Re: [gomp4] Add tables generation

[Ilya Verbin <iverbin at gmail dot com>]

Hi,

On 04 Sep 15:54, Thomas Schwinge wrote:
> Aha, it's gcc/gcc.c:LINK_PLUGIN_SPEC that is unconditionally adding the
> -fresolution option.  Here is a hack that seems to make it work, but that
> most certainly should be done differently:

Here is updated patch, which solves the problem with linker plugin.
I hope that it will not affect the regular LTO compilation.  At least, the
'make check' did not reveal any regression on the system with linker plugin.
Bootstrap also passed.  Ok for gomp-4_0-branch?

  -- Ilya


---
 gcc/cgraphunit.c        | 38 ++++++++++++++++++++-------
 gcc/lto-wrapper.c       | 69 ++++++++++++++++++++++++++-----------------------
 gcc/omp-low.c           |  6 +++++
 gcc/passes.c            |  2 +-
 lto-plugin/lto-plugin.c | 25 +++++++++++++++++-
 5 files changed, 97 insertions(+), 43 deletions(-)

diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index f0c9f5c..b87e6dd 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -2040,13 +2040,25 @@ output_in_order (void)
   free (nodes);
 }
 
-/* Collect all global variables with "omp declare target" attribute into
-   OFFLOAD_VARS.  It will be streamed out in ipa_write_summaries.  */
+/* Check whether there is at least one function or global variable to offload.
+   Also collect all such global variables into OFFLOAD_VARS, the functions were
+   already collected in omp-low.c.  They will be streamed out in
+   ipa_write_summaries.  */
 
-static void
-init_offload_var_table (void)
+static bool
+initialize_offload (void)
 {
+  bool have_offload = false;
+  struct cgraph_node *node;
   struct varpool_node *vnode;
+
+  FOR_EACH_DEFINED_FUNCTION (node)
+    if (lookup_attribute ("omp declare target", DECL_ATTRIBUTES (node->decl)))
+      {
+	have_offload = true;
+	break;
+      }
+
   FOR_EACH_DEFINED_VARIABLE (vnode)
     {
       if (!lookup_attribute ("omp declare target",
@@ -2054,13 +2066,17 @@ init_offload_var_table (void)
 	  || TREE_CODE (vnode->decl) != VAR_DECL
 	  || DECL_SIZE (vnode->decl) == 0)
 	continue;
+      have_offload = true;
       vec_safe_push (offload_vars, vnode->decl);
     }
+
+  return have_offload;
 }
 
 static void
 ipa_passes (void)
 {
+  bool have_offload = false;
   gcc::pass_manager *passes = g->get_passes ();
 
   set_cfun (NULL);
@@ -2068,6 +2084,14 @@ ipa_passes (void)
   gimple_register_cfg_hooks ();
   bitmap_obstack_initialize (NULL);
 
+  if (!in_lto_p && (flag_openacc || flag_openmp))
+    {
+      have_offload = initialize_offload ();
+      /* OpenACC / OpenMP offloading requires LTO infrastructure.  */
+      if (have_offload)
+	flag_generate_lto = 1;
+    }
+
   invoke_plugin_callbacks (PLUGIN_ALL_IPA_PASSES_START, NULL);
 
   if (!in_lto_p)
@@ -2108,11 +2132,7 @@ ipa_passes (void)
 
