belower: Remove be_Perm_reduce() and rewrite it at its only user.

Now the number of outputs is adjusted, too.
This did not cause any problems, because the Perm is lowered right afterwards.

ir/be/belower.c

@@ -417,20 +417,26 @@ done:
 		kill_node(perm);
 		return false;
 	} else if (new_size != arity) {
-		/* Some, but not all, values were pushed through; adjust the Perm. */
-		int *const map = ALLOCAN(int, new_size);
-		unsigned   n   = 0;
+		/* Some, but not all, values were pushed through.
+		 * Rewrite Perm to skip all moved slots. */
+		unsigned                          n         = 0;
+		backend_info_t             *const info      = be_get_info(perm);
+		arch_register_req_t const **const in_reqs   = info->in_reqs;
+		reg_out_info_t             *const out_infos = info->out_infos;
 		for (unsigned pn = 0; pn != arity; ++pn) {
 			ir_node *const proj = projs[pn];
 			if (!proj)
 				continue;
 			set_Proj_num(proj, n);
-			map[n] = pn;
-			n++;
+			in_reqs[n]   = in_reqs[pn];
+			out_infos[n] = out_infos[pn];
+			/* Reuse projs for reduced Perm inputs. */
+			projs[n]     = get_irn_n(perm, pn);
+			++n;
 		}
 		assert(n == new_size);
-
-		be_Perm_reduce(perm, new_size, map);
+		ARR_SHRINKLEN(out_infos, new_size);
+		set_irn_in(perm, n, projs);
 	}
 	return true;
 }

ir/be/benode.c

@@ -150,31 +150,6 @@ ir_node *be_new_Perm(arch_register_class_t const *const cls,
 	return irn;
 }
 
-void be_Perm_reduce(ir_node *perm, int new_size, int *map)
-{
-	assert(be_is_Perm(perm));
-	int arity = get_irn_arity(perm);
-	assert(new_size <= arity);
-	const arch_register_req_t **old_in_reqs
-		= ALLOCAN(const arch_register_req_t*, arity);
-	reg_out_info_t *old_infos = ALLOCAN(reg_out_info_t, arity);
-	backend_info_t *info      = be_get_info(perm);
-	ir_node       **new_in    = ALLOCAN(ir_node*, new_size);
-
-	/* save the old register data */
-	MEMCPY(old_in_reqs, info->in_reqs, arity);
-	MEMCPY(old_infos, info->out_infos, arity);
-
-	/* compose the new in array and set the new register data directly */
-	for (int i = 0; i < new_size; ++i) {
-		int idx = map[i];
-		new_in[i]          = get_irn_n(perm, idx);
-		info->in_reqs[i]   = old_in_reqs[idx];
-		info->out_infos[i] = old_infos[idx];
-	}
-	set_irn_in(perm, new_size, new_in);
-}
-
 ir_node *be_new_MemPerm(ir_node *const block, int n, ir_node *const *const in)
 {
 	ir_graph *const irg = get_irn_irg(block);

ir/be/benode.h

@@ -73,22 +73,6 @@ ir_node *be_get_Copy_op(const ir_node *cpy);
 ir_node *be_new_Perm(arch_register_class_t const *cls, ir_node *block, int n,
                      ir_node *const *in);
 
-/**
- * Reduce a Perm.
- * Basically, we provide a map to remap the Perm's arguments. If an entry in the
- * map is -1, the argument gets deleted.
- * This function takes care, that the register data and the input array reflects
- * the changes described by the map.
- * This is needed by the Perm optimization/movement in belower.c, see
- * push_through_perm().
- * @param perm     The perm node.
- * @param new_size The new number of arguments (must be smaller or equal to the
- *                 current one).
- * @param map      A map assigning each operand a new index (or -1 to indicate
- *                 deletion).
- */
-void be_Perm_reduce(ir_node *perm, int new_size, int *map);
-
 /**
  * Create a new MemPerm node.
  * A MemPerm node exchanges the values of memory locations. (Typically entities