Revert "DebugInfo: Fully integrate ctor type homing into 'limited' de…

…bug info"

Reverting to simplify some Google-internal rollout issues. Will recommit
in a week or two.

This reverts commit 517bbc6.

clang/docs/UsersManual.rst

@@ -2672,6 +2672,19 @@ below. If multiple flags are present, the last one is used.
    **-fno-standalone-debug** option can be used to get to turn on the
    vtable-based optimization described above.
 
+.. option:: -fuse-ctor-homing
+
+   This optimization is similar to the optimizations that are enabled as part
+   of -fno-standalone-debug. Here, Clang only emits type info for a
+   non-trivial, non-aggregate C++ class in the modules that contain a
+   definition of one of its constructors. This relies on the additional
+   assumption that all classes that are not trivially constructible have a
+   non-trivial constructor that is used somewhere. The negation,
+   -fno-use-ctor-homing, ensures that constructor homing is not used.
+
+   This flag is not enabled by default, and needs to be used with -cc1 or
+   -Xclang.
+
 .. option:: -g
 
   Generate complete debug info.

clang/include/clang/Basic/CodeGenOptions.h

@@ -468,7 +468,7 @@ class CodeGenOptions : public CodeGenOptionsBase {
 
   /// Check if type and variable info should be emitted.
   bool hasReducedDebugInfo() const {
-    return getDebugInfo() >= codegenoptions::LimitedDebugInfo;
+    return getDebugInfo() >= codegenoptions::DebugInfoConstructor;
   }
 
   /// Check if maybe unused type info should be emitted.

clang/include/clang/Basic/DebugInfoOptions.h

@@ -34,6 +34,12 @@ enum DebugInfoKind {
   /// (-gline-tables-only).
   DebugLineTablesOnly,
 
+  /// Limit generated debug info for classes to reduce size. This emits class
+  /// type info only where the constructor is emitted, if it is a class that
+  /// has a constructor.
+  /// FIXME: Consider combining this with LimitedDebugInfo.
+  DebugInfoConstructor,
+
   /// Limit generated debug info to reduce size (-fno-standalone-debug). This
   /// emits forward decls for types that could be replaced with forward decls in
   /// the source code. For dynamic C++ classes type info is only emitted into

clang/include/clang/Driver/Options.td

@@ -5246,6 +5246,11 @@ def mrelocation_model : Separate<["-"], "mrelocation-model">,
 def fno_math_builtin : Flag<["-"], "fno-math-builtin">,
   HelpText<"Disable implicit builtin knowledge of math functions">,
   MarshallingInfoFlag<LangOpts<"NoMathBuiltin">>;
+def fno_use_ctor_homing: Flag<["-"], "fno-use-ctor-homing">,
+    HelpText<"Don't use constructor homing for debug info">;
+def fuse_ctor_homing: Flag<["-"], "fuse-ctor-homing">,
+    HelpText<"Use constructor homing if we are using limited debug info already">;
+
 } // let Flags = [CC1Option, CC1AsOption, NoDriverOption]
 
 let Flags = [CC1Option, NoDriverOption] in {

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -27,7 +27,6 @@
 #include "clang/AST/RecordLayout.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/CodeGenOptions.h"
-#include "clang/Basic/DebugInfoOptions.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/Version.h"
@@ -587,6 +586,7 @@ void CGDebugInfo::CreateCompileUnit() {
   case codegenoptions::DebugDirectivesOnly:
     EmissionKind = llvm::DICompileUnit::DebugDirectivesOnly;
     break;
+  case codegenoptions::DebugInfoConstructor:
   case codegenoptions::LimitedDebugInfo:
   case codegenoptions::FullDebugInfo:
   case codegenoptions::UnusedTypeInfo:
@@ -1861,7 +1861,7 @@ llvm::DISubprogram *CGDebugInfo::CreateCXXMemberFunction(
 
