[PATCH, trunk, PR57358] Avoid IPA-CP analysis if attribute optimize precludes it

[Martin Jambor <mjambor at suse dot cz>]

Hi,

this is how I would like to fix the ICE when analyzing a function with
attribute optimize on trunk.  Inlining, the other user of the
analysis, is already smart enough not to analyze such functions, so
this teaches IPA-CP to do the same thing.  Consequently, functions
witrh attribute optimize(O0) or even optimize(fno-ipa-cp) will be
completely ignored by IPA-CP and friends, making it completely opaque
black box during the analysis.

It is a tiny bit more efficient than the simple fix for the branch
(but changes compiler behavior).  I assume it can also come handy
during some debugging/analysis.

Bootstrapped and tested on x86_64-linux.  OK for trunk?

Thanks,

Martin


2013-06-11  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/57358
	* ipa-prop.c (ipa_func_spec_opts_forbid_analysis_p): New function.
	(ipa_compute_jump_functions_for_edge): Bail out if it returns true.
	(ipa_analyze_params_uses): Generate pessimistic info when true.

testsuite
	* gcc.dg/ipa/pr57358.c: New test.

Index: src/gcc/ipa-prop.c
===================================================================
--- src.orig/gcc/ipa-prop.c
+++ src/gcc/ipa-prop.c
@@ -78,6 +78,21 @@ struct ipa_cst_ref_desc
 
 static alloc_pool ipa_refdesc_pool;
 
+/* Return true if DECL_FUNCTION_SPECIFIC_OPTIMIZATION of the decl associated
+   with NODE should prevent us from analyzing it for the purposes of IPA-CP.  */
+
+static bool
+ipa_func_spec_opts_forbid_analysis_p (struct cgraph_node *node)
+{
+  tree fs_opts = DECL_FUNCTION_SPECIFIC_OPTIMIZATION (node->symbol.decl);
+  struct cl_optimization *os;
+
+  if (!fs_opts)
+    return false;
+  os = TREE_OPTIMIZATION (fs_opts);
+  return !os->x_optimize || !os->x_flag_ipa_cp;
+}
+
 /* Return index of the formal whose tree is PTREE in function which corresponds
    to INFO.  */
 
@@ -1446,6 +1461,9 @@ ipa_compute_jump_functions_for_edge (str
     return;
   vec_safe_grow_cleared (args->jump_functions, arg_num);
 
+  if (ipa_func_spec_opts_forbid_analysis_p (cs->caller))
+    return;
+
   for (n = 0; n < arg_num; n++)
     {
       struct ipa_jump_func *jfunc = ipa_get_ith_jump_func (args, n);
@@ -1936,6 +1954,17 @@ ipa_analyze_params_uses (struct cgraph_n
   if (ipa_get_param_count (info) == 0 || info->uses_analysis_done)
     return;
 
+  info->uses_analysis_done = 1;
+  if (ipa_func_spec_opts_forbid_analysis_p (node))
+    {
+      for (i = 0; i < ipa_get_param_count (info); i++)
+	{
+	  ipa_set_param_used (info, i, true);
+	  ipa_set_controlled_uses (info, i, IPA_UNDESCRIBED_USE);
+	}
+      return;
+    }
+
   for (i = 0; i < ipa_get_param_count (info); i++)
     {
       tree parm = ipa_get_param (info, i);
@@ -1992,8 +2021,6 @@ ipa_analyze_params_uses (struct cgraph_n
 				       visit_ref_for_mod_analysis,
 				       visit_ref_for_mod_analysis);
     }
-
-  info->uses_analysis_done = 1;
 }
 
 /* Free stuff in PARMS_AINFO, assume there are PARAM_COUNT parameters.  */
Index: src/gcc/testsuite/gcc.dg/ipa/pr57358.c
===================================================================
--- /dev/null
+++ src/gcc/testsuite/gcc.dg/ipa/pr57358.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+struct t { void (*func)(void*); };
+void test_func(struct t* a) __attribute__((optimize("O0")));
+void test_func(struct t* a)
+{
+  a->func(0);
+}