   if (!in_lto_p)
     {
-      init_offload_var_table ();
-
-      if ((flag_openacc || flag_openmp)
-	  && !(vec_safe_is_empty (offload_funcs)
-	       && vec_safe_is_empty (offload_vars)))
+      if (have_offload)
 	{
 	  section_name_prefix = OMP_SECTION_NAME_PREFIX;
 	  ipa_write_summaries (true);
diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
index 80d10f3..01e8f06 100644
--- a/gcc/lto-wrapper.c
+++ b/gcc/lto-wrapper.c
@@ -668,6 +668,11 @@ run_gcc (unsigned argc, char *argv[])
 	  close (fd);
 	  continue;
 	}
+      /* We may choose not to write out this .opts section in the future.  In
+	 that case we'll have to use something else to look for.  */
+      if (simple_object_find_section (sobj, OMP_SECTION_NAME_PREFIX "." "opts",
+				      &offset, &length, &errmsg, &err))
+	have_offload = true;
       if (!simple_object_find_section (sobj, LTO_SECTION_NAME_PREFIX "." "opts",
 				       &offset, &length, &errmsg, &err))
 	{
@@ -675,11 +680,6 @@ run_gcc (unsigned argc, char *argv[])
 	  close (fd);
 	  continue;
 	}
-      /* We may choose not to write out this .opts section in the future.  In
-	 that case we'll have to use something else to look for.  */
-      if (simple_object_find_section (sobj, OMP_SECTION_NAME_PREFIX "." "opts",
-				      &offset, &length, &errmsg, &err))
-	have_offload = true;
       lseek (fd, file_offset + offset, SEEK_SET);
       data = (char *)xmalloc (length);
       read (fd, data, length);
@@ -871,7 +871,32 @@ run_gcc (unsigned argc, char *argv[])
   /* Remember at which point we can scrub args to re-use the commons.  */
   new_head_argc = obstack_object_size (&argv_obstack) / sizeof (void *);
 
-  if (lto_mode == LTO_MODE_LTO)
+  if (have_offload)
+    {
+      compile_images_for_openmp_targets (argc, argv);
+      if (offload_names)
+	{
+	  find_ompbeginend ();
+	  for (i = 0; offload_names[i]; i++)
+	    printf ("%s\n", offload_names[i]);
+	  free_array_of_ptrs ((void **) offload_names, i);
+	}
+    }
+
+  if (ompbegin)
+    printf ("%s\n", ompbegin);
+
+  if (lto_mode == LTO_MODE_NONE)
+    {
+      /* If we are in lto-wrapper, but -flto option is absent, it means that
+	 there is no need to perform a link-time recompilation, i.e. lto-wrapper
+	 is used only for compiling offload images.  */
+      for (i = 1; i < argc; ++i)
+	if (strncmp (argv[i], "-fresolution=", sizeof ("-fresolution=") - 1))
+	  printf ("%s\n", argv[i]);
+      goto finish;
+    }
+  else if (lto_mode == LTO_MODE_LTO)
     {
       flto_out = make_temp_file (".lto.o");
       if (linker_output)
@@ -879,7 +904,7 @@ run_gcc (unsigned argc, char *argv[])
       obstack_ptr_grow (&argv_obstack, "-o");
       obstack_ptr_grow (&argv_obstack, flto_out);
     }
-  else 
+  else if (lto_mode == LTO_MODE_WHOPR)
     {
       const char *list_option = "-fltrans-output-list=";
       size_t list_option_len = strlen (list_option);
@@ -939,7 +964,7 @@ run_gcc (unsigned argc, char *argv[])
       free (flto_out);
       flto_out = NULL;
     }
-  else
+  else if (lto_mode == LTO_MODE_WHOPR)
     {
       FILE *stream = fopen (ltrans_output_file, "r");
       FILE *mstream = NULL;
@@ -1084,25 +1109,6 @@ cont:
 	  for (i = 0; i < nr; ++i)
 	    maybe_unlink (input_names[i]);
 	}
-      if (have_offload)
-	{
-	  compile_images_for_openmp_targets (argc, argv);
-	  if (offload_names)
-	    {
-	      find_ompbeginend ();
-	      for (i = 0; offload_names[i]; i++)
-		{
-		  fputs (offload_names[i], stdout);
-		  putc ('\n', stdout);
-		}
-	      free_array_of_ptrs ((void **)offload_names, i);
-	    }
-	}
-      if (ompbegin)
-	{
-	  fputs (ompbegin, stdout);
-	  putc ('\n', stdout);
-	}
 
       for (i = 0; i < nr; ++i)
 	{
@@ -1110,11 +1116,6 @@ cont:
 	  putc ('\n', stdout);
 	  free (input_names[i]);
 	}
-      if (ompend)
-	{
-	  fputs (ompend, stdout);
-	  putc ('\n', stdout);
-	}
       nr = 0;
       free (output_names);
       free (input_names);
@@ -1122,6 +1123,10 @@ cont:
       obstack_free (&env_obstack, NULL);
     }
 
