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DebugInfo: Make DICompositeTypes distinct most of the time 

Since elements of most kinds of DICompositeType have back references,
most are involved in uniquing cycles.  Except via the ODR 'identifier:'
field, which doesn't care about the storage type (see r266549),
they have no hope of being uniqued.

Distinct nodes are far more efficient, so use them for most kinds of
DICompositeType definitions (i.e., when DIType::isForwardDecl is false).
The exceptions:

  - DW_TAG_array_type, since their elements never have back-references
    and they never have ODR 'identifier:' fields;

  - DW_TAG_enumeration_type when there is no ODR 'identifier:' field,
    since their elements usually don't have back-references.

This breaks the last major uniquing cycle I'm aware of in the debug info
graph.  The impact won't be enormous for C++ because references to
ODR-uniqued nodes still use string-based DITypeRefs; but this should
prevent a regression in C++ when we drop the string-based references.

This wouldn't have been reasonable until r266549, when composite types
stopped relying on being uniqued by structural equivalence to prevent
blow-ups at LTO time.

llvm-svn: 266556
This commit is contained in:
Duncan P. N. Exon Smith 2016-04-17 07:45:08 +00:00
parent 2c66b23d79
commit f9521b0bb7
12 changed files with 46 additions and 22 deletions
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24
clang/lib/CodeGen/CGDebugInfo.cpp
View File

@ -2374,6 +2374,30 @@ llvm::DICompositeType *CGDebugInfo::CreateLimitedType(const RecordType *Ty) {
getTagForRecord(RD), RDName, RDContext, DefUnit, Line, 0, Size, Align, 0,
FullName);
// Elements of composite types usually have back to the type, creating
// uniquing cycles. Distinct nodes are more efficient.
switch (RealDecl->getTag()) {
default:
llvm_unreachable("invalid composite type tag");
case llvm::dwarf::DW_TAG_array_type:
case llvm::dwarf::DW_TAG_enumeration_type:
// Array elements and most enumeration elements don't have back references,
// so they don't tend to be involved in uniquing cycles and there is some
// chance of merging them when linking together two modules. Only make
// them distinct if they are ODR-uniqued.
if (FullName.empty())
break;
case llvm::dwarf::DW_TAG_structure_type:
case llvm::dwarf::DW_TAG_union_type:
case llvm::dwarf::DW_TAG_class_type:
// Immediatley resolve to a distinct node.
RealDecl =
llvm::MDNode::replaceWithDistinct(llvm::TempDICompositeType(RealDecl));
break;
}
RegionMap[Ty->getDecl()].reset(RealDecl);
TypeCache[QualType(Ty, 0).getAsOpaquePtr()].reset(RealDecl);

2
clang/test/CodeGenCXX/debug-info-anon-union-vars.cpp
View File

@ -56,7 +56,7 @@ void instantiate(int x) {
// CHECK: !DILocalVariable(
// CHECK-NOT: name:
// CHECK: type: ![[UNION:[0-9]+]]
// CHECK: ![[UNION]] = !DICompositeType(tag: DW_TAG_union_type,
// CHECK: ![[UNION]] = distinct !DICompositeType(tag: DW_TAG_union_type,
// CHECK-NOT: name:
// CHECK: elements
// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "i", scope: ![[UNION]],

2
clang/test/CodeGenCXX/debug-info-artificial-arg.cpp
View File

@ -22,7 +22,7 @@ int main(int argc, char **argv) {
A reallyA (500);
}
// CHECK: ![[CLASSTYPE:.*]] = !DICompositeType(tag: DW_TAG_class_type, name: "A",
// CHECK: ![[CLASSTYPE:.*]] = distinct !DICompositeType(tag: DW_TAG_class_type, name: "A",
// CHECK-SAME: identifier: "_ZTS1A"
// CHECK: ![[ARTARG:.*]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS1A",
// CHECK-SAME: DIFlagArtificial

2
clang/test/CodeGenCXX/debug-info-class.cpp
View File

@ -101,7 +101,7 @@ int main(int argc, char **argv) {
// CHECK: ![[INT:[0-9]+]] = !DIBasicType(name: "int"
// CHECK: [[C:![0-9]*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "C",
// CHECK: [[C:![0-9]*]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "C",
// CHECK-NOT: DIFlagFwdDecl
// CHECK-SAME: elements: [[C_MEM:![0-9]*]]
// CHECK-SAME: vtableHolder: !"_ZTS1C"

