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llvm-project/llvm/test/Transforms/InstCombine/alloca-cast-debuginfo.ll

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Make salvageDebugInfo of casts work for dbg.declare and dbg.addr Summary: Instcombine (and probably other passes) sometimes want to change the type of an alloca. To do this, they generally create a new alloca with the desired type, create a bitcast to make the new pointer type match the old pointer type, replace all uses with the cast, and then simplify the casts. We already knew how to salvage dbg.value instructions when removing casts, but we can extend it to cover dbg.addr and dbg.declare. Fixes a debug info quality issue uncovered in Chromium in http://crbug.com/784609 Reviewers: aprantl, vsk Subscribers: hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D40042 llvm-svn: 318203
2017-11-15 05:49:06 +08:00
; RUN: opt < %s -S -instcombine -instcombine-lower-dbg-declare=0 | FileCheck %s
; In this example, instcombine wants to turn "local" into an i64, since that's
; how it is stored. It should keep the debug info referring to the alloca when
; it does the replacement.
; C source:
; struct Foo {
; int x, y;
; };
; void escape(const void*);
; void f(struct Foo *p) {
; struct Foo local;
; *(__int64 *)&local = *(__int64 *)p;
; escape(&local);
; }
; ModuleID = '<stdin>'
source_filename = "t.c"
target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc19.11.25508"
%struct.Foo = type { i32, i32 }
define void @f(%struct.Foo* %p) !dbg !11 {
entry:
%local = alloca %struct.Foo, align 4
%0 = bitcast %struct.Foo* %local to i8*, !dbg !24
call void @llvm.dbg.declare(metadata %struct.Foo* %local, metadata !22, metadata !DIExpression()), !dbg !25
%1 = bitcast %struct.Foo* %p to i64*, !dbg !26
%2 = load i64, i64* %1, align 8, !dbg !26, !tbaa !27
%3 = bitcast %struct.Foo* %local to i64*, !dbg !31
store i64 %2, i64* %3, align 4, !dbg !32, !tbaa !27
%4 = bitcast %struct.Foo* %local to i8*, !dbg !33
call void @escape(i8* %4), !dbg !34
%5 = bitcast %struct.Foo* %local to i8*, !dbg !35
ret void, !dbg !35
}
; CHECK-LABEL: define void @f(%struct.Foo* %p)
; CHECK: %local = alloca i64, align 8
; CHECK: call void @llvm.dbg.declare(metadata i64* %local, metadata !22, metadata !DIExpression())
[InstCombine] Preserve debug values for eliminable casts A cast from A to B is eliminable if its result is casted to C, and if the pair of casts could just be expressed as a single cast. E.g here, %c1 is eliminable: %c1 = zext i16 %A to i32 %c2 = sext i32 %c1 to i64 InstCombine optimizes away eliminable casts. This patch teaches it to insert a dbg.value intrinsic pointing to the final result, so that local variables pointing to the eliminable result are preserved. Differential Revision: https://reviews.llvm.org/D42566 llvm-svn: 323570
2018-01-27 06:02:52 +08:00
; CHECK: [[simplified:%.*]] = bitcast i64* %local to i8*
; CHECK: call void @llvm.dbg.value(metadata i8* [[simplified]], metadata !22, metadata !DIExpression())
; CHECK: call void @escape(i8* [[simplified]])
; CHECK: ret void
Make salvageDebugInfo of casts work for dbg.declare and dbg.addr Summary: Instcombine (and probably other passes) sometimes want to change the type of an alloca. To do this, they generally create a new alloca with the desired type, create a bitcast to make the new pointer type match the old pointer type, replace all uses with the cast, and then simplify the casts. We already knew how to salvage dbg.value instructions when removing casts, but we can extend it to cover dbg.addr and dbg.declare. Fixes a debug info quality issue uncovered in Chromium in http://crbug.com/784609 Reviewers: aprantl, vsk Subscribers: hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D40042 llvm-svn: 318203
2017-11-15 05:49:06 +08:00
declare void @llvm.dbg.declare(metadata, metadata, metadata)
declare void @escape(i8*)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!6, !7, !8, !9}
!llvm.ident = !{!10}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3)
!1 = !DIFile(filename: "t.c", directory: "C:\5Csrc\5Cllvm-project\5Cbuild", checksumkind: CSK_MD5, checksum: "d7473625866433067a75fd7d03d2abf7")
!2 = !{}
!3 = !{!4}
!4 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64)
!5 = !DIBasicType(name: "long long int", size: 64, encoding: DW_ATE_signed)
!6 = !{i32 2, !"CodeView", i32 1}
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{i32 1, !"wchar_size", i32 2}
!9 = !{i32 7, !"PIC Level", i32 2}
!10 = !{!"clang version 6.0.0 "}
!11 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 5, type: !12, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !20)
!12 = !DISubroutineType(types: !13)
!13 = !{null, !14}
!14 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !15, size: 64)
!15 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Foo", file: !1, line: 1, size: 64, elements: !16)
!16 = !{!17, !19}
!17 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !15, file: !1, line: 2, baseType: !18, size: 32)
!18 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!19 = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: !15, file: !1, line: 2, baseType: !18, size: 32, offset: 32)
!20 = !{!21, !22}
!21 = !DILocalVariable(name: "p", arg: 1, scope: !11, file: !1, line: 5, type: !14)
!22 = !DILocalVariable(name: "local", scope: !11, file: !1, line: 6, type: !15)
!23 = !DILocation(line: 5, column: 20, scope: !11)
!24 = !DILocation(line: 6, column: 3, scope: !11)
!25 = !DILocation(line: 6, column: 14, scope: !11)
!26 = !DILocation(line: 7, column: 24, scope: !11)
!27 = !{!28, !28, i64 0}
!28 = !{!"long long", !29, i64 0}
!29 = !{!"omnipotent char", !30, i64 0}
!30 = !{!"Simple C/C++ TBAA"}
!31 = !DILocation(line: 7, column: 3, scope: !11)
!32 = !DILocation(line: 7, column: 22, scope: !11)
!33 = !DILocation(line: 8, column: 10, scope: !11)
!34 = !DILocation(line: 8, column: 3, scope: !11)
!35 = !DILocation(line: 9, column: 1, scope: !11)