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qemu/target/arm/vfp_helper.c
Peter Maydell aaae563bc7 target/arm: Implement FPST_STD_F16 fpstatus 
Architecturally, Neon FP16 operations use the "standard FPSCR" like
all other Neon operations.  However, this is defined in the Arm ARM
pseudocode as "a fixed value, except that FZ16 (and AHP) follow the
FPSCR bits". In QEMU, the softfloat float_status doesn't include
separate flush-to-zero for FP16 operations, so we must keep separate
fp_status for "Neon non-FP16" and "Neon fp16" operations, in the
same way we do already for the non-Neon "fp_status" vs "fp_status_f16".

Add the extra float_status field to the CPU state structure,
ensure it is correctly initialized and updated on FPSCR writes,
and make fpstatus_ptr(FPST_STD_F16) return a pointer to it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20200806104453.30393-4-peter.maydell@linaro.org
2020-08-24 10:15:11 +01:00

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/*
* ARM VFP floating-point operations
*
* Copyright (c) 2003 Fabrice Bellard
*
* This 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.
*
* This 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 this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "exec/helper-proto.h"
#include "internals.h"
#ifdef CONFIG_TCG
#include "qemu/log.h"
#include "fpu/softfloat.h"
#endif
/* VFP support. We follow the convention used for VFP instructions:
Single precision routines have a "s" suffix, double precision a
"d" suffix. */
#ifdef CONFIG_TCG
/* Convert host exception flags to vfp form. */
static inline int vfp_exceptbits_from_host(int host_bits)
{
int target_bits = 0;
if (host_bits & float_flag_invalid) {
target_bits |= 1;
}
if (host_bits & float_flag_divbyzero) {
target_bits |= 2;
}
if (host_bits & float_flag_overflow) {
target_bits |= 4;
}
if (host_bits & (float_flag_underflow | float_flag_output_denormal)) {
target_bits |= 8;
}
if (host_bits & float_flag_inexact) {
target_bits |= 0x10;
}
if (host_bits & float_flag_input_denormal) {
target_bits |= 0x80;
}
return target_bits;
}
/* Convert vfp exception flags to target form. */
static inline int vfp_exceptbits_to_host(int target_bits)
{
int host_bits = 0;
if (target_bits & 1) {
host_bits |= float_flag_invalid;
}
if (target_bits & 2) {
host_bits |= float_flag_divbyzero;
}
if (target_bits & 4) {
host_bits |= float_flag_overflow;
}
if (target_bits & 8) {
host_bits |= float_flag_underflow;
}
if (target_bits & 0x10) {
host_bits |= float_flag_inexact;
}
if (target_bits & 0x80) {
host_bits |= float_flag_input_denormal;
}
return host_bits;
}
static uint32_t vfp_get_fpscr_from_host(CPUARMState *env)
{
uint32_t i;
i = get_float_exception_flags(&env->vfp.fp_status);
i |= get_float_exception_flags(&env->vfp.standard_fp_status);
/* FZ16 does not generate an input denormal exception. */
i |= (get_float_exception_flags(&env->vfp.fp_status_f16)
& ~float_flag_input_denormal);
i |= (get_float_exception_flags(&env->vfp.standard_fp_status_f16)
& ~float_flag_input_denormal);
return vfp_exceptbits_from_host(i);
}
static void vfp_set_fpscr_to_host(CPUARMState *env, uint32_t val)
{
int i;
uint32_t changed = env->vfp.xregs[ARM_VFP_FPSCR];
changed ^= val;
if (changed & (3 << 22)) {
i = (val >> 22) & 3;
switch (i) {
case FPROUNDING_TIEEVEN:
i = float_round_nearest_even;
break;
case FPROUNDING_POSINF:
i = float_round_up;
break;
case FPROUNDING_NEGINF:
i = float_round_down;
break;
case FPROUNDING_ZERO:
i = float_round_to_zero;
break;
}
set_float_rounding_mode(i, &env->vfp.fp_status);
set_float_rounding_mode(i, &env->vfp.fp_status_f16);
}
if (changed & FPCR_FZ16) {
bool ftz_enabled = val & FPCR_FZ16;
set_flush_to_zero(ftz_enabled, &env->vfp.fp_status_f16);
set_flush_to_zero(ftz_enabled, &env->vfp.standard_fp_status_f16);
set_flush_inputs_to_zero(ftz_enabled, &env->vfp.fp_status_f16);
set_flush_inputs_to_zero(ftz_enabled, &env->vfp.standard_fp_status_f16);
}
if (changed & FPCR_FZ) {
bool ftz_enabled = val & FPCR_FZ;
set_flush_to_zero(ftz_enabled, &env->vfp.fp_status);
set_flush_inputs_to_zero(ftz_enabled, &env->vfp.fp_status);
}
if (changed & FPCR_DN) {
bool dnan_enabled = val & FPCR_DN;
set_default_nan_mode(dnan_enabled, &env->vfp.fp_status);
set_default_nan_mode(dnan_enabled, &env->vfp.fp_status_f16);
}
/*
* The exception flags are ORed together when we read fpscr so we
* only need to preserve the current state in one of our
* float_status values.
