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

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.

2022-09-12  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.

6 files changed, 56 insertions, 31 deletions

diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index e3cc3a8..9aa81e1 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -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
diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver
index 9b80a31..7f30377 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -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 {
 
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 1772eef..07916d1 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -69034,7 +69034,7 @@ $as_echo "$as_me: WARNING: === Symbol versioning will be disabled." >&2;}
 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
diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h
index 0df64ea..cd24419 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -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,
diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc
index 4563c61..710c2df 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -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
diff --git a/libstdc++-v3/testsuite/util/testsuite_abi.cc b/libstdc++-v3/testsuite/util/testsuite_abi.cc
index 5c83835..09bd00e 100644
--- a/libstdc++-v3/testsuite/util/testsuite_abi.cc
+++ b/libstdc++-v3/testsuite/util/testsuite_abi.cc
@@ -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"