Re: [PATCH][RFC] Come up with -flive-patching master option.

["Martin Liška" <mliska@suse.cz>]

[-- Attachment #1: Type: text/plain, Size: 48 bytes --]

Hi.

Sorry for attaching a wrong patch.

Martin

[-- Attachment #2: 0001-Come-up-with-flive-patching-master-option.patch --]
[-- Type: text/x-patch, Size: 2865 bytes --]

From 7d3887b1b24901eca69614e601b6e8f36e5c86eb Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Fri, 9 Nov 2018 16:28:07 +0100
Subject: [PATCH] Come up with -flive-patching master option.

gcc/ChangeLog:

2018-11-09  Martin Liska  <mliska@suse.cz>

	* common.opt: Add -flive-patching option.
	* opts.c (disable_live_patching_related_optimizations): New
	function where we disable all optimizations that are potentially
	dangerous for live patching.
	(common_handle_option): Call the function.
---
 gcc/common.opt |  4 ++++
 gcc/opts.c     | 31 +++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/gcc/common.opt b/gcc/common.opt
index 98e8eb03ef3..475b667f26b 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2156,6 +2156,10 @@ flive-range-shrinkage
 Common Report Var(flag_live_range_shrinkage) Init(0) Optimization
 Relief of register pressure through live range shrinkage.
 
+flive-patching
+Common Report Var(flag_live_patching) Init(0) Optimization
+Perform only safe IPA transformations for live patching.
+
 frename-registers
 Common Report Var(flag_rename_registers) Init(2) Optimization
 Perform a register renaming optimization pass.
diff --git a/gcc/opts.c b/gcc/opts.c
index e21967ba84d..dd0c24ac2f9 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -1548,6 +1548,33 @@ enable_fdo_optimizations (struct gcc_options *opts,
     opts->x_flag_tree_loop_distribute_patterns = value;
 }
 
+/* Disable IPA optimization that are not safe for live patching.  */
+
+static void
+disable_live_patching_related_optimizations (gcc_options *opts,
+					     gcc_options *opts_set)
+{
+  if (!opts_set->x_flag_ipa_icf_functions)
+    opts->x_flag_ipa_icf_functions = 0;
+
+  if (!opts_set->x_flag_ipa_icf)
+      opts->x_flag_ipa_icf = 0;
+  if (!opts_set->x_flag_ipa_icf_variables)
+      opts->x_flag_ipa_icf_variables = 0;
+  if (!opts_set->x_flag_ipa_pure_const)
+      opts->x_flag_ipa_pure_const = 0;
+  if (!opts_set->x_flag_ipa_pta)
+      opts->x_flag_ipa_pta = 0;
+  if (!opts_set->x_flag_ipa_reference)
+      opts->x_flag_ipa_reference = 0;
+  if (!opts_set->x_flag_ipa_reference_addressable)
+      opts->x_flag_ipa_reference_addressable = 0;
+  if (!opts_set->x_flag_ipa_stack_alignment)
+      opts->x_flag_ipa_stack_alignment = 0;
+  if (!opts_set->x_flag_ipa_ra)
+      opts->x_flag_ipa_ra = 0;
+}
+
 /* -f{,no-}sanitize{,-recover}= suboptions.  */
 const struct sanitizer_opts_s sanitizer_opts[] =
 {
@@ -2266,6 +2293,10 @@ common_handle_option (struct gcc_options *opts,
 	(&opts->x_flag_instrument_functions_exclude_files, arg);
       break;
 
+    case OPT_flive_patching:
+      if (value)
+	disable_live_patching_related_optimizations (opts, opts_set);
+
     case OPT_fmessage_length_:
       pp_set_line_maximum_length (dc->printer, value);
       diagnostic_set_caret_max_width (dc, value);
-- 
2.19.1