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d31e2ce68d
qemu-e2k/target/arm/vfp_helper.c
Peter Maydell d31e2ce68d target/arm: Allow M-profile CPUs with FP16 to set FPSCR.FP16 
M-profile CPUs with half-precision floating point support should
be able to write to FPSCR.FZ16, but an M-profile specific masking
of the value at the top of vfp_set_fpscr() currently prevents that.
This is not yet an active bug because we have no M-profile
FP16 CPUs, but needs to be fixed before we can add any.

The bits that the masking is effectively preventing from being
set are the A-profile only short-vector Len and Stride fields,
plus the Neon QC bit. Rearrange the order of the function so
that those fields are handled earlier and only under a suitable
guard; this allows us to drop the M-profile specific masking,
making FZ16 writeable.

This change also makes the QC bit correctly RAZ/WI for older
no-Neon A-profile cores.

This refactoring also paves the way for the low-overhead-branch
LTPSIZE field, which uses some of the bits that are used for
A-profile Stride and Len.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20201019151301.2046-10-peter.maydell@linaro.org
2020-10-20 16:12:01 +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;
}
vfp_set_fpscr_to_host(env, val);
if (!arm_feature(env, ARM_FEATURE_M)) {
/*
* Short-vector length and stride; on M-profile these bits
* are used for different purposes.
* We can't make this conditional be "if MVFR0.FPShVec != 0",
* because in v7A no-short-vector-support cores still had to
* allow Stride/Len to be written with the only effect that
* some insns are required to UNDEF if the guest sets them.
*
* TODO: if M-profile MVE implemented, set LTPSIZE.
*/
env->vfp.vec_len = extract32(val, 16, 3);
env->vfp.vec_stride = extract32(val, 20, 2);
}
if (arm_feature(env, ARM_FEATURE_NEON)) {
/*
* The bit we set within fpscr_q is arbitrary; the register as a
* whole being zero/non-zero is what counts.
* TODO: M-profile MVE also has a QC bit.
*/
env->vfp.qc[0] = val & FPCR_QC;
env->vfp.qc[1] = 0;
env->vfp.qc[2] = 0;
env->vfp.qc[3] = 0;
}
/*
* We don't implement trapped exception handling, so the
* trap enable bits, IDE|IXE|UFE|OFE|DZE|IOE are all RAZ/WI (not RES0!)
*
* The exception flags IOC|DZC|OFC|UFC|IXC|IDC are stored in
* fp_status; QC, Len and Stride are stored separately earlier.
* Clear out all of those and the RES0 bits: only NZCV, AHP, DN,
* FZ, RMode and FZ16 are kept in vfp.xregs[FPSCR].
*/
env->vfp.xregs[ARM_VFP_FPSCR] = val & 0xf7c80000;
}
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) \
dh_ctype_f16 VFP_HELPER(name, h)(dh_ctype_f16 a, dh_ctype_f16 b, void *fpstp) \
{ \
float_status *fpst = fpstp; \
return float16_ ## name(a, b, fpst); \
} \
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
dh_ctype_f16 VFP_HELPER(neg, h)(dh_ctype_f16 a)
{
return float16_chs(a);
}
float32 VFP_HELPER(neg, s)(float32 a)
{
return float32_chs(a);
}
float64 VFP_HELPER(neg, d)(float64 a)
{
return float64_chs(a);
}
dh_ctype_f16 VFP_HELPER(abs, h)(dh_ctype_f16 a)
{
return float16_abs(a);
}
float32 VFP_HELPER(abs, s)(float32 a)
{
return float32_abs(a);
}
float64 VFP_HELPER(abs, d)(float64 a)
{
return float64_abs(a);
}
dh_ctype_f16 VFP_HELPER(sqrt, h)(dh_ctype_f16 a, CPUARMState *env)
{
return float16_sqrt(a, &env->vfp.fp_status_f16);
}
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, FLOATTYPE, ARGTYPE, FPST) \
void VFP_HELPER(cmp, P)(ARGTYPE a, ARGTYPE b, CPUARMState *env) \
{ \
softfloat_to_vfp_compare(env, \
FLOATTYPE ## _compare_quiet(a, b, &env->vfp.FPST)); \
} \
void VFP_HELPER(cmpe, P)(ARGTYPE a, ARGTYPE b, CPUARMState *env) \
{ \
softfloat_to_vfp_compare(env, \
