ipa-pure-const.c (special_builtlin_state): New function.

	* ipa-pure-const.c (special_builtlin_state): New function.
	(check_call): Use it instead of special casign BUILT_IN_RETURN.
	(propagate_pure_const): Use it.

	* gcc.dg/ipa/pure-const-2.c: New testcase.

From-SVN: r160615

gcc/ChangeLog

 2010-06-11  Jan Hubicka  <jh@suse.cz>
 
+	* ipa-pure-const.c (special_builtlin_state): New function.
+	(check_call): Use it instead of special casign BUILT_IN_RETURN.
+	(propagate_pure_const): Use it.
+
+2010-06-11  Jan Hubicka  <jh@suse.cz>
+
 	* df-problems.c (df_live_scratch): Convert to bitmap_head.
 	(df_live_alloc): Initialize df_live_scratch when initializing
 	problem_data.

gcc/ipa-pure-const.c

@@ -420,6 +420,40 @@ worse_state (enum pure_const_state_e *state, bool *looping,
   *looping = MAX (*looping, looping2);
 }
 
+/* Recognize special cases of builtins that are by themself not pure or const
+   but function using them is.  */
+static bool
+special_builtlin_state (enum pure_const_state_e *state, bool *looping,
+			tree callee)
+{
+  if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
+    switch (DECL_FUNCTION_CODE (callee))
+      {
+	case BUILT_IN_RETURN:
+	case BUILT_IN_UNREACHABLE:
+	case BUILT_IN_ALLOCA:
+	case BUILT_IN_STACK_SAVE:
+	case BUILT_IN_STACK_RESTORE:
+	case BUILT_IN_EH_POINTER:
+	case BUILT_IN_EH_FILTER:
+	case BUILT_IN_UNWIND_RESUME:
+	case BUILT_IN_CXA_END_CLEANUP:
+	case BUILT_IN_EH_COPY_VALUES:
+	case BUILT_IN_FRAME_ADDRESS:
+	case BUILT_IN_APPLY:
+	case BUILT_IN_APPLY_ARGS:
+	case BUILT_IN_ARGS_INFO:
+	  *looping = false;
+	  *state = IPA_CONST;
+	  return true;
+	case BUILT_IN_PREFETCH:
+	  *looping = true;
+	  *state = IPA_CONST;
+	  return true;
+      }
+  return false;
+}
+
 /* Check the parameters of a function call to CALL_EXPR to see if
    there are any references in the parameters that are not allowed for
    pure or const functions.  Also check to see if this is either an
@@ -470,9 +504,15 @@ check_call (funct_state local, gimple call, bool ipa)
      graph.  */
   if (callee_t)
     {
-      /* built_in_return is really just an return statemnt.  */
-      if (gimple_call_builtin_p (call, BUILT_IN_RETURN))
-	return;
+      enum pure_const_state_e call_state;
+      bool call_looping;
+
+      if (special_builtlin_state (&call_state, &call_looping, callee_t))
+	{
+	  worse_state (&local->pure_const_state, &local->looping,
+		       call_state, call_looping);
+	  return;
+	}
       /* When bad things happen to bad functions, they cannot be const
 	 or pure.  */
       if (setjmp_call_p (callee_t))
@@ -1153,10 +1193,13 @@ propagate_pure_const (void)
 		      edge_looping = y_l->looping;
 		    }
 		}
+	      else if (special_builtlin_state (&edge_state, &edge_looping,
+					       y->decl))
+		;
 	      else
 		state_from_flags (&edge_state, &edge_looping,
-			          flags_from_decl_or_type (y->decl),
-			          cgraph_edge_cannot_lead_to_return (e));
+				  flags_from_decl_or_type (y->decl),
+				  cgraph_edge_cannot_lead_to_return (e));
 
 	      /* Merge the results with what we already know.  */
 	      better_state (&edge_state, &edge_looping,

gcc/testsuite/ChangeLog

 2010-06-11  Jan Hubicka  <jh@suse.cz>
 
-	* testsuite/gcc.dg/noreturn-7.c: Update.
-	* testsuite/gcc.dg/noreturn-4.c: Update.
+	* gcc.dg/ipa/pure-const-2.c: New testcase.
+
+2010-06-11  Jan Hubicka  <jh@suse.cz>
+
+	* gcc.dg/noreturn-7.c: Update.
+	* gcc.dg/noreturn-4.c: Update.
 
 2010-06-10  Dodji Seketeli  <dodji@redhat.com>
 

gcc/testsuite/gcc.dg/ipa/pure-const-2.c

+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-local-pure-const1 -fdump-tree-optimized" } */
+static __attribute__ ((noinline, noclone))
+int i_am_pure(char *c, int n)
+{
+  char *d=__builtin_alloca (n);
+  int i;
+  int sum;
+  for (i=0;i<n;i++)
+    d[i] = c[i];
+  for (i=0;i<n;i++)
+    d[i] *= c[n-i];
+  for (i=0;i<n;i++)
+    sum+=d[i];
+  if (sum)
+    __builtin_unreachable ();
+  return sum;
+}
+char array[11];
+int
+main(void)
+{
+  i_am_pure (array,5);
+  i_am_pure (array,11);
+  return 0;
+}
+/* { dg-final { scan-tree-dump "found to be pure: i_am_pure" "local-pure-const1"} } */
+/* { dg-final { scan-tree-dump-not "i_am_pure" "optimized"} } */