def legalize_mp_3elt_comparison(optree):
""" Transform comparison on ML_Compound_FP_Format object into
comparison on sub-fields """
specifier = optree.specifier
lhs = optree.get_input(0)
rhs = optree.get_input(1)
# TODO/FIXME: assume than multi-limb operand are normalized
if specifier == Comparison.Equal:
return LogicalAnd(
Comparison(lhs.hi, rhs.hi, specifier=Comparison.Equal, precision=ML_Bool),
LogicalAnd(
Comparison(lhs.me, rhs.me, specifier=Comparison.Equal, precision=ML_Bool),
Comparison(lhs.lo, rhs.lo, specifier=Comparison.Equal, precision=ML_Bool),
precision=ML_Bool
),
precision=ML_Bool
)
elif specifier == Comparison.NotEqual:
return LogicalOr(
Comparison(lhs.hi, rhs.hi, specifier=Comparison.NotEqual, precision=ML_Bool),
LogicalOr(
Comparison(lhs.me, rhs.me, specifier=Comparison.NotEqual, precision=ML_Bool),
Comparison(lhs.lo, rhs.lo, specifier=Comparison.NotEqual, precision=ML_Bool),
precision=ML_Bool
),
precision=ML_Bool
)
elif specifier in [Comparison.LessOrEqual, Comparison.GreaterOrEqual, Comparison.Greater, Comparison.Less]:
strict_specifier = {
Comparison.Less: Comparison.Less,
Comparison.Greater: Comparison.Greater,
Comparison.LessOrEqual: Comparison.Less,
Comparison.GreaterOrEqual: Comparison.Greater
}[specifier]
return LogicalOr(
Comparison(lhs.hi, rhs.hi, specifier=strict_specifier, precision=ML_Bool),
LogicalAnd(
Comparison(lhs.hi, rhs.hi, specifier=Comparison.Equal, precision=ML_Bool),
LogicalOr(
Comparison(lhs.me, rhs.me, specifier=strict_specifier, precision=ML_Bool),
LogicalAnd(
Comparison(lhs.me, rhs.me, specifier=Comparison.Equal, precision=ML_Bool),
Comparison(lhs.lo, rhs.lo, specifier=specifier, precision=ML_Bool),
precision=ML_Bool
),
precision=ML_Bool
),
precision=ML_Bool
),
precision=ML_Bool
)
else:
Log.report(Log.Error, "unsupported specifier {} in legalize_mp_2elt_comparison", specifier)
def legalize_comp_sign(node):
""" legalize a Test.CompSign node to a series of
comparison with 0 and logical operation """
# TODO/IDEA: could also be implemented by two 2 copy sign with 1.0 and valuda
# comparison
lhs = node.get_input(0)
lhs_zero = Constant(0, precision=lhs.get_precision())
rhs = node.get_input(1)
rhs_zero = Constant(0, precision=rhs.get_precision())
return LogicalOr(
LogicalAnd(lhs >= lhs_zero, rhs >= rhs_zero),
LogicalAnd(lhs <= lhs_zero, rhs <= rhs_zero),
)
def generate_scheme(self):
""" main scheme generation """
input_precision = self.precision
output_precision = self.precision
# declaring main input variable
x_interval = Interval(-10.3, 10.7)
var_x = self.implementation.add_input_variable("x",
input_precision,
interval=x_interval)
y_interval = Interval(-17.9, 17.2)
var_y = self.implementation.add_input_variable("y",
input_precision,
interval=y_interval)
z_interval = Interval(-70.3, -57.7)
var_z = self.implementation.add_input_variable("z",
input_precision,
interval=z_interval)
min_yz = Min(var_z, var_y)
cst0 = Constant(42.5, tag="cst0", precision=self.precision)
cst1 = Constant(2.5, tag="cst1", precision=self.precision)
cst2 = Constant(12.5, tag="cst2", precision=self.precision)
new_cst = cst0 + cst1 * cst2
result = min_yz + new_cst
scheme = ConditionBlock(
LogicalAnd(
LogicalOr(cst0 > cst1, LogicalNot(cst1 > cst0)),
var_x > var_y,
), Return(result), Return(cst2))
return scheme
def generate_scalar_scheme(self, vx):
Log.set_dump_stdout(True)
Log.report(Log.Info, "\033[33;1m generating implementation scheme \033[0m")
if self.debug_flag:
Log.report(Log.Info, "\033[31;1m debug has been enabled \033[0;m")
# local overloading of RaiseReturn operation
def ExpRaiseReturn(*args, **kwords):
kwords["arg_value"] = vx
kwords["function_name"] = self.function_name
if self.libm_compliant:
return RaiseReturn(*args, precision=self.precision, **kwords)
else:
return Return(kwords["return_value"], precision=self.precision)
test_nan_or_inf = Test(
vx, specifier=Test.IsInfOrNaN, likely=False,
debug=debug_multi, tag="nan_or_inf")
test_nan = Test(
vx, specifier=Test.IsNaN, debug=debug_multi, tag="is_nan_test")
test_positive = Comparison(
vx, 0, specifier=Comparison.GreaterOrEqual, debug=debug_multi,
tag="inf_sign")
test_signaling_nan = Test(
vx, specifier=Test.IsSignalingNaN, debug=debug_multi,
tag="is_signaling_nan")
return_snan = Statement(
