This patch checks whether the current target supports conditional moves
with immediate then/else operands and allows noce_convert_multiple_sets
to deal with constants subsequently.
Also, minor refactoring is performed.
--
gcc/ChangeLog:
2018-11-14 Robin Dapp <rd...@linux.ibm.com>
* ifcvt.c (have_const_cmov): New function.
(noce_convert_multiple_sets): Allow constants if supported.
(bb_ok_for_noce_convert_multiple_sets): Likewise.
(check_cond_move_block): Refactor.
---
gcc/ifcvt.c | 46 ++++++++++++++++++++++++++++++++++++----------
1 file changed, 36 insertions(+), 10 deletions(-)
diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
index ddf077fa051..660bb46eb1c 100644
--- a/gcc/ifcvt.c
+++ b/gcc/ifcvt.c
@@ -3077,6 +3077,27 @@ bb_valid_for_noce_process_p (basic_block test_bb, rtx
cond,
return false;
}
+/* Check if we have a movcc pattern that accepts constants as then/else
+ operand (op 2/3). */
+static bool
+have_const_cmov (machine_mode mode)
+{
+ enum insn_code icode;
+ if ((icode = direct_optab_handler (movcc_optab, mode))
+ != CODE_FOR_nothing)
+ {
+ if (insn_data[(int) icode].operand[2].predicate
+ && (insn_data[(int) icode].operand[2].predicate
+ (const1_rtx, insn_data[(int) icode].operand[2].mode)))
+ if (insn_data[(int) icode].operand[3].predicate
+ && (insn_data[(int) icode].operand[3].predicate
+ (const1_rtx, insn_data[(int) icode].operand[3].mode)))
+ return true;
+ }
+
+ return false;
+}
+
/* We have something like:
if (x > y)
@@ -3194,7 +3215,12 @@ noce_convert_multiple_sets (struct noce_if_info *if_info)
we'll end up trying to emit r4:HI = cond ? (r1:SI) : (r3:HI).
Wrap the two cmove operands into subregs if appropriate to prevent
that. */
- if (GET_MODE (new_val) != GET_MODE (temp))
+
+ /* Check if we can emit a cmove with constant operands. */
+ bool allow_constants = have_const_cmov (GET_MODE (target));
+
+ if (!(allow_constants && CONST_INT_P (new_val))
+ && GET_MODE (new_val) != GET_MODE (temp))
{
machine_mode src_mode = GET_MODE (new_val);
machine_mode dst_mode = GET_MODE (temp);
@@ -3205,7 +3231,8 @@ noce_convert_multiple_sets (struct noce_if_info *if_info)
}
new_val = lowpart_subreg (dst_mode, new_val, src_mode);
}
- if (GET_MODE (old_val) != GET_MODE (temp))
+ if (!(allow_constants && CONST_INT_P (old_val))
+ && GET_MODE (old_val) != GET_MODE (temp))
{
machine_mode src_mode = GET_MODE (old_val);
machine_mode dst_mode = GET_MODE (temp);
@@ -3339,9 +3366,10 @@ bb_ok_for_noce_convert_multiple_sets (basic_block
test_bb)
if (!REG_P (dest))
return false;
- if (!(REG_P (src)
- || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
- && subreg_lowpart_p (src))))
+ if (!((REG_P (src)
+ || (have_const_cmov (GET_MODE (dest)) && CONST_INT_P (src)))
+ || (GET_CODE (src) == SUBREG && REG_P (SUBREG_REG (src))
+ && subreg_lowpart_p (src))))
return false;
/* Destination must be appropriate for a conditional write. */
@@ -3689,7 +3717,7 @@ check_cond_move_block (basic_block bb,
{
rtx set, dest, src;
- if (!NONDEBUG_INSN_P (insn) || JUMP_P (insn))
+ if (!active_insn_p (insn))
continue;
set = single_set (insn);
if (!set)
@@ -3705,10 +3733,8 @@ check_cond_move_block (basic_block bb,
if (!CONSTANT_P (src) && !register_operand (src, VOIDmode))
return FALSE;
- if (side_effects_p (src) || side_effects_p (dest))
- return FALSE;
-
- if (may_trap_p (src) || may_trap_p (dest))
+ /* Check for side effects and trapping. */
+ if (!noce_operand_ok (src) || !noce_operand_ok (dest))
return FALSE;
/* Don't try to handle this if the source register was
--
2.17.0
