- Get rid of the infamous Start->ProjX->Start backedge

[r26162]

ir/ana/irouts.c

@@ -420,32 +420,6 @@ static ir_def_use_edge *set_out_edges(ir_graph *irg, ir_def_use_edge *free) {
 	return free;
 }
 
-
-/**
- * We want that the out of ProjX from Start contains the next block at
- * position 0, the Start block at position 1.  This is necessary for
- * the out block walker.
- */
-static inline void fix_start_proj(ir_graph *irg) {
-	ir_node *startbl = get_irg_start_block(irg);
-
-	if (get_Block_n_cfg_outs(startbl)) {
-		ir_node *proj = get_irg_initial_exec(irg);
-		ir_node *irn;
-		int     block_pos, other_pos;
-
-		if (get_irn_n_outs(proj) == 2) {
-			if (get_irn_out_ex(proj, 0, &block_pos) == startbl) {
-				irn = get_irn_out_ex(proj, 1, &other_pos);
-				set_irn_out(proj, 0, irn, other_pos);
-				set_irn_out(proj, 1, startbl, block_pos);
-			}
-		} else {
-			assert(get_irg_phase_state(irg) == phase_backend);
-		}
-	}
-}
-
 /* compute the outs for a given graph */
 void compute_irg_outs(ir_graph *irg) {
 	ir_graph        *rem = current_ir_graph;
@@ -477,11 +451,6 @@ void compute_irg_outs(ir_graph *irg) {
 	/* Check how much memory we have used */
 	assert (end == (irg->outs + n_out_edges));
 
-	/* We want that the out of ProjX from Start contains the next block at
-	   position 0, the Start block at position 1.  This is necessary for
-	   code placement (place_early() ONLY if started GCSE on graphs with dead blocks) */
-	fix_start_proj(irg);
-
 	current_ir_graph->outs_state = outs_consistent;
 	current_ir_graph = rem;
 }

ir/ir/irgraph.c

@@ -262,7 +262,6 @@ ir_graph *new_r_ir_graph(ir_entity *ent, int n_loc) {
 	initial_mem             = new_Proj(start, mode_M, pn_Start_M);
 	set_irg_initial_mem(res, initial_mem);
 
-	add_immBlock_pred(start_block, projX);
 	set_store(initial_mem);
 
 	res->index       = get_irp_new_irg_idx();
@@ -270,11 +269,6 @@ ir_graph *new_r_ir_graph(ir_entity *ent, int n_loc) {
 	res->graph_nr    = get_irp_new_node_nr();
 #endif
 
-	/*
-	 * The code generation needs it. leave it in now.
-	 * Use of this edge is matter of discussion, unresolved. Also possible:
-	 * add_immBlock_pred(res->start_block, res->start_block), but invalid typed.
-	 */
 	mature_immBlock(res->current_block);
 
 	/*-- Make a block to start with --*/
@@ -358,7 +352,6 @@ ir_graph *new_const_code_irg(void)
 	/* Proj results of start node */
 	set_irg_initial_mem(res, new_Proj(start, mode_M, pn_Start_M));
 	projX = new_Proj(start, mode_X, pn_Start_X_initial_exec);
-	add_immBlock_pred(start_block, projX);
 	mature_immBlock(start_block);
 
 	body_block = new_immBlock();