2007-11-15  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/23848

	* tree-ssa-ccp.c (optimize_stack_restore): New function.

	(execute_fold_all_builtins): Call optimize_stack_restore for

	BUILT_IN_STACK_RESTORE.

	* gcc.dg/tree-ssa/pr23848-1.c: New test.

	* gcc.dg/tree-ssa/pr23848-2.c: New test.

	* gcc.dg/tree-ssa/pr23848-3.c: New test.

	* gcc.dg/tree-ssa/pr23848-4.c: New test.

--- gcc/tree-ssa-ccp.c	(revision 130205)

+++ gcc/tree-ssa-ccp.c	(revision 130206)

@@ -2394,6 +2394,75 @@ fold_stmt_inplace (tree stmt)

   return changed;

 }

+/* Try to optimize out __builtin_stack_restore.  Optimize it out

+   if there is another __builtin_stack_restore in the same basic

+   block and no calls or ASM_EXPRs are in between, or if this block's

+   only outgoing edge is to EXIT_BLOCK and there are no calls or

+   ASM_EXPRs after this __builtin_stack_restore.  */

+

+static tree

+optimize_stack_restore (basic_block bb, tree call, block_stmt_iterator i)

+{

+  tree stack_save, stmt, callee;

+

+  if (TREE_CODE (call) != CALL_EXPR

+      || TREE_OPERAND (call, 1) == NULL_TREE

+      || TREE_CHAIN (TREE_OPERAND (call, 1)) != NULL_TREE

+      || TREE_CODE (TREE_VALUE (TREE_OPERAND (call, 1))) != SSA_NAME

+      || !POINTER_TYPE_P (TREE_TYPE (TREE_VALUE (TREE_OPERAND (call, 1)))))

+    return NULL_TREE;

+

+  for (bsi_next (&i); !bsi_end_p (i); bsi_next (&i))

+    {

+      tree call;

+

+      stmt = bsi_stmt (i);

+      if (TREE_CODE (stmt) == ASM_EXPR)

+	return NULL_TREE;

+      call = get_call_expr_in (stmt);

+      if (call == NULL)

+	continue;

+

+      callee = get_callee_fndecl (call);

+      if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)

+	return NULL_TREE;

+

+      if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)

+	break;

+    }

+

+  if (bsi_end_p (i)

+      && (! single_succ_p (bb)

+	  || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR))

+    return NULL_TREE;

+

+  stack_save = SSA_NAME_DEF_STMT (TREE_VALUE (TREE_OPERAND (call, 1)));

+  if (TREE_CODE (stack_save) != MODIFY_EXPR

+      || TREE_OPERAND (stack_save, 0)

+	 != TREE_VALUE (TREE_OPERAND (call, 1))

+      || TREE_CODE (TREE_OPERAND (stack_save, 1)) != CALL_EXPR

+      || tree_could_throw_p (stack_save)

+      || !has_single_use (TREE_VALUE (TREE_OPERAND (call, 1))))

+    return NULL_TREE;

+

+  callee = get_callee_fndecl (TREE_OPERAND (stack_save, 1));

+  if (!callee

+      || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL

+      || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE

+      || TREE_OPERAND (TREE_OPERAND (stack_save, 1), 1) != NULL_TREE)

+    return NULL_TREE;

+

+  stmt = stack_save;

+  if (!set_rhs (&stmt,

+		build_int_cst (TREE_TYPE (TREE_VALUE (TREE_OPERAND (call,

+								    1))), 0)))

+    return NULL_TREE;

+  gcc_assert (stmt == stack_save);

+  mark_new_vars_to_rename (stmt);

+

+  return integer_zero_node;

+}

+

 /* Convert EXPR into a GIMPLE value suitable for substitution on the

    RHS of an assignment.  Insert the necessary statements before

    iterator *SI_P.  */

@@ -2469,6 +2538,12 @@ execute_fold_all_builtins (void)

 		result = integer_zero_node;

 		break;

+	      case BUILT_IN_STACK_RESTORE:

+		result = optimize_stack_restore (bb, *stmtp, i);

+		if (result)

+		  break;

+		/* FALLTHRU */

+

 	      default:

 		bsi_next (&i);

 		continue;

--- gcc/testsuite/gcc.dg/tree-ssa/pr23848-1.c	(revision 0)

+++ gcc/testsuite/gcc.dg/tree-ssa/pr23848-1.c	(revision 130206)

