Some cleanup of cfopt.

- renamed clear_link() to clear_link_and_mark_blocks_removable()
- renamed optimize_conds() to optimize_ifs()
- simplified has_*() implementations
- made some walker POST walker
- invalidate out edges
- and add some doxygen docu
- fixed some typos
- adapt to firm indentation style

diff --git a/ir/opt/cfopt.c b/ir/opt/cfopt.c
index 7cc98a7..d833f8f 100644 (file)
--- a/ir/opt/cfopt.c
+++ b/ir/opt/cfopt.c
@@ -66,22 +66,26 @@ typedef struct merge_env {
        bool      phis_moved;   /**< Set if Phi nodes were moved. */
 } merge_env;
 
+/** set or reset the removable property of a block. */
 static void set_Block_removable(ir_node *block, bool removable)
 {
        set_Block_mark(block, removable);
 }
 
+/** check if a block has the removable property set. */
 static bool is_Block_removable(ir_node *block)
 {
        return get_Block_mark(block);
 }
 
+/** checks if a given Cond node is a switch Cond. */
 static bool is_switch_Cond(ir_node *cond) {
        ir_node *sel = get_Cond_selector(cond);
        return get_irn_mode(sel) != mode_b;
 }
 
-static void clear_link(ir_node *node, void *ctx)
+/** Walker: clear link fields and mark all blocks as removable. */
+static void clear_link_and_mark_blocks_removable(ir_node *node, void *ctx)
 {
        (void) ctx;
        set_irn_link(node, NULL);
@@ -106,8 +110,10 @@ static void collect_nodes(ir_node *n, void *ctx)
                set_irn_link(n, get_irn_link(block));
                set_irn_link(block, n);
        } else if (is_Block(n)) {
-               if (has_Block_entity(n))
+               if (has_Block_entity(n)) {
+                       /* block with a jump label attached cannot be removed. */
                        set_Block_removable(n, false);
+               }
                return;
        } else if (!is_Jmp(n)) {  /* Check for non-empty block. */
                ir_node *block = get_nodes_block(n);
@@ -125,7 +131,7 @@ static void collect_nodes(ir_node *n, void *ctx)
        }
 }
 
-/** Returns true if pred is predecessor of block. */
+/** Returns true if pred is predecessor of block b. */
 static bool is_pred_of(ir_node *pred, ir_node *b)
 {
        int i;
@@ -502,7 +508,7 @@ static bool handle_switch_cond(ir_node *cond)
 
        /* handle Cond nodes with constant argument. In this case the localopt rules
         * should have killed all obviously impossible cases.
-        * So the only case left to handle here is 1 defaultProj + 1case
+        * So the only case left to handle here is 1 defaultProj + 1 case
         * (this one case should be the one taken) */
        if (get_irn_link(proj2) == NULL) {
                ir_tarval *tv = value_of(sel);
@@ -549,38 +555,9 @@ static bool handle_switch_cond(ir_node *cond)
        return false;
 }
 
-static bool get_phase_flag(ir_phase *block_info, ir_node *block, int offset) {
-       return ((int)phase_get_irn_data(block_info, block)) & (1<<offset);
-}
-static void set_phase_flag(ir_phase *block_info, ir_node *block, int offset) {
-       int data = (int)phase_get_irn_data(block_info, block);
-       data |= (1<<offset);
-       phase_set_irn_data(block_info, block, (void*)data);
-}
-
-static bool has_operations(ir_phase *block_info, ir_node *block) {
-       return get_phase_flag(block_info, block, 1);
-}
-static void set_has_operations(ir_phase *block_info, ir_node *block) {
-       set_phase_flag(block_info, block, 1);
-}
-
-static bool has_phis(ir_phase *block_info, ir_node *block) {
-       return get_phase_flag(block_info, block, 2);
-}
-static void set_has_phis(ir_phase *block_info, ir_node *block) {
-       set_phase_flag(block_info, block, 2);
-}
-
-static bool is_unknown_jump_target(ir_phase *block_info, ir_node *block) {
-       return get_phase_flag(block_info, block, 3);
-}
-static void set_is_unknown_jump_target(ir_phase *block_info, ir_node *block) {
-       set_phase_flag(block_info, block, 3);
-}
-
 /**
- * Optimize Conds, where true and false jump to the same block into a Jmp
+ * Optimize boolean Conds, where true and false jump to the same block into a Jmp
+ * Block must contain no Phi nodes.
  *
  *        Cond
  *       /    \
@@ -614,6 +591,45 @@ static bool optimize_pred_cond(ir_node *block, int i, int j)
        return true;
 }
 
