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Re: [gomp4] Add tables generation


On 03/21/2014 04:20 PM, Jakub Jelinek wrote:
On Fri, Mar 21, 2014 at 04:13:45PM +0100, Bernd Schmidt wrote:
On 03/20/2014 07:56 PM, Jakub Jelinek wrote:
When we were discussing the design last year, my strong preference was that
either this lives in some other crt object that mkoffload/linker plugin adds
to link, or that it would be completely mkoffload synthetized.

mkoffload is only concerned with generating target images. These
fragments are for the host tables.

How's this? It moves everything to ompbegin.o/ompend.o and only
links in these files if we have produced at least one target offload
image.

I'd call the files crtompbegin.o/crtompend.o instead.
And, what is the exact reason why you are using protected visibility rather
than hidden?
Also, supposedly if you've used section names without . in them, the linker
itself would provide the symbols automatically and you wouldn't actually
need begin/end, but just one object that would reference the linker created
symbols.  Just use say __gnu_offload_whatever__ or similar section names.

I've checked in the following which should address all this.


Bernd

Index: gcc/ChangeLog.gomp
===================================================================
--- gcc/ChangeLog.gomp	(revision 209074)
+++ gcc/ChangeLog.gomp	(working copy)
@@ -1,5 +1,15 @@
 2014-04-04  Bernd Schmidt  <bernds@codesourcery.com>
 
+	* lto-section-names.h (OFFLOAD_VAR_TABLE_SECTION_NAME,
+	OFFLOAD_FUNC_TABLE_SECTION_NAME): Define.
+	* lto-wrapper.c (OFFLOAD_FUNC_TABLE_SECTION_NAME): Don't define.
+	(ompend): New static variable.
+	(copy_file, find_ompend): New static functions.
+	(run_gcc): Call find_ompend if we have offload images.  Add its
+	return value to the output.
+	* omp-low.c: Include "lto-section-names.h".
+	(omp_finish_file): Initialize section names from macros defined there.
+	
 	* omp-low.c (offload_symbol_decl): New static variable.
 	(get_offload_symbol_decl): New static function.
 	(expand_oacc_offload, expand_omp_target): Use it.
Index: gcc/lto-section-names.h
===================================================================
--- gcc/lto-section-names.h	(revision 209072)
+++ gcc/lto-section-names.h	(working copy)
@@ -31,3 +31,6 @@ along with GCC; see the file COPYING3.
 /* Can be either OMP_SECTION_NAME_PREFIX when we stream pragma omp target
    stuff, or LTO_SECTION_NAME_PREFIX for lto case.  */
 extern const char  *section_name_prefix;
+
+#define OFFLOAD_VAR_TABLE_SECTION_NAME "__gnu_offload_vars"
+#define OFFLOAD_FUNC_TABLE_SECTION_NAME "__gnu_offload_funcs"
Index: gcc/lto-wrapper.c
===================================================================
--- gcc/lto-wrapper.c	(revision 209072)
+++ gcc/lto-wrapper.c	(working copy)
@@ -49,7 +49,6 @@ along with GCC; see the file COPYING3.
 #include "lto-section-names.h"
 #include "collect-utils.h"
 
-#define OFFLOAD_FUNC_TABLE_SECTION_NAME ".offload_func_table_section"
 #define OFFLOAD_TARGET_NAMES_ENV	"OFFLOAD_TARGET_NAMES"
 
 enum lto_mode_d {
@@ -67,6 +66,7 @@ static unsigned int nr;
 static char **input_names;
 static char **output_names;
 static char **offload_names;
+static const char *ompend;
 static char *makefile;
 
 const char tool_name[] = "lto-wrapper";
@@ -479,6 +479,54 @@ compile_images_for_openmp_targets (unsig
   free_array_of_ptrs ((void**) names, num_targets);
 }
 
