diff mbox series

libstdc++: Outline the overlapping case of string _M_replace into a separate function [PR105329]

Message ID YuEGaeli1LMF1Zce@tucnak
State New, archived
Headers
Series libstdc++: Outline the overlapping case of string _M_replace into a separate function [PR105329] |

Commit Message

Jakub Jelinek July 27, 2022, 9:33 a.m. UTC 
  Hi!

The following patch is partially a workaround for bogus warnings
when the compiler isn't able to fold _M_disjunct call into constant
false, but also an optimization attempt - assuming _M_disjunct (__s)
is rare, the patch should shrink code size for the common case and
use library or for non-standard instantiations an out of line
function to handle the rare case.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2022-07-27  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/105329
	* acinclude.m4 (libtool_VERSION): Change to 6:31:0.
	* config/abi/pre/gnu.ver (GLIBCXX_3.4.21): Don't export
	std::basic_string methods with name length of 15.
	(GLIBCXX_3.4.31): Export std::basic_string::_M_replace_cold.
	* testsuite/util/testsuite_abi.cc (check_version): Handle
	GLIBCXX_3.4.31.
	* include/bits/basic_string.h (std::basic_string::_M_replace_cold):
	Declare.
	* include/bits/basic_string.tcc (std::basic_string::_M_replace_cold):
	Define and export even for C++20.
	(std::basic_string::_M_replace): Use __builtin_expect, outline
	the overlapping case to _M_replace_cold.
	* configure: Regenerated.


	Jakub

Comments

Jakub Jelinek Aug. 10, 2022, 11:27 a.m. UTC | #1 
On Wed, Jul 27, 2022 at 11:33:29AM +0200, Jakub Jelinek via Gcc-patches wrote:
> The following patch is partially a workaround for bogus warnings
> when the compiler isn't able to fold _M_disjunct call into constant
> false, but also an optimization attempt - assuming _M_disjunct (__s)
> is rare, the patch should shrink code size for the common case and
> use library or for non-standard instantiations an out of line
> function to handle the rare case.

I'd like to ping this patch.

Thanks.

	Jakub
Jakub Jelinek Aug. 31, 2022, 9:38 a.m. UTC | #2 
Hi!

On Wed, Aug 10, 2022 at 01:27:51PM +0200, Jakub Jelinek via Gcc-patches wrote:
> On Wed, Jul 27, 2022 at 11:33:29AM +0200, Jakub Jelinek via Gcc-patches wrote:
> > The following patch is partially a workaround for bogus warnings
> > when the compiler isn't able to fold _M_disjunct call into constant
> > false, but also an optimization attempt - assuming _M_disjunct (__s)
> > is rare, the patch should shrink code size for the common case and
> > use library or for non-standard instantiations an out of line
> > function to handle the rare case.
> 
> I'd like to ping this patch.

I'd like to ping this patch again.
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598896.html

Thanks.

	Jakub
Jakub Jelinek Sept. 12, 2022, 9:15 a.m. UTC | #3 
On Wed, Aug 31, 2022 at 11:38:58AM +0200, Jakub Jelinek via Gcc-patches wrote:
> On Wed, Aug 10, 2022 at 01:27:51PM +0200, Jakub Jelinek via Gcc-patches wrote:
> > On Wed, Jul 27, 2022 at 11:33:29AM +0200, Jakub Jelinek via Gcc-patches wrote:
> > > The following patch is partially a workaround for bogus warnings
> > > when the compiler isn't able to fold _M_disjunct call into constant
> > > false, but also an optimization attempt - assuming _M_disjunct (__s)
> > > is rare, the patch should shrink code size for the common case and
> > > use library or for non-standard instantiations an out of line
> > > function to handle the rare case.
> > 
> > I'd like to ping this patch.
> 
> I'd like to ping this patch again.
> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598896.html

Ping again.

Thanks.

	Jakub
Jonathan Wakely Sept. 12, 2022, 9:24 a.m. UTC | #4 
On Mon, 12 Sept 2022 at 10:16, Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Wed, Aug 31, 2022 at 11:38:58AM +0200, Jakub Jelinek via Gcc-patches wrote:
> > On Wed, Aug 10, 2022 at 01:27:51PM +0200, Jakub Jelinek via Gcc-patches wrote:
> > > On Wed, Jul 27, 2022 at 11:33:29AM +0200, Jakub Jelinek via Gcc-patches wrote:
> > > > The following patch is partially a workaround for bogus warnings
> > > > when the compiler isn't able to fold _M_disjunct call into constant
> > > > false, but also an optimization attempt - assuming _M_disjunct (__s)
> > > > is rare, the patch should shrink code size for the common case and
> > > > use library or for non-standard instantiations an out of line
> > > > function to handle the rare case.
> > >
> > > I'd like to ping this patch.
> >
> > I'd like to ping this patch again.
> > https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598896.html
>
> Ping again.