ExpRaiseReturn(ML_FPE_Invalid, return_value=FP_QNaN(self.precision))
)
# return in case of infinity input
infty_return = Statement(
ConditionBlock(
test_positive,
Return(FP_PlusInfty(self.precision), precision=self.precision),
Return(FP_PlusZero(self.precision), precision=self.precision)
)
)
# return in case of specific value input (NaN or inf)
specific_return = ConditionBlock(
test_nan,
ConditionBlock(
test_signaling_nan,
return_snan,
Return(FP_QNaN(self.precision), precision=self.precision)
),
infty_return)
# return in case of standard (non-special) input
# exclusion of early overflow and underflow cases
precision_emax = self.precision.get_emax()
precision_max_value = S2 * S2**precision_emax
exp_overflow_bound = sollya.ceil(log(precision_max_value))
early_overflow_test = Comparison(
vx, exp_overflow_bound,
likely=False, specifier=Comparison.Greater)
early_overflow_return = Statement(
ClearException() if self.libm_compliant else Statement(),
ExpRaiseReturn(
ML_FPE_Inexact, ML_FPE_Overflow,
return_value=FP_PlusInfty(self.precision)
)
)
precision_emin = self.precision.get_emin_subnormal()
precision_min_value = S2 ** precision_emin
exp_underflow_bound = floor(log(precision_min_value))
early_underflow_test = Comparison(
vx, exp_underflow_bound,
likely=False, specifier=Comparison.Less)
early_underflow_return = Statement(
ClearException() if self.libm_compliant else Statement(),
ExpRaiseReturn(
ML_FPE_Inexact, ML_FPE_Underflow,
return_value=FP_PlusZero(self.precision)))
# constant computation
invlog2 = self.precision.round_sollya_object(1/log(2), sollya.RN)
interval_vx = Interval(exp_underflow_bound, exp_overflow_bound)
interval_fk = interval_vx * invlog2
interval_k = Interval(floor(inf(interval_fk)), sollya.ceil(sup(interval_fk)))
log2_hi_precision = self.precision.get_field_size() - (sollya.ceil(log2(sup(abs(interval_k)))) + 2)
Log.report(Log.Info, "log2_hi_precision: %d" % log2_hi_precision)
invlog2_cst = Constant(invlog2, precision = self.precision)
log2_hi = round(log(2), log2_hi_precision, sollya.RN)
log2_lo = self.precision.round_sollya_object(log(2) - log2_hi, sollya.RN)
# argument reduction
unround_k = vx * invlog2
unround_k.set_attributes(tag = "unround_k", debug = debug_multi)
k = NearestInteger(unround_k, precision = self.precision, debug = debug_multi, tag="k")
ik = NearestInteger(unround_k, precision = self.precision.get_integer_format(), debug = debug_multi, tag="ik")
exact_pre_mul = (k * log2_hi)
exact_pre_mul.set_attributes(exact= True)
exact_hi_part = vx - exact_pre_mul
exact_hi_part.set_attributes(exact = True, tag = "exact_hi", debug = debug_multi, prevent_optimization = True)
exact_lo_part = - k * log2_lo
exact_lo_part.set_attributes(tag = "exact_lo", debug = debug_multi, prevent_optimization = True)
r = exact_hi_part + exact_lo_part
r.set_tag("r")
r.set_attributes(debug = debug_multi)
approx_interval = Interval(-log(2)/2, log(2)/2)
approx_interval_half = approx_interval / 2
approx_interval_split = [Interval(-log(2)/2, inf(approx_interval_half)), approx_interval_half, Interval(sup(approx_interval_half), log(2)/2)]
# TODO: should be computed automatically
exact_hi_interval = approx_interval
exact_lo_interval = - interval_k * log2_lo
opt_r = self.optimise_scheme(r, copy = {})
tag_map = {}
self.opt_engine.register_nodes_by_tag(opt_r, tag_map)
cg_eval_error_copy_map = {
vx: Variable("x", precision=self.precision, interval=interval_vx),
tag_map["k"]: Variable("k", interval=interval_k, precision=self.precision)
}
#try:
if gappa_utils.is_gappa_installed():
eval_error = self.gappa_engine.get_eval_error_v2(
self.opt_engine, opt_r, cg_eval_error_copy_map,
gappa_filename=gappa_utils.generate_gappa_filename("red_arg.g"))
else:
eval_error = 0.0
Log.report(Log.Warning, "gappa is not installed in this environnement")
Log.report(Log.Info, "eval error: %s" % eval_error)
local_ulp = sup(ulp(sollya.exp(approx_interval), self.precision))
# FIXME refactor error_goal from accuracy
Log.report(Log.Info, "accuracy: %s" % self.accuracy)
if isinstance(self.accuracy, ML_Faithful):
error_goal = local_ulp
elif isinstance(self.accuracy, ML_CorrectlyRounded):
error_goal = S2**-1 * local_ulp
elif isinstance(self.accuracy, ML_DegradedAccuracyAbsolute):
error_goal = self.accuracy.goal
