Add -strip-nonlinetable-debuginfo capability

This adds a new function to DebugInfo.cpp that takes an llvm::Module
as input and removes all debug info metadata that is not directly
needed for line tables, thus effectively stripping all type and
variable information from the module.

The primary motivation for this feature was the bitcode work flow
(cf. http://lists.llvm.org/pipermail/llvm-dev/2016-June/100643.html
for more background). This is not wired up yet, but will be in
subsequent patches.  For testing, the new functionality is exposed to
opt with a -strip-nonlinetable-debuginfo option.

The secondary use-case (and one that works right now!) is as a
reduction pass in bugpoint. I added two new bugpoint options
(-disable-strip-debuginfo and -disable-strip-debug-types) to control
the new features. By default it will first attempt to remove all debug
information, then only the type info, and then proceed to hack at any
remaining MDNodes.

llvm-svn: 283473

4 files changed, 163 insertions, 0 deletions

diff --git a/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo.ll b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo.ll
new file mode 100644
index 00000000000..f7ffdf9cf9a
--- /dev/null
+++ b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo.ll
@@ -0,0 +1,24 @@
+; RUN: opt -S -strip-nonlinetable-debuginfo %s -o - | FileCheck %s
+!llvm.dbg.cu = !{!2, !6}
+!llvm.gcov = !{!3}
+!llvm.module.flags = !{!7}
+
+!1 = !DIFile(filename: "path/to/file", directory: "/path/to/dir")
+; The first CU is used for the line table, the second one is a module skeleton
+; and should be stripped.
+; CHECK: !llvm.dbg.cu = !{![[CU:[0-9]+]]}
+; CHECK: ![[CU]] = distinct !DICompileUnit({{.*}}"abc.debug"{{.*}}LineTablesOnly
+; CHECK-NOT: retainedTypes:
+; CHECK-SAME: )
+; CHECK-NOT: DICompositeType
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang",
+                             isOptimized: true, flags: "-O2", runtimeVersion: 2,
+                             splitDebugFilename: "abc.debug", emissionKind: FullDebug,
+                             retainedTypes: !4)
+!3 = !{!"path/to/file.o", !2}
+!4 = !{!5}
+!5 = !DICompositeType(tag: DW_TAG_structure_type, file: !1, identifier: "ThisWillBeStripped")
+!6 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang",
+                             splitDebugFilename: "abc.dwo", emissionKind: FullDebug,
+                             dwoId: 1234)
+!7 = !{i32 1, !"Debug Info Version", i32 3}
diff --git a/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo2.ll b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo2.ll
new file mode 100644
index 00000000000..7ef6b1c8771
--- /dev/null
+++ b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo2.ll
@@ -0,0 +1,36 @@
+; RUN: opt -S -strip-nonlinetable-debuginfo %s -o - | FileCheck %s
+; CHECK: define void @f() !dbg ![[F:[0-9]+]]
+define void @f() !dbg !4 {
+entry:
+  %i = alloca i32, align 4
+  ; CHECK-NOT: llvm.dbg.declare
+  call void @llvm.dbg.declare(metadata i32* %i, metadata !11, metadata !13), !dbg !14
+  store i32 42, i32* %i, align 4, !dbg !14
+  ret void, !dbg !15
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7, !8, !9}
+!llvm.ident = !{!10}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "LLVM", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2)
+!1 = !DIFile(filename: "f.c", directory: "/")
+!2 = !{}
+; CHECK: ![[F]] = distinct !DISubprogram(name: "f"
+; CHECK-NOT: variables:
+; CHECK-NOT: distinct !DISubprogram(name: "f"
+!4 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: false, unit: !0, variables: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{null}
+!7 = !{i32 2, !"Dwarf Version", i32 2}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"PIC Level", i32 2}
+!10 = !{!"LLVM"}
+!11 = !DILocalVariable(name: "i", scope: !4, file: !1, line: 1, type: !12)
+!12 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!13 = !DIExpression()
+!14 = !DILocation(line: 1, column: 16, scope: !4)
+!15 = !DILocation(line: 1, column: 24, scope: !4)
diff --git a/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo3.ll b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo3.ll
new file mode 100644
index 00000000000..1367e0b4c6b
--- /dev/null
+++ b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo3.ll
@@ -0,0 +1,21 @@
+; RUN: opt -S -strip-nonlinetable-debuginfo %s -o - | FileCheck %s
+define internal i32 @"__hidden#2878_"() #0 !dbg !12 {
+  ret i32 0, !dbg !634
+}
+!llvm.dbg.cu = !{!18}
+!llvm.module.flags = !{!482}
+!5 = !{}
+!2 = !{!12}
+; CHECK-NOT: DICompositeType
+; CHECK: distinct !DISubprogram(name: "f", {{.*}}, type: ![[FNTY:[0-9]+]]
+; CHECK: ![[FNTY]] = !DISubroutineType(types: ![[VOID:[0-9]+]])
+; CHECK: ![[VOID]] = !{}
+; CHECK-NOT: DICompositeType
