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llvm-mirror/test/DebugInfo/COFF/udts-complete.ll
Reid Kleckner 9569e05324 [codeview] Align symbol records to save 441MB during linking clang.pdb
In PDBs, symbol records must be aligned to four bytes. However, in the
object file, symbol records may not be aligned. MSVC does not pad out
symbol records to make sure they are aligned. That means the linker has
to do extra work to insert the padding. Currently, LLD calculates the
required space with alignment, and copies each record one at a time
while padding them out to the correct size. It has a fast path that
avoids this copy when the records are already aligned.

This change fixes a bug in that codepath so that the copy is actually
saved, and tweaks LLVM's symbol record emission to align symbol records.
Here's how things compare when doing a plain clang Release+PDB build:
- objs are 0.65% bigger (negligible)
- link is 3.3% faster (negligible)
- saves allocating 441MB
- new LLD high water mark is ~1.05GB

llvm-svn: 349431
2018-12-18 01:14:05 +00:00

73 lines
3.3 KiB
LLVM

; RUN: llc -filetype=obj %s -o %t.obj
; RUN: llvm-pdbutil dump -symbols -types %t.obj | FileCheck %s
; Make sure that `gv`, `Bar`, and `Baz` all point to the complete type index of
; Foo (0x1002), and not the forward declaration index (0x1000).
; C++ source:
; struct Foo {
; int x;
; };
; typedef Foo Bar;
; typedef Bar Baz;
; static_assert(sizeof(Foo) == 4, "");
; Baz gv;
; CHECK: Types (.debug$T)
; CHECK-NEXT: ============================================================
; CHECK: 0x1000 | LF_STRUCTURE [size = 36] `Foo`
; CHECK: unique name: `.?AUFoo@@`
; CHECK: vtable: <no type>, base list: <no type>, field list: <no type>
; CHECK: options: forward ref | has unique name, sizeof 0
; CHECK: 0x1001 | LF_FIELDLIST [size = 16]
; CHECK: - LF_MEMBER [name = `x`, Type = 0x0074 (int), offset = 0, attrs = public]
; CHECK: 0x1002 | LF_STRUCTURE [size = 36] `Foo`
; CHECK: unique name: `.?AUFoo@@`
; CHECK: vtable: <no type>, base list: <no type>, field list: 0x1001
; CHECK: options: has unique name, sizeof 4
; CHECK: 0x1004 | LF_UDT_SRC_LINE [size = 16]
; CHECK: udt = 0x1002, file = 4099, line = 1
; CHECK: Symbols
; CHECK: ============================================================
; CHECK: Mod 0000 | `.debug$S`:
; CHECK: 0 | S_GDATA32 [size = 20] `gv`
; CHECK: type = 0x1002 (Foo), addr = 0000:0000
; CHECK: 0 | S_UDT [size = 12] `Bar`
; CHECK: original type = 0x1002
; CHECK: 0 | S_UDT [size = 12] `Baz`
; CHECK: original type = 0x1002
; CHECK: 0 | S_UDT [size = 12] `Foo`
; CHECK: original type = 0x1002
; ModuleID = 't.cpp'
source_filename = "t.cpp"
target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc19.14.26433"
%struct.Foo = type { i32 }
@"?gv@@3UFoo@@A" = dso_local global %struct.Foo zeroinitializer, align 4, !dbg !0
!llvm.dbg.cu = !{!2}
!llvm.module.flags = !{!12, !13, !14, !15}
!llvm.ident = !{!16}
!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
!1 = distinct !DIGlobalVariable(name: "gv", linkageName: "?gv@@3UFoo@@A", scope: !2, file: !3, line: 7, type: !6, isLocal: false, isDefinition: true)
!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, producer: "clang version 8.0.0 ", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None)
!3 = !DIFile(filename: "t.cpp", directory: "C:\5Csrc\5Cllvm-project\5Cbuild", checksumkind: CSK_MD5, checksum: "e21cd263d43db2ff55050be3e41e789f")
!4 = !{}
!5 = !{!0}
!6 = !DIDerivedType(tag: DW_TAG_typedef, name: "Baz", file: !3, line: 5, baseType: !7)
!7 = !DIDerivedType(tag: DW_TAG_typedef, name: "Bar", file: !3, line: 4, baseType: !8)
!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Foo", file: !3, line: 1, size: 32, flags: DIFlagTypePassByValue | DIFlagTrivial, elements: !9, identifier: ".?AUFoo@@")
!9 = !{!10}
!10 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !8, file: !3, line: 2, baseType: !11, size: 32)
!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!12 = !{i32 2, !"CodeView", i32 1}
!13 = !{i32 2, !"Debug Info Version", i32 3}
!14 = !{i32 1, !"wchar_size", i32 2}
!15 = !{i32 7, !"PIC Level", i32 2}
!16 = !{!"clang version 8.0.0 "}