diff options
Diffstat (limited to 'gcc/tree-ssa-dce.c')
| -rw-r--r-- | gcc/tree-ssa-dce.c | 100 |
1 files changed, 12 insertions, 88 deletions
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c index 16ff4a30d1f..d8b32ef78b5 100644 --- a/gcc/tree-ssa-dce.c +++ b/gcc/tree-ssa-dce.c @@ -222,11 +222,11 @@ mark_stmt_necessary (tree stmt, bool add_to_worklist) VEC_safe_push (tree, heap, worklist, stmt); } -/* Mark the statement defining operand OP as necessary. PHIONLY is true - if we should only mark it necessary if it is a phi node. */ + +/* Mark the statement defining operand OP as necessary. */ static inline void -mark_operand_necessary (tree op, bool phionly) +mark_operand_necessary (tree op) { tree stmt; int ver; @@ -241,9 +241,7 @@ mark_operand_necessary (tree op, bool phionly) stmt = SSA_NAME_DEF_STMT (op); gcc_assert (stmt); - if (NECESSARY (stmt) - || IS_EMPTY_STMT (stmt) - || (phionly && TREE_CODE (stmt) != PHI_NODE)) + if (NECESSARY (stmt) || IS_EMPTY_STMT (stmt)) return; NECESSARY (stmt) = 1; @@ -489,7 +487,7 @@ propagate_necessity (struct edge_list *el) { tree arg = PHI_ARG_DEF (stmt, k); if (TREE_CODE (arg) == SSA_NAME) - mark_operand_necessary (arg, false); + mark_operand_necessary (arg); } if (aggressive) @@ -509,87 +507,22 @@ propagate_necessity (struct edge_list *el) else { /* Propagate through the operands. Examine all the USE, VUSE and - V_MAY_DEF operands in this statement. Mark all the statements - which feed this statement's uses as necessary. */ - ssa_op_iter iter; - tree use; - - /* The operands of V_MAY_DEF expressions are also needed as they + VDEF operands in this statement. Mark all the statements + which feed this statement's uses as necessary. The + operands of VDEF expressions are also needed as they represent potential definitions that may reach this - statement (V_MAY_DEF operands allow us to follow def-def + statement (VDEF operands allow us to follow def-def links). */ + ssa_op_iter iter; + tree use; FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES) - mark_operand_necessary (use, false); + mark_operand_necessary (use); } } } -/* Propagate necessity around virtual phi nodes used in kill operands. - The reason this isn't done during propagate_necessity is because we don't - want to keep phis around that are just there for must-defs, unless we - absolutely have to. After we've rewritten the reaching definitions to be - correct in the previous part of the fixup routine, we can simply propagate - around the information about which of these virtual phi nodes are really - used, and set the NECESSARY flag accordingly. - Note that we do the minimum here to ensure that we keep alive the phis that - are actually used in the corrected SSA form. In particular, some of these - phis may now have all of the same operand, and will be deleted by some - other pass. */ - -static void -mark_really_necessary_kill_operand_phis (void) -{ - basic_block bb; - int i; - - /* Seed the worklist with the new virtual phi arguments and virtual - uses */ - FOR_EACH_BB (bb) - { - block_stmt_iterator bsi; - tree phi; - - for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) - { - if (!is_gimple_reg (PHI_RESULT (phi)) && NECESSARY (phi)) - { - for (i = 0; i < PHI_NUM_ARGS (phi); i++) - mark_operand_necessary (PHI_ARG_DEF (phi, i), true); - } - } - - for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_prev (&bsi)) - { - tree stmt = bsi_stmt (bsi); - - if (NECESSARY (stmt)) - { - use_operand_p use_p; - ssa_op_iter iter; - FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, - SSA_OP_VIRTUAL_USES | SSA_OP_VIRTUAL_KILLS) - { - tree use = USE_FROM_PTR (use_p); - mark_operand_necessary (use, true); - } - } - } - } - - /* Mark all virtual phis still in use as necessary, and all of their - arguments that are phis as necessary. */ - while (VEC_length (tree, worklist) > 0) - { - tree use = VEC_pop (tree, worklist); - - for (i = 0; i < PHI_NUM_ARGS (use); i++) - mark_operand_necessary (PHI_ARG_DEF (use, i), true); - } -} - - /* Remove dead PHI nodes from block BB. */ static void @@ -634,9 +567,6 @@ static void remove_dead_stmt (block_stmt_iterator *i, basic_block bb) { tree t = bsi_stmt (*i); - def_operand_p def_p; - - ssa_op_iter iter; if (dump_file && (dump_flags & TDF_DETAILS)) { @@ -711,11 +641,6 @@ remove_dead_stmt (block_stmt_iterator *i, basic_block bb) } } - FOR_EACH_SSA_DEF_OPERAND (def_p, t, iter, SSA_OP_VIRTUAL_DEFS) - { - tree def = DEF_FROM_PTR (def_p); - mark_sym_for_renaming (SSA_NAME_VAR (def)); - } bsi_remove (i, true); release_defs (t); } @@ -875,7 +800,6 @@ perform_tree_ssa_dce (bool aggressive) propagate_necessity (el); - mark_really_necessary_kill_operand_phis (); eliminate_unnecessary_stmts (); if (aggressive) |