1; RUN: opt -early-cse -earlycse-debug-hash -S %s -o - | FileCheck %s
2
3; PR40628: The first load below is determined to be redundant by EarlyCSE.
4; During salvaging, the corresponding dbg.value could have a DW_OP_deref used
5; in its DIExpression to represent the redundant operation -- however LLVM
6; cannot currently determine that the subsequent store should terminate the
7; variables location range. A debugger would display zero for the "redundant"
8; variable after stepping onto the return instruction.
9
10; Test that the load being removed results in the corresponding dbg.value
11; being assigned the 'undef' value.
12
13; CHECK:      @foo
14; CHECK-NEXT: dbg.value(metadata i32 undef, metadata ![[DEADVAR:[0-9]+]],
15; CHECK-NEXT: load
16; CHECK-NEXT: dbg.value(metadata i32 %{{[0-9]+}}, metadata ![[LIVEVAR:[0-9]+]],
17; CHECK-NEXT: store
18; CHECK-NEXT: ret
19
20; CHECK:      ![[DEADVAR]] = !DILocalVariable(name: "redundant",
21; CHECK:      ![[LIVEVAR]] = !DILocalVariable(name: "loaded",
22
23target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
24target triple = "x86_64-unknown-linux-gnu"
25
26define dso_local i32 @foo(i32*) !dbg !7 {
27  %2 = load i32, i32* %0, align 4, !dbg !23
28  call void @llvm.dbg.value(metadata i32 %2, metadata !16, metadata !DIExpression()), !dbg !23
29  %3 = load i32, i32* %0, align 4, !dbg !23
30  call void @llvm.dbg.value(metadata i32 %3, metadata !17, metadata !DIExpression()), !dbg !23
31  store i32 0, i32* %0, align 4, !dbg !23
32  ret i32 %3, !dbg !23
33}
34
35declare void @llvm.dbg.value(metadata, metadata, metadata)
36
37!llvm.dbg.cu = !{!0}
38!llvm.module.flags = !{!3, !4, !5}
39!llvm.ident = !{!6}
40
41!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
42!1 = !DIFile(filename: "pr40628.c", directory: ".")
43!2 = !{}
44!3 = !{i32 2, !"Dwarf Version", i32 4}
45!4 = !{i32 2, !"Debug Info Version", i32 3}
46!5 = !{i32 1, !"wchar_size", i32 4}
47!6 = !{!"clang"}
48!7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 2, type: !8, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
49!8 = !DISubroutineType(types: !9)
50!9 = !{!10, !11}
51!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
52!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)
53!12 = !{!16, !17}
54!16 = !DILocalVariable(name: "redundant", scope: !7, file: !1, line: 4, type: !10)
55!17 = !DILocalVariable(name: "loaded", scope: !7, file: !1, line: 5, type: !10)
56!23 = !DILocation(line: 4, column: 7, scope: !7)
57