kernel-ark/arch/arm/nwfpe/fpa11_cprt.c
Richard Purdie f148af2593 [PATCH] ARM: 2837/2: Re: ARM: Make NWFPE preempt safe
Patch from Richard Purdie

NWFPE used global variables which meant it wasn't safe for use with
preemptive kernels. This patch removes them and communicates the
information between functions in a preempt safe manner. Generation
of some exceptions was broken and this has also been corrected.
Tests with glibc's maths test suite show no change in the results
before/after this patch.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-08-03 19:49:17 +01:00

380 lines
9.2 KiB
C

/*
NetWinder Floating Point Emulator
(c) Rebel.COM, 1998,1999
(c) Philip Blundell, 1999, 2001
Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/config.h>
#include "fpa11.h"
#include "fpopcode.h"
#include "fpa11.inl"
#include "fpmodule.h"
#include "fpmodule.inl"
#ifdef CONFIG_FPE_NWFPE_XP
extern flag floatx80_is_nan(floatx80);
#endif
extern flag float64_is_nan(float64);
extern flag float32_is_nan(float32);
unsigned int PerformFLT(const unsigned int opcode);
unsigned int PerformFIX(const unsigned int opcode);
static unsigned int PerformComparison(const unsigned int opcode);
unsigned int EmulateCPRT(const unsigned int opcode)
{
if (opcode & 0x800000) {
/* This is some variant of a comparison (PerformComparison
will sort out which one). Since most of the other CPRT
instructions are oddball cases of some sort or other it
makes sense to pull this out into a fast path. */
return PerformComparison(opcode);
}
/* Hint to GCC that we'd like a jump table rather than a load of CMPs */
switch ((opcode & 0x700000) >> 20) {
case FLT_CODE >> 20:
return PerformFLT(opcode);
break;
case FIX_CODE >> 20:
return PerformFIX(opcode);
break;
case WFS_CODE >> 20:
writeFPSR(readRegister(getRd(opcode)));
break;
case RFS_CODE >> 20:
writeRegister(getRd(opcode), readFPSR());
break;
default:
return 0;
}
return 1;
}
unsigned int PerformFLT(const unsigned int opcode)
{
FPA11 *fpa11 = GET_FPA11();
struct roundingData roundData;
roundData.mode = SetRoundingMode(opcode);
roundData.precision = SetRoundingPrecision(opcode);
roundData.exception = 0;
switch (opcode & MASK_ROUNDING_PRECISION) {
case ROUND_SINGLE:
{
fpa11->fType[getFn(opcode)] = typeSingle;
fpa11->fpreg[getFn(opcode)].fSingle = int32_to_float32(&roundData, readRegister(getRd(opcode)));
}
break;
case ROUND_DOUBLE:
{
fpa11->fType[getFn(opcode)] = typeDouble;
fpa11->fpreg[getFn(opcode)].fDouble = int32_to_float64(readRegister(getRd(opcode)));
}
break;
#ifdef CONFIG_FPE_NWFPE_XP
case ROUND_EXTENDED:
{
fpa11->fType[getFn(opcode)] = typeExtended;
fpa11->fpreg[getFn(opcode)].fExtended = int32_to_floatx80(readRegister(getRd(opcode)));
}
break;
#endif
default:
return 0;
}
if (roundData.exception)
float_raise(roundData.exception);
return 1;
}
unsigned int PerformFIX(const unsigned int opcode)
{
FPA11 *fpa11 = GET_FPA11();
unsigned int Fn = getFm(opcode);
struct roundingData roundData;
roundData.mode = SetRoundingMode(opcode);
roundData.precision = SetRoundingPrecision(opcode);
roundData.exception = 0;
switch (fpa11->fType[Fn]) {
case typeSingle:
{
writeRegister(getRd(opcode), float32_to_int32(&roundData, fpa11->fpreg[Fn].fSingle));
}
break;
case typeDouble:
{
writeRegister(getRd(opcode), float64_to_int32(&roundData, fpa11->fpreg[Fn].fDouble));
}
break;
#ifdef CONFIG_FPE_NWFPE_XP
case typeExtended:
{
writeRegister(getRd(opcode), floatx80_to_int32(&roundData, fpa11->fpreg[Fn].fExtended));
}
break;
#endif
default:
return 0;
}
if (roundData.exception)
float_raise(roundData.exception);
return 1;
}
/* This instruction sets the flags N, Z, C, V in the FPSR. */
static unsigned int PerformComparison(const unsigned int opcode)
{
FPA11 *fpa11 = GET_FPA11();
unsigned int Fn = getFn(opcode), Fm = getFm(opcode);
int e_flag = opcode & 0x400000; /* 1 if CxFE */
int n_flag = opcode & 0x200000; /* 1 if CNxx */
unsigned int flags = 0;
#ifdef CONFIG_FPE_NWFPE_XP
floatx80 rFn, rFm;
/* Check for unordered condition and convert all operands to 80-bit
format.
?? Might be some mileage in avoiding this conversion if possible.
Eg, if both operands are 32-bit, detect this and do a 32-bit
comparison (cheaper than an 80-bit one). */
