#include "irflag_t.h"
#include "firmstat.h"
#include "irpass.h"
+#include "irphase_t.h"
#include "iropt_dbg.h"
typedef struct merge_env {
bool changed; /**< Set if the graph was changed. */
bool phis_moved; /**< Set if Phi nodes were moved. */
- ir_node **switch_conds; /**< Helper list for all found Switch Conds. */
} merge_env;
static void set_Block_removable(ir_node *block, bool removable)
return get_Block_mark(block);
}
+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)
{
(void) ctx;
*/
static void collect_nodes(ir_node *n, void *ctx)
{
- merge_env *env = (merge_env*)ctx;
+ ir_node ***switch_conds = (ir_node***)ctx;
if (is_Phi(n)) {
/* Collect Phi nodes to compact ins along with block's ins. */
ir_node *pred = get_Proj_pred(n);
set_irn_link(n, get_irn_link(pred));
set_irn_link(pred, n);
- } else if (is_Cond(n)) {
- ir_node *sel = get_Cond_selector(n);
- if (get_irn_mode(sel) != mode_b) {
- /* found a switch-Cond, collect */
- ARR_APP1(ir_node*, env->switch_conds, n);
- }
+ } else if (is_Cond(n) && is_switch_Cond(n)) {
+ /* found a switch-Cond, collect */
+ ARR_APP1(ir_node*, *switch_conds, n);
}
}
}
xfree(in);
}
-/**
- * Block walker: optimize all blocks using the default optimizations.
- * This removes Blocks with only a Jmp predecessor.
- */
-static void remove_simple_blocks(ir_node *block, void *ctx)
-{
- merge_env *env = (merge_env*)ctx;
- ir_node *new_blk = equivalent_node(block);
-
- if (new_blk != block) {
- exchange(block, new_blk);
- env->changed = true;
- }
-}
-
/**
* Optimize table-switch Conds.
*
return false;
}
-/* Optimizations of the control flow that also require changes of Phi nodes.
- *
- * This optimization performs two passes over the graph.
- *
- * The first pass collects all Phi nodes in a link list in the block
- * nodes. Further it performs simple control flow optimizations.
- * Finally it marks all blocks that do not contain useful
- * computations, i.e., these blocks might be removed.
- *
- * The second pass performs the optimizations intended by this algorithm.
- * It walks only over block nodes and adapts these and the Phi nodes in these
- * blocks, which it finds in a linked list computed by the first pass.
+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
*
- * We use the mark flag to mark removable blocks in the first phase.
+ * Cond
+ * / \
+ * projA projB => Jmp Bad
+ * \ / \ /
+ * block block
*/
+static bool optimize_pred_cond(ir_node *block, int i, int j)
+{
+ ir_node *projA, *projB, *cond, *pred_block, *jmp, *bad;
+ assert(i != j);
+
+ projA = get_Block_cfgpred(block, i);
+ if (!is_Proj(projA)) return false;
+ projB = get_Block_cfgpred(block, j);
+ if (!is_Proj(projB)) return false;
+ cond = get_Proj_pred(projA);
+ if (!is_Cond(cond)) return false;
+
+ if (cond != get_Proj_pred(projB)) return false;
+ if (is_switch_Cond(cond)) return false;
+
+ /* cond should actually be a Jmp */
+ pred_block = get_nodes_block(cond);
+ jmp = new_r_Jmp(pred_block);
+ bad = new_r_Bad(get_irn_irg(block), mode_X);
+
+ assert(projA != projB);
+ exchange(projA, jmp);
+ exchange(projB, bad);
+ return true;
+}
+
+static void compute_block_info(ir_node *n, void *x)
+{
+ ir_phase *block_info = (ir_phase *)x;
+
+ if (is_Block(n)) {
+ int i, max = get_Block_n_cfgpreds(n);
+ for (i=0; i<max; i++) {
+ ir_node *pred = get_Block_cfgpred(n,i);
+ if (is_unknown_jump(pred)) {
+ set_is_unknown_jump_target(block_info, n);
+ }
+ }
+ } else if (is_Phi(n)) {
+ ir_node *block = get_nodes_block(n);
+ set_has_phis(block_info, block);
+ } else if (is_Jmp(n) || is_Cond(n) || is_Cmp(n) || is_Proj(n)) {
+ /* ignore */
+ } else {
