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Commit d7fde18c by Jakub Jelinek Committed by Jakub Jelinek
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re PR rtl-optimization/50339 (suboptimal register allocation for abs(__int128_t)) 

	PR rtl-optimization/50339
	* lower-subreg.h (struct lower_subreg_choices): Add splitting_ashiftrt
	field.
	* lower-subreg.c (compute_splitting_shift): Handle ASHIFTRT.
	(compute_costs): Call compute_splitting_shift also for ASHIFTRT
	into splitting_ashiftrt field.
	(find_decomposable_shift_zext, resolve_shift_zext): Handle also
	ASHIFTRT.
	(dump_choices): Fix up printing LSHIFTRT choices, print ASHIFTRT
	choices.

From-SVN: r196214
parent 6aad4455
Showing with 55 additions and 15 deletions
gcc/ChangeLog
2013-02-21 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/50339
* lower-subreg.h (struct lower_subreg_choices): Add splitting_ashiftrt
field.
* lower-subreg.c (compute_splitting_shift): Handle ASHIFTRT.
(compute_costs): Call compute_splitting_shift also for ASHIFTRT
into splitting_ashiftrt field.
(find_decomposable_shift_zext, resolve_shift_zext): Handle also
ASHIFTRT.
(dump_choices): Fix up printing LSHIFTRT choices, print ASHIFTRT
choices.
2013-02-20 Aldy Hernandez <aldyh@redhat.com>
PR middle-end/56108
......
gcc/lower-subreg.c
......@@ -57,9 +57,9 @@ along with GCC; see the file COPYING3. If not see
to do this.
This pass only splits moves with modes that are wider than
word_mode and ASHIFTs, LSHIFTRTs and ZERO_EXTENDs with integer
modes that are twice the width of word_mode. The latter could be
generalized if there was a need to do this, but the trend in
word_mode and ASHIFTs, LSHIFTRTs, ASHIFTRTs and ZERO_EXTENDs with
integer modes that are twice the width of word_mode. The latter
could be generalized if there was a need to do this, but the trend in
architectures is to not need this.
There are two useful preprocessor defines for use by maintainers:
......@@ -152,7 +152,7 @@ compute_splitting_shift (bool speed_p, struct cost_rtxes *rtxes,
bool *splitting, enum rtx_code code,
int word_move_zero_cost, int word_move_cost)
{
int wide_cost, narrow_cost, i;
int wide_cost, narrow_cost, upper_cost, i;
for (i = 0; i < BITS_PER_WORD; i++)
{
......@@ -163,13 +163,20 @@ compute_splitting_shift (bool speed_p, struct cost_rtxes *rtxes,
else
narrow_cost = shift_cost (speed_p, rtxes, code, word_mode, i);
if (code != ASHIFTRT)
upper_cost = word_move_zero_cost;
else if (i == BITS_PER_WORD - 1)
upper_cost = word_move_cost;
else
upper_cost = shift_cost (speed_p, rtxes, code, word_mode,
BITS_PER_WORD - 1);
if (LOG_COSTS)
fprintf (stderr, "%s %s by %d: original cost %d, split cost %d + %d\n",
GET_MODE_NAME (twice_word_mode), GET_RTX_NAME (code),
i + BITS_PER_WORD, wide_cost, narrow_cost,
word_move_zero_cost);
i + BITS_PER_WORD, wide_cost, narrow_cost, upper_cost);
if (FORCE_LOWERING || wide_cost >= narrow_cost + word_move_zero_cost)
if (FORCE_LOWERING || wide_cost >= narrow_cost + upper_cost)
splitting[i] = true;
}
}
......@@ -248,6 +255,9 @@ compute_costs (bool speed_p, struct cost_rtxes *rtxes)
compute_splitting_shift (speed_p, rtxes,
choices[speed_p].splitting_lshiftrt, LSHIFTRT,
word_move_zero_cost, word_move_cost);
compute_splitting_shift (speed_p, rtxes,
choices[speed_p].splitting_ashiftrt, ASHIFTRT,
word_move_zero_cost, word_move_cost);
}
}
......@@ -1153,6 +1163,7 @@ find_decomposable_shift_zext (rtx insn, bool speed_p)
op = SET_SRC (set);
if (GET_CODE (op) != ASHIFT