+!12 = distinct !DISubprogram(name: "f", scope: !16, file: !16, line: 133, type: !13, isLocal: true, isDefinition: true, scopeLine: 133, flags: DIFlagPrototyped, isOptimized: true, unit: !18, variables: !5)
+!13 = !DISubroutineType(types: !14)
+!14 = !{!17}
+!16 = !DIFile(filename: "f.m", directory: "/")
+!17 = !DICompositeType(tag: DW_TAG_enumeration_type, name: "e", scope: !18, file: !16, line: 13, size: 32, align: 32, flags: DIFlagFwdDecl)
+!18 = distinct !DICompileUnit(language: DW_LANG_ObjC, file: !16, producer: "clang", isOptimized: true, runtimeVersion: 2, emissionKind: 1, enums: !14, retainedTypes: !14, globals: !5, imports: !5)
+!482 = !{i32 2, !"Debug Info Version", i32 3}
+!634 = !DILocation(line: 143, column: 5, scope: !12)
diff --git a/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo4.ll b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo4.ll
new file mode 100644
index 00000000000..e4b8d56a718
--- /dev/null
+++ b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo4.ll
@@ -0,0 +1,82 @@
+; RUN: opt -S -strip-nonlinetable-debuginfo %s -o - | FileCheck %s
+; Generated an reduced from:
+; struct A {
+;   virtual ~A();
+; };
+; struct B : A {};
+; B b;
+
+source_filename = "t.cpp"
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.12.0"
+
+%struct.B = type { %struct.A }
+%struct.A = type { i32 (...)** }
+
+; CHECK: @b = global
+; CHECK-NOT: !dbg
+@b = global %struct.B zeroinitializer, align 8, !dbg !0
+
+declare void @_ZN1BC2Ev(%struct.B*) unnamed_addr
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
+
+; Function Attrs: inlinehint nounwind ssp uwtable
+; CHECK: define
+define linkonce_odr void @_ZN1BC1Ev(%struct.B* %this) unnamed_addr #1 align 2 !dbg !24 {
+entry:
+  %this.addr = alloca %struct.B*, align 8
+  store %struct.B* %this, %struct.B** %this.addr, align 8
+  ; CHECK-NOT: @llvm.dbg.declare
+  call void @llvm.dbg.declare(metadata %struct.B** %this.addr, metadata !29, metadata !31), !dbg !32
+  %this1 = load %struct.B*, %struct.B** %this.addr, align 8
+  ; CHECK: call void @_ZN1BC2Ev(%struct.B* %this1){{.*}} !dbg !
+  call void @_ZN1BC2Ev(%struct.B* %this1) #2, !dbg !33
+  ret void, !dbg !33
+}
+
+attributes #0 = { nounwind readnone }
+attributes #1 = { inlinehint nounwind ssp uwtable }
+attributes #2 = { nounwind }
+
+!llvm.dbg.cu = !{!1}
+!llvm.module.flags = !{!20, !21, !22}
+!llvm.ident = !{!23}
+
+; CHECK-NOT: !DI{{Basic|Composite|Derived}}Type
+
+!0 = distinct !DIGlobalVariable(name: "b", scope: !1, file: !2, line: 5, type: !5, isLocal: false, isDefinition: true)
+!1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, producer: "clang version 4.0.0 (trunk 282583) (llvm/trunk 282611)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !3, globals: !4)
+!2 = !DIFile(filename: "t.cpp", directory: "/")
+!3 = !{}
+!4 = !{!0}
+!5 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "B", file: !2, line: 4, size: 64, align: 64, elements: !6, vtableHolder: !8, identifier: "_ZTS1B")
+!6 = !{!7}
+!7 = !DIDerivedType(tag: DW_TAG_inheritance, scope: !5, baseType: !8)
+!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "A", file: !2, line: 1, size: 64, align: 64, elements: !9, vtableHolder: !8, identifier: "_ZTS1A")
+!9 = !{!10, !16}
+!10 = !DIDerivedType(tag: DW_TAG_member, name: "_vptr$A", scope: !2, file: !2, baseType: !11, size: 64, flags: DIFlagArtificial)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "__vtbl_ptr_type", baseType: !13, size: 64)
+!13 = !DISubroutineType(types: !14)
+!14 = !{!15}
+!15 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!16 = !DISubprogram(name: "~A", scope: !8, file: !2, line: 2, type: !17, isLocal: false, isDefinition: false, scopeLine: 2, containingType: !8, virtuality: DW_VIRTUALITY_virtual, virtualIndex: 0, flags: DIFlagPrototyped, isOptimized: false)
+!17 = !DISubroutineType(types: !18)
+!18 = !{null, !19}
+!19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!20 = !{i32 2, !"Dwarf Version", i32 4}
+!21 = !{i32 2, !"Debug Info Version", i32 3}
+!22 = !{i32 1, !"PIC Level", i32 2}
+!23 = !{!"clang version 4.0.0 (trunk 282583) (llvm/trunk 282611)"}
+!24 = distinct !DISubprogram(name: "B", linkageName: "_ZN1BC1Ev", scope: !5, file: !2, line: 4, type: !25, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false, unit: !1, declaration: !28, variables: !3)
+!25 = !DISubroutineType(types: !26)
+!26 = !{null, !27}
+!27 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64, align: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!28 = !DISubprogram(name: "B", scope: !5, type: !25, isLocal: false, isDefinition: false, flags: DIFlagArtificial | DIFlagPrototyped, isOptimized: false)
+!29 = !DILocalVariable(name: "this", arg: 1, scope: !24, type: !30, flags: DIFlagArtificial | DIFlagObjectPointer)
+!30 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !5, size: 64, align: 64)
+!31 = !DIExpression()
+!32 = !DILocation(line: 0, scope: !24)
+!33 = !DILocation(line: 4, column: 8, scope: !24)