*/
i = vfp_exceptbits_to_host(val);
set_float_exception_flags(i, &env->vfp.fp_status);
set_float_exception_flags(0, &env->vfp.fp_status_f16);
set_float_exception_flags(0, &env->vfp.standard_fp_status);
set_float_exception_flags(0, &env->vfp.standard_fp_status_f16);
}
#else
static uint32_t vfp_get_fpscr_from_host(CPUARMState *env)
{
return 0;
}
static void vfp_set_fpscr_to_host(CPUARMState *env, uint32_t val)
{
}
#endif
uint32_t HELPER(vfp_get_fpscr)(CPUARMState *env)
{
uint32_t i, fpscr;
fpscr = env->vfp.xregs[ARM_VFP_FPSCR]
| (env->vfp.vec_len << 16)
| (env->vfp.vec_stride << 20);
fpscr |= vfp_get_fpscr_from_host(env);
i = env->vfp.qc[0] | env->vfp.qc[1] | env->vfp.qc[2] | env->vfp.qc[3];
fpscr |= i ? FPCR_QC : 0;
return fpscr;
}
uint32_t vfp_get_fpscr(CPUARMState *env)
{
return HELPER(vfp_get_fpscr)(env);
}
void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val)
{
/* When ARMv8.2-FP16 is not supported, FZ16 is RES0. */
if (!cpu_isar_feature(any_fp16, env_archcpu(env))) {
val &= ~FPCR_FZ16;
}
if (arm_feature(env, ARM_FEATURE_M)) {
/*
* M profile FPSCR is RES0 for the QC, STRIDE, FZ16, LEN bits
* and also for the trapped-exception-handling bits IxE.
*/
val &= 0xf7c0009f;
}
vfp_set_fpscr_to_host(env, val);
/*
* We don't implement trapped exception handling, so the
* trap enable bits, IDE|IXE|UFE|OFE|DZE|IOE are all RAZ/WI (not RES0!)
*
* If we exclude the exception flags, IOC|DZC|OFC|UFC|IXC|IDC
* (which are stored in fp_status), and the other RES0 bits
* in between, then we clear all of the low 16 bits.
*/
env->vfp.xregs[ARM_VFP_FPSCR] = val & 0xf7c80000;
env->vfp.vec_len = (val >> 16) & 7;
env->vfp.vec_stride = (val >> 20) & 3;
/*
* The bit we set within fpscr_q is arbitrary; the register as a
* whole being zero/non-zero is what counts.
*/
env->vfp.qc[0] = val & FPCR_QC;
env->vfp.qc[1] = 0;
env->vfp.qc[2] = 0;
env->vfp.qc[3] = 0;
}
void vfp_set_fpscr(CPUARMState *env, uint32_t val)
{
HELPER(vfp_set_fpscr)(env, val);
}
#ifdef CONFIG_TCG
#define VFP_HELPER(name, p) HELPER(glue(glue(vfp_,name),p))
#define VFP_BINOP(name) \
float32 VFP_HELPER(name, s)(float32 a, float32 b, void *fpstp) \
{ \
float_status *fpst = fpstp; \
return float32_ ## name(a, b, fpst); \
} \
float64 VFP_HELPER(name, d)(float64 a, float64 b, void *fpstp) \
{ \
float_status *fpst = fpstp; \
return float64_ ## name(a, b, fpst); \
}
VFP_BINOP(add)
VFP_BINOP(sub)
VFP_BINOP(mul)
VFP_BINOP(div)
VFP_BINOP(min)
VFP_BINOP(max)
VFP_BINOP(minnum)
VFP_BINOP(maxnum)
#undef VFP_BINOP
float32 VFP_HELPER(neg, s)(float32 a)
{
return float32_chs(a);
}
float64 VFP_HELPER(neg, d)(float64 a)
{
return float64_chs(a);
}
float32 VFP_HELPER(abs, s)(float32 a)
{
return float32_abs(a);
}
float64 VFP_HELPER(abs, d)(float64 a)
{
return float64_abs(a);
}
float32 VFP_HELPER(sqrt, s)(float32 a, CPUARMState *env)
{
return float32_sqrt(a, &env->vfp.fp_status);
}
float64 VFP_HELPER(sqrt, d)(float64 a, CPUARMState *env)
{
return float64_sqrt(a, &env->vfp.fp_status);
}
static void softfloat_to_vfp_compare(CPUARMState *env, FloatRelation cmp)
{
uint32_t flags;
switch (cmp) {
case float_relation_equal:
flags = 0x6;
break;
case float_relation_less:
flags = 0x8;
break;
case float_relation_greater:
flags = 0x2;
break;
case float_relation_unordered:
flags = 0x3;
break;
default:
g_assert_not_reached();
}
env->vfp.xregs[ARM_VFP_FPSCR] =
deposit32(env->vfp.xregs[ARM_VFP_FPSCR], 28, 4, flags);
}
/* XXX: check quiet/signaling case */
#define DO_VFP_cmp(p, type) \
void VFP_HELPER(cmp, p)(type a, type b, CPUARMState *env) \
{ \
softfloat_to_vfp_compare(env, \
type ## _compare_quiet(a, b, &env->vfp.fp_status)); \
} \
void VFP_HELPER(cmpe, p)(type a, type b, CPUARMState *env) \
{ \
softfloat_to_vfp_compare(env, \
type ## _compare(a, b, &env->vfp.fp_status)); \
}
DO_VFP_cmp(s, float32)
DO_VFP_cmp(d, float64)
#undef DO_VFP_cmp
/* Integer to float and float to integer conversions */
#define CONV_ITOF(name, ftype, fsz, sign) \
ftype HELPER(name)(uint32_t x, void *fpstp) \
{ \
float_status *fpst = fpstp; \
return sign##int32_to_##float##fsz((sign##int32_t)x, fpst); \
}
#define CONV_FTOI(name, ftype, fsz, sign, round) \
sign##int32_t HELPER(name)(ftype x, void *fpstp) \
{ \
float_status *fpst = fpstp; \
if (float##fsz##_is_any_nan(x)) { \
float_raise(float_flag_invalid, fpst); \
return 0; \
} \
return float##fsz##_to_##sign##int32##round(x, fpst); \
}