+/* Copy a file from SRC to DEST.  */
+static void
+copy_file (const char *dest, const char *src)
+{
+  FILE *d = fopen (dest, "wb");
+  FILE *s = fopen (src, "rb");
+  char buffer[512];
+  while (!feof (s))
+    {
+      size_t len = fread (buffer, 1, 512, s);
+      if (ferror (s) != 0)
+	fatal ("reading input file");
+      if (len > 0)
+	{
+	  fwrite (buffer, 1, len, d);
+	  if (ferror (d) != 0)
+	    fatal ("writing output file");
+	}
+    }
+}
+
+/* Find the crtompend.o file in LIBRARY_PATH, make a copy and store
+   the name of the copy in ompend.  */
+
+static void
+find_ompend (void)
+{
+  char **paths;
+  const char *library_path = getenv ("LIBRARY_PATH");
+  if (library_path == NULL)
+    return;
+  int n_paths = parse_env_var (library_path, &paths, "/crtompend.o");
+
+  for (int i = 0; i < n_paths; i++)
+    if (access_check (paths[i], R_OK) == 0)
+      {
+	/* The linker will delete the filenames we give it, so make
+	   copies.  */
+	const char *omptmp = make_temp_file (".o");
+	copy_file (omptmp, paths[i]);
+	ompend = omptmp;
+	break;
+      }
+  if (ompend == 0)
+    fatal ("installation error, can't find crtompend.o");
+
+  free_array_of_ptrs ((void**) paths, n_paths);
+}
 
 /* Execute gcc. ARGC is the number of arguments. ARGV contains the arguments. */
 
@@ -964,6 +1012,7 @@ cont:
 	  compile_images_for_openmp_targets (argc, argv);
 	  if (offload_names)
 	    {
+	      find_ompend ();
 	      for (i = 0; offload_names[i]; i++)
 		{
 		  fputs (offload_names[i], stdout);
@@ -972,12 +1021,18 @@ cont:
 	      free_array_of_ptrs ((void **)offload_names, i);
 	    }
 	}
+
       for (i = 0; i < nr; ++i)
 	{
 	  fputs (output_names[i], stdout);
 	  putc ('\n', stdout);
 	  free (input_names[i]);
 	}
+      if (ompend)
+	{
+	  fputs (ompend, stdout);
+	  putc ('\n', stdout);
+	}
       nr = 0;
       free (output_names);
       free (input_names);
Index: gcc/omp-low.c
===================================================================
--- gcc/omp-low.c	(revision 209074)
+++ gcc/omp-low.c	(working copy)
@@ -72,7 +72,7 @@ along with GCC; see the file COPYING3.
 #include "ipa-prop.h"
 #include "tree-nested.h"
 #include "tree-eh.h"
-
+#include "lto-section-names.h"
 
 /* Lowering of OpenMP parallel and workshare constructs proceeds in two
    phases.  The first phase scans the function looking for OMP statements
@@ -12851,8 +12851,8 @@ omp_finish_file (void)
 {
   struct cgraph_node *node;
   struct varpool_node *vnode;
-  const char *funcs_section_name = ".offload_func_table_section";
-  const char *vars_section_name = ".offload_var_table_section";
+  const char *funcs_section_name = OFFLOAD_FUNC_TABLE_SECTION_NAME;
+  const char *vars_section_name = OFFLOAD_VAR_TABLE_SECTION_NAME;
   vec<tree, va_gc> *v_funcs, *v_vars;
 
   vec_alloc (v_vars, 0);
Index: libgcc/ChangeLog.gomp
===================================================================
--- libgcc/ChangeLog.gomp	(revision 209074)
+++ libgcc/ChangeLog.gomp	(working copy)
@@ -1,6 +1,16 @@
 2014-04-04  Bernd Schmidt  <bernds@codesourcery.com>
 
-	* crtstuff.c (__OPENMP_TARGET__): Revert previous change.
+	* Makefile.in (crtompend$(objext)): New rule.
+	* configure.ac (--enable-accelerator, --enable-offload-targets):
+	Handle options.
+	(offload_targets): Compute list.
+	(extra_parts): Add crtompend.o if offload_targets is not empty.
+	* configure: Regenerate.
+	* crtstuff.c (_omp_func_table, _omp_var_table, _omp_funcs_end)
+	_omp_vars_end, __OPENMP_TARGET__): Remove.
+	* ompstuff.c: New file.
+
+	(* crtstuff.c (__OPENMP_TARGET__): Revert previous change.
 