elif isinstance(self.accuracy, ML_DegradedAccuracyRelative):
error_goal = self.accuracy.goal
else:
Log.report(Log.Error, "unknown accuracy: %s" % self.accuracy)
# error_goal = local_ulp #S2**-(self.precision.get_field_size()+1)
error_goal_approx = S2**-1 * error_goal
Log.report(Log.Info, "\033[33;1m building mathematical polynomial \033[0m\n")
poly_degree = max(sup(guessdegree(expm1(sollya.x)/sollya.x, approx_interval, error_goal_approx)) - 1, 2)
init_poly_degree = poly_degree
error_function = lambda p, f, ai, mod, t: dirtyinfnorm(f - p, ai)
polynomial_scheme_builder = PolynomialSchemeEvaluator.generate_estrin_scheme
#polynomial_scheme_builder = PolynomialSchemeEvaluator.generate_horner_scheme
MAX_NUM_ITERATION = 20
for _ in range(MAX_NUM_ITERATION):
Log.report(Log.Info, "attempting poly degree: %d" % poly_degree)
precision_list = [1] + [self.precision] * (poly_degree)
poly_object, poly_approx_error = Polynomial.build_from_approximation_with_error(expm1(sollya.x), poly_degree, precision_list, approx_interval, sollya.absolute, error_function = error_function)
Log.report(Log.Info, "polynomial: %s " % poly_object)
sub_poly = poly_object.sub_poly(start_index = 2)
Log.report(Log.Info, "polynomial: %s " % sub_poly)
Log.report(Log.Info, "poly approx error: %s" % poly_approx_error)
Log.report(Log.Info, "\033[33;1m generating polynomial evaluation scheme \033[0m")
pre_poly = polynomial_scheme_builder(poly_object, r, unified_precision = self.precision)
pre_poly.set_attributes(tag = "pre_poly", debug = debug_multi)
pre_sub_poly = polynomial_scheme_builder(sub_poly, r, unified_precision = self.precision)
pre_sub_poly.set_attributes(tag = "pre_sub_poly", debug = debug_multi)
poly = 1 + (exact_hi_part + (exact_lo_part + pre_sub_poly))
poly.set_tag("poly")
# optimizing poly before evaluation error computation
#opt_poly = self.opt_engine.optimization_process(poly, self.precision, fuse_fma = fuse_fma)
#opt_sub_poly = self.opt_engine.optimization_process(pre_sub_poly, self.precision, fuse_fma = fuse_fma)
opt_poly = self.optimise_scheme(poly)
opt_sub_poly = self.optimise_scheme(pre_sub_poly)
# evaluating error of the polynomial approximation
r_gappa_var = Variable("r", precision = self.precision, interval = approx_interval)
exact_hi_gappa_var = Variable("exact_hi", precision = self.precision, interval = exact_hi_interval)
exact_lo_gappa_var = Variable("exact_lo", precision = self.precision, interval = exact_lo_interval)
vx_gappa_var = Variable("x", precision = self.precision, interval = interval_vx)
k_gappa_var = Variable("k", interval = interval_k, precision = self.precision)
#print "exact_hi interval: ", exact_hi_interval
sub_poly_error_copy_map = {
#r.get_handle().get_node(): r_gappa_var,
#vx.get_handle().get_node(): vx_gappa_var,
exact_hi_part.get_handle().get_node(): exact_hi_gappa_var,
exact_lo_part.get_handle().get_node(): exact_lo_gappa_var,
#k.get_handle().get_node(): k_gappa_var,
}
poly_error_copy_map = {
exact_hi_part.get_handle().get_node(): exact_hi_gappa_var,
exact_lo_part.get_handle().get_node(): exact_lo_gappa_var,
}
if gappa_utils.is_gappa_installed():
sub_poly_eval_error = -1.0
gappa_sub_poly_filename = gappa_utils.generate_gappa_filename("{}_gappa_sub_poly.g".format(self.function_name))
sub_poly_eval_error = self.gappa_engine.get_eval_error_v2(self.opt_engine, opt_sub_poly, sub_poly_error_copy_map, gappa_filename =gappa_sub_poly_filename)
dichotomy_map = [
{
exact_hi_part.get_handle().get_node(): approx_interval_split[0],
},
{
exact_hi_part.get_handle().get_node(): approx_interval_split[1],
},
{
exact_hi_part.get_handle().get_node(): approx_interval_split[2],
},
]
gappa_poly_filename = gappa_utils.generate_gappa_filename("gappa_poly.g")
poly_eval_error_dico = self.gappa_engine.get_eval_error_v3(self.opt_engine, opt_poly, poly_error_copy_map, gappa_filename=gappa_poly_filename, dichotomy = dichotomy_map)
poly_eval_error = max([sup(abs(err)) for err in poly_eval_error_dico])
else:
poly_eval_error = 0.0
sub_poly_eval_error = 0.0
Log.report(Log.Warning, "gappa is not installed in this environnement")
Log.report(Log.Info, "stopping autonomous degree research")
# incrementing polynomial degree to counteract initial decrementation effect
poly_degree += 1
