X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fopt%2Fcfopt.c;h=1569db97f320cf51f3a1f480a8340b4199b21ab7;hb=f1a1a6092d9e4ebd9e22dd1c57d76ef8aeda74fc;hp=80fdee5a2fb6cf3baa668ee367e5e1741c142fd1;hpb=1c9ba1bcb423f081cb177c3bf99958de5476e98f;p=libfirm diff --git a/ir/opt/cfopt.c b/ir/opt/cfopt.c index 80fdee5a2..1569db97f 100644 --- a/ir/opt/cfopt.c +++ b/ir/opt/cfopt.c @@ -36,6 +36,7 @@ #include "firmstat.h" #include "cfopt.h" +#include "iropt_dbg.h" /*------------------------------------------------------------------*/ /* Control flow optimization. */ @@ -46,6 +47,54 @@ /* semantics of Phi nodes. */ /*------------------------------------------------------------------*/ +/** + * Replace binary Conds that jumps twice into the same block + * by a simple Jmp. + * E.g. + * @verbatim + * Cond Jmp Bad + * / \ | / + * ProjX True ProjX False ==> | / + * \ / | / + * Block Block + * @endverbatim + * + * Such pattern are the result of if-conversion. + * + * Note that the simple case that Block has only these two + * predecessors are already handled in equivalent_node_Block(). + */ +static void remove_senseless_conds(ir_node *bl, void *data) +{ + int i, j; + int n = get_Block_n_cfgpreds(bl); + + assert(is_Block(bl)); + + for (i = 0; i < n; ++i) { + ir_node *pred_i = get_Block_cfgpred(bl, i); + ir_node *cond_i = skip_Proj(pred_i); + + for (j = i + 1; j < n; ++j) { + ir_node *pred_j = get_Block_cfgpred(bl, j); + ir_node *cond_j = skip_Proj(pred_j); + + if (cond_j == cond_i + && get_irn_op(cond_i) == op_Cond + && get_irn_mode(get_Cond_selector(cond_i)) == mode_b) { + + ir_node *jmp = new_r_Jmp(current_ir_graph, get_nodes_block(cond_i)); + set_irn_n(bl, i, jmp); + set_irn_n(bl, j, new_Bad()); + + DBG_OPT_IFSIM2(cond_i, jmp); + break; + } + } + } +} + + /** * Removes Tuples from Block control flow predecessors. * Optimizes blocks with equivalent_node(). This is tricky, @@ -71,18 +120,18 @@ static void merge_blocks(ir_node *n, void *env) { /* see below */ new_block = equivalent_node(n); - if (new_block != n && ! is_Bad(new_block)) + if (new_block != n && ! is_Block_dead(new_block)) exchange (n, new_block); } else if (get_opt_optimize() && (get_irn_mode(n) == mode_X)) { /* We will soon visit a block. Optimize it before visiting! */ ir_node *b = get_nodes_block(skip_Proj(n)); - if (!is_Bad(b)) { + if (!is_Block_dead(b)) { new_block = equivalent_node(b); - while (irn_not_visited(b) && (!is_Bad(new_block)) && (new_block != b)) { - /* We would have to run gigo if new is bad, so we + while (irn_not_visited(b) && (!is_Block_dead(new_block)) && (new_block != b)) { + /* We would have to run gigo() if new is bad, so we promote it directly below. Nevertheless, we sometimes reach a block the first time through a dataflow node. In this case we optimized the block as such and have to promote the Bad here. */ @@ -97,8 +146,8 @@ static void merge_blocks(ir_node *n, void *env) { /* normally, we would create a Bad block here, but this must be * prevented, so just set it's cf to Bad. */ - if (is_Bad(new_block)) - exchange(n, new_Bad()); + if (is_Block_dead(new_block)) + exchange(n, new_Bad()); } } } @@ -106,8 +155,8 @@ static void merge_blocks(ir_node *n, void *env) { /** * Remove cf from dead block by inspecting dominance info * Do not replace blocks by Bad. This optimization shall - * ensure, that all Bad cfg preds are removed, and no new - * other Bads are introduced. + * ensure, that all Bad control flow predecessors are + * removed, and no new other Bads are