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[LRA]: Exclude reloading of frame pointer in subreg for some cases

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LRA for avr port reloads frame pointer in subreg although we can just
simplify the subreg.  It results in generation of bad performance code.  The following
patch fixes this.

gcc/ChangeLog:

	* lra-constraints.cc (simplify_operand_subreg): Check frame pointer
	simplification.
This commit is contained in:
Vladimir N. Makarov 2023-07-20 14:34:26 -04:00
parent bdda084bc4
commit 4b8878fbf7
1 changed files with 16 additions and 0 deletions
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16
gcc/lra-constraints.cc
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@ -1797,6 +1797,16 @@ simplify_operand_subreg (int nop, machine_mode reg_mode)
alter_subreg (curr_id->operand_loc[nop], false);
return true;
}
auto fp_subreg_can_be_simplified_after_reload_p = [] (machine_mode innermode,
poly_uint64 offset,
machine_mode mode) {
reload_completed = 1;
bool res = simplify_subreg_regno (FRAME_POINTER_REGNUM,
innermode,
offset, mode) >= 0;
reload_completed = 0;
return res;
};
/* Force a reload of the SUBREG_REG if this is a constant or PLUS or
if there may be a problem accessing OPERAND in the outer
mode. */
@ -1809,6 +1819,12 @@ simplify_operand_subreg (int nop, machine_mode reg_mode)
>= hard_regno_nregs (hard_regno, mode))
&& simplify_subreg_regno (hard_regno, innermode,
SUBREG_BYTE (operand), mode) < 0
/* Exclude reloading of frame pointer in subreg if frame pointer can not
be simplified here only because the reload is not finished yet. */
&& (hard_regno != FRAME_POINTER_REGNUM
|| !fp_subreg_can_be_simplified_after_reload_p (innermode,
SUBREG_BYTE (operand),
mode))
/* Don't reload subreg for matching reload. It is actually
valid subreg in LRA. */
&& ! LRA_SUBREG_P (operand))