break
Log.report(Log.Info, "poly evaluation error: %s" % poly_eval_error)
Log.report(Log.Info, "sub poly evaluation error: %s" % sub_poly_eval_error)
global_poly_error = None
global_rel_poly_error = None
for case_index in range(3):
poly_error = poly_approx_error + poly_eval_error_dico[case_index]
rel_poly_error = sup(abs(poly_error / sollya.exp(approx_interval_split[case_index])))
if global_rel_poly_error == None or rel_poly_error > global_rel_poly_error:
global_rel_poly_error = rel_poly_error
global_poly_error = poly_error
flag = error_goal > global_rel_poly_error
if flag:
break
else:
poly_degree += 1
late_overflow_test = Comparison(
ik, self.precision.get_emax(),
specifier=Comparison.Greater, likely=False,
debug=debug_multi, tag="late_overflow_test")
overflow_exp_offset = int(self.precision.get_emax() - self.precision.get_field_size() / 2)
cst_overflow_exp_offset = Constant(overflow_exp_offset, precision=self.precision.get_integer_format())
diff_k = Subtraction(
ik,
cst_overflow_exp_offset,
precision=self.precision.get_integer_format(),
debug=debug_multi,
tag="diff_k",
)
late_overflow_result = (ExponentInsertion(diff_k, precision = self.precision) * poly) * ExponentInsertion(cst_overflow_exp_offset, precision = self.precision)
late_overflow_result.set_attributes(silent = False, tag = "late_overflow_result", debug = debug_multi, precision = self.precision)
late_overflow_return = ConditionBlock(Test(late_overflow_result, specifier = Test.IsInfty, likely = False), ExpRaiseReturn(ML_FPE_Overflow, return_value = FP_PlusInfty(self.precision)), Return(late_overflow_result, precision=self.precision))
late_underflow_test = Comparison(k, self.precision.get_emin_normal(), specifier = Comparison.LessOrEqual, likely=False, tag="late_underflow_test")
underflow_exp_offset = 2 * self.precision.get_field_size()
corrected_exp = Addition(
ik,
Constant(
underflow_exp_offset,
precision=self.precision.get_integer_format()
),
precision=self.precision.get_integer_format(),
tag="corrected_exp"
)
late_underflow_result = (ExponentInsertion(corrected_exp, precision = self.precision) * poly) * ExponentInsertion(-underflow_exp_offset, precision = self.precision)
late_underflow_result.set_attributes(debug = debug_multi, tag = "late_underflow_result", silent = False)
test_subnormal = Test(late_underflow_result, specifier = Test.IsSubnormal)
late_underflow_return = Statement(ConditionBlock(test_subnormal, ExpRaiseReturn(ML_FPE_Underflow, return_value = late_underflow_result)), Return(late_underflow_result, precision=self.precision))
twok = ExponentInsertion(ik, tag = "exp_ik", debug = debug_multi, precision = self.precision)
#std_result = twok * ((1 + exact_hi_part * pre_poly) + exact_lo_part * pre_poly)
std_result = twok * poly
std_result.set_attributes(tag = "std_result", debug = debug_multi)
std_cond = LogicalNot(LogicalOr(late_overflow_test, late_underflow_test), likely=True)
result_scheme = ConditionBlock(
std_cond,
Return(std_result, precision=self.precision),
ConditionBlock(
late_overflow_test,
late_overflow_return,
late_underflow_return,
)
)
std_return = ConditionBlock(early_overflow_test, early_overflow_return, ConditionBlock(early_underflow_test, early_underflow_return, result_scheme))
# main scheme
Log.report(Log.Info, "\033[33;1m MDL scheme \033[0m")
scheme = ConditionBlock(
test_nan_or_inf,
Statement(
ClearException() if self.libm_compliant else Statement(),
specific_return
),
std_return
)
return scheme
def generate_scalar_scheme(self, vx, vy):
# fixing inputs' node tag
vx.set_attributes(tag="x")
vy.set_attributes(tag="y")
int_precision = self.precision.get_integer_format()
# assuming x = m.2^e (m in [1, 2[)
# n, positive or null integers
#
# pow(x, n) = x^(y)
# = exp(y * log(x))
# = 2^(y * log2(x))
# = 2^(y * (log2(m) + e))
#
e = ExponentExtraction(vx, tag="e", precision=int_precision)
m = MantissaExtraction(vx, tag="m", precision=self.precision)
# approximation log2(m)
# retrieving processor inverse approximation table
dummy_var = Variable("dummy", precision = self.precision)
dummy_div_seed = ReciprocalSeed(dummy_var, precision = self.precision)
inv_approx_table = self.processor.get_recursive_implementation(
dummy_div_seed, language=None,
table_getter= lambda self: self.approx_table_map)
