gcc7/gcc7-pfe-0017-Backport-Add-patch_area_size-and-patch_area_entry-to.patch

From 961670bae0c7b37073dbc0bb58d730d1ed603d5d Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Fri, 1 May 2020 21:03:10 -0700
Subject: [PATCH 17/22] Backport 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.
---
 gcc/c-family/c-attribs.c                      |  9 ++++
 gcc/cfgexpand.c                               | 44 +++++++++++++++++++
 gcc/doc/invoke.texi                           |  1 +
 gcc/emit-rtl.h                                |  6 +++
 gcc/opts.c                                    |  4 +-
 .../patchable_function_entry-error-1.c        |  9 ++++
 .../patchable_function_entry-error-2.c        |  9 ++++
 .../patchable_function_entry-error-3.c        | 17 +++++++
 gcc/varasm.c                                  |  4 +-
 9 files changed, 100 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c
 create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c
 create mode 100644 gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c

diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index f0d2b1ed500..c01baffbc57 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -3206,6 +3206,15 @@ handle_patchable_function_entry_attribute (tree *, tree name, tree args,
 	  *no_add_attrs = true;
 	  return NULL_TREE;
 	}
+
+      if (tree_to_uhwi (val) > USHRT_MAX)
+	{
+	  warning (OPT_Wattributes,
+		   "%qE attribute argument %qE is out of range (> 65535)",
+		   name, val);
+	  *no_add_attrs = true;
+	  return NULL_TREE;
+	}
     }
   return NULL_TREE;
 }
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 7fd3916a3c7..2a603823a71 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -6481,6 +6481,50 @@ 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;
+
+  /* This function is not present in gcc 7, nor the profile_count datastructures,
+     so it may be safe to assume that there is not enough engine implemented so
+     far to support that.  */
+#if 0
+  /* BB subdivision may have created basic blocks that are only reachable
+     from unlikely bbs but not marked as such in the profile.  */
+
+  if (optimize)
+    propagate_unlikely_bbs_forward ();
+#endif
+
   /* Remove unreachable blocks, otherwise we cannot compute dominators
      which are needed for loop state verification.  As a side-effect
      this also compacts blocks.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index ad71be54e07..9fd3b013ff7 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -11445,6 +11445,7 @@ If @code{N=0}, no pad location is recorded.
 The NOP instructions are inserted at---and maybe before, depending on
 @var{M}---the function entry address, even before the prologue.
 
+The maximum value of @var{N} and @var{M} is 65535.
 @end table
 
 
diff --git a/gcc/emit-rtl.h b/gcc/emit-rtl.h
index da60a2d808c..66bc1bef391 100644
--- a/gcc/emit-rtl.h
+++ b/gcc/emit-rtl.h
@@ -163,6 +163,12 @@ struct GTY(()) rtl_data {
         local stack.  */
   unsigned int stack_alignment_estimated;
 
+  /* How many NOP insns to place at each function entry by default.  */
+  unsigned short patch_area_size;
+
+  /* How far the real asm entry point is into this area.  */
+  unsigned short patch_area_entry;
+
   /* For reorg.  */
 
   /* Nonzero if function being compiled called builtin_return_addr or
diff --git a/gcc/opts.c b/gcc/opts.c
index d0430e777ee..3de12b3662f 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -2220,10 +2220,12 @@ common_handle_option (struct gcc_options *opts,
 	    function_entry_patch_area_start = 0;
 	  }
 	if (function_entry_patch_area_size < 0
+	    || function_entry_patch_area_size > USHRT_MAX
 	    || function_entry_patch_area_start < 0
+	    || function_entry_patch_area_start > USHRT_MAX
 	    || function_entry_patch_area_size 
 		< function_entry_patch_area_start)
-	  error ("invalid arguments for %<-fpatchable_function_entry%>");
+	  error ("invalid arguments for %<-fpatchable-function-entry%>");
 	free (patch_area_arg);
       }
       break;
diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c b/gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c
new file mode 100644
index 00000000000..f60bf46cfe3
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/patchable_function_entry-error-1.c
@@ -0,0 +1,9 @@
+/* { dg-do compile { target { ! { nvptx*-*-* visium-*-* } } } } */
+/* { dg-options "-O2 -fpatchable-function-entry=65536,1" } */
+/* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */
+/* { dg-error "invalid arguments for '-fpatchable-function-entry'" "" { target *-*-* } 0 } */
+
+void
+foo (void)
+{
+}
diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c b/gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c
new file mode 100644
index 00000000000..90f88c78be7
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/patchable_function_entry-error-2.c
@@ -0,0 +1,9 @@
+/* { dg-do compile { target { ! { nvptx*-*-* visium-*-* } } } } */
+/* { dg-options "-O2 -fpatchable-function-entry=1,65536" } */
+/* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */
+/* { dg-error "invalid arguments for '-fpatchable-function-entry'" "" { target *-*-* } 0 } */
+
+void
+foo (void)
+{
+}
diff --git a/gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c b/gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c
new file mode 100644
index 00000000000..4490e5c15ca
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/patchable_function_entry-error-3.c
@@ -0,0 +1,17 @@
+/* { dg-do compile { target { ! { nvptx*-*-* visium-*-* } } } } */
+/* { dg-additional-options "-fno-pie" { target sparc*-*-* } } */
+
+void
+ __attribute__((patchable_function_entry(65536)))
+foo1 (void) { /* { dg-warning "'patchable_function_entry' attribute argument '65536' is out of range" } */
+}
+
+void
+ __attribute__((patchable_function_entry(65536,1)))
+foo2 (void) { /* { dg-warning "'patchable_function_entry' attribute argument '65536' is out of range" } */
+}
+
+void
+ __attribute__((patchable_function_entry(65536,65536)))
+foo3 (void) { /* { dg-warning "'patchable_function_entry' attribute argument '65536' is out of range" } */
+}
diff --git a/gcc/varasm.c b/gcc/varasm.c
index 0e6f20db361..8d4c0386fe3 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -1829,8 +1829,8 @@ 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;
+  unsigned short patch_area_size = crtl->patch_area_size;
+  unsigned short patch_area_entry = crtl->patch_area_entry;
 
   tree patchable_function_entry_attr
     = lookup_attribute ("patchable_function_entry", DECL_ATTRIBUTES (decl));
-- 
2.33.1