+ ir_node *block = get_nodes_block(n);
+ set_has_operations(block_info, block);
+ }
+}
+
+typedef struct skip_env {
+ bool changed;
+ ir_phase *phase;
+} skip_env;
+
+static void optimize_conds(ir_node *b, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i, j;
+ int n_preds = get_Block_n_cfgpreds(b);
+
+ if (has_phis(env->phase,b)) 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);
+ }
+ }
+}
+
+static void remove_empty_blocks(ir_node *b, void *x)
+{
+ skip_env *env = (skip_env*)x;
+ int i;
+ int n_preds = get_Block_n_cfgpreds(b);
+
+ 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_block = get_nodes_block(jmp);
+ 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;
+ pred = get_Block_cfgpred(jmp_block, 0);
+ exchange(jmp, pred);
+ env->changed = true;
+
+ /* cleanup: jmp_block might have a Keep edge! */
+ pred_block = get_nodes_block(pred);
+ exchange(jmp_block, pred_block);
+ }
+}
+
+/*
+ * 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(;;) {
+ env.changed = false;
+
+ /* Conds => Jmp optimization; might produce empty blocks */
+ irg_block_walk_graph(irg, optimize_conds, NULL, &env);
+
+ /* Remove empty blocks */
+ irg_block_walk_graph(irg, remove_empty_blocks, NULL, &env);
+ if (env.changed) {
+ set_irg_doms_inconsistent(irg);
+ /* Removing blocks might enable more Cond optimizations */
+ continue;
+ } else {
+ break;
+ }
+ }
+
+ phase_free(block_info);
+}
+
+/* Optimizations of the control flow that also require changes of Phi nodes. */
void optimize_cf(ir_graph *irg)
{
int i, j, n;
* here. Fix the edges! */
edges_deactivate(irg);
+ cfgopt_ignoring_phis(irg);
+
/* we use the mark flag to mark removable blocks */
ir_reserve_resources(irg, IR_RESOURCE_BLOCK_MARK | IR_RESOURCE_IRN_LINK);
-restart:
- env.changed = false;
- env.phis_moved = false;
- assure_doms(irg);
+ /* The switch Cond optimization might expose unreachable code, so we loop */
+ for (;;) {
+ int length;
+ ir_node **switch_conds = NULL;
+ env.changed = false;
+ env.phis_moved = false;
- env.switch_conds = NEW_ARR_F(ir_node*, 0);
- irg_walk(end, clear_link, collect_nodes, &env);
+ assure_doms(irg);
- /* handle all collected switch-Conds */
- n = ARR_LEN(env.switch_conds);
- for (i = 0; i < n; ++i) {
- ir_node *cond = env.switch_conds[i];
- env.changed |= handle_switch_cond(cond);
- }
- DEL_ARR_F(env.switch_conds);
+ /*
+ * This pass collects all Phi nodes in a link list in the block
+ * nodes. Further it performs simple control flow optimizations.
+ * Finally it marks all blocks that do not contain useful
+ * 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);
+
+ /* 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);
+ }
+ DEL_ARR_F(switch_conds);
+
+ if (!env.changed) break;
- if (env.changed) {
- /* Handle graph state if was changed. */
set_irg_doms_inconsistent(irg);
set_irg_extblk_inconsistent(irg);
set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
-
- /* The Cond optimization might generate unreachable code, so restart if
- it happens. */
- goto restart;
}
- /* Optimize the standard code. */
+ /* assert due to collect_nodes:
+ * 1. removable blocks are now marked as such
+ * 2. phi lists are up to date
+ */
+
+ /* Optimize the standard code.
+ * It walks only over block nodes and adapts these and the Phi nodes in these
+ * blocks, which it finds in a linked list computed before.
+ * */
assure_doms(irg);
- irg_block_walk_graph(irg, optimize_blocks, remove_simple_blocks, &env);
+ irg_block_walk_graph(irg, optimize_blocks, NULL, &env);
new_end = optimize_in_place(end);
if (new_end != end) {
projects / libfirm / blobdiff