- if all Condb has Cmp predecessors, allow Unknown nodes to produce TOP

- Cmp(a, TOP) produces !=, not TOP (like icc, Clicks work returns ==
  here because they congruent, but it isn't important waht to choose as
  long as it is monotone

[r21186]

diff --git a/ir/opt/combo.c b/ir/opt/combo.c
index b568b42..84d2fef 100644 (file)
--- a/ir/opt/combo.c
+++ b/ir/opt/combo.c
@@ -167,7 +167,8 @@ typedef struct environment_t {
        pmap            *type2id_map;   /**< The type->id map. */
        int             end_idx;        /**< -1 for local and 0 for global congruences. */
        int             lambda_input;   /**< Captured argument for lambda_partition(). */
-       int             modified;       /**< Set, if the graph was modified. */
+       char            nonstd_cond;    /**< Set, if a Condb note has a non-Cmp predecessor. */
+       char            modified;       /**< Set, if the graph was modified. */
 #ifdef DEBUG_libfirm
        partition_t     *dbg_list;      /**< List of all partitions. */
 #endif
@@ -190,6 +191,9 @@ DEBUG_ONLY(static firm_dbg_module_t *dbg;)
 /** Next partition number. */
 DEBUG_ONLY(static unsigned part_nr = 0);
 
+/** The tarval returned by Unknown nodes. */
+static tarval *tarval_UNKNOWN;
+
 /* forward */
 static node_t *identity(node_t *node);
 
@@ -619,6 +623,11 @@ static void create_initial_partitions(ir_node *irn, void *ctx) {
 
        if (is_Phi(irn)) {
                add_Block_phi(get_nodes_block(irn), irn);
+       } else if (is_Cond(irn)) {
+               /* check if all Cond's have a Cmp predecessor. */
+               if (get_irn_mode(irn) == mode_b && !is_Cmp(skip_Proj(get_Cond_selector(irn))))
+                       env->nonstd_cond = 1;
+
        }
 }  /* create_initial_partitions */
 
@@ -1588,10 +1597,8 @@ static void compute_Unknown(node_t *node) {
         * nodes are inputs to Conds. We check that first.
         * This is the way Frontends typically build Firm, but some optimizations
         * (cond_eval for instance) might replace them by Phib's...
-        *
-        * For now, we compute bottom here.
         */
-       node->type.tv = tarval_bottom;
+       node->type.tv = tarval_UNKNOWN;
 }  /* compute_Unknown */
 
 /**
@@ -1785,7 +1792,11 @@ static void compute_Cmp(node_t *node) {
        lattice_elem_t b     = r->type;
 
        if (a.tv == tarval_top || b.tv == tarval_top) {
-               node->type.tv = tarval_top;
+               /*
+                * Top is congruent to any other value, we can
+                * calculate the compare result.
+                */
+               node->type.tv = tarval_b_true;
        } else if (is_con(a) && is_con(b)) {
                /* both nodes are constants, we can probably do something */
                node->type.tv = tarval_b_true;
@@ -1813,7 +1824,9 @@ static void compute_Proj_Cmp(node_t *node, ir_node *cmp) {
        tarval         *tv;
 
        if (a.tv == tarval_top || b.tv == tarval_top) {
-               node->type.tv = tarval_top;
+               /* see above */
+               tv = new_tarval_from_long((pnc & pn_Cmp_Eq) ^ pn_Cmp_Eq, mode_b);
+               goto not_equal;
        } else if (is_con(a) && is_con(b)) {
                default_compute(node);
                node->by_all_const = 1;
@@ -1824,6 +1837,7 @@ static void compute_Proj_Cmp(node_t *node, ir_node *cmp) {
                 * NaN != NaN is defined, so we must check this here.
                 */
                tv = new_tarval_from_long(pnc & pn_Cmp_Eq, mode_b);
+not_equal:
 
                /* if the node was ONCE evaluated by all constants, but now
                   this breakes AND we cat by partition a different result, switch to bottom.
@@ -2852,6 +2866,7 @@ void combo(ir_graph *irg) {
        env.type2id_map    = pmap_create();
        env.end_idx        = get_opt_global_cse() ? 0 : -1;
        env.lambda_input   = 0;
+       env.nonstd_cond    = 0;
        env.modified       = 0;
 
        assure_irg_outs(irg);
@@ -2867,6 +2882,8 @@ void combo(ir_graph *irg) {
        add_to_worklist(env.initial, &env);
        irg_walk_graph(irg, init_block_phis, create_initial_partitions, &env);
 
+       tarval_UNKNOWN = env.nonstd_cond ? tarval_bad : tarval_top;
+
        /* all nodes on the initial partition have type Top */
        env.initial->type_is_T_or_C = 1;