log_f = sollya.log(sollya.x) # /sollya.log(self.basis)
ml_log_args = ML_GenericLog.get_default_args(precision=self.precision, basis=2)
ml_log = ML_GenericLog(ml_log_args)
log_table, log_table_tho, table_index_range = ml_log.generate_log_table(log_f, inv_approx_table)
log_approx = ml_log.generate_reduced_log_split(Abs(m, precision=self.precision), log_f, inv_approx_table, log_table)
log_approx = Select(Equal(vx, 0), FP_MinusInfty(self.precision), log_approx)
log_approx.set_attributes(tag="log_approx", debug=debug_multi)
r = Multiplication(log_approx, vy, tag="r", debug=debug_multi)
# 2^(y * (log2(m) + e)) = 2^(y * log2(m)) * 2^(y * e)
#
# log_approx = log2(Abs(m))
# r = y * log_approx ~ y * log2(m)
#
# NOTES: manage cases where e is negative and
# (y * log2(m)) AND (y * e) could cancel out
# if e positive, whichever the sign of y (y * log2(m)) and (y * e) CANNOT
# be of opposite signs
# log2(m) in [0, 1[ so cancellation can occur only if e == -1
# we split 2^x in 2^x = 2^t0 * 2^t1
# if e < 0: t0 = y * (log2(m) + e), t1=0
# else: t0 = y * log2(m), t1 = y * e
t_cond = e < 0
# e_y ~ e * y
e_f = Conversion(e, precision=self.precision)
#t0 = Select(t_cond, (e_f + log_approx) * vy, Multiplication(e_f, vy), tag="t0")
#NearestInteger(t0, precision=self.precision, tag="t0_int")
EY = NearestInteger(e_f * vy, tag="EY", precision=self.precision)
LY = NearestInteger(log_approx * vy, tag="LY", precision=self.precision)
t0_int = Select(t_cond, EY + LY, EY, tag="t0_int")
t0_frac = Select(t_cond, FMA(e_f, vy, -EY) + FMA(log_approx, vy, -LY) ,EY - t0_int, tag="t0_frac")
#t0_frac.set_attributes(tag="t0_frac")
ml_exp2_args = ML_Exp2.get_default_args(precision=self.precision)
ml_exp2 = ML_Exp2(ml_exp2_args)
exp2_t0_frac = ml_exp2.generate_scalar_scheme(t0_frac, inline_select=True)
exp2_t0_frac.set_attributes(tag="exp2_t0_frac", debug=debug_multi)
exp2_t0_int = ExponentInsertion(Conversion(t0_int, precision=int_precision), precision=self.precision, tag="exp2_t0_int")
t1 = Select(t_cond, Constant(0, precision=self.precision), r)
exp2_t1 = ml_exp2.generate_scalar_scheme(t1, inline_select=True)
exp2_t1.set_attributes(tag="exp2_t1", debug=debug_multi)
result_sign = Constant(1.0, precision=self.precision) # Select(n_is_odd, CopySign(vx, Constant(1.0, precision=self.precision)), 1)
y_int = NearestInteger(vy, precision=self.precision)
y_is_integer = Equal(y_int, vy)
y_is_even = LogicalOr(
# if y is a number (exc. inf) greater than 2**mantissa_size * 2,
# then it is an integer multiple of 2 => even
Abs(vy) >= 2**(self.precision.get_mantissa_size()+1),
LogicalAnd(
y_is_integer and Abs(vy) < 2**(self.precision.get_mantissa_size()+1),
# we want to limit the modulo computation to an integer input
Equal(Modulo(Conversion(y_int, precision=int_precision), 2), 0)
)
)
y_is_odd = LogicalAnd(
LogicalAnd(
Abs(vy) < 2**(self.precision.get_mantissa_size()+1),
y_is_integer
),
Equal(Modulo(Conversion(y_int, precision=int_precision), 2), 1)
)
# special cases management
special_case_results = Statement(
# x is sNaN OR y is sNaN
ConditionBlock(
LogicalOr(Test(vx, specifier=Test.IsSignalingNaN), Test(vy, specifier=Test.IsSignalingNaN)),
Return(FP_QNaN(self.precision))
),
# pow(x, ±0) is 1 if x is not a signaling NaN
ConditionBlock(
Test(vy, specifier=Test.IsZero),
Return(Constant(1.0, precision=self.precision))
),
# pow(±0, y) is ±∞ and signals the divideByZero exception for y an odd integer <0
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsZero), LogicalAnd(y_is_odd, vy < 0)),
Return(Select(Test(vx, specifier=Test.IsPositiveZero), FP_PlusInfty(self.precision), FP_MinusInfty(self.precision))),
),
# pow(±0, −∞) is +∞ with no exception
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsZero), Test(vy, specifier=Test.IsNegativeInfty)),
Return(FP_MinusInfty(self.precision)),
),
# pow(±0, +∞) is +0 with no exception
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsZero), Test(vy, specifier=Test.IsPositiveInfty)),
Return(FP_PlusInfty(self.precision)),
),
# pow(±0, y) is ±0 for finite y>0 an odd integer
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsZero), LogicalAnd(y_is_odd, vy > 0)),
Return(vx),
),
# pow(−1, ±∞) is 1 with no exception
ConditionBlock(
