From 85c2e6110c9a01ec817c30f1b7e20549d7229987 Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
Date: Thu, 20 Jun 2013 19:40:55 -0500
Subject: [PATCH] Fix loop construction to functions calls

Check wheter the compiler has the option -fno-tree-loop-distribute-patterns
to inhibit loop transformation to library calls and uses it on memset
and memmove default implementation to avoid recursive calls.
---
 ChangeLog                  | 16 ++++++++++++++++
 benchtests/bench-memmove.c |  1 +
 benchtests/bench-memset.c  |  1 +
 config.h.in                |  3 +++
 configure                  | 33 +++++++++++++++++++++++++++++++++
 configure.in               | 18 ++++++++++++++++++
 include/libc-symbols.h     | 10 ++++++++++
 string/memmove.c           |  1 +
 string/memset.c            |  1 +
 string/test-memmove.c      |  1 +
 string/test-memset.c       |  1 +
 11 files changed, 86 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 314a563e6a..6c65453eb4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2013-06-20  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
+	* config.h.in (HAVE_CC_INHIBIT_LOOP_TO_LIBCALL): New define.
+	* configure.in (libc_cv_cc_loop_to_function): Check if compiler
+	accepts -fno-tree-loop-distribute-patterns.
+	* include/libc-symbols.h (inhibit_loop_to_libcall): New macro.
+	* string/memmove.c (MEMMOVE): Disable loop transformation to avoid
+	recursive call.
+	* string/memset.c (memset): Likewise.
+	* string/test-memmove.c (simple_memmove): Disable loop transformation
+	to library calls.
+	* string/test-memset.c (simple_memset): Likewise.
+	* benchtests/bench-memmove.c (simple_memmove): Likewise.
+	* benchtests/bench-memset.c (simple_memset): Likewise.
+	* configure: Regenerated.
+
 2013-06-20  Joseph Myers  <joseph@codesourcery.com>
 
 	* math/test-misc.c (main): Ignore fesetround failure when failures
diff --git a/benchtests/bench-memmove.c b/benchtests/bench-memmove.c
index dccde5d14e..8925606af8 100644
--- a/benchtests/bench-memmove.c
+++ b/benchtests/bench-memmove.c
@@ -46,6 +46,7 @@ IMPL (memmove, 1)
 #endif
 
 char *
+inhibit_loop_to_libcall
 simple_memmove (char *dst, const char *src, size_t n)
 {
   char *ret = dst;
diff --git a/benchtests/bench-memset.c b/benchtests/bench-memset.c
index 92e34f0d61..ea29cf37fc 100644
--- a/benchtests/bench-memset.c
+++ b/benchtests/bench-memset.c
@@ -63,6 +63,7 @@ builtin_memset (char *s, int c, size_t n)
 #endif
 
 char *
+inhibit_loop_to_libcall
 simple_memset (char *s, int c, size_t n)
 {
   char *r = s, *end = s + n;
diff --git a/config.h.in b/config.h.in
index 8c2479ef48..b5c6f163a7 100644
--- a/config.h.in
+++ b/config.h.in
@@ -69,6 +69,9 @@
 /* Define if the compiler supports __builtin_memset.  */
 #undef	HAVE_BUILTIN_MEMSET
 