#define FLOAT_CONVS(name, p, ftype, fsz, sign) \
CONV_ITOF(vfp_##name##to##p, ftype, fsz, sign) \
CONV_FTOI(vfp_to##name##p, ftype, fsz, sign, ) \
CONV_FTOI(vfp_to##name##z##p, ftype, fsz, sign, _round_to_zero)
FLOAT_CONVS(si, h, uint32_t, 16, )
FLOAT_CONVS(si, s, float32, 32, )
FLOAT_CONVS(si, d, float64, 64, )
FLOAT_CONVS(ui, h, uint32_t, 16, u)
FLOAT_CONVS(ui, s, float32, 32, u)
FLOAT_CONVS(ui, d, float64, 64, u)
#undef CONV_ITOF
#undef CONV_FTOI
#undef FLOAT_CONVS
/* floating point conversion */
float64 VFP_HELPER(fcvtd, s)(float32 x, CPUARMState *env)
{
return float32_to_float64(x, &env->vfp.fp_status);
}
float32 VFP_HELPER(fcvts, d)(float64 x, CPUARMState *env)
{
return float64_to_float32(x, &env->vfp.fp_status);
}
/* VFP3 fixed point conversion. */
#define VFP_CONV_FIX_FLOAT(name, p, fsz, isz, itype) \
float##fsz HELPER(vfp_##name##to##p)(uint##isz##_t x, uint32_t shift, \
void *fpstp) \
{ return itype##_to_##float##fsz##_scalbn(x, -shift, fpstp); }
#define VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, isz, itype, ROUND, suff) \
uint##isz##_t HELPER(vfp_to##name##p##suff)(float##fsz x, uint32_t shift, \
void *fpst) \
{ \
if (unlikely(float##fsz##_is_any_nan(x))) { \
float_raise(float_flag_invalid, fpst); \
return 0; \
} \
return float##fsz##_to_##itype##_scalbn(x, ROUND, shift, fpst); \
}
#define VFP_CONV_FIX(name, p, fsz, isz, itype) \
VFP_CONV_FIX_FLOAT(name, p, fsz, isz, itype) \
VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, isz, itype, \
float_round_to_zero, _round_to_zero) \
VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, isz, itype, \
get_float_rounding_mode(fpst), )
#define VFP_CONV_FIX_A64(name, p, fsz, isz, itype) \
VFP_CONV_FIX_FLOAT(name, p, fsz, isz, itype) \
VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, isz, itype, \
get_float_rounding_mode(fpst), )
VFP_CONV_FIX(sh, d, 64, 64, int16)
VFP_CONV_FIX(sl, d, 64, 64, int32)
VFP_CONV_FIX_A64(sq, d, 64, 64, int64)
VFP_CONV_FIX(uh, d, 64, 64, uint16)
VFP_CONV_FIX(ul, d, 64, 64, uint32)
VFP_CONV_FIX_A64(uq, d, 64, 64, uint64)
VFP_CONV_FIX(sh, s, 32, 32, int16)
VFP_CONV_FIX(sl, s, 32, 32, int32)
VFP_CONV_FIX_A64(sq, s, 32, 64, int64)
VFP_CONV_FIX(uh, s, 32, 32, uint16)
VFP_CONV_FIX(ul, s, 32, 32, uint32)
VFP_CONV_FIX_A64(uq, s, 32, 64, uint64)
#undef VFP_CONV_FIX
#undef VFP_CONV_FIX_FLOAT
#undef VFP_CONV_FLOAT_FIX_ROUND
#undef VFP_CONV_FIX_A64
uint32_t HELPER(vfp_sltoh)(uint32_t x, uint32_t shift, void *fpst)
{
return int32_to_float16_scalbn(x, -shift, fpst);
}
uint32_t HELPER(vfp_ultoh)(uint32_t x, uint32_t shift, void *fpst)
{
return uint32_to_float16_scalbn(x, -shift, fpst);
}
uint32_t HELPER(vfp_sqtoh)(uint64_t x, uint32_t shift, void *fpst)
{
return int64_to_float16_scalbn(x, -shift, fpst);
}
uint32_t HELPER(vfp_uqtoh)(uint64_t x, uint32_t shift, void *fpst)
{
return uint64_to_float16_scalbn(x, -shift, fpst);
}
uint32_t HELPER(vfp_toshh)(uint32_t x, uint32_t shift, void *fpst)
{
if (unlikely(float16_is_any_nan(x))) {
float_raise(float_flag_invalid, fpst);
return 0;
}
return float16_to_int16_scalbn(x, get_float_rounding_mode(fpst),
shift, fpst);
}
uint32_t HELPER(vfp_touhh)(uint32_t x, uint32_t shift, void *fpst)
{
if (unlikely(float16_is_any_nan(x))) {
float_raise(float_flag_invalid, fpst);
return 0;
}
return float16_to_uint16_scalbn(x, get_float_rounding_mode(fpst),
shift, fpst);
}
uint32_t HELPER(vfp_toslh)(uint32_t x, uint32_t shift, void *fpst)
{
if (unlikely(float16_is_any_nan(x))) {
float_raise(float_flag_invalid, fpst);
return 0;
}
return float16_to_int32_scalbn(x, get_float_rounding_mode(fpst),
shift, fpst);
}
uint32_t HELPER(vfp_toulh)(uint32_t x, uint32_t shift, void *fpst)
{
if (unlikely(float16_is_any_nan(x))) {
float_raise(float_flag_invalid, fpst);
return 0;
}
return float16_to_uint32_scalbn(x, get_float_rounding_mode(fpst),
shift, fpst);
}
uint64_t HELPER(vfp_tosqh)(uint32_t x, uint32_t shift, void *fpst)
{
if (unlikely(float16_is_any_nan(x))) {
float_raise(float_flag_invalid, fpst);
return 0;
}
return float16_to_int64_scalbn(x, get_float_rounding_mode(fpst),
shift, fpst);
}
uint64_t HELPER(vfp_touqh)(uint32_t x, uint32_t shift, void *fpst)
{
if (unlikely(float16_is_any_nan(x))) {
float_raise(float_flag_invalid, fpst);
return 0;
}
return float16_to_uint64_scalbn(x, get_float_rounding_mode(fpst),
shift, fpst);
}
/* Set the current fp rounding mode and return the old one.
