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i386.c (ix86_emit_swdivsf): Implement more efficiently. 

2011-03-15  Richard Guenther  <rguenther@suse.de>

	* config/i386/i386.c (ix86_emit_swdivsf): Implement more
	efficiently.

From-SVN: r170981
This commit is contained in:
Richard Guenther 2011-03-15 09:30:13 +00:00 committed by Richard Biener
parent cc9ce9ffd6
commit 01c77a6055
2 changed files with 22 additions and 17 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2011-03-15 Richard Guenther <rguenther@suse.de>
* config/i386/i386.c (ix86_emit_swdivsf): Implement more
efficiently.
2011-03-15 Alan Modra <amodra@gmail.com>
PR target/48032

34
gcc/config/i386/i386.c
View File

@ -31935,38 +31935,38 @@ void ix86_emit_i387_log1p (rtx op0, rtx op1)
void ix86_emit_swdivsf (rtx res, rtx a, rtx b, enum machine_mode mode)
{
rtx x0, x1, e0, e1, two;
rtx x0, x1, e0, e1;
x0 = gen_reg_rtx (mode);
e0 = gen_reg_rtx (mode);
e1 = gen_reg_rtx (mode);
x1 = gen_reg_rtx (mode);
two = CONST_DOUBLE_FROM_REAL_VALUE (dconst2, SFmode);
if (VECTOR_MODE_P (mode))
two = ix86_build_const_vector (mode, true, two);
two = force_reg (mode, two);
/* a / b = a * rcp(b) * (2.0 - b * rcp(b)) */
/* a / b = a * ((rcp(b) + rcp(b)) - (b * rcp(b) * rcp (b))) */
/* x0 = rcp(b) estimate */
emit_insn (gen_rtx_SET (VOIDmode, x0,
gen_rtx_UNSPEC (mode, gen_rtvec (1, b),
UNSPEC_RCP)));
/* e0 = x0 * a */
/* e0 = x0 * b */
emit_insn (gen_rtx_SET (VOIDmode, e0,
gen_rtx_MULT (mode, x0, a)));
/* e1 = x0 * b */
emit_insn (gen_rtx_SET (VOIDmode, e1,
gen_rtx_MULT (mode, x0, b)));
/* x1 = 2. - e1 */
/* e0 = x0 * e0 */
emit_insn (gen_rtx_SET (VOIDmode, e0,
gen_rtx_MULT (mode, x0, e0)));
/* e1 = x0 + x0 */
emit_insn (gen_rtx_SET (VOIDmode, e1,
gen_rtx_PLUS (mode, x0, x0)));
/* x1 = e1 - e0 */
emit_insn (gen_rtx_SET (VOIDmode, x1,
gen_rtx_MINUS (mode, two, e1)));
/* res = e0 * x1 */
gen_rtx_MINUS (mode, e1, e0)));
/* res = a * x1 */
emit_insn (gen_rtx_SET (VOIDmode, res,
gen_rtx_MULT (mode, e0, x1)));
gen_rtx_MULT (mode, a, x1)));
}
/* Output code to perform a Newton-Rhapson approximation of a