2
clang/test/CodeGenCXX/debug-info-template-limit.cpp
View File

@ -1,7 +1,7 @@
// RUN: %clang_cc1 -emit-llvm -debug-info-kind=limited -triple %itanium_abi_triple %s -o - | FileCheck %s
// Check that this pointer type is TC<int>
// CHECK: ![[LINE:[0-9]+]] = !DICompositeType(tag: DW_TAG_class_type, name: "TC<int>"{{.*}}, identifier: "_ZTS2TCIiE")
// CHECK: ![[LINE:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_class_type, name: "TC<int>"{{.*}}, identifier: "_ZTS2TCIiE")
// CHECK: !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !"_ZTS2TCIiE"
template<typename T>

6
clang/test/CodeGenCXX/debug-info-template-member.cpp
View File

@ -24,7 +24,7 @@ inline int add3(int x) {
// CHECK-SAME: type: [[FOO_FUNC_TYPE:![0-9]*]]
// CHECK: [[FOO_FUNC_TYPE]] = !DISubroutineType(types: [[FOO_FUNC_PARAMS:![0-9]*]])
// CHECK: [[FOO_FUNC_PARAMS]] = !{null, !{{[0-9]*}}, !"[[OUTER_FOO_INNER_ID:.*]]"}
// CHECK: !{{[0-9]*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "inner"{{.*}}, identifier: "[[OUTER_FOO_INNER_ID]]")
// CHECK: !{{[0-9]*}} = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "inner"{{.*}}, identifier: "[[OUTER_FOO_INNER_ID]]")
// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "virt<elem>"
// CHECK-SAME: elements: [[VIRT_MEM:![0-9]*]]
@ -34,7 +34,7 @@ inline int add3(int x) {
// CHECK: [[VIRT_TEMP_PARAM]] = !{[[VIRT_T:![0-9]*]]}
// CHECK: [[VIRT_T]] = !DITemplateTypeParameter(name: "T", type: !"_ZTS4elem")
// CHECK: [[C:![0-9]*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "MyClass"
// CHECK: [[C:![0-9]*]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "MyClass"
// CHECK-SAME: elements: [[C_MEM:![0-9]*]]
// CHECK-SAME: vtableHolder: !"_ZTS7MyClass"
// CHECK-SAME: identifier: "_ZTS7MyClass")
@ -43,7 +43,7 @@ inline int add3(int x) {
// CHECK: [[C_FUNC]] = !DISubprogram(name: "func",{{.*}} line: 7,
// CHECK: [[ELEM:![0-9]*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "elem"
// CHECK: [[ELEM:![0-9]*]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "elem"
// CHECK-SAME: elements: [[ELEM_MEM:![0-9]*]]
// CHECK-SAME: identifier: "_ZTS4elem"
// CHECK: [[ELEM_MEM]] = !{[[ELEM_X:![0-9]*]]}

2
clang/test/CodeGenCXX/debug-info-template-quals.cpp
View File

@ -15,7 +15,7 @@ void foo (const char *c) {
str.assign(c, str);
}
// CHECK: [[BS:.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "basic_string<char>"
// CHECK: [[BS:.*]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "basic_string<char>"
// CHECK-SAME: line: 4
// CHECK-SAME: size: 8, align: 8
// CHECK: [[TYPE:![0-9]*]] = !DISubroutineType(types: [[ARGS:.*]])

4
clang/test/CodeGenCXX/debug-info-template.cpp
View File

@ -6,7 +6,7 @@
// CHECK: [[RETAIN]] = !{!{{[0-9]]*}}, [[FOO:![0-9]*]],
// CHECK: [[TC:![0-9]*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "TC<unsigned int, 2, &glb, &foo::e, &foo::f, &foo::g, 1, 2, 3>"
// CHECK: [[TC:![0-9]*]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "TC<unsigned int, 2, &glb, &foo::e, &foo::f, &foo::g, 1, 2, 3>"
// CHECK-SAME: templateParams: [[TCARGS:![0-9]*]]
// CHECK: [[TCARGS]] = !{[[TCARG1:![0-9]*]], [[TCARG2:![0-9]*]], [[TCARG3:![0-9]*]], [[TCARG4:![0-9]*]], [[TCARG5:![0-9]*]], [[TCARG6:![0-9]*]], [[TCARG7:![0-9]*]]}
//
@ -48,7 +48,7 @@
// We could just emit a declaration of 'foo' here, rather than the entire
// definition (same goes for any time we emit a member (function or data)
// pointer type)
// CHECK: [[FOO]] = !DICompositeType(tag: DW_TAG_structure_type, name: "foo", {{.*}}identifier: "_ZTS3foo")
// CHECK: [[FOO]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "foo", {{.*}}identifier: "_ZTS3foo")
// CHECK: !DISubprogram(name: "f", linkageName: "_ZN3foo1fEv", {{.*}}type: [[FTYPE:![0-9]*]]
//