FLOATTYPE ## _compare(a, b, &env->vfp.FPST)); \
}
DO_VFP_cmp(h, float16, dh_ctype_f16, fp_status_f16)
DO_VFP_cmp(s, float32, float32, fp_status)
DO_VFP_cmp(d, float64, float64, fp_status)
#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. The AArch32 versions of fix-to-float
* must always round-to-nearest; the AArch64 ones honour the FPSCR
* rounding mode. (For AArch32 Neon the standard-FPSCR is set to
* round-to-nearest so either helper will work.) AArch32 float-to-fix
* must round-to-zero.
*/
#define VFP_CONV_FIX_FLOAT(name, p, fsz, ftype, isz, itype) \
ftype 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_FIX_FLOAT_ROUND(name, p, fsz, ftype, isz, itype) \
ftype HELPER(vfp_##name##to##p##_round_to_nearest)(uint##isz##_t x, \
uint32_t shift, \
void *fpstp) \
{ \
ftype ret; \
float_status *fpst = fpstp; \
FloatRoundMode oldmode = fpst->float_rounding_mode; \
fpst->float_rounding_mode = float_round_nearest_even; \
ret = itype##_to_##float##fsz##_scalbn(x, -shift, fpstp); \
fpst->float_rounding_mode = oldmode; \
return ret; \
}
#define VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, ftype, isz, itype, ROUND, suff) \
uint##isz##_t HELPER(vfp_to##name##p##suff)(ftype 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, ftype, isz, itype) \
VFP_CONV_FIX_FLOAT(name, p, fsz, ftype, isz, itype) \
VFP_CONV_FIX_FLOAT_ROUND(name, p, fsz, ftype, isz, itype) \
VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, ftype, isz, itype, \
float_round_to_zero, _round_to_zero) \
VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, ftype, isz, itype, \
get_float_rounding_mode(fpst), )
#define VFP_CONV_FIX_A64(name, p, fsz, ftype, isz, itype) \
VFP_CONV_FIX_FLOAT(name, p, fsz, ftype, isz, itype) \
VFP_CONV_FLOAT_FIX_ROUND(name, p, fsz, ftype, isz, itype, \
get_float_rounding_mode(fpst), )
VFP_CONV_FIX(sh, d, 64, float64, 64, int16)
VFP_CONV_FIX(sl, d, 64, float64, 64, int32)
VFP_CONV_FIX_A64(sq, d, 64, float64, 64, int64)
VFP_CONV_FIX(uh, d, 64, float64, 64, uint16)
VFP_CONV_FIX(ul, d, 64, float64, 64, uint32)
VFP_CONV_FIX_A64(uq, d, 64, float64, 64, uint64)
VFP_CONV_FIX(sh, s, 32, float32, 32, int16)
VFP_CONV_FIX(sl, s, 32, float32, 32, int32)
VFP_CONV_FIX_A64(sq, s, 32, float32, 64, int64)
VFP_CONV_FIX(uh, s, 32, float32, 32, uint16)
VFP_CONV_FIX(ul, s, 32, float32, 32, uint32)
VFP_CONV_FIX_A64(uq, s, 32, float32, 64, uint64)
VFP_CONV_FIX(sh, h, 16, dh_ctype_f16, 32, int16)
VFP_CONV_FIX(sl, h, 16, dh_ctype_f16, 32, int32)
VFP_CONV_FIX_A64(sq, h, 16, dh_ctype_f16, 64, int64)
VFP_CONV_FIX(uh, h, 16, dh_ctype_f16, 32, uint16)
VFP_CONV_FIX(ul, h, 16, dh_ctype_f16, 32, uint32)
VFP_CONV_FIX_A64(uq, h, 16, dh_ctype_f16, 64, uint64)
#undef VFP_CONV_FIX
#undef VFP_CONV_FIX_FLOAT
#undef VFP_CONV_FLOAT_FIX_ROUND
#undef VFP_CONV_FIX_A64
/* 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;
}
/* 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;
}
/* 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 */
dh_ctype_f16 VFP_HELPER(muladd, h)(dh_ctype_f16 a, dh_ctype_f16 b,
dh_ctype_f16 c, void *fpstp)
{
float_status *fpst = fpstp;
return float16_muladd(a, b, c, 0, fpst);
}
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 */
dh_ctype_f16 HELPER(rinth_exact)(dh_ctype_f16 x, void *fp_status)
{
return float16_round_to_int(x, fp_status);
}
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);
}
dh_ctype_f16 HELPER(rinth)(dh_ctype_f16 x, void *fp_status)
{
int old_flags = get_float_exception_flags(fp_status), new_flags;
float16 ret;
ret = float16_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;
}
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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