introduced. * * Must be run in the post walker. */ @@ -122,7 +171,7 @@ static void remove_dead_block_cf(ir_node *block, void *env) if (! is_Bad(pred_X)) { ir_node *pred_bl = get_nodes_block(skip_Proj(pred_X)); - if (is_Bad(pred_bl) || (get_Block_dom_depth(pred_bl) == -1)) + if (is_Block_dead(pred_bl) || (get_Block_dom_depth(pred_bl) < 0)) exchange (pred_X, new_Bad()); } } @@ -162,7 +211,7 @@ static int is_pred_of(ir_node *pred, ir_node *b) { } -/** Test wether we can optimize away pred block pos of b. +/** Test whether we can optimize away pred block pos of b. * * @param b A block node. * @param pos The position of the predecessor block to judge about. @@ -172,21 +221,22 @@ static int is_pred_of(ir_node *pred, ir_node *b) { * The test is rather tricky. * * The situation is something like the following: - * + * @verbatim * if-block * / \ * then-b else-b * \ / * b + * @endverbatim * - * b merges the control flow of an if-then-else. We may not remove - * the 'then' _and_ the 'else' block of an 'if' if there is a Phi - * node in b, even if both are empty. The destruction of this Phi - * requires that a copy is added before the merge. We have to - * keep one of the case blocks to place the copies in. + * b merges the control flow of an if-then-else. We may not remove + * the 'then' _and_ the 'else' block of an 'if' if there is a Phi + * node in b, even if both are empty. The destruction of this Phi + * requires that a copy is added before the merge. We have to + * keep one of the case blocks to place the copies in. * - * To perform the test for pos, we must regard preds before pos - * as already removed. + * To perform the test for pos, we must regard predecessors before pos + * as already removed. **/ static int test_whether_dispensable(ir_node *b, int pos) { int i, j, n_preds = 1; @@ -244,7 +294,7 @@ static int test_whether_dispensable(ir_node *b, int pos) { /** - * This method removed Bad cf preds from Blocks and Phis, and removes + * This method removed Bad cf predecessors from Blocks and Phis, and removes * empty blocks. A block is empty if it only contains Phi and Jmp nodes. * * We first adapt Phi nodes, then Block nodes, as we need the old ins @@ -253,22 +303,23 @@ static int test_whether_dispensable(ir_node *b, int pos) { * for all nodes, not regarding whether there is a possibility for optimization. * * For each predecessor p of a Block b there are three cases: - * 1. The predecessor p is a Bad node: just skip it. The in array of b shrinks by one. - * 2. The predecessor p is empty. Remove p. All predecessors of p are now - * predecessors of b. - * 3. The predecessor p is a block containing useful code. Just keep p as is. + * -#. The predecessor p is a Bad node: just skip it. The in array of b shrinks by one. + * -#. The predecessor p is empty. Remove p. All predecessors of p are now + * predecessors of b. + * -#. The predecessor p is a block containing useful code. Just keep p as is. * * For Phi nodes f we have to check the conditions at the Block of f. * For cases 1 and 3 we proceed as for Blocks. For case 2 we can have two * cases: - * 2a: The old precessor of the Phi f is a Phi pred_f IN THE BLOCK REMOVED. In this + * -2a: The old predecessor of the Phi f is a Phi pred_f IN THE BLOCK REMOVED. In this * case we proceed as for blocks. We remove pred_f. All * predecessors of pred_f now are predecessors of f. - * 2b: The old predecessor of f is NOT in the block removed. It might be a Phi, too. + * -2b: The old predecessor of f is NOT in the