* sysdeps/alpha/Makefile <gnulib> (sysdep_routines): Merge divrem variable, add unsigned variants. * sysdeps/alpha/divrem.h: Remove file. * sysdeps/alpha/div_libc.h: New file. * sysdeps/alpha/divl.S: Rewrite from scratch. * sysdeps/alpha/reml.S: Likewise. * sysdeps/alpha/divq.S: Likewise. * sysdeps/alpha/remq.S: Likewise. * sysdeps/alpha/divlu.S: New file. * sysdeps/alpha/remlu.S: New file. * sysdeps/alpha/divqu.S: New file. * sysdeps/alpha/remqu.S: New file.

2004-03-26  Richard Henderson  <rth@redhat.com>

	* sysdeps/alpha/Makefile <gnulib> (sysdep_routines): Merge divrem
	variable, add unsigned variants.
	* sysdeps/alpha/divrem.h: Remove file.
	* sysdeps/alpha/div_libc.h: New file.
	* sysdeps/alpha/divl.S: Rewrite from scratch.
	* sysdeps/alpha/reml.S: Likewise.
	* sysdeps/alpha/divq.S: Likewise.
	* sysdeps/alpha/remq.S: Likewise.
	* sysdeps/alpha/divlu.S: New file.
	* sysdeps/alpha/remlu.S: New file.
	* sysdeps/alpha/divqu.S: New file.
	* sysdeps/alpha/remqu.S: New file.