+typedef enum block_flags_t {
+       BF_HAS_OPERATIONS         = 1 << 0,
+       BF_HAS_PHIS               = 1 << 1,
+       BF_IS_UNKNOWN_JUMP_TARGET = 1 << 2,
+} block_flags_t;
+
+static bool get_phase_flag(ir_phase *block_info, ir_node *block, int flag) {
+       return ((int)phase_get_irn_data(block_info, block)) & flag;
+}
+static void set_phase_flag(ir_phase *block_info, ir_node *block, int flag) {
+       int data = (int)phase_get_irn_data(block_info, block);
+       data |= flag;
+       phase_set_irn_data(block_info, block, (void*)data);
+}
+
+static bool has_operations(ir_phase *block_info, ir_node *block) {
+       return get_phase_flag(block_info, block, BF_HAS_OPERATIONS);
+}
+static void set_has_operations(ir_phase *block_info, ir_node *block) {
+       set_phase_flag(block_info, block, BF_HAS_OPERATIONS);
+}
+
+static bool has_phis(ir_phase *block_info, ir_node *block) {
+       return get_phase_flag(block_info, block, BF_HAS_PHIS);
+}
+static void set_has_phis(ir_phase *block_info, ir_node *block) {
+       set_phase_flag(block_info, block, BF_HAS_PHIS);
+}
+
+static bool is_unknown_jump_target(ir_phase *block_info, ir_node *block) {
+       return get_phase_flag(block_info, block, BF_IS_UNKNOWN_JUMP_TARGET);
+}
+static void set_is_unknown_jump_target(ir_phase *block_info, ir_node *block) {
+       set_phase_flag(block_info, block, BF_IS_UNKNOWN_JUMP_TARGET);
+}
+
+/**
+ * Walker: fill block info information.
+ */
 static void compute_block_info(ir_node *n, void *x)
 {
        ir_phase *block_info = (ir_phase *)x;
@@ -642,40 +658,53 @@ typedef struct skip_env {
        ir_phase *phase;
 } skip_env;
 
-static void optimize_conds(ir_node *b, void *x)
+/**
+ * Post-Block-walker: Optimize useless if's (boolean Cond nodes
+ * with same true/false target)
+ * away.
+ */
+static void optimize_ifs(ir_node *block, void *x)
 {
        skip_env *env = (skip_env*)x;
        int i, j;
-       int n_preds = get_Block_n_cfgpreds(b);
+       int n_preds = get_Block_n_cfgpreds(block);
 
-       if (has_phis(env->phase,b)) return;
+       if (has_phis(env->phase, block))
+               return;
 
        /* optimize Cond predecessors (might produce Bad predecessors) */
-       for (i = 0; i < n_preds; i++) {
-               for (j = i+1; j < n_preds; j++) {
-                       optimize_pred_cond(b, i, j);
+       for (i = 0; i < n_preds; ++i) {
+               for (j = i+1; j < n_preds; ++j) {
+                       optimize_pred_cond(block, i, j);
                }
        }
 }
 
-static void remove_empty_blocks(ir_node *b, void *x)
+/**
+ * Post-Block walker: remove empty blocks that are
+ * predecessors of the current block.
+ */
+static void remove_empty_blocks(ir_node *block, void *x)
 {
        skip_env *env = (skip_env*)x;
        int i;
-       int n_preds = get_Block_n_cfgpreds(b);
+       int n_preds = get_Block_n_cfgpreds(block);
 
        for (i = 0; i < n_preds; ++i) {
                ir_node *jmp, *jmp_block, *pred, *pred_block;
 