&& GET_CODE (op) != LSHIFTRT
&& GET_CODE (op) != ASHIFTRT
&& GET_CODE (op) != ZERO_EXTEND)
return false;
......@@ -1173,6 +1184,8 @@ find_decomposable_shift_zext (rtx insn, bool speed_p)
{
bool *splitting = (GET_CODE (op) == ASHIFT
? choices[speed_p].splitting_ashift
: GET_CODE (op) == ASHIFTRT
? choices[speed_p].splitting_ashiftrt
: choices[speed_p].splitting_lshiftrt);
if (!CONST_INT_P (XEXP (op, 1))
|| !IN_RANGE (INTVAL (XEXP (op, 1)), BITS_PER_WORD,
......@@ -1200,7 +1213,7 @@ resolve_shift_zext (rtx insn)
rtx op;
rtx op_operand;
rtx insns;
rtx src_reg, dest_reg, dest_zero;
rtx src_reg, dest_reg, dest_upper, upper_src = NULL_RTX;
int src_reg_num, dest_reg_num, offset1, offset2, src_offset;
set = single_set (insn);
......@@ -1210,6 +1223,7 @@ resolve_shift_zext (rtx insn)
op = SET_SRC (set);
if (GET_CODE (op) != ASHIFT
&& GET_CODE (op) != LSHIFTRT
&& GET_CODE (op) != ASHIFTRT
&& GET_CODE (op) != ZERO_EXTEND)
return NULL_RTX;
......@@ -1223,7 +1237,8 @@ resolve_shift_zext (rtx insn)
/* src_reg_num is the number of the word mode register which we
are operating on. For a left shift and a zero_extend on little
endian machines this is register 0. */
src_reg_num = GET_CODE (op) == LSHIFTRT ? 1 : 0;
src_reg_num = (GET_CODE (op) == LSHIFTRT || GET_CODE (op) == ASHIFTRT)
? 1 : 0;
if (WORDS_BIG_ENDIAN
&& GET_MODE_SIZE (GET_MODE (op_operand)) > UNITS_PER_WORD)
......@@ -1243,12 +1258,17 @@ resolve_shift_zext (rtx insn)
dest_reg = simplify_gen_subreg_concatn (word_mode, SET_DEST (set),
GET_MODE (SET_DEST (set)),
offset1);
dest_zero = simplify_gen_subreg_concatn (word_mode, SET_DEST (set),
GET_MODE (SET_DEST (set)),
offset2);
dest_upper = simplify_gen_subreg_concatn (word_mode, SET_DEST (set),
GET_MODE (SET_DEST (set)),
offset2);
src_reg = simplify_gen_subreg_concatn (word_mode, op_operand,
GET_MODE (op_operand),
src_offset);
if (GET_CODE (op) == ASHIFTRT
&& INTVAL (XEXP (op, 1)) != 2 * BITS_PER_WORD - 1)
upper_src = expand_shift (RSHIFT_EXPR, word_mode, copy_rtx (src_reg),
BITS_PER_WORD - 1, NULL_RTX, 0);
if (GET_CODE (op) != ZERO_EXTEND)
{
int shift_count = INTVAL (XEXP (op, 1));
......@@ -1257,12 +1277,17 @@ resolve_shift_zext (rtx insn)
LSHIFT_EXPR : RSHIFT_EXPR,
word_mode, src_reg,
shift_count - BITS_PER_WORD,
dest_reg, 1);
dest_reg, GET_CODE (op) != ASHIFTRT);
}
if (dest_reg != src_reg)
emit_move_insn (dest_reg, src_reg);
emit_move_insn (dest_zero, CONST0_RTX (word_mode));
if (GET_CODE (op) != ASHIFTRT)
emit_move_insn (dest_upper, CONST0_RTX (word_mode));
else if (INTVAL (XEXP (op, 1)) == 2 * BITS_PER_WORD - 1)
emit_move_insn (dest_upper, copy_rtx (src_reg));
else
emit_move_insn (dest_upper, upper_src);
insns = get_insns ();
end_sequence ();
......@@ -1328,7 +1353,8 @@ dump_choices (bool speed_p, const char *description)
GET_MODE_NAME (twice_word_mode));
dump_shift_choices (ASHIFT, choices[speed_p].splitting_ashift);
dump_shift_choices (LSHIFTRT, choices[speed_p].splitting_ashift);
dump_shift_choices (LSHIFTRT, choices[speed_p].splitting_lshiftrt);
dump_shift_choices (ASHIFTRT, choices[speed_p].splitting_ashiftrt);
fprintf (dump_file, "\n");
}
......
gcc/lower-subreg.h
......@@ -34,6 +34,7 @@ struct lower_subreg_choices {
should be split. */
bool splitting_ashift[MAX_BITS_PER_WORD];
bool splitting_lshiftrt[MAX_BITS_PER_WORD];
bool splitting_ashiftrt[MAX_BITS_PER_WORD];
/* True if there is at least one mode that is worth splitting. */
bool something_to_do;
......
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