LogicalAnd(Equal(vx, -1), Test(vy, specifier=Test.IsInfty)),
Return(Constant(1.0, precision=self.precision)),
),
# pow(+1, y) is 1 for any y (even a quiet NaN)
ConditionBlock(
vx == 1,
Return(Constant(1.0, precision=self.precision)),
),
# pow(x, +∞) is +0 for −1<x<1
ConditionBlock(
LogicalAnd(Abs(vx) < 1, Test(vy, specifier=Test.IsPositiveInfty)),
Return(FP_PlusZero(self.precision))
),
# pow(x, +∞) is +∞ for x<−1 or for 1<x (including ±∞)
ConditionBlock(
LogicalAnd(Abs(vx) > 1, Test(vy, specifier=Test.IsPositiveInfty)),
Return(FP_PlusInfty(self.precision))
),
# pow(x, −∞) is +∞ for −1<x<1
ConditionBlock(
LogicalAnd(Abs(vx) < 1, Test(vy, specifier=Test.IsNegativeInfty)),
Return(FP_PlusInfty(self.precision))
),
# pow(x, −∞) is +0 for x<−1 or for 1<x (including ±∞)
ConditionBlock(
LogicalAnd(Abs(vx) > 1, Test(vy, specifier=Test.IsNegativeInfty)),
Return(FP_PlusZero(self.precision))
),
# pow(+∞, y) is +0 for a number y < 0
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsPositiveInfty), vy < 0),
Return(FP_PlusZero(self.precision))
),
# pow(+∞, y) is +∞ for a number y > 0
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsPositiveInfty), vy > 0),
Return(FP_PlusInfty(self.precision))
),
# pow(−∞, y) is −0 for finite y < 0 an odd integer
# TODO: check y is finite
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsNegativeInfty), LogicalAnd(y_is_odd, vy < 0)),
Return(FP_MinusZero(self.precision)),
),
# pow(−∞, y) is −∞ for finite y > 0 an odd integer
# TODO: check y is finite
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsNegativeInfty), LogicalAnd(y_is_odd, vy > 0)),
Return(FP_MinusInfty(self.precision)),
),
# pow(−∞, y) is +0 for finite y < 0 and not an odd integer
# TODO: check y is finite
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsNegativeInfty), LogicalAnd(LogicalNot(y_is_odd), vy < 0)),
Return(FP_PlusZero(self.precision)),
),
# pow(−∞, y) is +∞ for finite y > 0 and not an odd integer
# TODO: check y is finite
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsNegativeInfty), LogicalAnd(LogicalNot(y_is_odd), vy > 0)),
Return(FP_PlusInfty(self.precision)),
),
# pow(±0, y) is +∞ and signals the divideByZero exception for finite y<0 and not an odd integer
# TODO: signal divideByZero exception
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsZero), LogicalAnd(LogicalNot(y_is_odd), vy < 0)),
Return(FP_PlusInfty(self.precision)),
),
# pow(±0, y) is +0 for finite y>0 and not an odd integer
ConditionBlock(
LogicalAnd(Test(vx, specifier=Test.IsZero), LogicalAnd(LogicalNot(y_is_odd), vy > 0)),
Return(FP_PlusZero(self.precision)),
),
)
# manage n=1 separately to avoid catastrophic propagation of errors
# between log2 and exp2 to eventually compute the identity function
# test-case #3
result = Statement(
special_case_results,
# fallback default cases
Return(result_sign * exp2_t1 * exp2_t0_int * exp2_t0_frac))
return result
def generate_scheme(self):
# We wish to compute vx / vy
vx = self.implementation.add_input_variable(
"x", self.precision, interval=self.input_intervals[0])
vy = self.implementation.add_input_variable(
"y", self.precision, interval=self.input_intervals[1])
# maximum exponent magnitude (to avoid overflow/ underflow during
# intermediary computations
int_prec = self.precision.get_integer_format()
max_exp_mag = Constant(self.precision.get_emax() - 1,
precision=int_prec)
exact_ex = ExponentExtraction(vx,
tag="exact_ex",
precision=int_prec,
debug=debug_multi)
exact_ey = ExponentExtraction(vy,
tag="exact_ey",
precision=int_prec,
debug=debug_multi)
ex = Max(Min(exact_ex, max_exp_mag, precision=int_prec),
-max_exp_mag,
tag="ex",
precision=int_prec)
ey = Max(Min(exact_ey, max_exp_mag, precision=int_prec),
-max_exp_mag,
tag="ey",
precision=int_prec)
Attributes.set_default_rounding_mode(ML_RoundToNearest)
Attributes.set_default_silent(True)
# computing the inverse square root
init_approx = None
scaling_factor_x = ExponentInsertion(-ex,
tag="sfx_ei",
precision=self.precision,
debug=debug_multi)
scaling_factor_y = ExponentInsertion(-ey,
tag="sfy_ei",
precision=self.precision,
debug=debug_multi)
def test_interval_out_of_bound_risk(x_range, y_range):
""" Try to determine from x and y's interval if there is a risk
of underflow or overflow """