-               jmp = get_Block_cfgpred(b, i);
-               if (!is_Jmp(jmp)) continue;
-               if (is_unknown_jump(jmp)) continue;
+               jmp = get_Block_cfgpred(block, i);
+               if (!is_Jmp(jmp))
+                       continue;
                jmp_block = get_nodes_block(jmp);
-               if (is_unknown_jump_target(env->phase, jmp_block)) continue;
-               if (has_operations(env->phase,jmp_block)) continue;
+               if (is_unknown_jump_target(env->phase, jmp_block))
+                       continue;
+               if (has_operations(env->phase,jmp_block))
+                       continue;
                /* jmp_block is an empty block! */
 
-               if (get_Block_n_cfgpreds(jmp_block) != 1) continue;
+               if (get_Block_n_cfgpreds(jmp_block) != 1)
+                       continue;
                pred = get_Block_cfgpred(jmp_block, 0);
                exchange(jmp, pred);
                env->changed = true;
@@ -687,21 +716,22 @@ static void remove_empty_blocks(ir_node *b, void *x)
 }
 
 /*
- * Some cfg optimizations, which do not touch Phi nodes */
+ * Some cfg optimizations, which do not touch Phi nodes
+ */
 static void cfgopt_ignoring_phis(ir_graph *irg) {
        ir_phase *block_info = new_phase(irg, NULL);
        skip_env env = { false, block_info };
 
        irg_walk_graph(irg, compute_block_info, NULL, block_info);
 
-       for(;;) {
+       for (;;) {
                env.changed = false;
 
-               /* Conds => Jmp optimization; might produce empty blocks */
-               irg_block_walk_graph(irg, optimize_conds, NULL, &env);
+               /* useless if optimization: will not touch empty blocks */
+               irg_block_walk_graph(irg, NULL, optimize_ifs, &env);
 
                /* Remove empty blocks */
-               irg_block_walk_graph(irg, remove_empty_blocks, NULL, &env);
+               irg_block_walk_graph(irg, NULL, remove_empty_blocks, &env);
                if (env.changed) {
                        set_irg_doms_inconsistent(irg);
                        /* Removing blocks might enable more Cond optimizations */
@@ -723,6 +753,9 @@ void optimize_cf(ir_graph *irg)
        ir_node *new_end;
        merge_env env;
 
+       env.changed    = false;
+       env.phis_moved = false;
+
        assert(get_irg_phase_state(irg) != phase_building);
 
        /* if the graph is not pinned, we cannot determine empty blocks */
@@ -742,8 +775,7 @@ void optimize_cf(ir_graph *irg)
        for (;;) {
                int length;
                ir_node **switch_conds = NULL;
-               env.changed    = false;
-               env.phis_moved = false;
+               bool changed = false;
 
                assure_doms(irg);
 
@@ -754,18 +786,20 @@ void optimize_cf(ir_graph *irg)
                 * computations, i.e., these blocks might be removed.
                 */
                switch_conds = NEW_ARR_F(ir_node*, 0);
-               irg_walk(end, clear_link, collect_nodes, &switch_conds);
+               irg_walk(end, clear_link_and_mark_blocks_removable, collect_nodes, &switch_conds);
 
                /* handle all collected switch-Conds */
                length = ARR_LEN(switch_conds);
                for (i = 0; i < length; ++i) {
                        ir_node *cond = switch_conds[i];
-                       env.changed |= handle_switch_cond(cond);
+                       changed |= handle_switch_cond(cond);
                }
                DEL_ARR_F(switch_conds);
 
-               if (!env.changed) break;
+               if (!changed)
+                       break;
 
+               set_irg_outs_inconsistent(irg);
                set_irg_doms_inconsistent(irg);
                set_irg_extblk_inconsistent(irg);
                set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
@@ -795,7 +829,7 @@ void optimize_cf(ir_graph *irg)
        if (env.phis_moved) {
                /* Bad: when we moved Phi's, we might produce dead Phi nodes
                   that are kept-alive.
-                  Some other phases cannot copy with this, so will them.
+                  Some other phases cannot copy with this, so kill them.
                 */
                n = get_End_n_keepalives(end);
                if (n > 0) {
@@ -830,6 +864,7 @@ void optimize_cf(ir_graph *irg)
 
        if (env.changed) {
                /* Handle graph state if was changed. */
+               set_irg_outs_inconsistent(irg);
                set_irg_doms_inconsistent(irg);
                set_irg_extblk_inconsistent(irg);
                set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);