   // In this debug mode, emit type info for a class when its constructor type
   // info is emitted.
-  if (DebugKind == codegenoptions::LimitedDebugInfo)
+  if (DebugKind == codegenoptions::DebugInfoConstructor)
     if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Method))
       completeUnusedClass(*CD->getParent());
 
@@ -2528,7 +2528,7 @@ static bool shouldOmitDefinition(codegenoptions::DebugInfoKind DebugKind,
 
   // In constructor homing mode, only emit complete debug info for a class
   // when its constructor is emitted.
-  if ((DebugKind == codegenoptions::LimitedDebugInfo) &&
+  if ((DebugKind == codegenoptions::DebugInfoConstructor) &&
       canUseCtorHoming(CXXDecl))
     return true;
 
@@ -3349,7 +3349,7 @@ void CGDebugInfo::completeTemplateDefinition(
 }
 
 void CGDebugInfo::completeUnusedClass(const CXXRecordDecl &D) {
-  if (DebugKind <= codegenoptions::DebugLineTablesOnly || D.isDynamicClass())
+  if (DebugKind <= codegenoptions::DebugLineTablesOnly)
     return;
 
   completeClassData(&D);

clang/lib/Driver/ToolChains/Clang.cpp

@@ -26,7 +26,6 @@
 #include "clang/Basic/CLWarnings.h"
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/CodeGenOptions.h"
-#include "clang/Basic/DebugInfoOptions.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/ObjCRuntime.h"
 #include "clang/Basic/Version.h"
@@ -526,7 +525,7 @@ static codegenoptions::DebugInfoKind DebugLevelToInfoKind(const Arg &A) {
     return codegenoptions::DebugLineTablesOnly;
   if (A.getOption().matches(options::OPT_gline_directives_only))
     return codegenoptions::DebugDirectivesOnly;
-  return codegenoptions::LimitedDebugInfo;
+  return codegenoptions::DebugInfoConstructor;
 }
 
 static bool mustUseNonLeafFramePointerForTarget(const llvm::Triple &Triple) {
@@ -1087,6 +1086,9 @@ static void RenderDebugEnablingArgs(const ArgList &Args, ArgStringList &CmdArgs,
   case codegenoptions::DebugLineTablesOnly:
     CmdArgs.push_back("-debug-info-kind=line-tables-only");
     break;
+  case codegenoptions::DebugInfoConstructor:
+    CmdArgs.push_back("-debug-info-kind=constructor");
+    break;
   case codegenoptions::LimitedDebugInfo:
     CmdArgs.push_back("-debug-info-kind=limited");
     break;
@@ -2668,7 +2670,7 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
           CmdArgs.push_back(Value.data());
         } else {
           RenderDebugEnablingArgs(Args, CmdArgs,
-                                  codegenoptions::LimitedDebugInfo,
+                                  codegenoptions::DebugInfoConstructor,
                                   DwarfVersion, llvm::DebuggerKind::Default);
         }
       } else if (Value.startswith("-mcpu") || Value.startswith("-mfpu") ||
@@ -4094,7 +4096,7 @@ static void renderDebugOptions(const ToolChain &TC, const Driver &D,
     }
   }
   if (const Arg *A = Args.getLastArg(options::OPT_g_Group)) {
-    DebugInfoKind = codegenoptions::LimitedDebugInfo;
+    DebugInfoKind = codegenoptions::DebugInfoConstructor;
 
     // If the last option explicitly specified a debug-info level, use it.
     if (checkDebugInfoOption(A, Args, D, TC) &&
@@ -4216,7 +4218,7 @@ static void renderDebugOptions(const ToolChain &TC, const Driver &D,
     if (checkDebugInfoOption(A, Args, D, TC)) {
       if (DebugInfoKind != codegenoptions::DebugLineTablesOnly &&
           DebugInfoKind != codegenoptions::DebugDirectivesOnly) {
-        DebugInfoKind = codegenoptions::LimitedDebugInfo;
+        DebugInfoKind = codegenoptions::DebugInfoConstructor;
         CmdArgs.push_back("-dwarf-ext-refs");
         CmdArgs.push_back("-fmodule-format=obj");
       }
@@ -4237,7 +4239,8 @@ static void renderDebugOptions(const ToolChain &TC, const Driver &D,
   if (const Arg *A = Args.getLastArg(options::OPT_fstandalone_debug))
     (void)checkDebugInfoOption(A, Args, D, TC);
 
