libstdc++: Define memory resource key functions non-inline (PR93208)

Message ID 20200109131739.GA1106066@redhat.com
State New
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  • libstdc++: Define memory resource key functions non-inline (PR93208)
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Commit Message

Jonathan Wakely Jan. 9, 2020, 1:17 p.m.
This prevents the vtables and RTTI from being emitted in every object
file that uses memory_resource and monotonic_buffer_resource.

Objects compiled by GCC 9.1 or 9.2 will contain inline definitions of
the destructors, vtable and RTTI, but this is harmless. The inline
definitions have identical effects to the ones that are now defined in
libstdc++.so so it doesn't matter if the inline ones are used instead of
calling the symbols exported from the runtime library.

	PR libstdc++/93208
	* config/abi/pre/gnu.ver: Add new exports.
	* include/std/memory_resource (memory_resource::~memory_resource()):
	Do not define inline.
	(monotonic_buffer_resource::~monotonic_buffer_resource()): Likewise.
	* src/c++17/memory_resource.cc (memory_resource::~memory_resource()):
	Define.
	(monotonic_buffer_resource::~monotonic_buffer_resource()): Define.
	* testsuite/20_util/monotonic_buffer_resource/93208.cc: New test.

Tested powerpc64le-linux (for trunk) and x86_64-linux (for
gcc-9-branch). Committed to trunk and gcc-9-branch.

We'll need to regen the baselines_symbols.txt files before the 9.3
release (I'll do that for a few arches next week).
commit d773997e6579a31a259cd574362d86c5b57ce822
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Jan 9 12:06:38 2020 +0000

    libstdc++: Define memory resource key functions non-inline (PR93208)
    
    This prevents the vtables and RTTI from being emitted in every object
    file that uses memory_resource and monotonic_buffer_resource.
    
    Objects compiled by GCC 9.1 or 9.2 will contain inline definitions of
    the destructors, vtable and RTTI, but this is harmless. The inline
    definitions have identical effects to the ones that are now defined in
    libstdc++.so so it doesn't matter if the inline ones are used instead of
    calling the symbols exported from the runtime library.
    
            PR libstdc++/93208
            * config/abi/pre/gnu.ver: Add new exports.
            * include/std/memory_resource (memory_resource::~memory_resource()):
            Do not define inline.
            (monotonic_buffer_resource::~monotonic_buffer_resource()): Likewise.
            * src/c++17/memory_resource.cc (memory_resource::~memory_resource()):
            Define.
            (monotonic_buffer_resource::~monotonic_buffer_resource()): Define.
            * testsuite/20_util/monotonic_buffer_resource/93208.cc: New test.

Patch

diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver
index 7f84f3e2644..edf4485e607 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -2291,6 +2291,12 @@  GLIBCXX_3.4.28 {
     _ZNSt12__shared_ptrINSt10filesystem28recursive_directory_iterator10_Dir_stackELN9__gnu_cxx12_Lock_policyE[012]EEC2EOS5_;
     _ZNSt12__shared_ptrINSt10filesystem7__cxx1128recursive_directory_iterator10_Dir_stackELN9__gnu_cxx12_Lock_policyE[012]EEC2EOS6_;
 
+    # key functions, vtables and rtti for memory resources
+    _ZNSt3pmr15memory_resourceD[0125]Ev;
+    _ZT[ISV]NSt3pmr15memory_resourceE;
+    _ZNSt3pmr25monotonic_buffer_resourceD[0125]Ev;
+    _ZT[ISV]NSt3pmr25monotonic_buffer_resourceE;
+
 } GLIBCXX_3.4.27;
 
 # Symbols in the support library (libsupc++) have their own tag.
diff --git a/libstdc++-v3/include/std/memory_resource b/libstdc++-v3/include/std/memory_resource
index ee2d9837050..13be3e9dc75 100644
--- a/libstdc++-v3/include/std/memory_resource
+++ b/libstdc++-v3/include/std/memory_resource
@@ -88,7 +88,7 @@  namespace pmr
   public:
     memory_resource() = default;
     memory_resource(const memory_resource&) = default;
-    virtual ~memory_resource() = default;
+    virtual ~memory_resource(); // key function
 
     memory_resource& operator=(const memory_resource&) = default;
 
@@ -600,7 +600,7 @@  namespace pmr
 
     monotonic_buffer_resource(const monotonic_buffer_resource&) = delete;
 
-    virtual ~monotonic_buffer_resource() { release(); }
+    virtual ~monotonic_buffer_resource(); // key function
 
     monotonic_buffer_resource&
     operator=(const monotonic_buffer_resource&) = delete;
diff --git a/libstdc++-v3/src/c++17/memory_resource.cc b/libstdc++-v3/src/c++17/memory_resource.cc
index fa3d6cd61f2..37386cdddfd 100644
--- a/libstdc++-v3/src/c++17/memory_resource.cc
+++ b/libstdc++-v3/src/c++17/memory_resource.cc
@@ -37,6 +37,10 @@  namespace std _GLIBCXX_VISIBILITY(default)
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 namespace pmr
 {
+  // This was defined inline in 9.1 and 9.2 so code compiled by those
+  // versions will not use this symbol.
+  memory_resource::~memory_resource() = default;
+
   namespace
   {
     class newdel_res_t final : public memory_resource
@@ -167,6 +171,10 @@  namespace pmr
 
   // Member functions for std::pmr::monotonic_buffer_resource
 
+  // This was defined inline in 9.1 and 9.2 so code compiled by those
+  // versions will not use this symbol.
+  monotonic_buffer_resource::~monotonic_buffer_resource() { release(); }
+
   // Memory allocated by the upstream resource is managed in a linked list
   // of _Chunk objects. A _Chunk object recording the size and alignment of
   // the allocated block and a pointer to the previous chunk is placed
diff --git a/libstdc++-v3/testsuite/20_util/monotonic_buffer_resource/93208.cc b/libstdc++-v3/testsuite/20_util/monotonic_buffer_resource/93208.cc
new file mode 100644
index 00000000000..b0cfdbddad2
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/monotonic_buffer_resource/93208.cc
@@ -0,0 +1,29 @@ 
+// Copyright (C) 2020 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do compile { target c++17 } }
+// { dg-final { scan-assembler-not "_ZT\[IS\]NSt3pmr15memory_resourceE" } }
+// { dg-final { scan-assembler-not "_ZT\[IS\]NSt3pmr25monotonic\[a-z_\]*E" } }
+
+#include <memory_resource>
+
+void* f(int n)
+{
+  std::pmr::monotonic_buffer_resource res;
+  return res.allocate(n);
+}