* The argument is a softfloat float_round_ value.
*/
uint32_t HELPER(set_rmode)(uint32_t rmode, void *fpstp)
{
float_status *fp_status = fpstp;
uint32_t prev_rmode = get_float_rounding_mode(fp_status);
set_float_rounding_mode(rmode, fp_status);
return prev_rmode;
}
/* Set the current fp rounding mode in the standard fp status and return
* the old one. This is for NEON instructions that need to change the
* rounding mode but wish to use the standard FPSCR values for everything
* else. Always set the rounding mode back to the correct value after
* modifying it.
* The argument is a softfloat float_round_ value.
*/
uint32_t HELPER(set_neon_rmode)(uint32_t rmode, CPUARMState *env)
{
float_status *fp_status = &env->vfp.standard_fp_status;
uint32_t prev_rmode = get_float_rounding_mode(fp_status);
set_float_rounding_mode(rmode, fp_status);
return prev_rmode;
}
/* Half precision conversions. */
float32 HELPER(vfp_fcvt_f16_to_f32)(uint32_t a, void *fpstp, uint32_t ahp_mode)
{
/* Squash FZ16 to 0 for the duration of conversion. In this case,
* it would affect flushing input denormals.
*/
float_status *fpst = fpstp;
bool save = get_flush_inputs_to_zero(fpst);
set_flush_inputs_to_zero(false, fpst);
float32 r = float16_to_float32(a, !ahp_mode, fpst);
set_flush_inputs_to_zero(save, fpst);
return r;
}
uint32_t HELPER(vfp_fcvt_f32_to_f16)(float32 a, void *fpstp, uint32_t ahp_mode)
{
/* Squash FZ16 to 0 for the duration of conversion. In this case,
* it would affect flushing output denormals.
*/
float_status *fpst = fpstp;
bool save = get_flush_to_zero(fpst);
set_flush_to_zero(false, fpst);
float16 r = float32_to_float16(a, !ahp_mode, fpst);
set_flush_to_zero(save, fpst);
return r;
}
float64 HELPER(vfp_fcvt_f16_to_f64)(uint32_t a, void *fpstp, uint32_t ahp_mode)
{
/* Squash FZ16 to 0 for the duration of conversion. In this case,
* it would affect flushing input denormals.
*/
float_status *fpst = fpstp;
bool save = get_flush_inputs_to_zero(fpst);
set_flush_inputs_to_zero(false, fpst);
float64 r = float16_to_float64(a, !ahp_mode, fpst);
set_flush_inputs_to_zero(save, fpst);
return r;
}
uint32_t HELPER(vfp_fcvt_f64_to_f16)(float64 a, void *fpstp, uint32_t ahp_mode)
{
/* Squash FZ16 to 0 for the duration of conversion. In this case,
* it would affect flushing output denormals.
*/
float_status *fpst = fpstp;
bool save = get_flush_to_zero(fpst);
set_flush_to_zero(false, fpst);
float16 r = float64_to_float16(a, !ahp_mode, fpst);
set_flush_to_zero(save, fpst);
return r;
}
#define float32_two make_float32(0x40000000)
#define float32_three make_float32(0x40400000)
#define float32_one_point_five make_float32(0x3fc00000)
float32 HELPER(recps_f32)(CPUARMState *env, float32 a, float32 b)
{
float_status *s = &env->vfp.standard_fp_status;
if ((float32_is_infinity(a) && float32_is_zero_or_denormal(b)) ||
(float32_is_infinity(b) && float32_is_zero_or_denormal(a))) {
if (!(float32_is_zero(a) || float32_is_zero(b))) {
float_raise(float_flag_input_denormal, s);
}
return float32_two;
}
return float32_sub(float32_two, float32_mul(a, b, s), s);
}
float32 HELPER(rsqrts_f32)(CPUARMState *env, float32 a, float32 b)
{
float_status *s = &env->vfp.standard_fp_status;
float32 product;
if ((float32_is_infinity(a) && float32_is_zero_or_denormal(b)) ||
(float32_is_infinity(b) && float32_is_zero_or_denormal(a))) {
if (!(float32_is_zero(a) || float32_is_zero(b))) {
float_raise(float_flag_input_denormal, s);
}
return float32_one_point_five;
}
product = float32_mul(a, b, s);
return float32_div(float32_sub(float32_three, product, s), float32_two, s);
}
/* NEON helpers. */
/* Constants 256 and 512 are used in some helpers; we avoid relying on
* int->float conversions at run-time. */
#define float64_256 make_float64(0x4070000000000000LL)
#define float64_512 make_float64(0x4080000000000000LL)
#define float16_maxnorm make_float16(0x7bff)
#define float32_maxnorm make_float32(0x7f7fffff)
#define float64_maxnorm make_float64(0x7fefffffffffffffLL)
/* Reciprocal functions
*
* The algorithm that must be used to calculate the estimate
* is specified by the ARM ARM, see FPRecipEstimate()/RecipEstimate
*/
/* See RecipEstimate()
*
* input is a 9 bit fixed point number
* input range 256 .. 511 for a number from 0.5 <= x < 1.0.
* result range 256 .. 511 for a number from 1.0 to 511/256.
*/
static int recip_estimate(int input)
{
int a, b, r;
assert(256 <= input && input < 512);
a = (input * 2) + 1;
b = (1 << 19) / a;
r = (b + 1) >> 1;
assert(256 <= r && r < 512);
return r;
}
/*
* Common wrapper to call recip_estimate
*
* The parameters are exponent and 64 bit fraction (without implicit
* bit) where the binary point is nominally at bit 52. Returns a
* float64 which can then be rounded to the appropriate size by the
* callee.