-  if (DebugInfoKind == codegenoptions::LimitedDebugInfo) {
+  if (DebugInfoKind == codegenoptions::LimitedDebugInfo ||
+      DebugInfoKind == codegenoptions::DebugInfoConstructor) {
     if (Args.hasFlag(options::OPT_fno_eliminate_unused_debug_types,
                      options::OPT_feliminate_unused_debug_types, false))
       DebugInfoKind = codegenoptions::UnusedTypeInfo;
@@ -5435,7 +5438,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // This controls whether or not we perform JustMyCode instrumentation.
   if (Args.hasFlag(options::OPT_fjmc, options::OPT_fno_jmc, false)) {
     if (TC.getTriple().isOSBinFormatELF()) {
-      if (DebugInfoKind >= codegenoptions::LimitedDebugInfo)
+      if (DebugInfoKind >= codegenoptions::DebugInfoConstructor)
         CmdArgs.push_back("-fjmc");
       else
         D.Diag(clang::diag::warn_drv_jmc_requires_debuginfo) << "-fjmc"
@@ -7562,7 +7565,7 @@ void Clang::AddClangCLArgs(const ArgList &Args, types::ID InputType,
                                           options::OPT_gline_tables_only)) {
     *EmitCodeView = true;
     if (DebugInfoArg->getOption().matches(options::OPT__SLASH_Z7))
-      *DebugInfoKind = codegenoptions::LimitedDebugInfo;
+      *DebugInfoKind = codegenoptions::DebugInfoConstructor;
     else
       *DebugInfoKind = codegenoptions::DebugLineTablesOnly;
   } else {
@@ -7574,7 +7577,7 @@ void Clang::AddClangCLArgs(const ArgList &Args, types::ID InputType,
   // This controls whether or not we perform JustMyCode instrumentation.
   if (Args.hasFlag(options::OPT__SLASH_JMC, options::OPT__SLASH_JMC_,
                    /*Default=*/false)) {
-    if (*EmitCodeView && *DebugInfoKind >= codegenoptions::LimitedDebugInfo)
+    if (*EmitCodeView && *DebugInfoKind >= codegenoptions::DebugInfoConstructor)
       CmdArgs.push_back("-fjmc");
     else
       D.Diag(clang::diag::warn_drv_jmc_requires_debuginfo) << "/JMC"
@@ -7899,7 +7902,7 @@ void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,
     // the guard for source type, however there is a test which asserts
     // that some assembler invocation receives no -debug-info-kind,
     // and it's not clear whether that test is just overly restrictive.
-    DebugInfoKind = (WantDebug ? codegenoptions::LimitedDebugInfo
+    DebugInfoKind = (WantDebug ? codegenoptions::DebugInfoConstructor
                                : codegenoptions::NoDebugInfo);
 
     addDebugPrefixMapArg(getToolChain().getDriver(), getToolChain(), Args,

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1360,6 +1360,9 @@ void CompilerInvocation::GenerateCodeGenArgs(
   case codegenoptions::DebugDirectivesOnly:
     DebugInfoVal = "line-directives-only";
     break;
+  case codegenoptions::DebugInfoConstructor:
+    DebugInfoVal = "constructor";
+    break;
   case codegenoptions::LimitedDebugInfo:
     DebugInfoVal = "limited";
     break;
@@ -1634,6 +1637,7 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
         llvm::StringSwitch<unsigned>(A->getValue())
             .Case("line-tables-only", codegenoptions::DebugLineTablesOnly)
             .Case("line-directives-only", codegenoptions::DebugDirectivesOnly)
+            .Case("constructor", codegenoptions::DebugInfoConstructor)
             .Case("limited", codegenoptions::LimitedDebugInfo)
             .Case("standalone", codegenoptions::FullDebugInfo)
             .Case("unused-types", codegenoptions::UnusedTypeInfo)
@@ -1645,6 +1649,18 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
       Opts.setDebugInfo(static_cast<codegenoptions::DebugInfoKind>(Val));
   }
 
