tree-cfgcleanup.c (fixup_noreturn_call): Break out from ...; remove return value.

	* tree-cfgcleanup.c (fixup_noreturn_call): Break out from ...;
	remove return value.
	(split_bbs_on_noreturn_calls) .... here.
	* tree-optimize.c (execute_fixup_cfg): Fixup noreturn calls too.
	* tree-flow.h (fixup_noreturn_call): New.
	* testsuite/gcc.dg/lto/noreturn-1_1.c: New testcase.
	* testsuite/gcc.dg/lto/noreturn-1_0.c: New testcase.

From-SVN: r160122

gcc/ChangeLog

 2010-06-01  Jan Hubicka  <jh@suse.cz>
 
+	* tree-cfgcleanup.c (fixup_noreturn_call): Break out from ...;
+	remove return value.
+	(split_bbs_on_noreturn_calls) .... here.
+	* tree-optimize.c (execute_fixup_cfg): Fixup noreturn calls too.
+	* tree-flow.h (fixup_noreturn_call): New.
+
+2010-06-01  Jan Hubicka  <jh@suse.cz>
+
 	* emit-rtl.c (remove_insn): Fix thinko in prevoius patch.
 
 2010-06-01  Nathan Froyd  <froydnj@codesourcery.com>

gcc/testsuite/ChangeLog

+2010-05-31 Jan Hubicka  <jh@suse.cz>
+
+	* testsuite/gcc.dg/lto/noreturn-1_1.c: New testcase.
+	* testsuite/gcc.dg/lto/noreturn-1_0.c: New testcase.
+
 2010-05-31  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/36928

gcc/testsuite/gcc.dg/lto/noreturn-1_0.c

@@ -5,17 +5,3 @@ call_me (void)
 {
   exit (0);
 }
-void exit (int);
-__attribute__ ((noreturn))
-int
-call_me (void)
-{
-  exit (0);
-}
-void exit (int);
-__attribute__ ((noreturn))
-int
-call_me (void)
-{
-  exit (0);
-}

gcc/testsuite/gcc.dg/lto/noreturn-1_1.c

@@ -7,21 +7,3 @@ main(void)
 {
  return call_me ();
 }
-/* { dg-lto-do run } */
-/* { dg-lto-options {{-O2 -fwhopr} } } */
-
-int call_me (void);
-int
-main(void)
-{
- return call_me ();
-}
-/* { dg-lto-do run } */
-/* { dg-lto-options {{-O2 -fwhopr} } } */
-
-int call_me (void);
-int
-main(void)
-{
- return call_me ();
-}

gcc/tree-cfgcleanup.c

@@ -538,6 +538,49 @@ remove_forwarder_block (basic_block bb)
   return true;
 }
 
+/* STMT is a call that has been discovered noreturn.  Fixup the CFG
+   and remove LHS.  Return true if something changed.  */
+
+bool
+fixup_noreturn_call (gimple stmt)
+{
+  basic_block bb = gimple_bb (stmt);
+  bool changed = false;
+
+  if (gimple_call_builtin_p (stmt, BUILT_IN_RETURN))
+    return false;
+
+  /* First split basic block if stmt is not last.  */
+  if (stmt != gsi_stmt (gsi_last_bb (bb)))
+    split_block (bb, stmt);
+
+  changed |= remove_fallthru_edge (bb->succs);
+
+  /* If there is LHS, remove it.  */
+  if (gimple_call_lhs (stmt))
+    {
+      tree op = gimple_call_lhs (stmt);
+      gimple_call_set_lhs (stmt, NULL_TREE);
+      /* We need to remove SSA name to avoid checking.
+	 All uses are dominated by the noreturn and thus will
+	 be removed afterwards.  */
+      if (TREE_CODE (op) == SSA_NAME)
+	{
+	  use_operand_p use_p;
+          imm_use_iterator iter;
+	  gimple use_stmt;
+
+          FOR_EACH_IMM_USE_STMT (use_stmt, iter, op)
+	    FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
+	      SET_USE (use_p, error_mark_node);
+	}
+      update_stmt (stmt);
+      changed = true;
+    }
+  return changed;
+}
+
+
 /* Split basic blocks on calls in the middle of a basic block that are now
    known not to return, and remove the unreachable code.  */
 
@@ -560,13 +603,10 @@ split_bbs_on_noreturn_calls (void)
 	    || bb->index < NUM_FIXED_BLOCKS
 	    || bb->index >= n_basic_blocks
 	    || BASIC_BLOCK (bb->index) != bb
-	    || last_stmt (bb) == stmt
 	    || !gimple_call_noreturn_p (stmt))
 	  continue;
 
-	changed = true;
-	split_block (bb, stmt);
-	remove_fallthru_edge (bb->succs);
+	changed |= fixup_noreturn_call (stmt);
       }
 
   return changed;

gcc/tree-flow.h

@@ -870,6 +870,7 @@ tree maybe_fold_tmr (tree);
 
 unsigned int execute_free_datastructures (void);
 unsigned int execute_fixup_cfg (void);
+bool fixup_noreturn_call (gimple stmt);
 
 #include "tree-flow-inline.h"
 

gcc/tree-optimize.c

@@ -231,7 +231,8 @@ execute_free_datastructures (void)
 }
 
 /* Pass: fixup_cfg.  IPA passes, compilation of earlier functions or inlining
-   might have changed some properties, such as marked functions nothrow.
+   might have changed some properties, such as marked functions nothrow,
+   pure, const or noreturn.
    Remove redundant edges and basic blocks, and create new ones if necessary.
 
    This pass can't be executed as stand alone pass from pass manager, because
@@ -267,19 +268,23 @@ execute_fixup_cfg (void)
 	  tree decl = is_gimple_call (stmt)
 		      ? gimple_call_fndecl (stmt)
 		      : NULL;
-
-	  if (decl
-	      && gimple_call_flags (stmt) & (ECF_CONST
-					     | ECF_PURE
-					     | ECF_LOOPING_CONST_OR_PURE))
+	  if (decl)
 	    {
-	      if (gimple_in_ssa_p (cfun))
+	      int flags = gimple_call_flags (stmt);
+	      if (flags & (ECF_CONST | ECF_PURE | ECF_LOOPING_CONST_OR_PURE))
 		{
-		  todo |= TODO_update_ssa | TODO_cleanup_cfg;
-		  mark_symbols_for_renaming (stmt);
-		  update_stmt (stmt);
+		  if (gimple_in_ssa_p (cfun))
+		    {
+		      todo |= TODO_update_ssa | TODO_cleanup_cfg;
+		      mark_symbols_for_renaming (stmt);
+		      update_stmt (stmt);
+		    }
 		}
-	    }
+	      
+	      if (flags & ECF_NORETURN
+		  && fixup_noreturn_call (stmt))
+		todo |= TODO_cleanup_cfg;
+	     }
 
 	  maybe_clean_eh_stmt (stmt);
 	}
@@ -293,6 +298,13 @@ execute_fixup_cfg (void)
   if (count_scale != REG_BR_PROB_BASE)
     compute_function_frequency ();
 
+  /* We just processed all calls.  */
+  if (cfun->gimple_df)
+    {
+      VEC_free (gimple, gc, MODIFIED_NORETURN_CALLS (cfun));
+      MODIFIED_NORETURN_CALLS (cfun) = NULL;
+    }
+
   /* Dump a textual representation of the flowgraph.  */
   if (dump_file)
     gimple_dump_cfg (dump_file, dump_flags);