[ThinLTO] Import composite types as declarations

Summary:
When reading the metadata bitcode, create a type declaration when
possible for composite types when we are importing. Doing this in
the bitcode reader saves memory. Also it works naturally in the case
when the type ODR map contains a definition for the same composite type
because it was used in the importing module (buildODRType will
automatically use the existing definition and not create a type
declaration).

For Chromium built with -g2, this reduces the aggregate size of the
generated native object files by 66% (from 31G to 10G). It reduced
the time through the ThinLTO link and backend phases by about 20% on
my machine.

Reviewers: mehdi_amini, dblaikie, aprantl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D27775

llvm-svn: 289993

2 files changed, 75 insertions, 0 deletions

diff --git a/llvm/test/ThinLTO/X86/Inputs/debuginfo-compositetype-import.ll b/llvm/test/ThinLTO/X86/Inputs/debuginfo-compositetype-import.ll
new file mode 100644
index 00000000000..7e80c4d7c44
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/Inputs/debuginfo-compositetype-import.ll
@@ -0,0 +1,13 @@
+; ModuleID = 'debuginfo-compositetype-import2.c'
+source_filename = "debuginfo-compositetype-import2.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind uwtable
+define i32 @main() {
+entry:
+  call void (...) @foo()
+  ret i32 0
+}
+
+declare void @foo(...) #1
diff --git a/llvm/test/ThinLTO/X86/debuginfo-compositetype-import.ll b/llvm/test/ThinLTO/X86/debuginfo-compositetype-import.ll
new file mode 100644
index 00000000000..0b3a7a45224
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/debuginfo-compositetype-import.ll
@@ -0,0 +1,62 @@
+; Test to ensure DICompositeType are imported as type declarations
+; for ThinLTO
+
+; RUN: opt -module-summary %s -o %t1.bc
+; RUN: opt -module-summary %p/Inputs/debuginfo-compositetype-import.ll -o %t2.bc
+; RUN: llvm-lto -thinlto-action=thinlink -o %t.index.bc %t1.bc %t2.bc
+
+; By default, composite types are imported as type declarations
+; RUN: llvm-lto -thinlto-action=import %t2.bc -thinlto-index=%t.index.bc -o - | llvm-dis -o - | FileCheck %s
+; RUN: llvm-lto2 %t1.bc %t2.bc -o %t.out -save-temps \
+; RUN:   -r %t2.bc,main,plx \
+; RUN:   -r %t2.bc,foo,l \
+; RUN:   -r %t1.bc,foo,pl
+; RUN: llvm-dis < %t.out.1.3.import.bc | FileCheck %s
+
+; CHECK: distinct !DICompositeType(tag: DW_TAG_enumeration_type, name: "enum", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 50, size: 32, flags: DIFlagFwdDecl, identifier: "enum")
+; CHECK: distinct !DICompositeType(tag: DW_TAG_class_type, name: "class", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 728, size: 448, flags: DIFlagFwdDecl, identifier: "class")
+; CHECK: distinct !DICompositeType(tag: DW_TAG_structure_type, name: "struct", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 309, size: 128, flags: DIFlagFwdDecl, identifier: "list")
+; CHECK: distinct !DICompositeType(tag: DW_TAG_union_type, file: !{{[0-9]+}}, line: 115, size: 384, flags: DIFlagFwdDecl, identifier: "union")
+
+; Ensure that full type definitions of composite types are imported if requested
+; RUN: llvm-lto -import-full-type-definitions -thinlto-action=import %t2.bc -thinlto-index=%t.index.bc -o - | llvm-dis -o - | FileCheck %s --check-prefix=FULL
+; RUN: llvm-lto2 %t1.bc %t2.bc -o %t.out -save-temps \
+; RUN:   -import-full-type-definitions \
+; RUN:   -r %t2.bc,main,plx \
+; RUN:   -r %t2.bc,foo,l \
+; RUN:   -r %t1.bc,foo,pl
+; RUN: llvm-dis < %t.out.1.3.import.bc | FileCheck %s --check-prefix=FULL
+
+; FULL: distinct !DICompositeType(tag: DW_TAG_enumeration_type, name: "enum", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 50, size: 32, elements: !{{[0-9]+}}, identifier: "enum")
+; FULL: distinct !DICompositeType(tag: DW_TAG_class_type, name: "class", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 728, size: 448, elements: !{{[0-9]+}}, identifier: "class")
+; FULL: distinct !DICompositeType(tag: DW_TAG_structure_type, name: "struct", scope: !{{[0-9]+}}, file: !{{[0-9]+}}, line: 309, baseType: !{{[0-9]+}}, size: 128, offset: 64, elements: !{{[0-9]+}}, vtableHolder: !{{[0-9]+}}, templateParams: !{{[0-9]+}}, identifier: "list")
+; FULL: distinct !DICompositeType(tag: DW_TAG_union_type, file: !{{[0-9]+}}, line: 115, size: 384, elements: !{{[0-9]+}}, identifier: "union")
+
+; ModuleID = 'debuginfo-compositetype-import.c'
+source_filename = "debuginfo-compositetype-import.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind uwtable
+define void @foo() #0 !dbg !6 {
+entry:
+    ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3}
+!llvm.ident = !{!4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0 (trunk 286863) (llvm/trunk 286875)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+!1 = !DIFile(filename: "debuginfo-compositetype-import.c", directory: "")
+!2 = !{i32 2, !"Dwarf Version", i32 4}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{!"clang version 4.0.0 (trunk 286863) (llvm/trunk 286875)"}
+!5 = !{}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: false, unit: !0, variables: !5)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !10, !11, !12}
+!9 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "enum", scope: !1, file: !1, line: 50, size: 32, elements: !5, identifier: "enum")
+!10 = !DICompositeType(tag: DW_TAG_class_type, name: "class", scope: !1, file: !1, line: 728, size: 448, elements: !5, identifier: "class")
+!11 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "struct", scope: !1, file: !1, line: 309, baseType: !10, size: 128, offset: 64, elements: !5, vtableHolder: !10, templateParams: !5, identifier: "list")
+!12 = distinct !DICompositeType(tag: DW_TAG_union_type, file: !1, line: 115, size: 384, elements: !5, identifier: "union")