OK for trunk, sorry for the slow review.
diff mbox series

Patch

--- libstdc++-v3/acinclude.m4.jj	2022-06-27 11:18:03.102052967 +0200
+++ libstdc++-v3/acinclude.m4	2022-07-26 13:15:51.187572177 +0200
@@ -3821,7 +3821,7 @@  changequote([,])dnl
 fi
 
 # For libtool versioning info, format is CURRENT:REVISION:AGE
-libtool_VERSION=6:30:0
+libtool_VERSION=6:31:0
 
 # Everything parsed; figure out what files and settings to use.
 case $enable_symvers in
--- libstdc++-v3/config/abi/pre/gnu.ver.jj	2022-03-17 09:22:50.135144471 +0100
+++ libstdc++-v3/config/abi/pre/gnu.ver	2022-07-26 13:12:13.098402944 +0200
@@ -1736,7 +1736,7 @@  GLIBCXX_3.4.21 {
     _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE12_M*;
     _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE13*;
     _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE14_M_replace_aux*;
-    _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE1[568-9]*;
+    _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE1[68-9]*;
     _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE2at*;
     _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE3end*;
     _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE4back*;
@@ -2444,6 +2444,10 @@  GLIBCXX_3.4.30 {
 
 } GLIBCXX_3.4.29;
 
+GLIBCXX_3.4.31 {
+    _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE15_M_replace_cold*;
+} GLIBCXX_3.4.30;
+
 # Symbols in the support library (libsupc++) have their own tag.
 CXXABI_1.3 {
 
--- libstdc++-v3/testsuite/util/testsuite_abi.cc.jj	2022-03-17 09:22:50.135144471 +0100
+++ libstdc++-v3/testsuite/util/testsuite_abi.cc	2022-07-26 13:16:44.042886118 +0200
@@ -211,6 +211,7 @@  check_version(symbol& test, bool added)
       known_versions.push_back("GLIBCXX_3.4.28");
       known_versions.push_back("GLIBCXX_3.4.29");
       known_versions.push_back("GLIBCXX_3.4.30");
+      known_versions.push_back("GLIBCXX_3.4.31");
       known_versions.push_back("GLIBCXX_LDBL_3.4.29");
       known_versions.push_back("GLIBCXX_IEEE128_3.4.29");
       known_versions.push_back("GLIBCXX_IEEE128_3.4.30");
@@ -247,7 +248,7 @@  check_version(symbol& test, bool added)
 	test.version_status = symbol::incompatible;
 
       // Check that added symbols are added in the latest pre-release version.
-      bool latestp = (test.version_name == "GLIBCXX_3.4.30"
+      bool latestp = (test.version_name == "GLIBCXX_3.4.31"
 	  // XXX remove next line when baselines have been regenerated.
 		     || test.version_name == "GLIBCXX_IEEE128_3.4.30"
 		     || test.version_name == "CXXABI_1.3.13"
--- libstdc++-v3/include/bits/basic_string.h.jj	2022-06-17 11:08:11.971491626 +0200
+++ libstdc++-v3/include/bits/basic_string.h	2022-07-26 12:42:38.008440082 +0200
@@ -2504,6 +2504,10 @@  _GLIBCXX_BEGIN_NAMESPACE_CXX11
       _M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
 		     _CharT __c);
 
+      __attribute__((__noinline__, __noclone__, __cold__)) void
+      _M_replace_cold(pointer __p, size_type __len1, const _CharT* __s,
+		      const size_type __len2, const size_type __how_much);
+
       _GLIBCXX20_CONSTEXPR
       basic_string&
       _M_replace(size_type __pos, size_type __len1, const _CharT* __s,
--- libstdc++-v3/include/bits/basic_string.tcc.jj	2022-06-15 10:43:46.796946222 +0200
+++ libstdc++-v3/include/bits/basic_string.tcc	2022-07-26 13:43:35.293012051 +0200
@@ -471,6 +471,37 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     }
 
