test/DebugInfo/MIR/X86/regcoalescing-clears-dead-dbgvals.mir

# RUN: llc -mtriple=x86_64-unknown-unknown %s -o - -run-pass=simple-register-coalescing | FileCheck %s
# PR40010: DBG_VALUEs do not contribute to the liveness of virtual registers,
# and the register coalescer would merge new live values on top of DBG_VALUEs,
# leading to them presenting new (wrong) values to the debugger. Test that
# when out of liveness, coalescing will mark DBG_VALUEs in non-live locations
# as undef.
--- |
  ; ModuleID = './test.ll'
  source_filename = "./test.ll"
  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"

  ; Function Attrs: nounwind readnone speculatable
  declare void @llvm.dbg.value(metadata, metadata, metadata) #0

  ; Original IR source here:
  define i32 @test(i32* %pin) {
  entry:
    br label %start.test1

  start.test1:                                       ; preds = %start, %entry
    %foo = phi i32 [ 0, %entry ], [ %bar, %start.test1 ]
    %baz = load i32, i32* %pin, align 1
    %qux = xor i32 %baz, 1234
    %bar = add i32 %qux, %foo
    call void @llvm.dbg.value(metadata i32 %foo, metadata !3, metadata !DIExpression()), !dbg !5
    %cmp = icmp ugt i32 %bar, 1000000
    br i1 %cmp, label %leave, label %start.test1

  leave:                                            ; preds = %start
    ret i32 %bar
  }

  ; Stubs to appease the MIR parser
  define i32 @test2(i32* %pin) {
  entry:
    ret i32 0
  start.test2:
    ret i32 0
  leave:
    ret i32 0
  }

  ; Function Attrs: nounwind
  declare void @llvm.stackprotector(i8*, i8**) #1

  attributes #0 = { nounwind readnone speculatable }
  attributes #1 = { nounwind }

  !llvm.module.flags = !{!0}
  !llvm.dbg.cu = !{!1}

  !0 = !{i32 2, !"Debug Info Version", i32 3}
  !1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, producer: "beards", isOptimized: true, runtimeVersion: 4, emissionKind: FullDebug)
  !2 = !DIFile(filename: "bees.cpp", directory: "")
  !3 = !DILocalVariable(name: "bees", scope: !4)
  !4 = distinct !DISubprogram(name: "nope", scope: !1, file: !2, line: 1, spFlags: DISPFlagDefinition, unit: !1)
  !5 = !DILocation(line: 0, scope: !4)

...
---
name:            test
tracksRegLiveness: true
body:             |
  bb.0.entry:
    successors: %bb.1(0x80000000)
    liveins: $rdi

    %2:gr64 = COPY killed $rdi
    %3:gr32 = MOV32r0 implicit-def dead $eflags
    %4:gr32 = MOV32ri 1234
    %7:gr32 = COPY killed %3

  bb.1.start.test1:
    successors: %bb.2(0x04000000), %bb.1(0x7c000000)

    ; CHECK-LABEL: name: test
    ;
    ; We currently expect %1 and %0 to merge into %7
    ;
    ; CHECK: %[[REG1:[0-9]+]]:gr32 = MOV32rm
    ; CHECK-NEXT: %[[REG2:[0-9]+]]:gr32 = XOR32rr %[[REG1]]
    ; CHECK-NEXT: %[[REG3:[0-9]+]]:gr32 = ADD32rr %[[REG3]], %[[REG2]]
    ; CHECK-NEXT: DBG_VALUE $noreg

    %0:gr32 = COPY killed %7
    %8:gr32 = MOV32rm %2, 1, $noreg, 0, $noreg :: (load 4 from %ir.pin, align 1)
    %5:gr32 = COPY killed %8
    %5:gr32 = XOR32rr %5, %4, implicit-def dead $eflags
    %1:gr32 = COPY killed %0
    %1:gr32 = ADD32rr %1, killed %5, implicit-def dead $eflags
    DBG_VALUE %0, $noreg, !3, !DIExpression(), debug-location !5
    CMP32ri %1, 1000001, implicit-def $eflags
    %7:gr32 = COPY %1
    JCC_1 %bb.1, 2, implicit killed $eflags
    JMP_1 %bb.2

  bb.2.leave:
    $eax = COPY killed %1
    RET 0, killed $eax

...
---
name:            test2
tracksRegLiveness: true
body:             |
  bb.0.entry:
    successors: %bb.1(0x80000000)
    liveins: $rdi

    %2:gr64 = COPY killed $rdi
    %3:gr32 = MOV32r0 implicit-def dead $eflags
    %4:gr32 = MOV32ri 1234
    %7:gr32 = COPY killed %3

  bb.1.start.test2:
    successors: %bb.2(0x04000000), %bb.1(0x7c000000)

    ; CHECK-LABEL: name: test2
    ;
    ; %0 should be merged into %7, but as %0 is live at this location the
    ; DBG_VALUE should be preserved and point at the operand of ADD32rr.
    ; RegisterCoalescer resolves %0 as CR_Erase: %0 is a redundant copy and
    ; can be erased.
    ;
    ; CHECK: %[[REG11:[0-9]+]]:gr32 = MOV32rm
    ; CHECK-NEXT: %[[REG12:[0-9]+]]:gr32 = XOR32rr %[[REG11]]
    ; CHECK-NEXT: DBG_VALUE %[[REG13:[0-9]+]]
    ; CHECK-NEXT: %[[REG13]]:gr32 = ADD32rr %[[REG13]], %[[REG12]]

    %0:gr32 = COPY killed %7
    %8:gr32 = MOV32rm %2, 1, $noreg, 0, $noreg :: (load 4 from %ir.pin, align 1)
    %8:gr32 = XOR32rr %8, %4, implicit-def dead $eflags
    DBG_VALUE %0, $noreg, !3, !DIExpression(), debug-location !5
    %0:gr32 = ADD32rr %0, killed %8, implicit-def dead $eflags
    CMP32ri %0, 1000001, implicit-def $eflags
    %7:gr32 = COPY %0
    JCC_1 %bb.1, 2, implicit killed $eflags
    JMP_1 %bb.2

  bb.2.leave:
    $eax = COPY killed %7
    RET 0, killed $eax

...