*/
static uint64_t call_recip_estimate(int *exp, int exp_off, uint64_t frac)
{
uint32_t scaled, estimate;
uint64_t result_frac;
int result_exp;
/* Handle sub-normals */
if (*exp == 0) {
if (extract64(frac, 51, 1) == 0) {
*exp = -1;
frac <<= 2;
} else {
frac <<= 1;
}
}
/* scaled = UInt('1':fraction<51:44>) */
scaled = deposit32(1 << 8, 0, 8, extract64(frac, 44, 8));
estimate = recip_estimate(scaled);
result_exp = exp_off - *exp;
result_frac = deposit64(0, 44, 8, estimate);
if (result_exp == 0) {
result_frac = deposit64(result_frac >> 1, 51, 1, 1);
} else if (result_exp == -1) {
result_frac = deposit64(result_frac >> 2, 50, 2, 1);
result_exp = 0;
}
*exp = result_exp;
return result_frac;
}
static bool round_to_inf(float_status *fpst, bool sign_bit)
{
switch (fpst->float_rounding_mode) {
case float_round_nearest_even: /* Round to Nearest */
return true;
case float_round_up: /* Round to +Inf */
return !sign_bit;
case float_round_down: /* Round to -Inf */
return sign_bit;
case float_round_to_zero: /* Round to Zero */
return false;
default:
g_assert_not_reached();
}
}
uint32_t HELPER(recpe_f16)(uint32_t input, void *fpstp)
{
float_status *fpst = fpstp;
float16 f16 = float16_squash_input_denormal(input, fpst);
uint32_t f16_val = float16_val(f16);
uint32_t f16_sign = float16_is_neg(f16);
int f16_exp = extract32(f16_val, 10, 5);
uint32_t f16_frac = extract32(f16_val, 0, 10);
uint64_t f64_frac;
if (float16_is_any_nan(f16)) {
float16 nan = f16;
if (float16_is_signaling_nan(f16, fpst)) {
float_raise(float_flag_invalid, fpst);
nan = float16_silence_nan(f16, fpst);
}
if (fpst->default_nan_mode) {
nan = float16_default_nan(fpst);
}
return nan;
} else if (float16_is_infinity(f16)) {
return float16_set_sign(float16_zero, float16_is_neg(f16));
} else if (float16_is_zero(f16)) {
float_raise(float_flag_divbyzero, fpst);
return float16_set_sign(float16_infinity, float16_is_neg(f16));
} else if (float16_abs(f16) < (1 << 8)) {
/* Abs(value) < 2.0^-16 */
float_raise(float_flag_overflow | float_flag_inexact, fpst);
if (round_to_inf(fpst, f16_sign)) {
return float16_set_sign(float16_infinity, f16_sign);
} else {
return float16_set_sign(float16_maxnorm, f16_sign);
}
} else if (f16_exp >= 29 && fpst->flush_to_zero) {
float_raise(float_flag_underflow, fpst);
return float16_set_sign(float16_zero, float16_is_neg(f16));
}
f64_frac = call_recip_estimate(&f16_exp, 29,
((uint64_t) f16_frac) << (52 - 10));
/* result = sign : result_exp<4:0> : fraction<51:42> */
f16_val = deposit32(0, 15, 1, f16_sign);
f16_val = deposit32(f16_val, 10, 5, f16_exp);
f16_val = deposit32(f16_val, 0, 10, extract64(f64_frac, 52 - 10, 10));
return make_float16(f16_val);
}
float32 HELPER(recpe_f32)(float32 input, void *fpstp)
{
float_status *fpst = fpstp;
float32 f32 = float32_squash_input_denormal(input, fpst);
uint32_t f32_val = float32_val(f32);
bool f32_sign = float32_is_neg(f32);
int f32_exp = extract32(f32_val, 23, 8);
uint32_t f32_frac = extract32(f32_val, 0, 23);
uint64_t f64_frac;
if (float32_is_any_nan(f32)) {
float32 nan = f32;
if (float32_is_signaling_nan(f32, fpst)) {
float_raise(float_flag_invalid, fpst);
nan = float32_silence_nan(f32, fpst);
}
if (fpst->default_nan_mode) {
nan = float32_default_nan(fpst);
}
return nan;
} else if (float32_is_infinity(f32)) {
return float32_set_sign(float32_zero, float32_is_neg(f32));
} else if (float32_is_zero(f32)) {
float_raise(float_flag_divbyzero, fpst);
return float32_set_sign(float32_infinity, float32_is_neg(f32));
} else if (float32_abs(f32) < (1ULL << 21)) {
/* Abs(value) < 2.0^-128 */
float_raise(float_flag_overflow | float_flag_inexact, fpst);
if (round_to_inf(fpst, f32_sign)) {
return float32_set_sign(float32_infinity, f32_sign);
} else {
return float32_set_sign(float32_maxnorm, f32_sign);
}
} else if (f32_exp >= 253 && fpst->flush_to_zero) {
float_raise(float_flag_underflow, fpst);
return float32_set_sign(float32_zero, float32_is_neg(f32));
}
f64_frac = call_recip_estimate(&f32_exp, 253,
((uint64_t) f32_frac) << (52 - 23));
/* result = sign : result_exp<7:0> : fraction<51:29> */
f32_val = deposit32(0, 31, 1, f32_sign);
f32_val = deposit32(f32_val, 23, 8, f32_exp);
f32_val = deposit32(f32_val, 0, 23, extract64(f64_frac, 52 - 23, 23));
return make_float32(f32_val);
}
float64 HELPER(recpe_f64)(float64 input, void *fpstp)
{
float_status *fpst = fpstp;