+  // If -fuse-ctor-homing is set and limited debug info is already on, then use
+  // constructor homing, and vice versa for -fno-use-ctor-homing.
+  if (const Arg *A =
+          Args.getLastArg(OPT_fuse_ctor_homing, OPT_fno_use_ctor_homing)) {
+    if (A->getOption().matches(OPT_fuse_ctor_homing) &&
+        Opts.getDebugInfo() == codegenoptions::LimitedDebugInfo)
+      Opts.setDebugInfo(codegenoptions::DebugInfoConstructor);
+    if (A->getOption().matches(OPT_fno_use_ctor_homing) &&
+        Opts.getDebugInfo() == codegenoptions::DebugInfoConstructor)
+      Opts.setDebugInfo(codegenoptions::LimitedDebugInfo);
+  }
+
   for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ)) {
     auto Split = StringRef(Arg).split('=');
     Opts.DebugPrefixMap.insert(

clang/test/CodeGen/attr-cpuspecific-renaming.cpp

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -no-opaque-pointers -triple x86_64-linux-gnu -emit-llvm -o - -debug-info-kind=limited -dwarf-version=4 -debugger-tuning=gdb %s | FileCheck %s --check-prefixes=CHECK,LIN
-// RUN: %clang_cc1 -no-opaque-pointers -triple x86_64-windows-pc -emit-llvm -o - -debug-info-kind=limited -dwarf-version=4 -debugger-tuning=gdb %s | FileCheck %s --check-prefixes=CHECK,WIN
+// RUN: %clang_cc1 -no-opaque-pointers -triple x86_64-linux-gnu -emit-llvm -o - -debug-info-kind=constructor -dwarf-version=4 -debugger-tuning=gdb %s | FileCheck %s --check-prefixes=CHECK,LIN
+// RUN: %clang_cc1 -no-opaque-pointers -triple x86_64-windows-pc -emit-llvm -o - -debug-info-kind=constructor -dwarf-version=4 -debugger-tuning=gdb %s | FileCheck %s --check-prefixes=CHECK,WIN
 
 // LIN: @[[S1_NAME:.+]].ifunc = weak_odr ifunc void (%struct.S1*), void (%struct.S1*)* ()* @[[S1_NAME]].resolver
 // LIN: @[[S2_NAME:.+]].ifunc = weak_odr ifunc void (%struct.S2*), void (%struct.S2*)* ()* @[[S2_NAME]].resolver

clang/test/CodeGen/pr52782-stdcall-func-decl.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple i686-w64-windows-gnu -o - -emit-llvm -debug-info-kind=limited %s | FileCheck %s
+// RUN: %clang_cc1 -triple i686-w64-windows-gnu -o - -emit-llvm -debug-info-kind=constructor %s | FileCheck %s
 
 enum nsresult {};
 

clang/test/CodeGenCXX/debug-info-class.cpp

@@ -32,21 +32,22 @@ struct D {
 };
 
 struct E {
+  E();
   virtual ~E();
   virtual void func() {
   }
 };
 
 struct F {
-  struct F_inner {
+  struct inner {
   };
   static const int i = 2;
   virtual ~F();
 };
 
 struct G {
   virtual void func();
-  struct G_inner {
+  struct inner {
     int j;
   };
 };
@@ -82,7 +83,7 @@ void f1() {
   x.func();
   E y;
   int i = F::i;
-  F::F_inner z;
+  F::inner z;
   K k;
   k.func();
   L l;
@@ -91,7 +92,7 @@ void f1() {
 
