[PATCH, x86] Add TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE hook

[Christian Bruel <christian dot bruel at st dot com>]

While trying to reduce the PR64835 case for ARM and x86, I noticed that 
the alignment flags are cleared for x86 when attribute optimized is used.

With the attached testcases, the visible effects are twofold :

1) Functions compiled in with attribute optimize (-O2) are not aligned 
as if they were with the -O2 flag.

2) can_inline_edge_p fails because opts_for_fn (caller->decl) != 
opts_for_fn (callee->decl)) even-though they are compiled with the same 
optimization level.

indeed we have:

 <optimization_node 0x7ffff7522000
    align_functions (0x10)
    align_jumps (0x10)
    align_loops (0x10)
    flag_sched_stalled_insns_dep (0x1)
    flag_tree_parallelize_loops (0x1)
    flag_fp_contract_mode (0x2)
    flag_ira_algorithm (0)
    flag_ira_region (0x2)
    flag_simd_cost_model (0)
    flag_vect_cost_model (0x1)
    optimize (0x2)
    flag_aggressive_loop_optimizations (0x1)
    ...

<optimization_node 0x7ffff7522188
    flag_sched_stalled_insns_dep (0x1)
    flag_tree_parallelize_loops (0x1)
    flag_fp_contract_mode (0x2)
    flag_ira_algorithm (0)
    flag_ira_region (0x2)
    flag_simd_cost_model (0)
    flag_vect_cost_model (0x1)
    optimize (0x2)
    flag_aggressive_loop_optimizations (0x1)
    ...

The problem is that the alignment flags are not recomputed when setting 
the attribute flags in DECL_FUNCTION_SPECIFIC_OPTIMIZATION. Implementing 
the TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE hook to set them fixes the problem.

NB: TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE is also used to hold options 
from attribute target, so.this patch is a prerequisite to fix PR/64835 
on ARM and x86

bootstrapped, regtested with no new failures for x86_64-unknown-linux-gnu

Comments ? I'd like to candidate this for trunk when stage1 opens again.

Many Thanks

Christian






2015-02-06  Christian Bruel  <christian.bruel@st.com>

	PR target/64835
	* config/i386/i386.c (ix86_default_align): New function.
	(ix86_override_options_after_change): Call ix86_default_align.
	(TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE): New hook.
	(ix86_override_options_after_change): New function.

2015-02-06  Christian Bruel  <christian.bruel@st.com>

	PR target/64835
	* gcc.dg/ipa/iinline-attr.c: New test.
	* gcc.target/i386/iinline-attr-2.c: New test.

Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c	(revision 220394)
+++ gcc/config/i386/i386.c	(working copy)
@@ -3105,6 +3105,35 @@
 }
 
 
+/* Default align_* from the processor table.  */
+
+static void
+ix86_default_align (struct gcc_options *opts)
+{
+  if (opts->x_align_loops == 0)
+    {
+      opts->x_align_loops = processor_target_table[ix86_tune].align_loop;
+      align_loops_max_skip = processor_target_table[ix86_tune].align_loop_max_skip;
+    }
+  if (opts->x_align_jumps == 0)
+    {
+      opts->x_align_jumps = processor_target_table[ix86_tune].align_jump;
+      align_jumps_max_skip = processor_target_table[ix86_tune].align_jump_max_skip;
+    }
+  if (opts->x_align_functions == 0)
+    {
+      opts->x_align_functions = processor_target_table[ix86_tune].align_func;
+    }
+}
+
+/* Implement TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE hook.  */
+
+static void
+ix86_override_options_after_change (void)
+{
+  ix86_default_align (&global_options);
+}
+
 /* Override various settings based on options.  If MAIN_ARGS_P, the
    options are from the command line, otherwise they are from
    attributes.  */
@@ -3902,20 +3931,7 @@
     opts->x_ix86_regparm = REGPARM_MAX;
 
   /* Default align_* from the processor table.  */
-  if (opts->x_align_loops == 0)
-    {
-      opts->x_align_loops = processor_target_table[ix86_tune].align_loop;
-      align_loops_max_skip = processor_target_table[ix86_tune].align_loop_max_skip;
-    }
-  if (opts->x_align_jumps == 0)
-    {
-      opts->x_align_jumps = processor_target_table[ix86_tune].align_jump;
-      align_jumps_max_skip = processor_target_table[ix86_tune].align_jump_max_skip;
-    }
-  if (opts->x_align_functions == 0)
-    {
-      opts->x_align_functions = processor_target_table[ix86_tune].align_func;
-    }
+  ix86_default_align (opts);
 
   /* Provide default for -mbranch-cost= value.  */
   if (!opts_set->x_ix86_branch_cost)
@@ -51928,6 +51944,9 @@
 #undef TARGET_PROMOTE_FUNCTION_MODE
 #define TARGET_PROMOTE_FUNCTION_MODE ix86_promote_function_mode
 
+#undef  TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE
+#define TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE ix86_override_options_after_change
+
 #undef TARGET_MEMBER_TYPE_FORCES_BLK
 #define TARGET_MEMBER_TYPE_FORCES_BLK ix86_member_type_forces_blk
 
Index: gcc/testsuite/gcc.dg/ipa/iinline-attr.c
===================================================================
--- gcc/testsuite/gcc.dg/ipa/iinline-attr.c	(revision 0)
+++ gcc/testsuite/gcc.dg/ipa/iinline-attr.c	(working copy)
@@ -0,0 +1,27 @@
+/* Verify that simple indirect calls are inlined even when
+   attribute __optimize is used.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-inline"  } */
+
+extern void non_existent(int);
+
+static void hooray ()
+{
+  non_existent (1);
+}
+
+__attribute__ ((__optimize__ ("O2")))
+static void hiphip (void (*f)())
+{
+  non_existent (2);
+  f ();
+}
+
+int test (void)
+{
+  hiphip (hooray);
+  return 0;
+}
+
+/* { dg-final { scan-ipa-dump "hooray\[^\\n\]*inline copy in test"  "inline"  } } */
+/* { dg-final { cleanup-ipa-dump "inline" } } */
Index: gcc/testsuite/gcc.target/i386/iinline-attr-2.c
===================================================================
--- gcc/testsuite/gcc.target/i386/iinline-attr-2.c	(revision 0)
+++ gcc/testsuite/gcc.target/i386/iinline-attr-2.c	(working copy)
@@ -0,0 +1,29 @@
+/* Verify that alignment flags are set when  attribute __optimize is used.  */
+/* { dg-do compile } */
+/* { dg-options "-O2"  } */
+
+extern void non_existent(int);
+
+__attribute__ ((__optimize__ ("O2")))
+static void hooray ()
+{
+  non_existent (1);
+}
+
+__attribute__ ((__optimize__ ("O2")))
+static void hiphip (void (*f)())
+{
+  non_existent (2);
+  f ();
+}
+
+__attribute__ ((__optimize__ ("O2")))
+int test (void)
+{
+  hiphip (hooray);
+  return 0;
+}
+
+/* { dg-final { scan-assembler "p2align" } } */
+
+