@@ -0,0 +1,32 @@

+/* PR middle-end/23848 */

+/* { dg-do compile } */

+/* { dg-options "-O2 -fdump-tree-optimized" } */

+

+void bar1 (char *, int);

+void foo1 (int size)

+{

+  char temp[size];

+  temp[size-1] = '\0';

+  bar1 (temp, size);

+}

+

+void bar2 (char *, char *, char *, char *, int);

+void foo2 (int size)

+{

+  char temp[size];

+  temp[size-1] = '\0';

+  {

+    char temp2[size];

+    {

+      char temp3[size];

+      {

+	char temp4[size];

+	bar2 (temp, temp2, temp3, temp4, size);

+      }

+    }

+  }

+}

+

+/* { dg-final { scan-tree-dump-not "__builtin_stack_save" "optimized"} } */

+/* { dg-final { scan-tree-dump-not "__builtin_stack_restore" "optimized"} } */

+/* { dg-final { cleanup-tree-dump "optimized" } } */

--- gcc/testsuite/gcc.dg/tree-ssa/pr23848-2.c	(revision 0)

+++ gcc/testsuite/gcc.dg/tree-ssa/pr23848-2.c	(revision 130206)

@@ -0,0 +1,25 @@

+/* PR middle-end/23848 */

+/* { dg-do compile } */

+/* { dg-options "-O2 -fdump-tree-optimized" } */

+

+void bar (char *, char *, char *, char *, int);

+void foo (int size)

+{

+  char temp[size];

+  temp[size-1] = '\0';

+  {

+    char temp2[size];

+    {

+      char temp3[size];

+      {

+	char temp4[size];

+	bar (temp, temp2, temp3, temp4, size);

+      }

+    }

+    bar (temp, temp2, (char *) 0, (char *) 0, size);

+  }

+}

+

+/* { dg-final { scan-tree-dump-times "__builtin_stack_save" 1 "optimized"} } */

+/* { dg-final { scan-tree-dump-times "__builtin_stack_restore" 1 "optimized"} } */

+/* { dg-final { cleanup-tree-dump "optimized" } } */

--- gcc/testsuite/gcc.dg/tree-ssa/pr23848-3.c	(revision 0)

+++ gcc/testsuite/gcc.dg/tree-ssa/pr23848-3.c	(revision 130206)

@@ -0,0 +1,28 @@

+/* PR middle-end/23848 */

+/* { dg-do compile } */

+/* { dg-options "-O2 -fdump-tree-optimized" } */

+

+void bar (int, char *, char *, char *, char *, int);

+void foo (int size)

+{

+  int i;

+  for (i = 0; i < size; i++)

+    {

+      char temp[size];

+      temp[size-1] = '\0';

+      {

+	char temp2[size];

+	{

+	  char temp3[size];

+	  {

+	    char temp4[size];

+	    bar (i, temp, temp2, temp3, temp4, size);

+	  }

+	}

+      }

+    }

+}

+

+/* { dg-final { scan-tree-dump-times "__builtin_stack_save" 1 "optimized"} } */

+/* { dg-final { scan-tree-dump-times "__builtin_stack_restore" 1 "optimized"} } */

+/* { dg-final { cleanup-tree-dump "optimized" } } */

--- gcc/testsuite/gcc.dg/tree-ssa/pr23848-4.c	(revision 0)

+++ gcc/testsuite/gcc.dg/tree-ssa/pr23848-4.c	(revision 130206)

@@ -0,0 +1,25 @@

+/* PR middle-end/23848 */

+/* { dg-do compile } */

+/* { dg-options "-O2 -fdump-tree-optimized" } */

+

+void bar (char *, char *, char *, char *, int);

+void foo (int size)

+{

+  char temp[size];

+  temp[size-1] = '\0';

+  {

+    char temp2[size];

+    {

+      char temp3[size];

+      {

+	char temp4[size];

+	bar (temp, temp2, temp3, temp4, size);

+      }

+    }

+    __asm __volatile ("" : : "r" (&temp[0]), "r" (&temp2[0]) : "memory");

+  }

+}

+

+/* { dg-final { scan-tree-dump-times "__builtin_stack_save" 1 "optimized"} } */

+/* { dg-final { scan-tree-dump-times "__builtin_stack_restore" 1 "optimized"} } */

+/* { dg-final { cleanup-tree-dump "optimized" } } */