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i386.c (ix86_emit_swsqrtsf): Use negative constants in order to use commutative addition instead of subtraction. 

* config/i386/i386.c (ix86_emit_swsqrtsf): Use negative constants in
        order to use commutative addition instead of subtraction.

From-SVN: r131358
This commit is contained in:
Uros Bizjak 2008-01-06 19:59:38 +01:00 committed by Uros Bizjak
parent e39bd31393
commit 43db797998
2 changed files with 43 additions and 29 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2008-01-06 Uros Bizjak <ubizjak@gmail.com>
* config/i386/i386.c (ix86_emit_swsqrtsf): Use negative constants in
order to use commutative addition instead of subtraction.
2008-01-06 Andrew Pinski <andrew_pinski@playstation.sony.com>
Mircea Namolaru <namolaru@il.ibm.com>
Vladimir Yanovsky <yanov@il.ibm.com>

67
gcc/config/i386/i386.c
View File

@ -24187,7 +24187,7 @@ void ix86_emit_swdivsf (rtx res, rtx a, rtx b, enum machine_mode mode)
/* a / b = a * rcp(b) * (2.0 - b * rcp(b)) */
/* x0 = 1./b estimate */
/* x0 = rcp(b) estimate */
emit_insn (gen_rtx_SET (VOIDmode, x0,
gen_rtx_UNSPEC (mode, gen_rtvec (1, b),
UNSPEC_RCP)));
@ -24211,7 +24211,8 @@ void ix86_emit_swdivsf (rtx res, rtx a, rtx b, enum machine_mode mode)
void ix86_emit_swsqrtsf (rtx res, rtx a, enum machine_mode mode,
bool recip)
{
rtx x0, e0, e1, e2, e3, three, half, zero, mask;
rtx x0, e0, e1, e2, e3, mthree, mhalf;
REAL_VALUE_TYPE r;
x0 = gen_reg_rtx (mode);
e0 = gen_reg_rtx (mode);
@ -24219,55 +24220,63 @@ void ix86_emit_swsqrtsf (rtx res, rtx a, enum machine_mode mode,
e2 = gen_reg_rtx (mode);
e3 = gen_reg_rtx (mode);
three = CONST_DOUBLE_FROM_REAL_VALUE (dconst3, SFmode);
half = CONST_DOUBLE_FROM_REAL_VALUE (dconsthalf, SFmode);
real_arithmetic (&r, NEGATE_EXPR, &dconst3, NULL);
mthree = CONST_DOUBLE_FROM_REAL_VALUE (r, SFmode);
mask = gen_reg_rtx (mode);
real_arithmetic (&r, NEGATE_EXPR, &dconsthalf, NULL);
mhalf = CONST_DOUBLE_FROM_REAL_VALUE (r, SFmode);
if (VECTOR_MODE_P (mode))
{
three = ix86_build_const_vector (SFmode, true, three);
half = ix86_build_const_vector (SFmode, true, half);
mthree = ix86_build_const_vector (SFmode, true, mthree);
mhalf = ix86_build_const_vector (SFmode, true, mhalf);
}
three = force_reg (mode, three);
half = force_reg (mode, half);
/* sqrt(a) = -0.5 * a * rsqrtss(a) * (a * rsqrtss(a) * rsqrtss(a) - 3.0)
rsqrt(a) = -0.5 * rsqrtss(a) * (a * rsqrtss(a) * rsqrtss(a) - 3.0) */
zero = force_reg (mode, CONST0_RTX(mode));
/* sqrt(a) = 0.5 * a * rsqrtss(a) * (3.0 - a * rsqrtss(a) * rsqrtss(a))
1.0 / sqrt(a) = 0.5 * rsqrtss(a) * (3.0 - a * rsqrtss(a) * rsqrtss(a)) */
/* Compare a to zero. */
if (!recip)
emit_insn (gen_rtx_SET (VOIDmode, mask,
gen_rtx_NE (mode, zero, a)));
/* x0 = 1./sqrt(a) estimate */
/* x0 = rsqrt(a) estimate */
emit_insn (gen_rtx_SET (VOIDmode, x0,
gen_rtx_UNSPEC (mode, gen_rtvec (1, a),
UNSPEC_RSQRT)));
/* Filter out infinity. */
/* If (a == 0.0) Filter out infinity to prevent NaN for sqrt(0.0). */
if (!recip)
emit_insn (gen_rtx_SET (VOIDmode, x0,
gen_rtx_AND (mode, x0, mask)));
{
rtx zero, mask;
zero = gen_reg_rtx (mode);
mask = gen_reg_rtx (mode);
zero = force_reg (mode, CONST0_RTX(mode));
emit_insn (gen_rtx_SET (VOIDmode, mask,
gen_rtx_NE (mode, zero, a)));
emit_insn (gen_rtx_SET (VOIDmode, x0,
gen_rtx_AND (mode, x0, mask)));
}
/* e0 = x0 * a */
emit_insn (gen_rtx_SET (VOIDmode, e0,
gen_rtx_MULT (mode, x0, a)));
/* e1 = e0 * x0 */
emit_insn (gen_rtx_SET (VOIDmode, e1,
gen_rtx_MULT (mode, e0, x0)));
/* e2 = 3. - e1 */
/* e2 = e1 - 3. */
mthree = force_reg (mode, mthree);
emit_insn (gen_rtx_SET (VOIDmode, e2,
gen_rtx_MINUS (mode, three, e1)));
gen_rtx_PLUS (mode, e1, mthree)));
mhalf = force_reg (mode, mhalf);
if (recip)
/* e3 = .5 * x0 */
/* e3 = -.5 * x0 */
emit_insn (gen_rtx_SET (VOIDmode, e3,
gen_rtx_MULT (mode, half, x0)));
gen_rtx_MULT (mode, x0, mhalf)));
else
/* e3 = .5 * e0 */
/* e3 = -.5 * e0 */
emit_insn (gen_rtx_SET (VOIDmode, e3,
gen_rtx_MULT (mode, half, e0)));
gen_rtx_MULT (mode, e0, mhalf)));
/* ret = e2 * e3 */
emit_insn (gen_rtx_SET (VOIDmode, res,
gen_rtx_MULT (mode, e2, e3)));