 int main(int argc, char **argv) {
   B b;
-  G::G_inner c_i;
+  G::inner c_i;
   if (argc) {
     A a;
   }
@@ -115,13 +116,11 @@ int main(int argc, char **argv) {
 // CHECK-SAME:                             DIFlagFwdDecl
 // CHECK-NOT:                             identifier:
 // CHECK-SAME:                            ){{$}}
-// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "A"
-// CHECK: ![[INT:[0-9]+]] = !DIBasicType(name: "int"
-// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "HdrSize"
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "I"
 // CHECK-NOT:              DIFlagFwdDecl
 // CHECK-SAME:             ){{$}}
 
+// CHECK: ![[INT:[0-9]+]] = !DIBasicType(name: "int"
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "foo"
 // CHECK: !DICompositeType(tag: DW_TAG_class_type, name: "bar"
 // CHECK: !DICompositeType(tag: DW_TAG_union_type, name: "baz"
@@ -174,10 +173,10 @@ int main(int argc, char **argv) {
 // CHECK-SAME:          DISPFlagLocalToUnit | DISPFlagDefinition
 // CHECK-SAME:          declaration: [[L_FUNC_DECL]]
 
-// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "G_inner",
+// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "inner",{{.*}} line: 50
 // CHECK-NOT: DIFlagFwdDecl
 // CHECK-SAME: elements: [[G_INNER_MEM:![0-9]*]]
-// CHECK-SAME: identifier: "_ZTSN1G7G_innerE"
+// CHECK-SAME: identifier: "_ZTSN1G5innerE"
 
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "G"
 // CHECK-SAME:             DIFlagFwdDecl
@@ -187,6 +186,8 @@ int main(int argc, char **argv) {
 // CHECK: [[G_INNER_I]] = !DIDerivedType(tag: DW_TAG_member, name: "j"
 // CHECK-SAME:                           baseType: ![[INT]]
 
+// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "A"
+// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "HdrSize"
 //
-// CHECK: ![[EXCEPTLOC]] = !DILocation(line: 99,
-// CHECK: ![[RETLOC]] = !DILocation(line: 98,
+// CHECK: ![[EXCEPTLOC]] = !DILocation(line: 100,
+// CHECK: ![[RETLOC]] = !DILocation(line: 99,

clang/test/CodeGenCXX/debug-info-ctor-homing-flag.cpp

@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -debug-info-kind=constructor -emit-llvm %s -o - \
+// RUN:        | FileCheck %s -check-prefix=CTOR_HOMING
+// RUN: %clang_cc1 -debug-info-kind=limited -fuse-ctor-homing -emit-llvm %s -o - \
+// RUN:        | FileCheck %s -check-prefix=CTOR_HOMING
+// RUN: %clang_cc1 -debug-info-kind=standalone -fuse-ctor-homing -emit-llvm %s -o - \
+// RUN:        | FileCheck %s -check-prefix=FULL_DEBUG
+// RUN: %clang_cc1 -debug-info-kind=line-tables-only -fuse-ctor-homing -emit-llvm %s -o - \
+// RUN:        | FileCheck %s -check-prefix=NO_DEBUG
+// RUN: %clang_cc1 -fuse-ctor-homing -emit-llvm %s -o - \
+// RUN:        | FileCheck %s -check-prefix=NO_DEBUG
+//
+// RUN: %clang_cc1 -debug-info-kind=constructor -fno-use-ctor-homing \
+// RUN:        -emit-llvm %s -o - | FileCheck %s -check-prefix=FULL_DEBUG
+
+// This tests that the -fuse-ctor-homing is only used if limited debug info would have
+// been used otherwise.
+
+// CTOR_HOMING: !DICompositeType(tag: DW_TAG_structure_type, name: "A"{{.*}}flags: DIFlagFwdDecl
+// FULL_DEBUG: !DICompositeType(tag: DW_TAG_structure_type, name: "A"{{.*}}DIFlagTypePassByValue
+// NO_DEBUG-NOT: !DICompositeType(tag: DW_TAG_structure_type, name: "A"
+struct A {
+  A();
+} TestA;

