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(instantiate_virtual_regs_1, case PLUS): If offset is

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zero, make sure register replacement is still validated.

From-SVN: r8649
This commit is contained in:
Doug Evans 1994-12-13 15:04:05 +00:00
parent ae4311830e
commit b1f82ccff1
1 changed files with 21 additions and 12 deletions
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33
gcc/function.c
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@ -2675,7 +2675,7 @@ instantiate_virtual_regs_1 (loc, object, extra_insns)
/* Handle special case of virtual register plus constant. */ /* Handle special case of virtual register plus constant. */
if (CONSTANT_P (XEXP (x, 1))) if (CONSTANT_P (XEXP (x, 1)))
{ {
rtx old; rtx old, new_offset;
/* Check for (plus (plus VIRT foo) (const_int)) first. */ /* Check for (plus (plus VIRT foo) (const_int)) first. */
if (GET_CODE (XEXP (x, 0)) == PLUS) if (GET_CODE (XEXP (x, 0)) == PLUS)
@ -2722,18 +2722,26 @@ instantiate_virtual_regs_1 (loc, object, extra_insns)
return 1; return 1;
} }
old = XEXP (x, 0); new_offset = plus_constant (XEXP (x, 1), offset);
XEXP (x, 0) = new;
new = plus_constant (XEXP (x, 1), offset);
/* If the new constant is zero, try to replace the sum with its /* If the new constant is zero, try to replace the sum with just
first operand. */ the register. */
if (new == const0_rtx if (new_offset == const0_rtx
&& validate_change (object, loc, XEXP (x, 0), 0)) && validate_change (object, loc, new, 0))
return 1; return 1;
/* Next try to replace constant with new one. */ /* Next try to replace the register and new offset.
if (!validate_change (object, &XEXP (x, 1), new, 0)) There are two changes to validate here and we can't assume that
in the case of old offset equals new just changing the register
will yield a valid insn. In the interests of a little efficiency,
however, we only call validate change once (we don't queue up the
changes and then call apply_change_group). */
old = XEXP (x, 0);
if (offset == 0
? ! validate_change (object, &XEXP (x, 0), new, 0)
: (XEXP (x, 0) = new,
! validate_change (object, &XEXP (x, 1), new_offset, 0)))
{ {
if (! extra_insns) if (! extra_insns)
{ {
@ -2744,15 +2752,16 @@ instantiate_virtual_regs_1 (loc, object, extra_insns)
/* Otherwise copy the new constant into a register and replace /* Otherwise copy the new constant into a register and replace
constant with that register. */ constant with that register. */
temp = gen_reg_rtx (Pmode); temp = gen_reg_rtx (Pmode);
XEXP (x, 0) = new;
if (validate_change (object, &XEXP (x, 1), temp, 0)) if (validate_change (object, &XEXP (x, 1), temp, 0))
emit_insn_before (gen_move_insn (temp, new), object); emit_insn_before (gen_move_insn (temp, new_offset), object);
else else
{ {
/* If that didn't work, replace this expression with a /* If that didn't work, replace this expression with a
register containing the sum. */ register containing the sum. */
new = gen_rtx (PLUS, Pmode, XEXP (x, 0), new);
XEXP (x, 0) = old; XEXP (x, 0) = old;
new = gen_rtx (PLUS, Pmode, new, new_offset);
start_sequence (); start_sequence ();
temp = force_operand (new, NULL_RTX); temp = force_operand (new, NULL_RTX);