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regclass.c (record_reg_classes): Update comment for merging register class preferences in reg->reg copies.

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* regclass.c (record_reg_classes): Update comment for merging
        register class preferences in reg->reg copies.  Tighten conditions
        for merging register class preferences in reg->reg copies.

From-SVN: r30943
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Jeffrey A Law 1999-12-15 08:29:37 +00:00 committed by Jeff Law
parent 705e873389
commit accef10312
2 changed files with 27 additions and 9 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
Wed Dec 15 01:23:29 1999 Jeffrey A Law (law@cygnus.com)
* regclass.c (record_reg_classes): Update comment for merging
register class preferences in reg->reg copies. Tighten conditions
for merging register class preferences in reg->reg copies.
Wed Dec 15 02:19:32 1999 David Edelsohn <edelsohn@gnu.org>
* rs6000.md (tablejumpdi): Generate DImode LABEL_REF.

30
gcc/regclass.c
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@ -1622,11 +1622,18 @@ record_reg_classes (n_alts, n_ops, ops, modes, subreg_changes_size,
}
/* If this insn is a single set copying operand 1 to operand 0
and one is a pseudo with the other a hard reg that is in its
own register class, set the cost of that register class to -1.
Do this only when source dies to avoid stressing of register
allocator by preferrencing two coliding registers into single
place. */
and one operand is a pseudo with the other a hard reg or a pseudo
that prefers a register that is in its own register class then
we may want to adjust the cost of that register class to -1.
Avoid the adjustment if the source does not die to avoid stressing of
register allocator by preferrencing two coliding registers into single
class.
Also avoid the adjustment if a copy between registers of the class
is expensive (ten times the cost of a default copy is considered
arbitrarily expensive). This avoids losing when the preferred class
is very expensive as the source of a copy instruction. */
if ((set = single_set (insn)) != 0
&& ops[0] == SET_DEST (set) && ops[1] == SET_SRC (set)
@ -1640,10 +1647,15 @@ record_reg_classes (n_alts, n_ops, ops, modes, subreg_changes_size,
int class;
int nr;
if (regno >= FIRST_PSEUDO_REGISTER && reg_pref != 0
&& (reg_class_size[(unsigned char) reg_pref[regno].prefclass]
== CLASS_MAX_NREGS (reg_pref[regno].prefclass, mode)))
op_costs[i].cost[(unsigned char) reg_pref[regno].prefclass] = -1;
if (regno >= FIRST_PSEUDO_REGISTER && reg_pref != 0)
{
enum reg_class pref = reg_pref[regno].prefclass;
if ((reg_class_size[(unsigned char) pref]
== CLASS_MAX_NREGS (pref, mode))
&& REGISTER_MOVE_COST (pref, pref) < 10 * 2)
op_costs[i].cost[(unsigned char) pref] = -1;
}
else if (regno < FIRST_PSEUDO_REGISTER)
for (class = 0; class < N_REG_CLASSES; class++)
if (TEST_HARD_REG_BIT (reg_class_contents[class], regno)