 2014-04-02  Thomas Schwinge  <thomas@codesourcery.com>
 
Index: libgcc/Makefile.in
===================================================================
--- libgcc/Makefile.in	(revision 209072)
+++ libgcc/Makefile.in	(working copy)
@@ -975,6 +975,9 @@ crtbegin$(objext): $(srcdir)/crtstuff.c
 crtend$(objext): $(srcdir)/crtstuff.c
 	$(crt_compile) $(CRTSTUFF_T_CFLAGS) -c $< -DCRT_END
 
+crtompend$(objext): $(srcdir)/ompstuff.c
+	$(crt_compile) $(CRTSTUFF_T_CFLAGS) -c $< -DCRT_END
+
 # These are versions of crtbegin and crtend for shared libraries.
 crtbeginS$(objext): $(srcdir)/crtstuff.c
 	$(crt_compile) $(CRTSTUFF_T_CFLAGS_S) -c $< -DCRT_BEGIN -DCRTSTUFFS_O
Index: libgcc/configure
===================================================================
--- libgcc/configure	(revision 209072)
+++ libgcc/configure	(working copy)
@@ -566,6 +566,7 @@ sfp_machine_header
 set_use_emutls
 set_have_cc_tls
 vis_hide
+enable_accelerator
 fixed_point
 enable_decimal_float
 decimal_float
@@ -664,6 +665,8 @@ with_build_libsubdir
 enable_decimal_float
 with_system_libunwind
 enable_sjlj_exceptions
+enable_accelerator
+enable_offload_targets
 enable_tls
 '
       ac_precious_vars='build_alias
@@ -1301,6 +1304,9 @@ Optional Features:
 			to use
   --enable-sjlj-exceptions
                           force use of builtin_setjmp for exceptions
+  --enable-accelerator    build accelerator [ARG={no,device-triplet}]
+  --enable-offload-targets=LIST
+                          enable offloading to devices from LIST
   --enable-tls            Use thread-local storage [default=yes]
 
 Optional Packages:
@@ -4357,6 +4363,43 @@ esac
 # Collect host-machine-specific information.
 . ${srcdir}/config.host
 
+offload_targets=
+# Check whether --enable-accelerator was given.
+if test "${enable_accelerator+set}" = set; then :
+  enableval=$enable_accelerator;
+  case $enable_accelerator in
+  no) ;;
+  *)
+    offload_targets=$enable_accelerator
+    ;;
+  esac
+
+fi
+
+
+
+# Check whether --enable-offload-targets was given.
+if test "${enable_offload_targets+set}" = set; then :
+  enableval=$enable_offload_targets;
+  if test x$enable_offload_targets = x; then
+    as_fn_error "no offload targets specified" "$LINENO" 5
+  else
+    if test x$offload_targets = x; then
+      offload_targets=$enable_offload_targets
+    else
+      offload_targets=$offload_targets,$enable_offload_targets
+    fi
+  fi
+
+else
+  enable_accelerator=no
+fi
+
+
+if test x$offload_targets != x; then
+  extra_parts="${extra_parts} crtompend.o"
+fi
+
 # Check if Solaris/x86 linker supports ZERO terminator unwind entries.
 # This is after config.host so we can augment tmake_file.
 # Link with -nostartfiles -nodefaultlibs since neither are present while
Index: libgcc/configure.ac
===================================================================
--- libgcc/configure.ac	(revision 209072)
+++ libgcc/configure.ac	(working copy)
@@ -307,6 +307,38 @@ esac
 # Collect host-machine-specific information.
 . ${srcdir}/config.host
 
