop: 5, subreg: 1 } # sub_8bit
stack:
  - { id: 0, name: '', type: spill-slot, offset: -16, size: 8, alignment: 8,
      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
body:  |
  bb.0:
  liveins: $rdi, $rax
    CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $rax, debug-instr-number 4, debug-location !12
    ; CHECK:      CALL64pcrel32
    DBG_INSTR_REF 1, 0, !11, !DIExpression(), debug-location !12
    ; CHECK-NEXT: DBG_INSTR_REF 1, 0
    ; CHECK-NEXT: DBG_VALUE $al
    DBG_INSTR_REF 5, 0, !11, !DIExpression(), debug-location !12
    ; CHECK-NEXT: DBG_INSTR_REF 5, 0
    ; CHECK-NEXT: DBG_VALUE $ah
    DBG_INSTR_REF 8, 0, !11, !DIExpression(), debug-location !12
    ; CHECK-NEXT: DBG_INSTR_REF 8, 0
    ; CHECK-NEXT: DBG_VALUE $ah
    DBG_INSTR_REF 13, 0, !11, !DIExpression(), debug-location !12
    ; CHECK-NEXT: DBG_INSTR_REF 13, 0
    ; CHECK-NEXT: DBG_VALUE $noreg
    MOV64mr $rsp, 1, $noreg, 16, $noreg, $rax :: (store 8 into %stack.0)
    $rax = MOV64ri 0, debug-location !12
    ; CHECK:      $rax = MOV64ri 0
    ; The value is now located in a spill slot, as a subregister within the
    ; slot, which InstrRefBasedLDV should be able to find.
    DBG_INSTR_REF 1, 0, !11, !DIExpression(), debug-location !12
    ; CHECK-NEXT: DBG_INSTR_REF 1, 0
    ; CHECK-NEXT: DBG_VALUE $rsp, 0, !{{[0-9]*}}, !DIExpression(DW_OP_constu, 8, DW_OP_minus)
    DBG_INSTR_REF 5, 0, !11, !DIExpression(), debug-location !12
    ; This and the next DBG_INSTR_REF refer to a value that is on the stack, but
    ; is located at a non-zero offset from the start of the slot -- $ah within
    ; $rax is 8 bits in. Today, InstrRefBasedLDV can't express this. It also
    ; doesn't seem likely to be profitable.
    ; CHECK-NEXT: DBG_INSTR_REF 5, 0
    ; CHECK-NEXT: DBG_VALUE $noreg
    DBG_INSTR_REF 8, 0, !11, !DIExpression(), debug-location !12
    ; CHECK-NEXT: DBG_INSTR_REF 8, 0
    ; CHECK-NEXT: DBG_VALUE $noreg
    DBG_INSTR_REF 13, 0, !11, !DIExpression(), debug-location !12
    ; CHECK-NEXT: DBG_INSTR_REF 13, 0
    ; CHECK-NEXT: DBG_VALUE $noreg
    $rax = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
    RET64 $rax, debug-location !12
...