float64 f64 = float64_squash_input_denormal(input, fpst);
uint64_t f64_val = float64_val(f64);
bool f64_sign = float64_is_neg(f64);
int f64_exp = extract64(f64_val, 52, 11);
uint64_t f64_frac = extract64(f64_val, 0, 52);
/* Deal with any special cases */
if (float64_is_any_nan(f64)) {
float64 nan = f64;
if (float64_is_signaling_nan(f64, fpst)) {
float_raise(float_flag_invalid, fpst);
nan = float64_silence_nan(f64, fpst);
}
if (fpst->default_nan_mode) {
nan = float64_default_nan(fpst);
}
return nan;
} else if (float64_is_infinity(f64)) {
return float64_set_sign(float64_zero, float64_is_neg(f64));
} else if (float64_is_zero(f64)) {
float_raise(float_flag_divbyzero, fpst);
return float64_set_sign(float64_infinity, float64_is_neg(f64));
} else if ((f64_val & ~(1ULL << 63)) < (1ULL << 50)) {
/* Abs(value) < 2.0^-1024 */
float_raise(float_flag_overflow | float_flag_inexact, fpst);
if (round_to_inf(fpst, f64_sign)) {
return float64_set_sign(float64_infinity, f64_sign);
} else {
return float64_set_sign(float64_maxnorm, f64_sign);
}
} else if (f64_exp >= 2045 && fpst->flush_to_zero) {
float_raise(float_flag_underflow, fpst);
return float64_set_sign(float64_zero, float64_is_neg(f64));
}
f64_frac = call_recip_estimate(&f64_exp, 2045, f64_frac);
/* result = sign : result_exp<10:0> : fraction<51:0>; */
f64_val = deposit64(0, 63, 1, f64_sign);
f64_val = deposit64(f64_val, 52, 11, f64_exp);
f64_val = deposit64(f64_val, 0, 52, f64_frac);
return make_float64(f64_val);
}
/* The algorithm that must be used to calculate the estimate
* is specified by the ARM ARM.
*/
static int do_recip_sqrt_estimate(int a)
{
int b, estimate;
assert(128 <= a && a < 512);
if (a < 256) {
a = a * 2 + 1;
} else {
a = (a >> 1) << 1;
a = (a + 1) * 2;
}
b = 512;
while (a * (b + 1) * (b + 1) < (1 << 28)) {
b += 1;
}
estimate = (b + 1) / 2;
assert(256 <= estimate && estimate < 512);
return estimate;
}
static uint64_t recip_sqrt_estimate(int *exp , int exp_off, uint64_t frac)
{
int estimate;
uint32_t scaled;
if (*exp == 0) {
while (extract64(frac, 51, 1) == 0) {
frac = frac << 1;
*exp -= 1;
}
frac = extract64(frac, 0, 51) << 1;
}
if (*exp & 1) {
/* scaled = UInt('01':fraction<51:45>) */
scaled = deposit32(1 << 7, 0, 7, extract64(frac, 45, 7));
} else {
/* scaled = UInt('1':fraction<51:44>) */
scaled = deposit32(1 << 8, 0, 8, extract64(frac, 44, 8));
}
estimate = do_recip_sqrt_estimate(scaled);
*exp = (exp_off - *exp) / 2;
return extract64(estimate, 0, 8) << 44;
}
uint32_t HELPER(rsqrte_f16)(uint32_t input, void *fpstp)
{
float_status *s = fpstp;
float16 f16 = float16_squash_input_denormal(input, s);
uint16_t val = float16_val(f16);
bool f16_sign = float16_is_neg(f16);
int f16_exp = extract32(val, 10, 5);
uint16_t f16_frac = extract32(val, 0, 10);
uint64_t f64_frac;
if (float16_is_any_nan(f16)) {
float16 nan = f16;
if (float16_is_signaling_nan(f16, s)) {
float_raise(float_flag_invalid, s);
nan = float16_silence_nan(f16, s);
}
if (s->default_nan_mode) {
nan = float16_default_nan(s);
}
return nan;
} else if (float16_is_zero(f16)) {
float_raise(float_flag_divbyzero, s);
return float16_set_sign(float16_infinity, f16_sign);
} else if (f16_sign) {
float_raise(float_flag_invalid, s);
return float16_default_nan(s);
} else if (float16_is_infinity(f16)) {
return float16_zero;
}
/* Scale and normalize to a double-precision value between 0.25 and 1.0,
* preserving the parity of the exponent. */
f64_frac = ((uint64_t) f16_frac) << (52 - 10);
f64_frac = recip_sqrt_estimate(&f16_exp, 44, f64_frac);
/* result = sign : result_exp<4:0> : estimate<7:0> : Zeros(2) */
val = deposit32(0, 15, 1, f16_sign);
val = deposit32(val, 10, 5, f16_exp);
val = deposit32(val, 2, 8, extract64(f64_frac, 52 - 8, 8));
return make_float16(val);
}
float32 HELPER(rsqrte_f32)(float32 input, void *fpstp)
{
float_status *s = fpstp;
float32 f32 = float32_squash_input_denormal(input, s);
uint32_t val = float32_val(f32);
uint32_t f32_sign = float32_is_neg(f32);
int f32_exp = extract32(val, 23, 8);
uint32_t f32_frac = extract32(val, 0, 23);
uint64_t f64_frac;
if (float32_is_any_nan(f32)) {
float32 nan = f32;
if (float32_is_signaling_nan(f32, s)) {
float_raise(float_flag_invalid, s);
nan = float32_silence_nan(f32, s);
}
if (s->default_nan_mode) {
nan = float32_default_nan(s);
}
return nan;
} else if (float32_is_zero(f32)) {
float_raise(float_flag_divbyzero, s);
