Patch #1: Suppress debug info associated with the body of an
artificial method. We already suppress debug info for its declaration
inside the class description.
Fixes PR14097.
Patch #2: Suppress debug info for the declaration of a class method
marked __attribute__((nodebug)). We already suppress debug info for
the body of the method.
Here's the story:
r158009 suppressed debug-info entries for artificial (compiler
generated) methods, typically constructors and destructors, from the
debug info for a class. The idea is that these aren't interesting or
useful. Which is pretty much true.
Unfortunately, the method _definitions_ still get debug info, and if
there's no declaration in the class for it to refer to, Clang
spontaneously generates debug info for a declaration. If a ctor has
multiple definitions, which they sometimes do (e.g. when there's a
virtual base class), each instance produces its own separate
declaration. And so the total debug info size _increases_. Patch #1
suppresses debug-info on the definitions as well.
While finding the fix, I noticed that the 'nodebug' attribute will
suppress debug info for a method definition, but we don't suppress
debug info for the corresponding declaration inside a class.
(Non-class functions don't have this problem because Clang doesn't
emit debug info for a function declaration anyway.) Patch #2
addresses that oversight.
I renamed the Sema and CodeGen tests for the 'nodebug' attribute from
.c to .cpp and added test points for methods, rather than add whole
new test files. Hope that's okay.
--paulr
Index: clang/test/CodeGenCXX/debug-info-user-def.cpp
===================================================================
--- clang/test/CodeGenCXX/debug-info-user-def.cpp (revision 165971)
+++ clang/test/CodeGenCXX/debug-info-user-def.cpp (working copy)
@@ -1,14 +1,23 @@
// RUN: %clang_cc1 -emit-llvm -g -triple x86_64-apple-darwin -std=c++11 %s -o
- | FileCheck %s
class A {
+ virtual void foo(); // Force a nontrivial artificial constructor.
};
template <typename T> class B {
T t;
};
-A a;
-B<int> b;
+// Need to instantiate the ctors and prove the debug info is not there.
+int main() {
+ A a;
+ B<A> b;
+ return 0;
+}
-// Check that no subprograms are emitted into debug info.
-// CHECK-NOT: [ DW_TAG_subprogram ]
+// We should see subprogram entries for main() and foo() only.
+// CHECK-NOT: DW_TAG_subprogram
+// CHECK: DW_TAG_subprogram {{.*}} [main]
+// CHECK-NOT: DW_TAG_subprogram
+// CHECK: DW_TAG_subprogram {{.*}} [foo]
+// CHECK-NOT: DW_TAG_subprogram
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp (revision 165971)
+++ clang/lib/CodeGen/CodeGenFunction.cpp (working copy)
@@ -493,7 +493,9 @@
const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
// Check if we should generate debug info for this function.
- if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>())
+ const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
+ if (CGM.getModuleDebugInfo() && !FD->hasAttr<NoDebugAttr>() &&
+ (!MD || MD->isUserProvided()))
DebugInfo = CGM.getModuleDebugInfo();
FunctionArgList Args;
Index: clang/test/Sema/attr-nodebug.c
===================================================================
--- clang/test/Sema/attr-nodebug.c (revision 165971)
+++ clang/test/Sema/attr-nodebug.c (working copy)
@@ -1,11 +0,0 @@
-// RUN: %clang_cc1 %s -verify -fsyntax-only
-
-int a __attribute__((nodebug));
-
-void b() {
- int b __attribute__((nodebug)); // expected-warning {{'nodebug' only applies
to variables with static storage duration and functions}}
-}
-
-void t1() __attribute__((nodebug));
-
-void t2() __attribute__((nodebug(2))); // expected-error {{attribute takes no
arguments}}
Index: clang/test/Sema/attr-nodebug.cpp
===================================================================
--- clang/test/Sema/attr-nodebug.cpp (revision 165971)
+++ clang/test/Sema/attr-nodebug.cpp (working copy)
@@ -9,3 +9,7 @@
void t1() __attribute__((nodebug));
void t2() __attribute__((nodebug(2))); // expected-error {{attribute takes no
arguments}}
+
+class c {
+ void t3() __attribute__((nodebug));
+};
Index: clang/test/CodeGen/attr-nodebug.cpp
===================================================================
--- clang/test/CodeGen/attr-nodebug.cpp (revision 165971)
+++ clang/test/CodeGen/attr-nodebug.cpp (working copy)
@@ -1,5 +1,6 @@
-// RUN: %clang_cc1 -g -emit-llvm -o %t %s
-// RUN: not grep 'call void @llvm.dbg.func.start' %t
+// RUN: %clang_cc1 -g -emit-llvm %s -o - | FileCheck %s
+// CHECK-NOT: call void @llvm.dbg.func.start
+// CHECK-NOT: DW_TAG_subprogram
void t1() __attribute__((nodebug));
@@ -10,3 +11,14 @@
a++;
}
+class C {
+ void t2() __attribute__((nodebug));
+};
+
+void C::t2()
+{
+ int a = 10;
+ a++;
+}
+
+C obj;
Index: clang/test/CodeGen/attr-nodebug.c
===================================================================
--- clang/test/CodeGen/attr-nodebug.c (revision 165971)
+++ clang/test/CodeGen/attr-nodebug.c (working copy)
@@ -1,12 +0,0 @@
-// RUN: %clang_cc1 -g -emit-llvm -o %t %s
-// RUN: not grep 'call void @llvm.dbg.func.start' %t
-
-void t1() __attribute__((nodebug));
-
-void t1()
-{
- int a = 10;
-
- a++;
-}
-
Index: clang/lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- clang/lib/CodeGen/CGDebugInfo.cpp (revision 165971)
+++ clang/lib/CodeGen/CGDebugInfo.cpp (working copy)
@@ -1024,9 +1024,9 @@
continue;
if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
- // Only emit debug information for user provided functions, we're
- // unlikely to want info for artificial functions.
- if (Method->isUserProvided())
+ // Only emit debug information for user provided functions
+ // not marked with 'nodebug'. No artificial functions.
+ if (Method->isUserProvided() && !Method->hasAttr<NoDebugAttr>())
EltTys.push_back(CreateCXXMemberFunction(Method, Unit, RecordTy));
}
else if (FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(D))
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