* 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.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@160615 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 48 insertions, 5 deletions

diff --git a/gcc/ipa-pure-const.c b/gcc/ipa-pure-const.c
index da8d442107b..8678663ed6c 100644
--- a/gcc/ipa-pure-const.c
+++ b/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,