+finish:
+  if (ompend)
+    printf ("%s\n", ompend);
+
   obstack_free (&argv_obstack, NULL);
 }
 
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 6ed8239..cf00407 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -13774,6 +13774,12 @@ omp_finish_file (void)
 				   get_identifier (".omp_var_table"),
 				   vars_decl_type);
       TREE_STATIC (funcs_decl) = TREE_STATIC (vars_decl) = 1;
+      /* Do not align tables more than TYPE_ALIGN (pointer_sized_int_node),
+	 otherwise a joint table in a binary will contain padding between
+	 tables from multiple object files.  */
+      DECL_USER_ALIGN (funcs_decl) = DECL_USER_ALIGN (vars_decl) = 1;
+      DECL_ALIGN (funcs_decl) = TYPE_ALIGN (funcs_decl_type);
+      DECL_ALIGN (vars_decl) = TYPE_ALIGN (vars_decl_type);
       DECL_INITIAL (funcs_decl) = ctor_f;
       DECL_INITIAL (vars_decl) = ctor_v;
       set_decl_section_name (funcs_decl, funcs_section_name);
diff --git a/gcc/passes.c b/gcc/passes.c
index 8172185..e776059 100644
--- a/gcc/passes.c
+++ b/gcc/passes.c
@@ -2303,7 +2303,7 @@ ipa_write_summaries (bool is_omp)
   struct cgraph_node *node;
   struct cgraph_node **order;
 
-  if (!(flag_generate_lto || flag_openacc || flag_openmp) || seen_error () )
+  if (!flag_generate_lto || seen_error ())
     return;
 
   select_what_to_dump (is_omp);
diff --git a/lto-plugin/lto-plugin.c b/lto-plugin/lto-plugin.c
index 910e23c..f53d9e2 100644
--- a/lto-plugin/lto-plugin.c
+++ b/lto-plugin/lto-plugin.c
@@ -86,6 +86,8 @@ along with this program; see the file COPYING3.  If not see
 
 #define LTO_SECTION_PREFIX	".gnu.lto_.symtab"
 #define LTO_SECTION_PREFIX_LEN	(sizeof (LTO_SECTION_PREFIX) - 1)
+#define OFFLOAD_SECTION		".gnu.target_lto_.opts"
+#define OFFLOAD_SECTION_LEN	(sizeof (OFFLOAD_SECTION) - 1)
 
 /* The part of the symbol table the plugin has to keep track of. Note that we
    must keep SYMS until all_symbols_read is called to give the linker time to
@@ -111,6 +113,7 @@ struct plugin_symtab
 struct plugin_objfile
 {
   int found;
+  int offload;
   simple_object_read *objfile;
   struct plugin_symtab *out;
   const struct ld_plugin_input_file *file;
@@ -862,6 +865,21 @@ err:
   return 0;
 }
 
+/* Find an offload section of an object file.  */
+
+static int
+process_offload_section (void *data, const char *name, off_t offset, off_t len)
+{
+  if (!strncmp (name, OFFLOAD_SECTION, OFFLOAD_SECTION_LEN))
+    {
+      struct plugin_objfile *obj = (struct plugin_objfile *) data;
+      obj->offload = 1;
+      return 0;
+    }
+
+  return 1;
+}
+
 /* Callback used by gold to check if the plugin will claim FILE. Writes
    the result in CLAIMED. */
 
@@ -899,6 +917,7 @@ claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
   *claimed = 0;
   obj.file = file;
   obj.found = 0;
+  obj.offload = 0;
   obj.out = &lto_file.symtab;
   errmsg = NULL;
   obj.objfile = simple_object_start_read (file->fd, file->offset, LTO_SEGMENT_NAME,
@@ -920,7 +939,11 @@ claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
       goto err;
     }
 
-  if (obj.found == 0)
+  if (obj.objfile)
+    simple_object_find_sections (obj.objfile, process_offload_section,
+				 &obj, &err);
+
+  if (obj.found == 0 && obj.offload == 0)
     goto err;
 
   if (obj.found > 1)
-- 
1.8.3.1