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Implement TARGET_ATOMIC_ASSIGN_EXPAND_FENV for powerpc*-*-linux* soft-float and e500

This patch implements support for TARGET_ATOMIC_ASSIGN_EXPAND_FENV for
powerpc*-*-linux* soft-float and e500, provided GCC is configured for
glibc 2.19 or later on the target.

New functions __atomic_feholdexcept, __atomic_feclearexcept and
__atomic_feupdateenv were added (to libc) in that glibc version (for
powerpc soft-float / e500 only) in order to support this part of C11.
For soft-float, libc functions are needed because the floating-point
exception state is in TLS variables in libc that aren't directly
accessible outside of glibc.  For e500, they are also needed because
of the prctl syscalls involved in controlling trapping for exceptions
and informing the kernel when certain exception flags have been
cleared.  The actual implementation in GCC is a straightforward matter
of calling those functions.

Tested with no regressions for cross to powerpc-linux-gnu
(soft-float); the c11-atomic-exec-5.c results go from FAIL to PASS.
OK to commit?

2014-11-01  Joseph Myers  <joseph@codesourcery.com>

	* configure.ac (TARGET_GLIBC_MAJOR, TARGET_GLIBC_MINOR): Define
	macros.
	* configure, config.h.in: Regenerate.
	* config/rs6000/linux.h [TARGET_GLIBC_MAJOR > 2 ||
	(TARGET_GLIBC_MAJOR == 2 && TARGET_GLIBC_MINOR >= 19)]
	(RS6000_GLIBC_ATOMIC_FENV): New macro.
	* config/rs6000/linux64.h [TARGET_GLIBC_MAJOR > 2 ||
	(TARGET_GLIBC_MAJOR == 2 && TARGET_GLIBC_MINOR >= 19)]
	(RS6000_GLIBC_ATOMIC_FENV): New macro.
	* config/rs6000/rs6000.c (atomic_hold_decl, atomic_clear_decl)
	(atomic_update_decl): New static variables.
	(rs6000_atomic_assign_expand_fenv) [RS6000_GLIBC_ATOMIC_FENV]:
	Generate calls to __atomic_feholdexcept, __atomic_feclearexcept
	and __atomic_feupdateenv for soft-float and no-FPRs.

Index: gcc/config/rs6000/linux.h
===================================================================
--- gcc/config/rs6000/linux.h	(revision 216974)
+++ gcc/config/rs6000/linux.h	(working copy)
@@ -127,3 +127,10 @@
 #undef TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P
 #define TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P \
   rs6000_linux_float_exceptions_rounding_supported_p
+
+/* Support for TARGET_ATOMIC_ASSIGN_EXPAND_FENV without FPRs depends
+   on glibc 2.19 or greater.  */
+#if TARGET_GLIBC_MAJOR > 2 \
+  || (TARGET_GLIBC_MAJOR == 2 && TARGET_GLIBC_MINOR >= 19)
+#define RS6000_GLIBC_ATOMIC_FENV 1
+#endif
Index: gcc/config/rs6000/linux64.h
===================================================================
--- gcc/config/rs6000/linux64.h	(revision 216974)
+++ gcc/config/rs6000/linux64.h	(working copy)
@@ -557,3 +557,10 @@ extern int dot_symbols;
 #undef TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P
 #define TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P \
   rs6000_linux_float_exceptions_rounding_supported_p
+
+/* Support for TARGET_ATOMIC_ASSIGN_EXPAND_FENV without FPRs depends
+   on glibc 2.19 or greater.  */
+#if TARGET_GLIBC_MAJOR > 2 \
+  || (TARGET_GLIBC_MAJOR == 2 && TARGET_GLIBC_MINOR >= 19)
+#define RS6000_GLIBC_ATOMIC_FENV 1
+#endif
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c	(revision 216974)
+++ gcc/config/rs6000/rs6000.c	(working copy)
@@ -34589,6 +34589,9 @@ make_pass_analyze_swaps (gcc::context *ctxt)
   return new pass_analyze_swaps (ctxt);
 }
 
+/* Function declarations for rs6000_atomic_assign_expand_fenv.  */
+static tree atomic_hold_decl, atomic_clear_decl, atomic_update_decl;
+
 /* Implement TARGET_ATOMIC_ASSIGN_EXPAND_FENV hook.  */
 
 static void
@@ -34595,8 +34598,58 @@ static void
 rs6000_atomic_assign_expand_fenv (tree *hold, tree *clear, tree *update)
 {
   if (!TARGET_HARD_FLOAT || !TARGET_FPRS)
-    return;
+    {
+#ifdef RS6000_GLIBC_ATOMIC_FENV
+      if (atomic_hold_decl == NULL_TREE)
+	{
+	  atomic_hold_decl
+	    = build_decl (BUILTINS_LOCATION, FUNCTION_DECL,
+			  get_identifier ("__atomic_feholdexcept"),
+			  build_function_type_list (void_type_node,
+						    double_ptr_type_node,
+						    NULL_TREE));
+	  TREE_PUBLIC (atomic_hold_decl) = 1;
+	  DECL_EXTERNAL (atomic_hold_decl) = 1;
+	}
 
