Added silent/loud mode for constraint handling

[libfirm] / ir / be / bechordal.c

diff --git a/ir/be/bechordal.c b/ir/be/bechordal.c
index 52c4e49..4c23dad 100644 (file)
--- a/ir/be/bechordal.c
+++ b/ir/be/bechordal.c
@@ -475,12 +475,13 @@ static ir_node *pre_process_constraints(be_chordal_alloc_env_t *alloc_env, insn_
        return perm;
 }
 
-static ir_node *handle_constraints(be_chordal_alloc_env_t *alloc_env, ir_node *irn)
+static ir_node *handle_constraints(be_chordal_alloc_env_t *alloc_env, ir_node *irn, int *silent)
 {
        be_chordal_env_t *env  = alloc_env->chordal_env;
        void *base             = obstack_base(&env->obst);
        insn_t *insn           = scan_insn(alloc_env, irn, &env->obst);
        ir_node *res           = insn->next_insn;
+       int be_silent          = *silent;
 
        if(insn->pre_colored) {
                int i;
@@ -488,7 +489,17 @@ static ir_node *handle_constraints(be_chordal_alloc_env_t *alloc_env, ir_node *i
                        pset_insert_ptr(alloc_env->pre_colored, insn->ops[i].carrier);
        }
 
-       if(be_is_Perm(irn) || be_is_RegParams(irn) || (be_is_Barrier(irn) && !insn->in_constraints))
+       /*
+               If the current node is a barrier toggle the silent flag.
+               If we are in the start block, we are ought to be silent at the beginning,
+               so the toggling activates the constraint handling but skips the barrier.
+               If we are in the end block we handle the in requirements of the barrier
+               and set the rest to silent.
+       */
+       if(be_is_Barrier(irn))
+               *silent = !*silent;
+
+       if(be_silent)
                goto end;
 
        /*
@@ -646,20 +657,32 @@ end:
 
 /**
  * Handle constraint nodes in each basic block.
- * be_insert_constr_perms() inserts Perm nodes which perm
+ * handle_constraints() inserts Perm nodes which perm
  * over all values live at the constrained node right in front
  * of the constrained node. These Perms signal a constrained node.
- * For further comments, refer to handle_constraints_at_perm().
+ * For further comments, refer to handle_constraints().
  */
 static void constraints(ir_node *bl, void *data)
 {
-       firm_dbg_module_t *dbg      = firm_dbg_register("firm.be.chordal.constr");
        be_chordal_alloc_env_t *env = data;
+       firm_dbg_module_t *dbg      = firm_dbg_register("firm.be.chordal.constr");
        arch_env_t *arch_env        = env->chordal_env->birg->main_env->arch_env;
+
+       /*
+               Start silent in the start block.
+               The silence remains until the first barrier is seen.
+               Each other block is begun loud.
+       */
+       int silent                  = bl == get_irg_start_block(get_irn_irg(bl));
        ir_node *irn;
 
+       /*
+               If the block is the start block search the barrier and
+               start handling constraints from there.
+       */
+
        for(irn = sched_first(bl); !sched_is_end(irn);) {
-               irn = handle_constraints(env, irn);
+               irn = handle_constraints(env, irn, &silent);
        }
 }