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(alpha_emit_conditional_move): New function.

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From-SVN: r11814
This commit is contained in:
Richard Kenner 1996-04-16 10:53:48 -04:00
parent 04aa3b9c26
commit 758d2c0c2f
1 changed files with 61 additions and 0 deletions
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61
gcc/config/alpha/alpha.c
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@ -965,6 +965,67 @@ alpha_emit_set_const_1 (target, mode, c, n)
return 0;
}
/* Rewrite a comparison against zero CMP of the form
(CODE (cc0) (const_int 0)) so it can be written validly in
a conditional move (if_then_else CMP ...).
If both of the operands that set cc0 are non-zero we must emit
an insn to perform the compare (it can't be done within
the conditional move). */
rtx
alpha_emit_conditional_move (cmp, mode)
rtx cmp;
enum machine_mode mode;
{
rtx op0 = alpha_compare_op0;
rtx op1 = alpha_compare_op1;
rtx zero = CONST0_RTX (mode);
rtx tmp;
enum rtx_code code = GET_CODE (cmp), code2;
if (alpha_compare_fp_p != FLOAT_MODE_P(mode))
return 0;
/* We may be able to use a conditional move directly.
This avoids emitting spurious compares. */
if (signed_comparison_operator (cmp, mode) && (op0 == zero || op1 == zero))
return gen_rtx (code, mode, op0, op1);
/* We can't put the comparison insides a conditional move;
emit a compare instruction and put that inside the
conditional move. */
/* The alpha does not have NE GE GT compares for any mode. Avoid them. */
code2 = NE;
switch (code)
{
/* We have these compares: */
case EQ: case LE: case LT:
break;
/* These must be inverted: */
case NE:
code = code2 = EQ;
break;
case GE:
code = LE;
op0 = force_reg (mode, alpha_compare_op1);
op1 = alpha_compare_op0;
break;
case GT:
code = LT;
op0 = force_reg (mode, alpha_compare_op1);
op1 = alpha_compare_op0;
break;
default:
return 0;
}
cmp = gen_rtx (code, mode, op0, op1);
tmp = gen_reg_rtx (mode);
emit_insn (gen_rtx (SET, VOIDmode, tmp, cmp));
cmp = gen_rtx (code2, VOIDmode, tmp, zero);
return cmp;
}
/* Adjust the cost of a scheduling dependency. Return the new cost of
a dependency LINK or INSN on DEP_INSN. COST is the current cost. */