[GlobalISel] Fix a combine causing DBG_VALUE with dangling vregs.

We should use MachineInstr::eraseFromParentAndMarkDBGValuesForRemoval()
instead of eraseFromParent().

We should probably use that in other places too but fix this issue which
affects clang bootstrap builds for now.

Author: aemerson

llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp

@@ -1932,8 +1932,8 @@ void CombinerHelper::applyShiftOfShiftedLogic(MachineInstr &MI,
   Builder.buildInstr(MatchInfo.Logic->getOpcode(), {Dest}, {Shift1, Shift2});
 
   // These were one use so it's safe to remove them.
-  MatchInfo.Shift2->eraseFromParent();
-  MatchInfo.Logic->eraseFromParent();
+  MatchInfo.Shift2->eraseFromParentAndMarkDBGValuesForRemoval();
+  MatchInfo.Logic->eraseFromParentAndMarkDBGValuesForRemoval();
 
   MI.eraseFromParent();
 }

llvm/test/CodeGen/AArch64/GlobalISel/combine-shift-of-shifted-dbg-value-fallback.ll

@@ -0,0 +1,106 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -global-isel -mtriple=arm64-linux-gnu -global-isel-abort=1 | FileCheck %s
+target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+target triple = "arm64-apple-ios9.0.0"
+
+; Check we don't fall back due to hitting a DBG_VALUE with a deleted vreg.
+
+%0 = type { %1, %3, %5, %8, i8, i32, i8, i64, [4096 x %9], i64, i64, [4096 x %11], i64, i64, %13, %21, i8*, %35, i64, [504 x i8] }
+%1 = type { [32 x %2] }
+%2 = type { i32, i32 }
+%3 = type { [32 x %4] }
+%4 = type { i64, i64 }
+%5 = type { [32 x %6] }
+%6 = type { %7, %7 }
+%7 = type { i8, [64 x i8] }
+%8 = type { [1024 x %7], %7 }
+%9 = type { %10*, i64 }
+%10 = type { i8*, i8*, i8, i8 }
+%11 = type { %12*, %12* }
+%12 = type { i64, i64 }
+%13 = type { %14 }
+%14 = type { %15*, %17, %19 }
+%15 = type { %16* }
+%16 = type <{ %15, %16*, %15*, i8, [7 x i8] }>
+%17 = type { %18 }
+%18 = type { %15 }
+%19 = type { %20 }
+%20 = type { i64 }
+%21 = type { %22 }
+%22 = type <{ %23, %30, %32, %33, [4 x i8] }>
+%23 = type { %24 }
+%24 = type { %25, %27 }
+%25 = type { %26** }
+%26 = type { %26* }
+%27 = type { %28 }
+%28 = type { %29 }
+%29 = type { %20 }
+%30 = type { %31 }
+%31 = type { %26 }
+%32 = type { %20 }
+%33 = type { %34 }
+%34 = type { float }
+%35 = type { [1024 x i64] }
+
+@global = external hidden global %0, align 512
+
+define void @baz(i8* %arg) !dbg !6 {
+; CHECK-LABEL: baz:
+; CHECK:       .Lfunc_begin0:
+; CHECK-NEXT:    .file 1 "/" "tmp.ll"
+; CHECK-NEXT:    .loc 1 1 0 // tmp.ll:1:0
+; CHECK-NEXT:    .cfi_startproc
+; CHECK-NEXT:  // %bb.0: // %bb
+; CHECK-NEXT:    //DEBUG_VALUE: baz:3 <- undef
+; CHECK-NEXT:    .loc 1 4 1 prologue_end // tmp.ll:4:1
+; CHECK-NEXT:    lsl x8, x0, #4
+; CHECK-NEXT:    .loc 1 0 0 is_stmt 0 // tmp.ll:0:0
+; CHECK-NEXT:    adrp x9, global+202752
+; CHECK-NEXT:    .loc 1 4 1 // tmp.ll:4:1
+; CHECK-NEXT:    and x8, x8, #0x1ff0
+; CHECK-NEXT:    .loc 1 0 0 // tmp.ll:0:0
+; CHECK-NEXT:    add x9, x9, :lo12:global+202752
+; CHECK-NEXT:    .loc 1 5 1 is_stmt 1 // tmp.ll:5:1
+; CHECK-NEXT:    str xzr, [x9, x8]
+; CHECK-NEXT:    .loc 1 6 1 // tmp.ll:6:1
+; CHECK-NEXT:    ret
+; CHECK-NEXT:  .Ltmp0:
+bb:
+  %tmp = ptrtoint i8* %arg to i64, !dbg !14
+  %tmp1 = shl i64 %tmp, 1, !dbg !15
+  %tmp2 = and i64 %tmp1, 1022, !dbg !16
+  call void @llvm.dbg.value(metadata i64 %tmp2, metadata !12, metadata !DIExpression()), !dbg !16
+  %tmp3 = getelementptr inbounds %0, %0* @global, i64 0, i32 17, i32 0, i64 %tmp2, !dbg !17
+  store i64 0, i64* %tmp3, align 16, !dbg !18
+  ret void, !dbg !19
+}
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+attributes #1 = { nofree nosync nounwind readnone speculatable willreturn }
+
+!llvm.module.flags = !{!0}
+!llvm.dbg.cu = !{!1}
+!llvm.debugify = !{!4, !5}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = distinct !DICompileUnit(language: DW_LANG_C, file: !2, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !3)
+!2 = !DIFile(filename: "tmp.ll", directory: "/")
+!3 = !{}
+!4 = !{i32 6}
+!5 = !{i32 4}
+!6 = distinct !DISubprogram(name: "baz", linkageName: "baz", scope: null, file: !2, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1, retainedNodes: !8)
+!7 = !DISubroutineType(types: !3)
+!8 = !{!9, !11, !12, !13}
+!9 = !DILocalVariable(name: "1", scope: !6, file: !2, line: 1, type: !10)
+!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "2", scope: !6, file: !2, line: 2, type: !10)
+!12 = !DILocalVariable(name: "3", scope: !6, file: !2, line: 3, type: !10)
+!13 = !DILocalVariable(name: "4", scope: !6, file: !2, line: 4, type: !10)
+!14 = !DILocation(line: 1, column: 1, scope: !6)
+!15 = !DILocation(line: 2, column: 1, scope: !6)
+!16 = !DILocation(line: 3, column: 1, scope: !6)
+!17 = !DILocation(line: 4, column: 1, scope: !6)
+!18 = !DILocation(line: 5, column: 1, scope: !6)
+!19 = !DILocation(line: 6, column: 1, scope: !6)