return float32_set_sign(float32_infinity, float32_is_neg(f32));
} else if (float32_is_neg(f32)) {
float_raise(float_flag_invalid, s);
return float32_default_nan(s);
} else if (float32_is_infinity(f32)) {
return float32_zero;
}
/* Scale and normalize to a double-precision value between 0.25 and 1.0,
* preserving the parity of the exponent. */
f64_frac = ((uint64_t) f32_frac) << 29;
f64_frac = recip_sqrt_estimate(&f32_exp, 380, f64_frac);
/* result = sign : result_exp<4:0> : estimate<7:0> : Zeros(15) */
val = deposit32(0, 31, 1, f32_sign);
val = deposit32(val, 23, 8, f32_exp);
val = deposit32(val, 15, 8, extract64(f64_frac, 52 - 8, 8));
return make_float32(val);
}
float64 HELPER(rsqrte_f64)(float64 input, void *fpstp)
{
float_status *s = fpstp;
float64 f64 = float64_squash_input_denormal(input, s);
uint64_t val = float64_val(f64);
bool f64_sign = float64_is_neg(f64);
int f64_exp = extract64(val, 52, 11);
uint64_t f64_frac = extract64(val, 0, 52);
if (float64_is_any_nan(f64)) {
float64 nan = f64;
if (float64_is_signaling_nan(f64, s)) {
float_raise(float_flag_invalid, s);
nan = float64_silence_nan(f64, s);
}
if (s->default_nan_mode) {
nan = float64_default_nan(s);
}
return nan;
} else if (float64_is_zero(f64)) {
float_raise(float_flag_divbyzero, s);
return float64_set_sign(float64_infinity, float64_is_neg(f64));
} else if (float64_is_neg(f64)) {
float_raise(float_flag_invalid, s);
return float64_default_nan(s);
} else if (float64_is_infinity(f64)) {
return float64_zero;
}
f64_frac = recip_sqrt_estimate(&f64_exp, 3068, f64_frac);
/* result = sign : result_exp<4:0> : estimate<7:0> : Zeros(44) */
val = deposit64(0, 61, 1, f64_sign);
val = deposit64(val, 52, 11, f64_exp);
val = deposit64(val, 44, 8, extract64(f64_frac, 52 - 8, 8));
return make_float64(val);
}
uint32_t HELPER(recpe_u32)(uint32_t a)
{
int input, estimate;
if ((a & 0x80000000) == 0) {
return 0xffffffff;
}
input = extract32(a, 23, 9);
estimate = recip_estimate(input);
return deposit32(0, (32 - 9), 9, estimate);
}
uint32_t HELPER(rsqrte_u32)(uint32_t a)
{
int estimate;
if ((a & 0xc0000000) == 0) {
return 0xffffffff;
}
estimate = do_recip_sqrt_estimate(extract32(a, 23, 9));
return deposit32(0, 23, 9, estimate);
}
/* VFPv4 fused multiply-accumulate */
float32 VFP_HELPER(muladd, s)(float32 a, float32 b, float32 c, void *fpstp)
{
float_status *fpst = fpstp;
return float32_muladd(a, b, c, 0, fpst);
}
float64 VFP_HELPER(muladd, d)(float64 a, float64 b, float64 c, void *fpstp)
{
float_status *fpst = fpstp;
return float64_muladd(a, b, c, 0, fpst);
}
/* ARMv8 round to integral */
float32 HELPER(rints_exact)(float32 x, void *fp_status)
{
return float32_round_to_int(x, fp_status);
}
float64 HELPER(rintd_exact)(float64 x, void *fp_status)
{
return float64_round_to_int(x, fp_status);
}
float32 HELPER(rints)(float32 x, void *fp_status)
{
int old_flags = get_float_exception_flags(fp_status), new_flags;
float32 ret;
ret = float32_round_to_int(x, fp_status);
/* Suppress any inexact exceptions the conversion produced */
if (!(old_flags & float_flag_inexact)) {
new_flags = get_float_exception_flags(fp_status);
set_float_exception_flags(new_flags & ~float_flag_inexact, fp_status);
}
return ret;
}
float64 HELPER(rintd)(float64 x, void *fp_status)
{
int old_flags = get_float_exception_flags(fp_status), new_flags;
float64 ret;
ret = float64_round_to_int(x, fp_status);
new_flags = get_float_exception_flags(fp_status);
/* Suppress any inexact exceptions the conversion produced */
if (!(old_flags & float_flag_inexact)) {
new_flags = get_float_exception_flags(fp_status);
set_float_exception_flags(new_flags & ~float_flag_inexact, fp_status);
}
return ret;
}
/* Convert ARM rounding mode to softfloat */
int arm_rmode_to_sf(int rmode)
{
switch (rmode) {
case FPROUNDING_TIEAWAY:
rmode = float_round_ties_away;
break;
case FPROUNDING_ODD:
/* FIXME: add support for TIEAWAY and ODD */
qemu_log_mask(LOG_UNIMP, "arm: unimplemented rounding mode: %d\n",
rmode);
/* fall through for now */
case FPROUNDING_TIEEVEN:
default:
rmode = float_round_nearest_even;
break;
case FPROUNDING_POSINF:
rmode = float_round_up;
break;
case FPROUNDING_NEGINF:
rmode = float_round_down;
break;
case FPROUNDING_ZERO:
rmode = float_round_to_zero;
break;
}
return rmode;
}
/*
* Implement float64 to int32_t conversion without saturation;
* the result is supplied modulo 2^32.