   template<typename _CharT, typename _Traits, typename _Alloc>
+    __attribute__((__noinline__, __noclone__, __cold__)) void
+    basic_string<_CharT, _Traits, _Alloc>::
+    _M_replace_cold(pointer __p, size_type __len1, const _CharT* __s,
+		    const size_type __len2, const size_type __how_much)
+    {
+      // Work in-place.
+      if (__len2 && __len2 <= __len1)
+	this->_S_move(__p, __s, __len2);
+      if (__how_much && __len1 != __len2)
+	this->_S_move(__p + __len2, __p + __len1, __how_much);
+      if (__len2 > __len1)
+	{
+	  if (__s + __len2 <= __p + __len1)
+	    this->_S_move(__p, __s, __len2);
+	  else if (__s >= __p + __len1)
+	    {
+	      // Hint to middle end that __p and __s overlap
+	      // (PR 98465).
+	      const size_type __poff = (__s - __p) + (__len2 - __len1);
+	      this->_S_copy(__p, __p + __poff, __len2);
+	    }
+	  else
+	    {
+	      const size_type __nleft = (__p + __len1) - __s;
+	      this->_S_move(__p, __s, __nleft);
+	      this->_S_copy(__p + __nleft, __p + __len2, __len2 - __nleft);
+	    }
+	}
+    }
+
+  template<typename _CharT, typename _Traits, typename _Alloc>
     _GLIBCXX20_CONSTEXPR
     basic_string<_CharT, _Traits, _Alloc>&
     basic_string<_CharT, _Traits, _Alloc>::
@@ -500,7 +531,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    }
 	  else
 #endif
-	  if (_M_disjunct(__s))
+	  if (__builtin_expect(_M_disjunct(__s), true))
 	    {
 	      if (__how_much && __len1 != __len2)
 		this->_S_move(__p + __len2, __p + __len1, __how_much);
@@ -508,32 +539,7 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		this->_S_copy(__p, __s, __len2);
 	    }
 	  else
-	    {
-	      // Work in-place.
-	      if (__len2 && __len2 <= __len1)
-		this->_S_move(__p, __s, __len2);
-	      if (__how_much && __len1 != __len2)
-		this->_S_move(__p + __len2, __p + __len1, __how_much);
-	      if (__len2 > __len1)
-		{
-		  if (__s + __len2 <= __p + __len1)
-		    this->_S_move(__p, __s, __len2);
-		  else if (__s >= __p + __len1)
-		    {
-		      // Hint to middle end that __p and __s overlap
-		      // (PR 98465).
-		      const size_type __poff = (__s - __p) + (__len2 - __len1);
-		      this->_S_copy(__p, __p + __poff, __len2);
-		    }
-		  else
-		    {
-		      const size_type __nleft = (__p + __len1) - __s;
-		      this->_S_move(__p, __s, __nleft);
-		      this->_S_copy(__p + __nleft, __p + __len2,
-				    __len2 - __nleft);
-		    }
-		}
-	    }
+	    _M_replace_cold(__p, __len1, __s, __len2, __how_much);
 	}
       else
 	this->_M_mutate(__pos, __len1, __s, __len2);
@@ -1000,6 +1006,11 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // to ensure the definition in libstdc++.so is unique (PR 86138).
   extern template basic_string<char>::size_type
     basic_string<char>::_Rep::_S_empty_rep_storage[];
+# elif _GLIBCXX_EXTERN_TEMPLATE > 0
+  // Export _M_replace_cold even for C++20.
+  extern template void
+    basic_string<char>::_M_replace_cold(char *, size_type, const char*,
+					const size_type, const size_type);
 # endif
 
   extern template
@@ -1021,6 +1032,11 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
 # elif ! _GLIBCXX_USE_CXX11_ABI
   extern template basic_string<wchar_t>::size_type
     basic_string<wchar_t>::_Rep::_S_empty_rep_storage[];
+# elif _GLIBCXX_EXTERN_TEMPLATE > 0
+  // Export _M_replace_cold even for C++20.
+  extern template void
+    basic_string<wchar_t>::_M_replace_cold(wchar_t*, size_type, const wchar_t*,
+					   const size_type, const size_type);
 # endif
 
   extern template
--- libstdc++-v3/configure.jj	2022-07-26 10:32:24.395262574 +0200
+++ libstdc++-v3/configure	2022-07-26 13:16:09.830330197 +0200
@@ -69048,7 +69048,7 @@  $as_echo "$as_me: WARNING: === Symbol ve
 fi
 
 # For libtool versioning info, format is CURRENT:REVISION:AGE
-libtool_VERSION=6:30:0
+libtool_VERSION=6:31:0
 
 # Everything parsed; figure out what files and settings to use.
 case $enable_symvers in