1 files changed, 244 insertions, 0 deletions

diff --git a/sysdeps/alpha/divqu.S b/sysdeps/alpha/divqu.S
new file mode 100644
index 0000000000..6ff6c035e2
--- /dev/null
+++ b/sysdeps/alpha/divqu.S
@@ -0,0 +1,244 @@
+/* Copyright (C) 2004 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include "div_libc.h"
+
+
+/* 64-bit unsigned long divide.  These are not normal C functions.  Argument
+   registers are t10 and t11, the result goes in t12.  Only t12 and AT may be
+   clobbered.
+
+   Theory of operation here is that we can use the FPU divider for virtually
+   all operands that we see: all dividend values between -2**53 and 2**53-1
+   can be computed directly.  Note that divisor values need not be checked
+   against that range because the rounded fp value will be close enough such
+   that the quotient is < 1, which will properly be truncated to zero when we
+   convert back to integer.
+
+   When the dividend is outside the range for which we can compute exact
+   results, we use the fp quotent as an estimate from which we begin refining
+   an exact integral value.  This reduces the number of iterations in the
+   shift-and-subtract loop significantly.  */
+
+	.text
+	.align	4
+	.globl	__divqu
+	.type	__divqu, @function
+	.usepv	__divqu, no
+
+	cfi_startproc
+	cfi_return_column (RA)
+__divqu:
+	lda	sp, -FRAME(sp)
+	cfi_def_cfa_offset (FRAME)
+	CALL_MCOUNT
+
+	/* Get the fp divide insn issued as quickly as possible.  After
+	   that's done, we have at least 22 cycles until its results are
+	   ready -- all the time in the world to figure out how we're
+	   going to use the results.  */
+	stq	X, 16(sp)
+	stq	Y, 24(sp)
+	beq	Y, DIVBYZERO
+
+	stt	$f0, 0(sp)
+	stt	$f1, 8(sp)
+	cfi_rel_offset ($f0, 0)
+	cfi_rel_offset ($f1, 8)
+	ldt	$f0, 16(sp)
+	ldt	$f1, 24(sp)
+
+	cvtqt	$f0, $f0
+	cvtqt	$f1, $f1
+	blt	X, $x_is_neg
+	divt/c	$f0, $f1, $f0
+
+	/* Check to see if Y was mis-converted as signed value.  */
+	ldt	$f1, 8(sp)
+	unop
+	nop
+	blt	Y, $y_is_neg
+
+	/* Check to see if X fit in the double as an exact value.  */
+	srl	X, 53, AT
+	bne	AT, $x_big
+
+	/* If we get here, we're expecting exact results from the division.
+	   Do nothing else besides convert and clean up.  */
+	cvttq/c	$f0, $f0
+	stt	$f0, 16(sp)
+
+	ldq	RV, 16(sp)
+	ldt	$f0, 0(sp)
+	cfi_remember_state
+	cfi_restore ($f0)
+	cfi_restore ($f1)
+	cfi_def_cfa_offset (0)
+	lda	sp, FRAME(sp)
+	ret	$31, (RA), 1
+
+	.align	4
+	cfi_restore_state
+$x_is_neg:
+	/* If we get here, X is so big that bit 63 is set, which made the
+	   conversion come out negative.  Fix it up lest we not even get
+	   a good estimate.  */
+	ldah	AT, 0x5f80		/* 2**64 as float.  */
+	stt	$f2, 24(sp)
+	cfi_rel_offset ($f2, 24)
+	stl	AT, 16(sp)
+	lds	$f2, 16(sp)
+
+	addt	$f0, $f2, $f0
+	unop
+	divt/c	$f0, $f1, $f0
+	unop
+
+	/* Ok, we've now the divide issued.  Continue with other checks.  */
+	ldt	$f1, 8(sp)
+	unop
+	ldt	$f2, 24(sp)
+	blt	Y, $y_is_neg
+	cfi_restore ($f1)
+	cfi_restore ($f2)
+	cfi_remember_state	/* for y_is_neg */
+
+	.align	4
+$x_big:
+	/* If we get here, X is large enough that we don't expect exact
+	   results, and neither X nor Y got mis-translated for the fp
+	   division.  Our task is to take the fp result, figure out how
+	   far it's off from the correct result and compute a fixup.  */
+	stq	t0, 16(sp)
+	stq	t1, 24(sp)
+	stq	t2, 32(sp)
+	stq	t3, 40(sp)
+	cfi_rel_offset (t0, 16)
+	cfi_rel_offset (t1, 24)
+	cfi_rel_offset (t2, 32)
+	cfi_rel_offset (t3, 40)
+
+#define Q	RV		/* quotient */
+#define R	t0		/* remainder */
+#define SY	t1		/* scaled Y */
+#define S	t2		/* scalar */
+#define QY	t3		/* Q*Y */
+
+	cvttq/c	$f0, $f0
+	stt	$f0, 8(sp)
+	ldq	Q, 8(sp)
+	mulq	Q, Y, QY
+
+	stq	t4, 8(sp)
+	unop
+	ldt	$f0, 0(sp)
+	unop
+	cfi_rel_offset (t4, 8)
+	cfi_restore ($f0)
+
+	subq	QY, X, R
+	mov	Y, SY
+	mov	1, S
+	bgt	R, $q_high
+
+$q_high_ret:
+	subq	X, QY, R
+	mov	Y, SY
+	mov	1, S
+	bgt	R, $q_low
+
+$q_low_ret:
+	ldq	t4, 8(sp)
+	ldq	t0, 16(sp)
+	ldq	t1, 24(sp)
+	ldq	t2, 32(sp)
+
+	ldq	t3, 40(sp)
+	lda	sp, FRAME(sp)
+	cfi_remember_state
+	cfi_restore (t0)
+	cfi_restore (t1)
+	cfi_restore (t2)
+	cfi_restore (t3)
+	cfi_restore (t4)
+	cfi_def_cfa_offset (0)
+	ret	$31, (RA), 1
+
+	.align	4
+	cfi_restore_state
+	/* The quotient that we computed was too large.  We need to reduce
+	   it by S such that Y*S >= R.  Obviously the closer we get to the
+	   correct value the better, but overshooting high is ok, as we'll
+	   fix that up later.  */
+0:
+	addq	SY, SY, SY
+	addq	S, S, S
+$q_high:
+	cmpult	SY, R, AT
+	bne	AT, 0b
+
+	subq	Q, S, Q
+	unop
+	subq	QY, SY, QY
+	br	$q_high_ret
+
+	.align	4
+	/* The quotient that we computed was too small.  Divide Y by the 
+	   current remainder (R) and add that to the existing quotient (Q).
+	   The expectation, of course, is that R is much smaller than X.  */
+	/* Begin with a shift-up loop.  Compute S such that Y*S >= R.  We
+	   already have a copy of Y in SY and the value 1 in S.  */
+0:
+	addq	SY, SY, SY
+	addq	S, S, S
+$q_low:
+	cmpult	SY, R, AT
+	bne	AT, 0b
+
+	/* Shift-down and subtract loop.  Each iteration compares our scaled
+	   Y (SY) with the remainder (R); if SY <= R then X is divisible by
+	   Y's scalar (S) so add it to the quotient (Q).  */
+2:	addq	Q, S, t3
+	srl	S, 1, S
+	cmpule	SY, R, AT
+	subq	R, SY, t4
+
+	cmovne	AT, t3, Q
+	cmovne	AT, t4, R
+	srl	SY, 1, SY
+	bne	S, 2b
+
+	br	$q_low_ret
+
+	.align	4
+	cfi_restore_state
+$y_is_neg:
+	/* If we get here, Y is so big that bit 63 is set.  The results
+	   from the divide will be completely wrong.  Fortunately, the
+	   quotient must be either 0 or 1, so just compute it directly.  */
+	cmpult	Y, X, RV
+	ldt	$f0, 0(sp)
+	lda	sp, FRAME(sp)
+	cfi_restore ($f0)
+	cfi_def_cfa_offset (0)
+	ret	$31, (RA), 1
+
+	cfi_endproc
+	.size	__divqu, .-__divqu
+
+	DO_DIVBYZERO