+offload_targets=
+AC_ARG_ENABLE(accelerator,
+[AS_HELP_STRING([--enable-accelerator], [build accelerator @<:@ARG={no,device-triplet}@:>@])],
+[
+  case $enable_accelerator in
+  no) ;;
+  *)
+    offload_targets=$enable_accelerator
+    ;;
+  esac
+], [])
+AC_SUBST(enable_accelerator)
+
+AC_ARG_ENABLE(offload-targets,
+[AS_HELP_STRING([--enable-offload-targets=LIST],
+ [enable offloading to devices from LIST])],
+[
+  if test x$enable_offload_targets = x; then
+    AC_MSG_ERROR([no offload targets specified])
+  else
+    if test x$offload_targets = x; then
+      offload_targets=$enable_offload_targets
+    else
+      offload_targets=$offload_targets,$enable_offload_targets
+    fi
+  fi
+], [enable_accelerator=no])
+AC_SUBST(enable_accelerator)
+if test x$offload_targets != x; then
+  extra_parts="${extra_parts} crtompend.o"
+fi
+
 # Check if Solaris/x86 linker supports ZERO terminator unwind entries.
 # This is after config.host so we can augment tmake_file.
 # Link with -nostartfiles -nodefaultlibs since neither are present while
Index: libgcc/crtstuff.c
===================================================================
--- libgcc/crtstuff.c	(revision 209074)
+++ libgcc/crtstuff.c	(working copy)
@@ -311,15 +311,6 @@ register_tm_clones (void)
 }
 #endif /* USE_TM_CLONE_REGISTRY */
 
-#if defined(HAVE_GAS_HIDDEN) && defined(ENABLE_OFFLOADING)
-void *_omp_func_table[0]
-  __attribute__ ((__used__, visibility ("protected"),
-		  section (".offload_func_table_section"))) = { };
-void *_omp_var_table[0]
-  __attribute__ ((__used__, visibility ("protected"),
-		  section (".offload_var_table_section"))) = { };
-#endif
-
 #if defined(INIT_SECTION_ASM_OP) || defined(INIT_ARRAY_SECTION_ASM_OP)
 
 #ifdef OBJECT_FORMAT_ELF
@@ -761,22 +752,6 @@ __do_global_ctors (void)
 #error "What are you doing with crtstuff.c, then?"
 #endif
 
-#if defined(HAVE_GAS_HIDDEN) && defined(ENABLE_OFFLOADING)
-void *_omp_funcs_end[0]
-  __attribute__ ((__used__, visibility ("protected"),
-		  section (".offload_func_table_section"))) = { };
-void *_omp_vars_end[0]
-  __attribute__ ((__used__, visibility ("protected"),
-		  section (".offload_var_table_section"))) = { };
-extern void *_omp_func_table[];
-extern void *_omp_var_table[];
-void *__OPENMP_TARGET__[] __attribute__ ((__visibility__ ("protected"))) =
-{
-  &_omp_func_table, &_omp_funcs_end,
-  &_omp_var_table, &_omp_vars_end
-};
-#endif
-
 
 #else /* ! CRT_BEGIN && ! CRT_END */
 #error "One of CRT_BEGIN or CRT_END must be defined."
Index: libgcc/ompstuff.c
===================================================================
--- libgcc/ompstuff.c	(revision 0)
+++ libgcc/ompstuff.c	(working copy)
@@ -0,0 +1,52 @@
+/* Specialized bits of code needed for the OpenMP offloading tables.
+   Copyright (C) 2014 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC 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.
+
+GCC 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.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+/* Target machine header files require this define. */
+#define IN_LIBGCC2
+
+/* FIXME: Including auto-host is incorrect, but until we have
+   identified the set of defines that need to go into auto-target.h,
+   this will have to do.  */
+#include "auto-host.h"
+#undef pid_t
+#undef rlim_t
+#undef ssize_t
+#undef vfork
+#include "tconfig.h"
+#include "tsystem.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "libgcc_tm.h"
+
+#if defined(HAVE_GAS_HIDDEN) && defined(ENABLE_OFFLOADING)
+extern void __start___gnu_offload_funcs;
+extern void __stop___gnu_offload_funcs;
+extern void __start___gnu_offload_vars;
+extern void __stop___gnu_offload_vars;
+void *__OPENMP_TARGET__[] __attribute__ ((__visibility__ ("hidden"))) =
+{
+  &__start___gnu_offload_funcs, &__stop___gnu_offload_funcs,
+  &__start___gnu_offload_vars, &__stop___gnu_offload_vars
+};
+#endif

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