*/
uint64_t HELPER(fjcvtzs)(float64 value, void *vstatus)
{
float_status *status = vstatus;
uint32_t exp, sign;
uint64_t frac;
uint32_t inexact = 1; /* !Z */
sign = extract64(value, 63, 1);
exp = extract64(value, 52, 11);
frac = extract64(value, 0, 52);
if (exp == 0) {
/* While not inexact for IEEE FP, -0.0 is inexact for JavaScript. */
inexact = sign;
if (frac != 0) {
if (status->flush_inputs_to_zero) {
float_raise(float_flag_input_denormal, status);
} else {
float_raise(float_flag_inexact, status);
inexact = 1;
}
}
frac = 0;
} else if (exp == 0x7ff) {
/* This operation raises Invalid for both NaN and overflow (Inf). */
float_raise(float_flag_invalid, status);
frac = 0;
} else {
int true_exp = exp - 1023;
int shift = true_exp - 52;
/* Restore implicit bit. */
frac |= 1ull << 52;
/* Shift the fraction into place. */
if (shift >= 0) {
/* The number is so large we must shift the fraction left. */
if (shift >= 64) {
/* The fraction is shifted out entirely. */
frac = 0;
} else {
frac <<= shift;
}
} else if (shift > -64) {
/* Normal case -- shift right and notice if bits shift out. */
inexact = (frac << (64 + shift)) != 0;
frac >>= -shift;
} else {
/* The fraction is shifted out entirely. */
frac = 0;
}
/* Notice overflow or inexact exceptions. */
if (true_exp > 31 || frac > (sign ? 0x80000000ull : 0x7fffffff)) {
/* Overflow, for which this operation raises invalid. */
float_raise(float_flag_invalid, status);
inexact = 1;
} else if (inexact) {
float_raise(float_flag_inexact, status);
}
/* Honor the sign. */
if (sign) {
frac = -frac;
}
}
/* Pack the result and the env->ZF representation of Z together. */
return deposit64(frac, 32, 32, inexact);
}
uint32_t HELPER(vjcvt)(float64 value, CPUARMState *env)
{
uint64_t pair = HELPER(fjcvtzs)(value, &env->vfp.fp_status);
uint32_t result = pair;
uint32_t z = (pair >> 32) == 0;
/* Store Z, clear NCV, in FPSCR.NZCV. */
env->vfp.xregs[ARM_VFP_FPSCR]
= (env->vfp.xregs[ARM_VFP_FPSCR] & ~CPSR_NZCV) | (z * CPSR_Z);
return result;
}
/* Round a float32 to an integer that fits in int32_t or int64_t. */
static float32 frint_s(float32 f, float_status *fpst, int intsize)
{
int old_flags = get_float_exception_flags(fpst);
uint32_t exp = extract32(f, 23, 8);
if (unlikely(exp == 0xff)) {
/* NaN or Inf. */
goto overflow;
}
/* Round and re-extract the exponent. */
f = float32_round_to_int(f, fpst);
exp = extract32(f, 23, 8);
/* Validate the range of the result. */
if (exp < 126 + intsize) {
/* abs(F) <= INT{N}_MAX */
return f;
}
if (exp == 126 + intsize) {
uint32_t sign = extract32(f, 31, 1);
uint32_t frac = extract32(f, 0, 23);
if (sign && frac == 0) {
/* F == INT{N}_MIN */
return f;
}
}
overflow:
/*
* Raise Invalid and return INT{N}_MIN as a float. Revert any
* inexact exception float32_round_to_int may have raised.
*/
set_float_exception_flags(old_flags | float_flag_invalid, fpst);
return (0x100u + 126u + intsize) << 23;
}
float32 HELPER(frint32_s)(float32 f, void *fpst)
{
return frint_s(f, fpst, 32);
}
float32 HELPER(frint64_s)(float32 f, void *fpst)
{
return frint_s(f, fpst, 64);
}
/* Round a float64 to an integer that fits in int32_t or int64_t. */
static float64 frint_d(float64 f, float_status *fpst, int intsize)
{
int old_flags = get_float_exception_flags(fpst);
uint32_t exp = extract64(f, 52, 11);
if (unlikely(exp == 0x7ff)) {
/* NaN or Inf. */
goto overflow;
}
/* Round and re-extract the exponent. */
f = float64_round_to_int(f, fpst);
exp = extract64(f, 52, 11);
/* Validate the range of the result. */
if (exp < 1022 + intsize) {
/* abs(F) <= INT{N}_MAX */
return f;
}
if (exp == 1022 + intsize) {
uint64_t sign = extract64(f, 63, 1);
uint64_t frac = extract64(f, 0, 52);
if (sign && frac == 0) {
/* F == INT{N}_MIN */
return f;
}
}
overflow:
/*
* Raise Invalid and return INT{N}_MIN as a float. Revert any
* inexact exception float64_round_to_int may have raised.
*/
set_float_exception_flags(old_flags | float_flag_invalid, fpst);
return (uint64_t)(0x800 + 1022 + intsize) << 52;
}
float64 HELPER(frint32_d)(float64 f, void *fpst)
{
return frint_d(f, fpst, 32);
}
float64 HELPER(frint64_d)(float64 f, void *fpst)
{
return frint_d(f, fpst, 64);
}
void HELPER(check_hcr_el2_trap)(CPUARMState *env, uint32_t rt, uint32_t reg)
{
uint32_t syndrome;
switch (reg) {
case ARM_VFP_MVFR0:
case ARM_VFP_MVFR1:
case ARM_VFP_MVFR2:
if (!(arm_hcr_el2_eff(env) & HCR_TID3)) {
return;
}
break;
case ARM_VFP_FPSID:
if (!(arm_hcr_el2_eff(env) & HCR_TID0)) {
return;
}
break;
default:
g_assert_not_reached();
}
syndrome = ((EC_FPIDTRAP << ARM_EL_EC_SHIFT)
| ARM_EL_IL
| (1 << 24) | (0xe << 20) | (7 << 14)
| (reg << 10) | (rt << 5) | 1);
raise_exception(env, EXCP_HYP_TRAP, syndrome, 2);
}
#endif
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