Add patch_area_size and patch_area_entry to crtl

Currently patchable area is at the wrong place.  It is placed immediately
after function label and before .cfi_startproc.  A backend should be able
to add a pseudo patchable area instruction durectly into RTL.  This patch
adds patch_area_size and patch_area_entry to crtl so that the patchable
area info is available in RTL passes.

It also limits patch_area_size and patch_area_entry to 65535, which is
a reasonable maximum size for patchable area.

gcc/

	PR target/93492
	* cfgexpand.c (pass_expand::execute): Set crtl->patch_area_size
	and crtl->patch_area_entry.
	* emit-rtl.h (rtl_data): Add patch_area_size and patch_area_entry.
	* opts.c (common_handle_option): Limit
	function_entry_patch_area_size and function_entry_patch_area_start
	to USHRT_MAX.  Fix a typo in error message.
	* varasm.c (assemble_start_function): Use crtl->patch_area_size
	and crtl->patch_area_entry.
	* doc/invoke.texi: Document the maximum value for
	-fpatchable-function-entry.

gcc/c-family/

	PR target/93492
	* c-attribs.c (handle_patchable_function_entry_attribute): Limit
	value to USHRT_MAX (65535).

gcc/testsuite/

	PR target/93492
	* c-c++-common/patchable_function_entry-error-1.c: New test.
	* c-c++-common/patchable_function_entry-error-2.c: Likewise.
	* c-c++-common/patchable_function_entry-error-3.c: Likewise.

1 files changed, 33 insertions, 0 deletions

diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index a7ec77d..86efa22 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -6656,6 +6656,39 @@ pass_expand::execute (function *fun)
   if (crtl->tail_call_emit)
     fixup_tail_calls ();
 
+  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 (cfun->decl));
+  if (patchable_function_entry_attr)
+    {
+      tree pp_val = TREE_VALUE (patchable_function_entry_attr);
+      tree patchable_function_entry_value1 = TREE_VALUE (pp_val);
+
+      patch_area_size = tree_to_uhwi (patchable_function_entry_value1);
+      patch_area_entry = 0;
+      if (TREE_CHAIN (pp_val) != NULL_TREE)
+	{
+	  tree patchable_function_entry_value2
+	    = TREE_VALUE (TREE_CHAIN (pp_val));
+	  patch_area_entry = tree_to_uhwi (patchable_function_entry_value2);
+	}
+    }
+
+  if (patch_area_entry > patch_area_size)
+    {
+      if (patch_area_size > 0)
+	warning (OPT_Wattributes,
+		 "patchable function entry %wu exceeds size %wu",
+		 patch_area_entry, patch_area_size);
+      patch_area_entry = 0;
+    }
+
+  crtl->patch_area_size = patch_area_size;
+  crtl->patch_area_entry = patch_area_entry;
+
   /* BB subdivision may have created basic blocks that are only reachable
      from unlikely bbs but not marked as such in the profile.  */
   if (optimize)