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re PR target/17959 (-mpowerpc64 can cause worse code than without it)

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PR target/17959
	* expr.c (emit_group_store):  Optimize group stores into a pseudo
	register by using a paradoxical subreg to initialize the destination
	if the first or last member of the group specifies a "low part".

From-SVN: r112543
This commit is contained in:
Roger Sayle 2006-03-30 17:47:48 +00:00 committed by Roger Sayle
parent 105aa1532e
commit 79edfde8fb
2 changed files with 56 additions and 6 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2006-03-30 Roger Sayle <roger@eyesopen.com>
PR target/17959
* expr.c (emit_group_store): Optimize group stores into a pseudo
register by using a paradoxical subreg to initialize the destination
if the first or last member of the group specifies a "low part".
2006-03-30 Maxim Kuvyrkov <mkuvyrkov@ispras.ru>
PR target/26734

55
gcc/expr.c
View File

@ -1857,7 +1857,7 @@ void
emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED, int ssize)
{
rtx *tmps, dst;
int start, i;
int start, finish, i;
enum machine_mode m = GET_MODE (orig_dst);
gcc_assert (GET_CODE (src) == PARALLEL);
@ -1883,11 +1883,12 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED, int ssize)
start = 0;
else
start = 1;
finish = XVECLEN (src, 0);
tmps = alloca (sizeof (rtx) * XVECLEN (src, 0));
tmps = alloca (sizeof (rtx) * finish);
/* Copy the (probable) hard regs into pseudos. */
for (i = start; i < XVECLEN (src, 0); i++)
for (i = start; i < finish; i++)
{
rtx reg = XEXP (XVECEXP (src, 0, i), 0);
if (!REG_P (reg) || REGNO (reg) < FIRST_PSEUDO_REGISTER)
@ -1923,14 +1924,56 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED, int ssize)
}
else if (!MEM_P (dst) && GET_CODE (dst) != CONCAT)
{
enum machine_mode outer = GET_MODE (dst);
enum machine_mode inner;
unsigned int bytepos;
bool done = false;
rtx temp;
if (!REG_P (dst) || REGNO (dst) < FIRST_PSEUDO_REGISTER)
dst = gen_reg_rtx (GET_MODE (orig_dst));
dst = gen_reg_rtx (outer);
/* Make life a bit easier for combine. */
emit_move_insn (dst, CONST0_RTX (GET_MODE (orig_dst)));
/* If the first element of the vector is the low part
of the destination mode, use a paradoxical subreg to
initialize the destination. */
if (start < finish)
{
inner = GET_MODE (tmps[start]);
bytepos = subreg_lowpart_offset (outer, inner);
if (INTVAL (XEXP (XVECEXP (src, 0, start), 1)) == bytepos)
{
temp = simplify_gen_subreg (outer, tmps[start],
inner, bytepos);
emit_move_insn (dst, temp);
done = true;
start++;
}
}
/* If the first element wasn't the low part, try the last. */
if (!done
&& start < finish - 1)
{
inner = GET_MODE (tmps[finish - 1]);
bytepos = subreg_lowpart_offset (outer, inner);
if (INTVAL (XEXP (XVECEXP (src, 0, finish - 1), 1)) == bytepos)
{
temp = simplify_gen_subreg (outer, tmps[finish - 1],
inner, bytepos);
emit_move_insn (dst, temp);
done = true;
finish--;
}
}
/* Otherwise, simply initialize the result to zero. */
if (!done)
emit_move_insn (dst, CONST0_RTX (outer));
}
/* Process the pieces. */
for (i = start; i < XVECLEN (src, 0); i++)
for (i = start; i < finish; i++)
{
HOST_WIDE_INT bytepos = INTVAL (XEXP (XVECEXP (src, 0, i), 1));
enum machine_mode mode = GET_MODE (tmps[i]);