block removed. It might be a Phi, too. * We have to replicate f for each predecessor of the removed block. Or, with * other words, the removed predecessor block has exactly one predecessor. * * Further there is a special case for self referencing blocks: + * @verbatim * * then_b else_b then_b else_b * \ / \ / @@ -281,6 +332,7 @@ static int test_whether_dispensable(ir_node *b, int pos) { * | | | | | | * | |____| | |____| * | | + * @endverbatim * * If there is a Phi in pred_b, but we remove pred_b, we have to generate a * Phi in loop_b, that has the ins of the Phi in pred_b and a self referencing @@ -353,7 +405,7 @@ static void optimize_blocks(ir_node *b, void *env) { Therefore we replace the old phi by the new one. Further we have to remove the old Phi node by replacing it - by Bad. Else it will remain in the keepalive array of End + by Bad. Else it will remain in the keep alive array of End and cause illegal situations. So if there is no loop, we should replace it by Bad. */ @@ -511,7 +563,7 @@ static void optimize_blocks(ir_node *b, void *env) { * phase. * @@@ It would be better to add a struct in the link field * that keeps the Phi list and the mark. Place it on an obstack, as - * we will lose blocks and thereby generate mem leaks. + * we will lose blocks and thereby generate memory leaks. */ void optimize_cf(ir_graph *irg) { int i, n; @@ -521,6 +573,10 @@ void optimize_cf(ir_graph *irg) { irg_dom_state dom_state = get_irg_dom_state(current_ir_graph); current_ir_graph = irg; + /* if the graph is not pinned, we cannot determine empty blocks */ + assert(get_irg_pinned(irg) != op_pin_state_floats && + "Control flow optimization need a pinned graph"); + /* Handle graph state */ assert(get_irg_phase_state(irg) != phase_building); if (get_irg_outs_state(current_ir_graph) == outs_consistent) @@ -531,20 +587,24 @@ void optimize_cf(ir_graph *irg) { if (dom_state == dom_consistent && get_opt_optimize() && get_opt_unreachable_code()) { ir_node *end = get_irg_end(irg); - /* we have dominace info, we can kill dead block */ + /* we have dominance info, we can kill dead block */ irg_block_walk_graph(irg, NULL, remove_dead_block_cf, NULL); /* fix the keep-alives */ for (i = 0, n = get_End_n_keepalives(end); i < n; ++i) { ir_node *ka = get_End_keepalive(end, i); - if (is_Block(ka) && (get_Block_dom_depth(ka) == -1)) - set_End_keepalive(end, i, new_Bad()); - if (is_Phi(ka) && (get_Block_dom_depth(get_nodes_block(ka)) == -1)) - set_End_keepalive(end, i, new_Bad()); + if (is_Block(ka)) { + if (get_Block_dom_depth(ka) == -1) + set_End_keepalive(end, i, new_Bad()); + } + else if (get_Block_dom_depth(get_nodes_block(ka)) == -1) + set_End_keepalive(end, i, new_Bad()); } } + irg_block_walk_graph(current_ir_graph, NULL, remove_senseless_conds, NULL); + /* Use block visited flag to mark non-empty blocks. */ inc_irg_block_visited(irg); irg_walk(end, merge_blocks, collect_nodes, NULL); @@ -571,13 +631,17 @@ void optimize_cf(ir_graph *irg) { } else if (get_irn_op(ka) == op_Phi) { mark_irn_visited(ka); ARR_APP1 (ir_node *, in, ka); + } else if (get_irn_op(ka) == op_IJmp) { + mark_irn_visited(ka); + ARR_APP1 (ir_node *, in, ka); } } } /* DEL_ARR_F(end->in); GL @@@ tut nicht ! */ end->in = in; - /* the verifyer doesn't work yet with floating nodes */ + + /* the verifier doesn't work yet with floating nodes */ if (get_irg_pinned(irg) == op_pin_state_pinned) { /* after optimize_cf(), only Bad data flow may remain. */ if (irg_vrfy_bads(irg, BAD_DF | BAD_BLOCK | TUPLE)) {