c-attribs.c (c_common_attribute_table): Add entry for "patchable_function_entry".

2017-07-07  Torsten Duwe  <duwe@suse.de>

        c-family/
	* c-attribs.c (c_common_attribute_table): Add entry for
	"patchable_function_entry".

        lto/
	* lto-lang.c (lto_attribute_table): Add entry for
	"patchable_function_entry".

	* common.opt: Introduce -fpatchable-function-entry
	command line option, and its variables function_entry_patch_area_size
	and function_entry_patch_area_start.
	* opts.c (common_handle_option): Add -fpatchable_function_entry_ case,
	including a two-value parser.
	* target.def (print_patchable_function_entry): New target hook.
	* targhooks.h (default_print_patchable_function_entry): New function.
	* targhooks.c (default_print_patchable_function_entry): Likewise.
	* toplev.c (process_options): Switch off IPA-RA if
	patchable function entries are being generated.
	* varasm.c (assemble_start_function): Look at the
	patchable-function-entry command line switch and current
	function attributes and maybe generate NOP instructions by
	calling the print_patchable_function_entry hook.
	* doc/extend.texi: Document patchable_function_entry attribute.
	* doc/invoke.texi: Document -fpatchable_function_entry
	command line option.
	* doc/tm.texi.in (TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY):
	New target hook.
	* doc/tm.texi: Re-generate.

	* c-c++-common/patchable_function_entry-default.c: New test.
	* c-c++-common/patchable_function_entry-decl.c: Likewise.
	* c-c++-common/patchable_function_entry-definition.c: Likewise.

From-SVN: r250521

1 files changed, 46 insertions, 0 deletions

diff --git a/gcc/varasm.c b/gcc/varasm.c
index 45611a9..6eccbe4 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -1825,6 +1825,46 @@ assemble_start_function (tree decl, const char *fnname)
   if (DECL_PRESERVE_P (decl))
     targetm.asm_out.mark_decl_preserved (fnname);
 
+  unsigned HOST_WIDE_INT patch_area_size = function_entry_patch_area_size;
+  unsigned HOST_WIDE_INT patch_area_entry = function_entry_patch_area_start;
+
+  tree patchable_function_entry_attr
+    = lookup_attribute ("patchable_function_entry", DECL_ATTRIBUTES (decl));
+  if (patchable_function_entry_attr)
+    {
+      tree pp_val = TREE_VALUE (patchable_function_entry_attr);
+      tree patchable_function_entry_value1 = TREE_VALUE (pp_val);
+
+      if (tree_fits_uhwi_p (patchable_function_entry_value1))
+	patch_area_size = tree_to_uhwi (patchable_function_entry_value1);
+      else
+	gcc_unreachable ();
+
+      patch_area_entry = 0;
+      if (list_length (pp_val) > 1)
+	{
+	  tree patchable_function_entry_value2 =
+	    TREE_VALUE (TREE_CHAIN (pp_val));
+
+	  if (tree_fits_uhwi_p (patchable_function_entry_value2))
+	    patch_area_entry = tree_to_uhwi (patchable_function_entry_value2);
+	  else
+	    gcc_unreachable ();
+	}
+    }
+
+  if (patch_area_entry > patch_area_size)
+    {
+      if (patch_area_size > 0)
+	warning (OPT_Wattributes, "Patchable function entry > size");
+      patch_area_entry = 0;
+    }
+
+  /* Emit the patching area before the entry label, if any.  */
+  if (patch_area_entry > 0)
+    targetm.asm_out.print_patchable_function_entry (asm_out_file,
+						    patch_area_entry, true);
+
   /* Do any machine/system dependent processing of the function name.  */
 #ifdef ASM_DECLARE_FUNCTION_NAME
   ASM_DECLARE_FUNCTION_NAME (asm_out_file, fnname, current_function_decl);
@@ -1833,6 +1873,12 @@ assemble_start_function (tree decl, const char *fnname)
   ASM_OUTPUT_FUNCTION_LABEL (asm_out_file, fnname, current_function_decl);
 #endif /* ASM_DECLARE_FUNCTION_NAME */
 
+  /* And the area after the label.  Record it if we haven't done so yet.  */
+  if (patch_area_size > patch_area_entry)
+    targetm.asm_out.print_patchable_function_entry (asm_out_file,
+					     patch_area_size-patch_area_entry,
+						    patch_area_entry == 0);
+
   if (lookup_attribute ("no_split_stack", DECL_ATTRIBUTES (decl)))
     saw_no_split_stack = true;
 }