12
clang/test/CodeGenCXX/debug-lambda-expressions.cpp
View File

@ -23,7 +23,7 @@ int d(int x) { D y[10]; return [x,y] { return y[x].x; }(); }
// CHECK: !DIGlobalVariable(name: "cvar"
// CHECK-SAME: line: [[CVAR_LINE:[0-9]+]]
// CHECK-SAME: type: ![[CVAR_T:[0-9]+]]
// CHECK: ![[CVAR_T]] = !DICompositeType(tag: DW_TAG_class_type
// CHECK: ![[CVAR_T]] = distinct !DICompositeType(tag: DW_TAG_class_type
// CHECK-SAME: line: [[CVAR_LINE]],
// CHECK-SAME: elements: ![[CVAR_ARGS:[0-9]+]]
// CHECK: ![[CVAR_ARGS]] = !{!{{[0-9]+}}}
@ -32,7 +32,7 @@ int d(int x) { D y[10]; return [x,y] { return y[x].x; }(); }
// CHECK: !DIGlobalVariable(name: "var"
// CHECK-SAME: line: [[VAR_LINE:[0-9]+]]
// CHECK-SAME: type: ![[VAR_T:[0-9]+]]
// CHECK: ![[VAR_T]] = !DICompositeType(tag: DW_TAG_class_type
// CHECK: ![[VAR_T]] = distinct !DICompositeType(tag: DW_TAG_class_type
// CHECK-SAME: line: [[VAR_LINE]],
// CHECK-SAME: elements: ![[VAR_ARGS:[0-9]+]]
// CHECK: ![[VAR_ARGS]] = !{!{{[0-9]+}}}
@ -41,7 +41,7 @@ int d(int x) { D y[10]; return [x,y] { return y[x].x; }(); }
// CHECK: ![[A_FUNC:.*]] = distinct !DISubprogram(name: "a"{{.*}}, line: [[A_LINE:[0-9]+]]{{.*}}, isDefinition: true
// Back to A. -- 78
// CHECK: ![[LAM_A:.*]] = !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[A_FUNC]]{{.*}}, line: [[A_LINE]],
// CHECK: ![[LAM_A:.*]] = distinct !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[A_FUNC]]{{.*}}, line: [[A_LINE]],
// CHECK-SAME: elements: ![[LAM_A_ARGS:[0-9]+]]
// CHECK: ![[LAM_A_ARGS]] = !{![[CON_LAM_A:[0-9]+]]}
// CHECK: ![[CON_LAM_A]] = !DISubprogram(name: "operator()"
@ -53,7 +53,7 @@ int d(int x) { D y[10]; return [x,y] { return y[x].x; }(); }
// CHECK: ![[B_FUNC:.*]] = distinct !DISubprogram(name: "b"{{.*}}, line: [[B_LINE:[0-9]+]]{{.*}}, isDefinition: true
// Back to B. -- 67
// CHECK: ![[LAM_B:.*]] = !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[B_FUNC]]{{.*}}, line: [[B_LINE]],
// CHECK: ![[LAM_B:.*]] = distinct !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[B_FUNC]]{{.*}}, line: [[B_LINE]],
// CHECK-SAME: elements: ![[LAM_B_ARGS:[0-9]+]]
// CHECK: ![[LAM_B_ARGS]] = !{![[CAP_B:[0-9]+]], ![[CON_LAM_B:[0-9]+]]}
// CHECK: ![[CAP_B]] = !DIDerivedType(tag: DW_TAG_member, name: "x"
@ -69,7 +69,7 @@ int d(int x) { D y[10]; return [x,y] { return y[x].x; }(); }
// CHECK: ![[C_FUNC:.*]] = distinct !DISubprogram(name: "c"{{.*}}, line: [[C_LINE:[0-9]+]]{{.*}}, isDefinition: true
// Back to C. -- 55
// CHECK: ![[LAM_C:.*]] = !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[C_FUNC]]{{.*}}, line: [[C_LINE]],
// CHECK: ![[LAM_C:.*]] = distinct !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[C_FUNC]]{{.*}}, line: [[C_LINE]],
// CHECK-SAME: elements: ![[LAM_C_ARGS:[0-9]+]]
// CHECK: ![[LAM_C_ARGS]] = !{![[CAP_C:[0-9]+]], ![[CON_LAM_C:[0-9]+]]}
// CHECK: ![[CAP_C]] = !DIDerivedType(tag: DW_TAG_member, name: "x"
@ -86,7 +86,7 @@ int d(int x) { D y[10]; return [x,y] { return y[x].x; }(); }
// CHECK: ![[D_FUNC:.*]] = distinct !DISubprogram(name: "d"{{.*}}, line: [[D_LINE:[0-9]+]]{{.*}}, isDefinition: true
// Back to D. -- 24
// CHECK: ![[LAM_D:.*]] = !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[D_FUNC]]{{.*}}, line: [[D_LINE]],
// CHECK: ![[LAM_D:.*]] = distinct !DICompositeType(tag: DW_TAG_class_type{{.*}}, scope: ![[D_FUNC]]{{.*}}, line: [[D_LINE]],
// CHECK-SAME: elements: ![[LAM_D_ARGS:[0-9]+]]
// CHECK: ![[LAM_D_ARGS]] = !{![[CAP_D_X:[0-9]+]], ![[CAP_D_Y:[0-9]+]], ![[CON_LAM_D:[0-9]+]]}
// CHECK: ![[CAP_D_X]] = !DIDerivedType(tag: DW_TAG_member, name: "x"