div_range = abs(x_range / y_range)
underflow_risk = sollya.inf(div_range) < S2**(
self.precision.get_emin_normal() + 2)
overflow_risk = sollya.sup(div_range) > S2**(
self.precision.get_emax() - 2)
return underflow_risk or overflow_risk
out_of_bound_risk = (self.input_intervals[0] is None
or self.input_intervals[1] is None
) or test_interval_out_of_bound_risk(
self.input_intervals[0],
self.input_intervals[1])
Log.report(Log.Debug,
"out_of_bound_risk: {}".format(out_of_bound_risk))
# scaled version of vx and vy, to avoid overflow and underflow
if out_of_bound_risk:
scaled_vx = vx * scaling_factor_x
scaled_vy = vy * scaling_factor_y
scaled_interval = MetaIntervalList(
[MetaInterval(Interval(-2, -1)),
MetaInterval(Interval(1, 2))])
scaled_vx.set_attributes(tag="scaled_vx",
debug=debug_multi,
interval=scaled_interval)
scaled_vy.set_attributes(tag="scaled_vy",
debug=debug_multi,
interval=scaled_interval)
seed_interval = 1 / scaled_interval
print("seed_interval=1/{}={}".format(scaled_interval,
seed_interval))
else:
scaled_vx = vx
scaled_vy = vy
seed_interval = 1 / scaled_vy.get_interval()
# We need a first approximation to 1 / scaled_vy
dummy_seed = ReciprocalSeed(EmptyOperand(precision=self.precision),
precision=self.precision)
if self.processor.is_supported_operation(dummy_seed, self.language):
init_approx = ReciprocalSeed(scaled_vy,
precision=self.precision,
tag="init_approx",
debug=debug_multi)
else:
# generate tabulated version of seed
raise NotImplementedError
current_approx_std = init_approx
# correctly-rounded inverse computation
num_iteration = self.num_iter
Attributes.unset_default_rounding_mode()
Attributes.unset_default_silent()
# check if inputs are zeros
x_zero = Test(vx,
specifier=Test.IsZero,
likely=False,
precision=ML_Bool)
y_zero = Test(vy,
specifier=Test.IsZero,
likely=False,
precision=ML_Bool)
comp_sign = Test(vx,
vy,
specifier=Test.CompSign,
tag="comp_sign",
debug=debug_multi)
# check if divisor is NaN
y_nan = Test(vy, specifier=Test.IsNaN, likely=False, precision=ML_Bool)
# check if inputs are signaling NaNs
x_snan = Test(vx,
specifier=Test.IsSignalingNaN,
likely=False,
precision=ML_Bool)
y_snan = Test(vy,
specifier=Test.IsSignalingNaN,
likely=False,
precision=ML_Bool)
# check if inputs are infinities
x_inf = Test(vx,
specifier=Test.IsInfty,
likely=False,
tag="x_inf",
precision=ML_Bool)
y_inf = Test(vy,
specifier=Test.IsInfty,
likely=False,
tag="y_inf",
debug=debug_multi,
precision=ML_Bool)
scheme = None
gappa_vx, gappa_vy = None, None
# initial reciprocal approximation of 1.0 / scaled_vy
inv_iteration_list, recp_approx = compute_reduced_reciprocal(
init_approx, scaled_vy, self.num_iter)
recp_approx.set_attributes(tag="recp_approx", debug=debug_multi)
# approximation of scaled_vx / scaled_vy
yerr_last, reduced_div_approx, div_iteration_list = compute_reduced_division(
scaled_vx, scaled_vy, recp_approx)
eval_error_range, div_eval_error_range = self.solve_eval_error(
init_approx, recp_approx, reduced_div_approx, scaled_vx, scaled_vy,
inv_iteration_list, div_iteration_list, S2**-7, seed_interval)
eval_error = sup(abs(eval_error_range))
recp_interval = 1 / scaled_vy.get_interval() + eval_error_range
recp_approx.set_interval(recp_interval)
div_interval = scaled_vx.get_interval() / scaled_vy.get_interval(
) + div_eval_error_range
reduced_div_approx.set_interval(div_interval)
reduced_div_approx.set_tag("reduced_div_approx")
if out_of_bound_risk:
unscaled_result = scaling_div_result(reduced_div_approx, ex,
scaling_factor_y,
self.precision)
subnormal_result = subnormalize_result(recp_approx,
reduced_div_approx, ex, ey,
yerr_last, self.precision)
else:
unscaled_result = reduced_div_approx
subnormal_result = reduced_div_approx
x_inf_or_nan = Test(vx, specifier=Test.IsInfOrNaN, likely=False)
y_inf_or_nan = Test(vy,
specifier=Test.IsInfOrNaN,
likely=False,
tag="y_inf_or_nan",
debug=debug_multi)
# generate IEEE exception raising only of libm-compliant
# mode is enabled
enable_raise = self.libm_compliant
# managing special cases
# x inf and y inf
pre_scheme = ConditionBlock(
x_inf_or_nan,
ConditionBlock(
x_inf,
ConditionBlock(
y_inf_or_nan,
Statement(
# signaling NaNs raise invalid operation flags
ConditionBlock(y_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision)),