+/* Define if compiler accepts -ftree-loop-distribute-patterns.  */
+#undef  HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
+
 /* Define if the regparm attribute shall be used for local functions
    (gcc on ix86 only).  */
 #undef	USE_REGPARMS
diff --git a/configure b/configure
index 09d8336f10..14bff72a3d 100755
--- a/configure
+++ b/configure
@@ -598,6 +598,7 @@ have_selinux
 have_libcap
 have_libaudit
 LIBGD
+libc_cv_cc_loop_to_function
 libc_cv_cc_submachine
 libc_cv_cc_nofma
 exceptions
@@ -6933,6 +6934,38 @@ $as_echo "$libc_cv_cc_submachine" >&6; }
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking if $CC accepts -fno-tree-loop-distribute-patterns with \
+__attribute__ ((__optimize__))" >&5
+$as_echo_n "checking if $CC accepts -fno-tree-loop-distribute-patterns with \
+__attribute__ ((__optimize__))... " >&6; }
+if ${libc_cv_cc_loop_to_function+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.c <<EOF
+void
+__attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
+foo (void) {}
+EOF
+libc_cv_cc_loop_to_function=no
+if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  libc_cv_cc_loop_to_function=yes
+fi
+rm -f conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_cc_loop_to_function" >&5
+$as_echo "$libc_cv_cc_loop_to_function" >&6; }
+if test $libc_cv_cc_loop_to_function = yes; then
+  $as_echo "#define HAVE_CC_INHIBIT_LOOP_TO_LIBCALL 1" >>confdefs.h
+
+fi
+
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for libgd" >&5
 $as_echo_n "checking for libgd... " >&6; }
 if test "$with_gd" != "no"; then
diff --git a/configure.in b/configure.in
index 8b110817bc..56cd61c171 100644
--- a/configure.in
+++ b/configure.in
@@ -1964,6 +1964,24 @@ if test -n "$submachine"; then
 fi
 AC_SUBST(libc_cv_cc_submachine)
 
+AC_CACHE_CHECK(if $CC accepts -fno-tree-loop-distribute-patterns with \
+__attribute__ ((__optimize__)), libc_cv_cc_loop_to_function, [dnl
+cat > conftest.c <<EOF
+void
+__attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
+foo (void) {}
+EOF
+libc_cv_cc_loop_to_function=no
+if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c])
+then
+  libc_cv_cc_loop_to_function=yes
+fi
+rm -f conftest*])
+if test $libc_cv_cc_loop_to_function = yes; then
+  AC_DEFINE(HAVE_CC_INHIBIT_LOOP_TO_LIBCALL)
+fi
+AC_SUBST(libc_cv_cc_loop_to_function)
+
 dnl Check whether we have the gd library available.
 AC_MSG_CHECKING(for libgd)
 if test "$with_gd" != "no"; then
diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index f043ce0850..a3b6274bad 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -782,4 +782,14 @@ for linking")
 #define libc_ifunc_hidden_def(name) \
   libc_ifunc_hidden_def1 (__GI_##name, name)
 
+/* Add the compiler optimization to inhibit loop transformation to library
+   calls.  This is used to avoid recursive calls in memset and memmove
+   default implementations.  */
+#ifdef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
+# define inhibit_loop_to_libcall \
+    __attribute__ ((__optimize__ ("-fno-tree-loop-distribute-patterns")))
+#else
+# define inhibit_loop_to_libcall
+#endif
+
 #endif /* libc-symbols.h */
diff --git a/string/memmove.c b/string/memmove.c
index 9dcd2f1f68..ec61e28c60 100644
--- a/string/memmove.c
+++ b/string/memmove.c
@@ -41,6 +41,7 @@
 #endif
 
 rettype
+inhibit_loop_to_libcall
 MEMMOVE (a1, a2, len)
      a1const void *a1;
      a2const void *a2;
diff --git a/string/memset.c b/string/memset.c
index 868be53bf9..74b5409218 100644
--- a/string/memset.c
+++ b/string/memset.c
@@ -21,6 +21,7 @@
 #undef memset
 
 void *
+inhibit_loop_to_libcall
 memset (dstpp, c, len)
      void *dstpp;
      int c;
diff --git a/string/test-memmove.c b/string/test-memmove.c
index 4ec55b2fcc..94576a299b 100644
--- a/string/test-memmove.c
+++ b/string/test-memmove.c
@@ -47,6 +47,7 @@ IMPL (memmove, 1)
 #endif
 
 char *
+inhibit_loop_to_libcall
 simple_memmove (char *dst, const char *src, size_t n)
 {
   char *ret = dst;
diff --git a/string/test-memset.c b/string/test-memset.c
index 9981fcef46..72a390e7d9 100644
--- a/string/test-memset.c
+++ b/string/test-memset.c
@@ -64,6 +64,7 @@ builtin_memset (char *s, int c, size_t n)
 #endif
 
 char *
+inhibit_loop_to_libcall
 simple_memset (char *s, int c, size_t n)
 {
   char *r = s, *end = s + n;