llvm/test/DebugInfo/MIR/InstrRef/phi-coalescing.mir

# RUN: llc %s -o - -mtriple=x86_64-unknown-unknown \
# RUN:    -experimental-debug-variable-locations \
# RUN:    -run-pass=phi-node-elimination,simple-register-coalescing \
# RUN:    | FileCheck %s --check-prefix=DOESCOALESCE
# RUN: llc %s -o - -mtriple=x86_64-unknown-unknown \
# RUN:    -experimental-debug-variable-locations \
# RUN:    -run-pass=phi-node-elimination,simple-register-coalescing,livedebugvars,greedy,virtregrewriter \
# RUN:    | FileCheck %s --check-prefix=CHECK
#
# Test that a PHI with a debug instruction number attached survives register
# coalescing, when its vreg gets coalesced. This test comes in two parts, first
# that coalescing actually happens, second that a DBG_PHI is still produced
# afterwards.
#
# Original C code, the PHI is of the value of 'bar' after the control flow.
# Compiled at -O0, applied -mem2reg, llc -O0, then manually added the PHI
# instruction label. Additional variable locations removed.
#
#    void ext(long);
#    long getlong(void);
#    int foo(long bar, long baz) {
#      ext(bar);
#      bar += 12;
#      ext(bar);
#    
#      if (getlong())
#        bar += 1;
#    
#      bar += baz;
#      ext(bar);
#      return bar;
#    }
#
--- |
  ; ModuleID = 'promoted.ll'
  source_filename = "test.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"
  
  define dso_local i32 @foo(i64 %bar, i64 %baz) !dbg !7 {
  entry:
    call void @llvm.dbg.value(metadata i64 %bar, metadata !12, metadata !DIExpression()), !dbg !13
    call void @llvm.dbg.value(metadata i64 %baz, metadata !14, metadata !DIExpression()), !dbg !13
    call void @ext(i64 %bar), !dbg !13
    %add = add nsw i64 %bar, 12, !dbg !13
    call void @llvm.dbg.value(metadata i64 %add, metadata !12, metadata !DIExpression()), !dbg !13
    call void @ext(i64 %add), !dbg !13
    %call = call i64 @getlong(), !dbg !13
    %tobool = icmp ne i64 %call, 0, !dbg !13
    br i1 %tobool, label %if.then, label %if.end, !dbg !13
  
  if.then:                                          ; preds = %entry
    %add1 = add nsw i64 %add, 1, !dbg !13
    call void @llvm.dbg.value(metadata i64 %add1, metadata !12, metadata !DIExpression()), !dbg !13
    br label %if.end, !dbg !13
  
  if.end:                                           ; preds = %if.then, %entry
    %bar.addr.0 = phi i64 [ %add1, %if.then ], [ %add, %entry ], !dbg !13
    call void @llvm.dbg.value(metadata i64 %bar.addr.0, metadata !12, metadata !DIExpression()), !dbg !13
    %add2 = add nsw i64 %bar.addr.0, %baz, !dbg !13
    call void @llvm.dbg.value(metadata i64 %add2, metadata !12, metadata !DIExpression()), !dbg !13
    call void @ext(i64 %add2), !dbg !13
    %conv = trunc i64 %add2 to i32, !dbg !13
    ret i32 %conv, !dbg !13
  }
  
  ; Function Attrs: nounwind readnone speculatable willreturn
  declare void @llvm.dbg.declare(metadata, metadata, metadata)
  
  declare dso_local void @ext(i64)
  
  declare dso_local i64 @getlong()
  
  ; Function Attrs: nounwind readnone speculatable willreturn
  declare void @llvm.dbg.value(metadata, metadata, metadata)
  
  !llvm.dbg.cu = !{!0}
  !llvm.module.flags = !{!3, !4, !5}
  !llvm.ident = !{!6}
  
  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
  !1 = !DIFile(filename: "test.c", directory: "/tmp/out.c")
  !2 = !{}
  !3 = !{i32 7, !"Dwarf Version", i32 4}
  !4 = !{i32 2, !"Debug Info Version", i32 3}
  !5 = !{i32 1, !"wchar_size", i32 4}
  !6 = !{!""}
  !7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 3, type: !8, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
  !8 = !DISubroutineType(types: !9)
  !9 = !{!10, !11, !11}
  !10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
  !11 = !DIBasicType(name: "long int", size: 64, encoding: DW_ATE_signed)
  !12 = !DILocalVariable(name: "bar", arg: 1, scope: !7, file: !1, line: 3, type: !11)
  !13 = !DILocation(line: 0, scope: !7)
  !14 = !DILocalVariable(name: "baz", arg: 2, scope: !7, file: !1, line: 3, type: !11)
  !15 = distinct !DILexicalBlock(scope: !7, file: !1, line: 8, column: 7)

...
---
name:            foo
alignment:       16
tracksRegLiveness: true
liveins:
  - { reg: '$rdi', virtual-reg: '%3' }
  - { reg: '$rsi', virtual-reg: '%5' }
frameInfo:
  maxAlignment:    1
  hasCalls:        true
machineFunctionInfo: {}
body:             |
  bb.0.entry:
    liveins: $rdi, $rsi
  
    %5:gr64 = COPY $rsi
    %3:gr64 = COPY $rdi
    %4:gr64 = COPY killed %3
    %6:gr64 = COPY killed %5
    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    $rdi = COPY %4, debug-location !13
    CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, debug-location !13
    ADJCALLSTACKUP64 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    %9:gr64 = ADD64ri32 %4, 12, implicit-def $eflags, debug-location !13
    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    $rdi = COPY %9, debug-location !13
    CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, debug-location !13
    ADJCALLSTACKUP64 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    CALL64pcrel32 @getlong, csr_64, implicit $rsp, implicit $ssp, implicit-def $rax, debug-location !13
    ADJCALLSTACKUP64 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    %8:gr64 = COPY $rax, debug-location !13
    CMP64ri8 %8, 0, implicit-def $eflags, debug-location !13
    JCC_1 %bb.2, 4, implicit $eflags, debug-location !13
  
  ; DOESCOALESCE-LABEL: bb.1.if.then:
  ; CHECK-LABEL:        bb.1.if.then:
  bb.1.if.then:
    %10:gr64 = ADD64ri32 %9, 1, implicit-def $eflags, debug-location !13

  ; Verify that the vreg is different immediately after register coalescing.
  ; DOESCOALESCE-NOT:   %10:gr64 ADD64ri32
  ; DOESCOALESCE:       %{{[0-9]+}}:gr64 = ADD64ri32
  ; Verify that all these registers land in rbx.
  ; CHECK:              renamable $rbx = ADD64ri32 killed renamable $rbx
  
  ; DOESCOALESCE-LABEL: bb.2.if.end:
  ; CHECK-LABEL:        bb.2.if.end:
  bb.2.if.end:
    %2:gr64 = PHI %9, %bb.0, %10, %bb.1, debug-instr-number 1, debug-location !13
  ; CHECK:              DBG_PHI $rbx, 1
    DBG_INSTR_REF 1, 0, !12, !DIExpression(), debug-location !13
    %14:gr64 = ADD64rr killed %2, %6, implicit-def $eflags, debug-location !13
    ADJCALLSTACKDOWN64 0, 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    $rdi = COPY %14, debug-location !13
    CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, debug-location !13
    ADJCALLSTACKUP64 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
    %13:gr32 = COPY %14.sub_32bit, debug-location !13
    $eax = COPY %13, debug-location !13
    RET64 implicit $eax, debug-location !13

...