4
clang/test/Modules/ExtDebugInfo.cpp
View File

@ -91,11 +91,11 @@ void foo() {
// CHECK: !DIGlobalVariable(name: "GlobalUnion",
// CHECK-SAME: type: ![[GLOBAL_UNION:[0-9]+]]
// CHECK: ![[GLOBAL_UNION]] = !DICompositeType(tag: DW_TAG_union_type,
// CHECK: ![[GLOBAL_UNION]] = distinct !DICompositeType(tag: DW_TAG_union_type,
// CHECK-SAME: elements: !{{[0-9]+}})
// CHECK: !DIGlobalVariable(name: "GlobalStruct",
// CHECK-SAME: type: ![[GLOBAL_STRUCT:[0-9]+]]
// CHECK: ![[GLOBAL_STRUCT]] = !DICompositeType(tag: DW_TAG_structure_type,
// CHECK: ![[GLOBAL_STRUCT]] = distinct !DICompositeType(tag: DW_TAG_structure_type,
// CHECK-SAME: elements: !{{[0-9]+}})
// CHECK: !DIGlobalVariable(name: "anon",

4
clang/test/Modules/ExtDebugInfo.m
View File

@ -32,12 +32,12 @@ int foo(ObjCClass *c) {
// CHECK: !DIGlobalVariable(name: "GlobalUnion",
// CHECK-SAME: type: ![[GLOBAL_UNION:[0-9]+]]
// CHECK: ![[MOD:.*]] = !DIModule(scope: null, name: "DebugObjC
// CHECK: ![[GLOBAL_UNION]] = !DICompositeType(tag: DW_TAG_union_type,
// CHECK: ![[GLOBAL_UNION]] = distinct !DICompositeType(tag: DW_TAG_union_type,
// CHECK-SAME: elements: !{{[0-9]+}})
// CHECK: !DIGlobalVariable(name: "GlobalStruct",
// CHECK-SAME: type: ![[GLOBAL_STRUCT:[0-9]+]]
// CHECK: ![[GLOBAL_STRUCT]] = !DICompositeType(tag: DW_TAG_structure_type,
// CHECK: ![[GLOBAL_STRUCT]] = distinct !DICompositeType(tag: DW_TAG_structure_type,
// CHECK-SAME: elements: !{{[0-9]+}})
// CHECK: !DIDerivedType(tag: DW_TAG_typedef, name: "TypedefUnion",

4
clang/test/Modules/ModuleDebugInfo.m
View File

@ -50,7 +50,7 @@
// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "FwdDeclared"
// CHECK-SAME: elements:
// CHECK: ![[TD_UNION:.*]] = !DICompositeType(tag: DW_TAG_union_type,
// CHECK: ![[TD_UNION:.*]] = distinct !DICompositeType(tag: DW_TAG_union_type,
// CHECK-NOT: name:
// CHECK-SAME: elements:
// CHECK-SAME: )
@ -61,7 +61,7 @@
// CHECK: !DIDerivedType(tag: DW_TAG_typedef, name: "TypedefEnum",
// CHECK-SAME: baseType: ![[TD_ENUM:.*]])
// CHECK: ![[TD_STRUCT:.*]] = !DICompositeType(tag: DW_TAG_structure_type,
// CHECK: ![[TD_STRUCT:.*]] = distinct !DICompositeType(tag: DW_TAG_structure_type,
// CHECK-NOT: name:
// CHECK-SAME: elements:
// CHECK: !DIDerivedType(tag: DW_TAG_typedef, name: "TypedefStruct",