switch (fpa11->fType[Fn]) {
case typeSingle:
//printk("single.\n");
if (float32_is_nan(fpa11->fpreg[Fn].fSingle))
goto unordered;
rFn = float32_to_floatx80(fpa11->fpreg[Fn].fSingle);
break;
case typeDouble:
//printk("double.\n");
if (float64_is_nan(fpa11->fpreg[Fn].fDouble))
goto unordered;
rFn = float64_to_floatx80(fpa11->fpreg[Fn].fDouble);
break;
case typeExtended:
//printk("extended.\n");
if (floatx80_is_nan(fpa11->fpreg[Fn].fExtended))
goto unordered;
rFn = fpa11->fpreg[Fn].fExtended;
break;
default:
return 0;
}
if (CONSTANT_FM(opcode)) {
//printk("Fm is a constant: #%d.\n",Fm);
rFm = getExtendedConstant(Fm);
if (floatx80_is_nan(rFm))
goto unordered;
} else {
//printk("Fm = r%d which contains a ",Fm);
switch (fpa11->fType[Fm]) {
case typeSingle:
//printk("single.\n");
if (float32_is_nan(fpa11->fpreg[Fm].fSingle))
goto unordered;
rFm = float32_to_floatx80(fpa11->fpreg[Fm].fSingle);
break;
case typeDouble:
//printk("double.\n");
if (float64_is_nan(fpa11->fpreg[Fm].fDouble))
goto unordered;
rFm = float64_to_floatx80(fpa11->fpreg[Fm].fDouble);
break;
case typeExtended:
//printk("extended.\n");
if (floatx80_is_nan(fpa11->fpreg[Fm].fExtended))
goto unordered;
rFm = fpa11->fpreg[Fm].fExtended;
break;
default:
return 0;
}
}
if (n_flag)
rFm.high ^= 0x8000;
/* test for less than condition */
if (floatx80_lt(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (floatx80_eq(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (floatx80_lt(rFm, rFn))
flags |= CC_CARRY;
#else
if (CONSTANT_FM(opcode)) {
/* Fm is a constant. Do the comparison in whatever precision
Fn happens to be stored in. */
if (fpa11->fType[Fn] == typeSingle) {
float32 rFm = getSingleConstant(Fm);
float32 rFn = fpa11->fpreg[Fn].fSingle;
if (float32_is_nan(rFn))
goto unordered;
if (n_flag)
rFm ^= 0x80000000;
/* test for less than condition */
if (float32_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float32_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float32_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
} else {
float64 rFm = getDoubleConstant(Fm);
float64 rFn = fpa11->fpreg[Fn].fDouble;
if (float64_is_nan(rFn))
goto unordered;
if (n_flag)
rFm ^= 0x8000000000000000ULL;
/* test for less than condition */
if (float64_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float64_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float64_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
}
} else {
/* Both operands are in registers. */
if (fpa11->fType[Fn] == typeSingle
&& fpa11->fType[Fm] == typeSingle) {
float32 rFm = fpa11->fpreg[Fm].fSingle;
float32 rFn = fpa11->fpreg[Fn].fSingle;
if (float32_is_nan(rFn)
|| float32_is_nan(rFm))
goto unordered;
if (n_flag)
rFm ^= 0x80000000;
/* test for less than condition */
if (float32_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float32_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float32_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
} else {
/* Promote 32-bit operand to 64 bits. */
float64 rFm, rFn;
rFm = (fpa11->fType[Fm] == typeSingle) ?
float32_to_float64(fpa11->fpreg[Fm].fSingle)
: fpa11->fpreg[Fm].fDouble;
rFn = (fpa11->fType[Fn] == typeSingle) ?
float32_to_float64(fpa11->fpreg[Fn].fSingle)
: fpa11->fpreg[Fn].fDouble;
if (float64_is_nan(rFn)
|| float64_is_nan(rFm))
goto unordered;
if (n_flag)
rFm ^= 0x8000000000000000ULL;
/* test for less than condition */
if (float64_lt_nocheck(rFn, rFm))
flags |= CC_NEGATIVE;
/* test for equal condition */
if (float64_eq_nocheck(rFn, rFm))
flags |= CC_ZERO;
/* test for greater than or equal condition */
if (float64_lt_nocheck(rFm, rFn))
flags |= CC_CARRY;
}
}
#endif
writeConditionCodes(flags);
return 1;
unordered:
/* ?? The FPA data sheet is pretty vague about this, in particular
about whether the non-E comparisons can ever raise exceptions.
This implementation is based on a combination of what it says in
the data sheet, observation of how the Acorn emulator actually
behaves (and how programs expect it to) and guesswork. */
flags |= CC_OVERFLOW;
flags &= ~(CC_ZERO | CC_NEGATIVE);
if (BIT_AC & readFPSR())
flags |= CC_CARRY;
if (e_flag)
float_raise(float_flag_invalid);
writeConditionCodes(flags);
return 1;
}