diff options
Diffstat (limited to 'gcc/ifcvt.c')
-rw-r--r-- | gcc/ifcvt.c | 141 |
1 files changed, 122 insertions, 19 deletions
diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c index 56d9d9e..ff75ed1 100644 --- a/gcc/ifcvt.c +++ b/gcc/ifcvt.c @@ -103,6 +103,7 @@ static int noce_find_if_block (basic_block, edge, edge, int); static int cond_exec_find_if_block (ce_if_block_t *); static int find_if_case_1 (basic_block, edge, edge); static int find_if_case_2 (basic_block, edge, edge); +static int find_memory (rtx *, void *); static int dead_or_predicable (basic_block, basic_block, basic_block, basic_block, int); static void noce_emit_move_insn (rtx, rtx); @@ -3975,6 +3976,15 @@ find_if_case_2 (basic_block test_bb, edge then_edge, edge else_edge) return TRUE; } +/* A subroutine of dead_or_predicable called through for_each_rtx. + Return 1 if a memory is found. */ + +static int +find_memory (rtx *px, void *data ATTRIBUTE_UNUSED) +{ + return MEM_P (*px); +} + /* Used by the code above to perform the actual rtl transformations. Return TRUE if successful. @@ -4076,38 +4086,131 @@ dead_or_predicable (basic_block test_bb, basic_block merge_bb, earliest = jump; } #endif - /* If we allocated new pseudos (e.g. in the conditional move - expander called from noce_emit_cmove), we must resize the - array first. */ - if (max_regno < max_reg_num ()) - max_regno = max_reg_num (); - /* Try the NCE path if the CE path did not result in any changes. */ if (n_validated_changes == 0) { - rtx cond; - regset live; - bool success; - /* In the non-conditional execution case, we have to verify that there are no trapping operations, no calls, no references to memory, and that any registers modified are dead at the branch site. */ - if (!any_condjump_p (jump)) + rtx insn, cond, prev; + bitmap merge_set, merge_set_noclobber, test_live, test_set; + unsigned i, fail = 0; + bitmap_iterator bi; + + /* Check for no calls or trapping operations. */ + for (insn = head; ; insn = NEXT_INSN (insn)) + { + if (CALL_P (insn)) + return FALSE; + if (NONDEBUG_INSN_P (insn)) + { + if (may_trap_p (PATTERN (insn))) + return FALSE; + + /* ??? Even non-trapping memories such as stack frame + references must be avoided. For stores, we collect + no lifetime info; for reads, we'd have to assert + true_dependence false against every store in the + TEST range. */ + if (for_each_rtx (&PATTERN (insn), find_memory, NULL)) + return FALSE; + } + if (insn == end) + break; + } + + if (! any_condjump_p (jump)) return FALSE; /* Find the extent of the conditional. */ cond = noce_get_condition (jump, &earliest, false); - if (!cond) + if (! cond) return FALSE; - live = BITMAP_ALLOC (®_obstack); - simulate_backwards_to_point (merge_bb, live, end); - success = can_move_insns_across (head, end, earliest, jump, - merge_bb, live, - df_get_live_in (other_bb), NULL); - BITMAP_FREE (live); - if (!success) + /* Collect: + MERGE_SET = set of registers set in MERGE_BB + MERGE_SET_NOCLOBBER = like MERGE_SET, but only includes registers + that are really set, not just clobbered. + TEST_LIVE = set of registers live at EARLIEST + TEST_SET = set of registers set between EARLIEST and the + end of the block. */ + + merge_set = BITMAP_ALLOC (®_obstack); + merge_set_noclobber = BITMAP_ALLOC (®_obstack); + test_live = BITMAP_ALLOC (®_obstack); + test_set = BITMAP_ALLOC (®_obstack); + + /* ??? bb->local_set is only valid during calculate_global_regs_live, + so we must recompute usage for MERGE_BB. Not so bad, I suppose, + since we've already asserted that MERGE_BB is small. */ + /* If we allocated new pseudos (e.g. in the conditional move + expander called from noce_emit_cmove), we must resize the + array first. */ + if (max_regno < max_reg_num ()) + max_regno = max_reg_num (); + + FOR_BB_INSNS (merge_bb, insn) + { + if (NONDEBUG_INSN_P (insn)) + { + df_simulate_find_defs (insn, merge_set); + df_simulate_find_noclobber_defs (insn, merge_set_noclobber); + } + } + + /* For small register class machines, don't lengthen lifetimes of + hard registers before reload. */ + if (! reload_completed + && targetm.small_register_classes_for_mode_p (VOIDmode)) + { + EXECUTE_IF_SET_IN_BITMAP (merge_set_noclobber, 0, i, bi) + { + if (i < FIRST_PSEUDO_REGISTER + && ! fixed_regs[i] + && ! global_regs[i]) + fail = 1; + } + } + + /* For TEST, we're interested in a range of insns, not a whole block. + Moreover, we're interested in the insns live from OTHER_BB. */ + + /* The loop below takes the set of live registers + after JUMP, and calculates the live set before EARLIEST. */ + bitmap_copy (test_live, df_get_live_in (other_bb)); + df_simulate_initialize_backwards (test_bb, test_live); + for (insn = jump; ; insn = prev) + { + if (INSN_P (insn)) + { + df_simulate_find_defs (insn, test_set); + df_simulate_one_insn_backwards (test_bb, insn, test_live); + } + prev = PREV_INSN (insn); + if (insn == earliest) + break; + } + + /* We can perform the transformation if + MERGE_SET_NOCLOBBER & TEST_SET + and + MERGE_SET & TEST_LIVE) + and + TEST_SET & DF_LIVE_IN (merge_bb) + are empty. */ + + if (bitmap_intersect_p (test_set, merge_set_noclobber) + || bitmap_intersect_p (test_live, merge_set) + || bitmap_intersect_p (test_set, df_get_live_in (merge_bb))) + fail = 1; + + BITMAP_FREE (merge_set_noclobber); + BITMAP_FREE (merge_set); + BITMAP_FREE (test_live); + BITMAP_FREE (test_set); + + if (fail) return FALSE; } |