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Revert: [RTL ifcvt] Transform (X == CST) ? -CST : Y into (X == CST) ? -X : Y when conditional negation is available

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Revert
	2016-09-30  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	* ifcvt.c (noce_try_avoid_const_materialization): New function.
	(noce_process_if_block): Use it.

	* gcc.target/aarch64/ifcvt_avoid_const_materialization_1.c: New test.

From-SVN: r240708
This commit is contained in:
Kyrylo Tkachov 2016-10-03 09:28:28 +00:00 committed by Kyrylo Tkachov
parent f41f1ceba6
commit b44a42cfab
4 changed files with 15 additions and 102 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2016-10-03 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Revert
2016-09-30 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
* ifcvt.c (noce_try_avoid_const_materialization): New function.
(noce_process_if_block): Use it.
2016-10-03 Bernd Edlinger <bernd.edlinger@hotmail.de>
* doc/invoke.texi: Update -Wint-in-bool-context.

80
gcc/ifcvt.c
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@ -1313,84 +1313,6 @@ noce_try_inverse_constants (struct noce_if_info *if_info)
return false;
}
/* Try to avoid materializing a constant if we know it's in one of the
registers. For example:
(X == CST) ? -CST : Y --> (X == CST) ? -X : Y.
Do this only if conditional negation is available.
Similar for bitwise NOT. */
static bool
noce_try_avoid_const_materialization (struct noce_if_info *if_info)
{
if (!noce_simple_bbs (if_info))
return false;
rtx cond = if_info->cond;
rtx a = if_info->a;
rtx b = if_info->b;
rtx_code code = GET_CODE (cond);
machine_mode mode = GET_MODE (if_info->x);
if (!(code == EQ || code == NE)
|| !REG_P (XEXP (cond, 0))
|| !REG_P (if_info->x)
|| GET_MODE (XEXP (cond, 0)) != mode
|| !CONST_INT_P (XEXP (cond, 1)))
return false;
rtx cst = XEXP (cond, 1);
if (cst == CONST0_RTX (mode))
return false;
rtx non_cst = XEXP (cond, 0);
rtx eq_side = code == EQ ? b : a;
if (!CONST_INT_P (eq_side))
return false;
HOST_WIDE_INT cstval = INTVAL (cst);
HOST_WIDE_INT eq_side_val = INTVAL (eq_side);
rtx_code op_code;
if (eq_side_val == ~cstval)
op_code = NOT;
else if (eq_side_val != HOST_WIDE_INT_MIN && (cstval == -eq_side_val))
op_code = NEG;
else
return false;
/* By the rules of the negcc/notcc optabs must happen when the COND is true,
in this case when register in COND is equal to CST so always set the
comparison to EQ. */
if (code == NE)
{
a = non_cst;
cond = gen_rtx_fmt_ee (EQ, GET_MODE (cond), non_cst, cst);
}
else
b = non_cst;
start_sequence ();
rtx target
= emit_conditional_neg_or_complement (if_info->x, op_code, mode,
cond, a, b);
if (!target)
{
end_sequence ();
return false;
}
if (target != if_info->x)
noce_emit_move_insn (if_info->x, target);
rtx_insn *seq = end_ifcvt_sequence (if_info);
if (!seq)
return false;
emit_insn_before_setloc (seq, if_info->jump,
INSN_LOCATION (if_info->insn_a));
if_info->transform_name = "noce_try_avoid_const_materialization";
return true;
}
/* Convert "if (test) x = a; else x = b", for A and B constant.
Also allow A = y + c1, B = y + c2, with a common y between A
@ -3684,8 +3606,6 @@ noce_process_if_block (struct noce_if_info *if_info)
goto success;
if (noce_try_inverse_constants (if_info))
goto success;
if (noce_try_avoid_const_materialization (if_info))
goto success;
if (!targetm.have_conditional_execution ()
&& noce_try_store_flag_constants (if_info))
goto success;

7
gcc/testsuite/ChangeLog
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@ -1,3 +1,10 @@
2016-10-03 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Revert
2016-09-30 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
* gcc.target/aarch64/ifcvt_avoid_const_materialization_1.c: New test.
2016-10-03 Marek Polacek <polacek@redhat.com>
* g++.dg/cpp0x/nullptr37.C: New test.

22
gcc/testsuite/gcc.target/aarch64/ifcvt_avoid_const_materialization_1.c
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@ -1,22 +0,0 @@
/* { dg-do compile } */
/* { dg-options "-O2" } */
/* Check that we avoid moving the immediate into a register
if comparison has shown that the inverse or negated form is
already in one of the registers. */
int
foo (int a, int b)
{
return a == 5 ? -5 : b;
}
int
bar (int a, int b)
{
return a != 5 ? b : ~5;
}
/* { dg-final { scan-assembler-not "mov\\tw\[0-9\]+" } } */
/* { dg-final { scan-assembler-times "csneg\\tw\[0-9\]+" 1 } } */
/* { dg-final { scan-assembler-times "csinv\\tw\[0-9\]+" 1 } } */