Re: Patch: jcf-write and last_bc

[Per Bothner <per at bothner dot com>]

This patch seems to work.  Basically, it re-implements "synchronized"
to used TRY_FINALLY_EXPR instead of WITH_CLEANUP_EXPR.
This works because the former already has working support for handling
empty statements.  I also think TRY_FINALLY_EXPR is easier to
understand and work with and that WITH_CLEANUP_EXPR is redundant.
A follow-up patch (if this works) will remove remaining uses of
WITH_CLEANUP_EXPR and CLEANUP_POINT_EXPR.


Index: parse.y
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/parse.y,v
retrieving revision 1.318
diff -u -p -r1.318 parse.y
--- parse.y	2001/10/09 05:40:35	1.318
+++ parse.y	2001/10/10 00:02:47
@@ -11579,21 +11579,6 @@ java_complete_lhs (node)
       TREE_TYPE (node) = TREE_TYPE (TREE_OPERAND (node, 0));
       return node;
 
-    case CLEANUP_POINT_EXPR:
-      COMPLETE_CHECK_OP_0 (node);
-      TREE_TYPE (node) = void_type_node;
-      CAN_COMPLETE_NORMALLY (node) = 
-	CAN_COMPLETE_NORMALLY (TREE_OPERAND (node, 0));
-      return node;
-
-    case WITH_CLEANUP_EXPR:
-      COMPLETE_CHECK_OP_0 (node);
-      COMPLETE_CHECK_OP_1 (node);
-      CAN_COMPLETE_NORMALLY (node) = 
-	CAN_COMPLETE_NORMALLY (TREE_OPERAND (node, 0));
-      TREE_TYPE (node) = void_type_node;
-      return node;
-
     case LABELED_BLOCK_EXPR:
       PUSH_LABELED_BLOCK (node);
       if (LABELED_BLOCK_BODY (node))
@@ -15668,13 +15667,9 @@ patch_synchronized_statement (node, wfl_
   CAN_COMPLETE_NORMALLY (exit) = 1;
   assignment = build (MODIFY_EXPR, NULL_TREE, expr_decl, expr);
   TREE_SIDE_EFFECTS (assignment) = 1;
-  node = build1 (CLEANUP_POINT_EXPR, NULL_TREE,
-		 build (COMPOUND_EXPR, NULL_TREE,
-			build (WITH_CLEANUP_EXPR, NULL_TREE,
-			       build (COMPOUND_EXPR, NULL_TREE,
-				      assignment, enter),
-			       exit, NULL_TREE),
-			block));
+  node = build (COMPOUND_EXPR, NULL_TREE,
+		build (COMPOUND_EXPR, NULL_TREE, assignment, enter),
+		build (TRY_FINALLY_EXPR, NULL_TREE, block, exit));
   node = build_expr_block (node, expr_decl);
 
   return java_complete_tree (node);
Index: jcf-write.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/jcf-write.c,v
retrieving revision 1.90
diff -u -p -r1.90 jcf-write.c
--- jcf-write.c	2001/10/08 20:35:03	1.90
+++ jcf-write.c	2001/10/10 00:36:12
@@ -57,7 +57,7 @@ char *jcf_write_base_directory = NULL;
 /* Add a 1-byte instruction/operand I to bytecode.data,
    assuming space has already been RESERVE'd. */
 
-#define OP1(I) (state->last_bc = *state->bytecode.ptr++ = (I), CHECK_OP(state))
+#define OP1(I) (*state->bytecode.ptr++ = (I), CHECK_OP(state))
 
 /* Like OP1, but I is a 2-byte big endian integer. */
 
@@ -275,8 +275,6 @@ struct jcf_partial
 
   /* Information about the current switch statement. */
   struct jcf_switch_state *sw_state;
-
-  enum java_opcode last_bc;	/* The last emitted bytecode */
 };
 
 static void generate_bytecode_insns PARAMS ((tree, int, struct jcf_partial *));
@@ -2167,16 +2165,7 @@ generate_bytecode_insns (exp, target, st
 	tree src = TREE_OPERAND (exp, 0);
 	tree src_type = TREE_TYPE (src);
 	tree dst_type = TREE_TYPE (exp);
-	/* Detect the situation of compiling an empty synchronized
-	   block.  A nop should be emitted in order to produce
-	   verifiable bytecode. */
-	if (exp == empty_stmt_node
-	    && state->last_bc == OPCODE_monitorenter
-	    && state->labeled_blocks
-	    && state->labeled_blocks->pc == PENDING_CLEANUP_PC)
-	  OP1 (OPCODE_nop);
-	else
-	  generate_bytecode_insns (TREE_OPERAND (exp, 0), target, state);
+	generate_bytecode_insns (TREE_OPERAND (exp, 0), target, state);
 	if (target == IGNORE_TARGET || src_type == dst_type)
 	  break;
 	if (TREE_CODE (dst_type) == POINTER_TYPE)