clang/test/CodeGenCXX/debug-info-limited-ctor.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -debug-info-kind=limited -emit-llvm %s -o - | FileCheck %s
+// RUN: %clang_cc1 -debug-info-kind=constructor -emit-llvm %s -o - | FileCheck %s
 
 // CHECK-DAG: !DICompositeType(tag: DW_TAG_structure_type, name: "A"{{.*}}DIFlagTypePassByValue
 struct A {

clang/test/CodeGenCXX/debug-info-template-explicit-specialization.cpp

@@ -1,5 +1,8 @@
 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -debug-info-kind=limited %s -o - | FileCheck %s
 
+// Make sure this still works with constructor homing.
+// RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -debug-info-kind=constructor %s -o - | FileCheck %s
+
 // Run again with -gline-tables-only or -gline-directives-only and verify we don't crash.  We won't output
 // type info at all.
 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple -debug-info-kind=line-tables-only %s -o - | FileCheck %s -check-prefix LINES-ONLY

clang/test/CodeGenCXX/debug-lambda-this.cpp

@@ -12,7 +12,7 @@ int D::d(int x) {
   }();
 }
 
-// CHECK: ![[D:[0-9]+]] = !DICompositeType(tag: DW_TAG_structure_type, name: "D",
+// CHECK: ![[D:[0-9]+]] = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "D",
 // CHECK: ![[POINTER:.*]] = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: ![[D]], size: 64)
 // CHECK: !DIDerivedType(tag: DW_TAG_member, name: "this",
 // CHECK-SAME:           line: 11

clang/test/CodeGenCXX/ibm128-declarations.cpp

@@ -174,7 +174,5 @@ int main(void) {
 // CHECK:   ret void
 // CHECK: }
 
-// CHECK: [[GF_TYPE:!.*]] = !DIBasicType(name: "__ibm128", size: 128, encoding: DW_ATE_float)
-// CHECK: = distinct !DIGlobalVariable(name: "gf",
-// CHECK-SAME: type: [[GF_TYPE]],
-// CHECK-SAME: isDefinition: true)
+// CHECK: !6 = distinct !DIGlobalVariable(name: "gf", scope: !2, file: !7, line: {{[0-9]+}}, type: !8, isLocal: false, isDefinition: true)
+// CHECK: !8 = !DIBasicType(name: "__ibm128", size: 128, encoding: DW_ATE_float)

clang/test/CodeGenCXX/standalone-debug-attribute.cpp

@@ -1,5 +1,6 @@
-// RUN: %clang_cc1 -DSETATTR=0 -triple x86_64-unknown-linux-gnu -emit-llvm -debug-info-kind=limited %s -o - | FileCheck %s --check-prefix=DEBUG
-// RUN: %clang_cc1 -DSETATTR=1 -triple x86_64-unknown-linux-gnu -emit-llvm -debug-info-kind=limited %s -o - | FileCheck %s --check-prefix=WITHATTR
+// RUN: %clang_cc1 -DSETATTR=0 -triple x86_64-unknown-linux-gnu -emit-llvm -debug-info-kind=constructor %s -o - | FileCheck %s --check-prefix=DEBUG
+// RUN: %clang_cc1 -DSETATTR=1 -triple x86_64-unknown-linux-gnu -emit-llvm -debug-info-kind=constructor %s -o - | FileCheck %s --check-prefix=WITHATTR
+// Use -debug-info-kind=constructor because it includes all the optimizations.
 
 #if SETATTR
 #define STANDALONEDEBUGATTR __attribute__((standalone_debug))