+      if (atomic_clear_decl == NULL_TREE)
+	{
+	  atomic_clear_decl
+	    = build_decl (BUILTINS_LOCATION, FUNCTION_DECL,
+			  get_identifier ("__atomic_feclearexcept"),
+			  build_function_type_list (void_type_node,
+						    NULL_TREE));
+	  TREE_PUBLIC (atomic_clear_decl) = 1;
+	  DECL_EXTERNAL (atomic_clear_decl) = 1;
+	}
+
+      tree const_double = build_qualified_type (double_type_node,
+						TYPE_QUAL_CONST);
+      tree const_double_ptr = build_pointer_type (const_double);
+      if (atomic_update_decl == NULL_TREE)
+	{
+	  atomic_update_decl
+	    = build_decl (BUILTINS_LOCATION, FUNCTION_DECL,
+			  get_identifier ("__atomic_feupdateenv"),
+			  build_function_type_list (void_type_node,
+						    const_double_ptr,
+						    NULL_TREE));
+	  TREE_PUBLIC (atomic_update_decl) = 1;
+	  DECL_EXTERNAL (atomic_update_decl) = 1;
+	}
+
+      tree fenv_var = create_tmp_var (double_type_node, NULL);
+      mark_addressable (fenv_var);
+      tree fenv_addr = build1 (ADDR_EXPR, double_ptr_type_node, fenv_var);
+
+      *hold = build_call_expr (atomic_hold_decl, 1, fenv_addr);
+      *clear = build_call_expr (atomic_clear_decl, 0);
+      *update = build_call_expr (atomic_update_decl, 1,
+				 fold_convert (const_double_ptr, fenv_addr));
+#endif
+      return;
+    }
+
   tree mffs = rs6000_builtin_decls[RS6000_BUILTIN_MFFS];
   tree mtfsf = rs6000_builtin_decls[RS6000_BUILTIN_MTFSF];
   tree call_mffs = build_call_expr (mffs, 0);
Index: gcc/config.in
===================================================================
--- gcc/config.in	(revision 216974)
+++ gcc/config.in	(working copy)
@@ -1699,10 +1699,6 @@
 #undef HAVE_WORKING_VFORK
 #endif
 
-/* Define if isl is in use. */
-#ifndef USED_FOR_TARGET
-#undef HAVE_isl
-#endif
 
 /* Define if cloog is in use. */
 #ifndef USED_FOR_TARGET
@@ -1709,6 +1705,13 @@
 #undef HAVE_cloog
 #endif
 
+
+/* Define if isl is in use. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_isl
+#endif
+
+
 /* Define if F_SETLKW supported by fcntl. */
 #ifndef USED_FOR_TARGET
 #undef HOST_HAS_F_SETLKW
@@ -1882,6 +1885,18 @@
 /* Define if your target C library provides the `dl_iterate_phdr' function. */
 #undef TARGET_DL_ITERATE_PHDR
 
+/* GNU C Library major version number used on the target, or 0. */
+#ifndef USED_FOR_TARGET
+#undef TARGET_GLIBC_MAJOR
+#endif
+
+
+/* GNU C Library minor version number used on the target, or 0. */
+#ifndef USED_FOR_TARGET
+#undef TARGET_GLIBC_MINOR
+#endif
+
+
 /* Define if your target C library provides stack protector support */
 #ifndef USED_FOR_TARGET
 #undef TARGET_LIBC_PROVIDES_SSP
Index: gcc/configure
===================================================================
--- gcc/configure	(revision 216974)
+++ gcc/configure	(working copy)
@@ -26700,6 +26700,16 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibc_version_major.$glibc_version_minor" >&5
 $as_echo "$glibc_version_major.$glibc_version_minor" >&6; }
 
+cat >>confdefs.h <<_ACEOF
+#define TARGET_GLIBC_MAJOR $glibc_version_major
+_ACEOF
+
+
+cat >>confdefs.h <<_ACEOF
+#define TARGET_GLIBC_MINOR $glibc_version_minor
+_ACEOF
+
+
 # Check whether --enable-gnu-unique-object was given.
 if test "${enable_gnu_unique_object+set}" = set; then :
   enableval=$enable_gnu_unique_object; case $enable_gnu_unique_object in
Index: gcc/configure.ac
===================================================================
--- gcc/configure.ac	(revision 216974)
+++ gcc/configure.ac	(working copy)
@@ -4503,6 +4503,10 @@ glibc_version_minor=0
   glibc_version_minor=`echo "$glibc_version_minor_define" | sed -e 's/.*__GLIBC_MINOR__[ 	]*//'`
 fi]])
 AC_MSG_RESULT([$glibc_version_major.$glibc_version_minor])
+AC_DEFINE_UNQUOTED([TARGET_GLIBC_MAJOR], [$glibc_version_major],
+[GNU C Library major version number used on the target, or 0.])
+AC_DEFINE_UNQUOTED([TARGET_GLIBC_MINOR], [$glibc_version_minor],
+[GNU C Library minor version number used on the target, or 0.])
 
 AC_ARG_ENABLE(gnu-unique-object,
  [AS_HELP_STRING([--enable-gnu-unique-object],

-- 
Joseph S. Myers
joseph@codesourcery.com
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