; RUN: llc %s -o %t.s ; RUN: llvm-mc %t.s -filetype=obj -triple=x86_64-windows-msvc -o %t.o ; RUN: FileCheck %s < %t.s --check-prefix=ASM ; RUN: llvm-dwarfdump %t.o | FileCheck %s --check-prefix=DWARF ; In this example, the variable lives mostly in memory, but at the point of the ; assignment to global, it lives nowhere, and is described as the constant ; value 1. ; C source: ; ; void escape(int *); ; extern int global; ; void f(int x) { ; escape(&x); ; x = 1; // DSE should delete and insert dbg.value(i32 1) ; global = x; ; x = 2; // DSE should insert dbg.addr ; escape(&x); ; } ; ModuleID = 'dse.c' source_filename = "dse.c" target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-pc-windows-msvc19.0.24215" declare void @llvm.dbg.addr(metadata, metadata, metadata) #2 declare void @llvm.dbg.value(metadata, metadata, metadata) #2 declare void @escape(i32*) @global = external global i32, align 4 ; Function Attrs: nounwind uwtable define void @f(i32 %x) #0 !dbg !8 { entry: %x.addr = alloca i32, align 4 store i32 %x, i32* %x.addr, align 4 call void @llvm.dbg.addr(metadata i32* %x.addr, metadata !13, metadata !DIExpression()), !dbg !18 call void @escape(i32* %x.addr), !dbg !19 call void @llvm.dbg.value(metadata i32 1, metadata !13, metadata !DIExpression()), !dbg !20 store i32 1, i32* @global, align 4, !dbg !22 call void @llvm.dbg.addr(metadata i32* %x.addr, metadata !13, metadata !DIExpression()), !dbg !23 store i32 2, i32* %x.addr, align 4, !dbg !23 call void @escape(i32* %x.addr), !dbg !24 ret void, !dbg !25 } ; ASM-LABEL: f: # @f ; ASM: movl %ecx, [[OFF_X:[0-9]+]](%rsp) ; ASM: #DEBUG_VALUE: f:x <- [DW_OP_plus_uconst [[OFF_X]]] [$rsp+0] ; ASM: callq escape ; ASM: #DEBUG_VALUE: f:x <- 1 ; ASM: movl $1, global(%rip) ; FIXME: Needs a fix to LiveDebugVariables ; ASMX: #DEBUG_VALUE: f:x <- [DW_OP_plus_uconst [[OFF_X]]] [$rsp+0] ; ASM: movl $2, [[OFF_X]](%rsp) ; ASM: callq escape ; ASM: retq ; DWARF: DW_TAG_formal_parameter ; DWARF-NEXT: DW_AT_location (0x00000000 ; DWARF-NEXT: {{[^:]*}}: DW_OP_breg7 RSP+{{[0-9]+}} ; DWARF-NEXT: {{[^:]*}}: DW_OP_consts +1, DW_OP_stack_value ; DWARF-NEXT: {{[^:]*}}: DW_OP_breg7 RSP+{{[0-9]+}}) ; DWARF-NEXT: DW_AT_name ("x") attributes #0 = { nounwind uwtable } attributes #2 = { nounwind readnone speculatable } !llvm.dbg.cu = !{!0} !llvm.module.flags = !{!3, !4, !5, !6} !llvm.ident = !{!7} !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2) !1 = !DIFile(filename: "dse.c", directory: "C:\5Csrc\5Cllvm-project\5Cbuild") !2 = !{} !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 = !{!"clang version 6.0.0 "} !8 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 3, type: !9, isLocal: false, isDefinition: true, scopeLine: 3, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !12) !9 = !DISubroutineType(types: !10) !10 = !{null, !11} !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) !12 = !{!13} !13 = !DILocalVariable(name: "x", arg: 1, scope: !8, file: !1, line: 3, type: !11) !14 = !{!15, !15, i64 0} !15 = !{!"int", !16, i64 0} !16 = !{!"omnipotent char", !17, i64 0} !17 = !{!"Simple C/C++ TBAA"} !18 = !DILocation(line: 3, column: 12, scope: !8) !19 = !DILocation(line: 4, column: 3, scope: !8) !20 = !DILocation(line: 5, column: 5, scope: !8) !21 = !DILocation(line: 6, column: 12, scope: !8) !22 = !DILocation(line: 6, column: 10, scope: !8) !23 = !DILocation(line: 7, column: 5, scope: !8) !24 = !DILocation(line: 8, column: 3, scope: !8) !25 = !DILocation(line: 9, column: 1, scope: !8)