),
ConditionBlock(comp_sign,
Return(FP_MinusInfty(self.precision)),
Return(FP_PlusInfty(self.precision)))),
Statement(
ConditionBlock(x_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision)))),
ConditionBlock(
x_zero,
ConditionBlock(
LogicalOr(y_zero, y_nan, precision=ML_Bool),
Statement(
ConditionBlock(y_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision))), Return(vx)),
ConditionBlock(
y_inf_or_nan,
ConditionBlock(
y_inf,
Return(
Select(comp_sign, FP_MinusZero(self.precision),
FP_PlusZero(self.precision))),
Statement(
ConditionBlock(y_snan, Raise(ML_FPE_Invalid))
if enable_raise else Statement(),
Return(FP_QNaN(self.precision)))),
ConditionBlock(
y_zero,
Statement(
Raise(ML_FPE_DivideByZero)
if enable_raise else Statement(),
ConditionBlock(
comp_sign,
Return(FP_MinusInfty(self.precision)),
Return(FP_PlusInfty(self.precision)))),
# managing numerical value result cases
Statement(
recp_approx,
reduced_div_approx,
ConditionBlock(
Test(unscaled_result,
specifier=Test.IsSubnormal,
likely=False),
# result is subnormal
Statement(
# inexact flag should have been raised when computing yerr_last
# ConditionBlock(
# Comparison(
# yerr_last, 0,
# specifier=Comparison.NotEqual, likely=True),
# Statement(Raise(ML_FPE_Inexact, ML_FPE_Underflow))
#),
Return(subnormal_result), ),
# result is normal
Statement(
# inexact flag should have been raised when computing yerr_last
#ConditionBlock(
# Comparison(
# yerr_last, 0,
# specifier=Comparison.NotEqual, likely=True),
# Raise(ML_FPE_Inexact)
#),
Return(unscaled_result))),
)))))
# managing rounding mode save and restore
# to ensure intermediary computations are performed in round-to-nearest
# clearing exception before final computation
#rnd_mode = GetRndMode()
#scheme = Statement(
# rnd_mode,
# SetRndMode(ML_RoundToNearest),
# yerr_last,
# SetRndMode(rnd_mode),
# unscaled_result,
# ClearException(),
# pre_scheme
#)
scheme = pre_scheme
return scheme
def generic_atan2_generate(self, _vx, vy=None):
""" if vy is None, compute atan(_vx), else compute atan2(vy / vx) """
if vy is None:
# approximation
# if abs_vx <= 1.0 then atan(abx_vx) is directly approximated
# if abs_vx > 1.0 then atan(abs_vx) = pi/2 - atan(1 / abs_vx)
#
# for vx >= 0, atan(vx) = atan(abs_vx)
#
# for vx < 0, atan(vx) = -atan(abs_vx) for vx < 0
# = -pi/2 + atan(1 / abs_vx)
vx = _vx
sign_cond = vx < 0
abs_vx = Select(vx < 0, -vx, vx, tag="abs_vx", debug=debug_multi)
bound_cond = abs_vx > 1
inv_abs_vx = 1 / abs_vx
# condition to select subtraction
cond = LogicalOr(LogicalAnd(vx < 0, LogicalNot(bound_cond)),
vx > 1,
tag="cond",
debug=debug_multi)
# reduced argument
red_vx = Select(bound_cond,
inv_abs_vx,
abs_vx,
tag="red_vx",
debug=debug_multi)
offset = None
else:
# bound_cond is True iff Abs(vy / _vx) > 1.0
bound_cond = Abs(vy) > Abs(_vx)
bound_cond.set_attributes(tag="bound_cond", debug=debug_multi)
# vx and vy are of opposite signs
#sign_cond = (_vx * vy) < 0
# using cast to int(signed) and bitwise xor
# to determine if _vx and vy are of opposite sign rapidly
fast_sign_cond = BitLogicXor(
TypeCast(_vx, precision=self.precision.get_integer_format()),
TypeCast(vy, precision=self.precision.get_integer_format()),
precision=self.precision.get_integer_format()) < 0
# sign_cond = (_vx * vy) < 0
sign_cond = fast_sign_cond
sign_cond.set_attributes(tag="sign_cond", debug=debug_multi)
# condition to select subtraction
# TODO: could be accelerated if LogicalXor existed
slow_cond = LogicalOr(
LogicalAnd(sign_cond,
LogicalNot(bound_cond)), # 1 < (vy / _vx) < 0
LogicalAnd(bound_cond,
LogicalNot(sign_cond)), # (vy / _vx) > 1
tag="cond",
debug=debug_multi)
cond = slow_cond
numerator = Select(bound_cond,
_vx,
vy,
tag="numerator",
debug=debug_multi)
denominator = Select(bound_cond,
vy,
_vx,
tag="denominator",
debug=debug_multi)
# reduced argument
red_vx = Abs(numerator) / Abs(denominator)
red_vx.set_attributes(tag="red_vx", debug=debug_multi)
offset = Select(
_vx > 0,
Constant(0, precision=self.precision),
# vx < 0
Select(
sign_cond,
# vy > 0
Constant(sollya.pi, precision=self.precision),
Constant(-sollya.pi, precision=self.precision),
precision=self.precision),
precision=self.precision,
tag="offset")
approx_fct = sollya.atan(sollya.x)
if self.method == "piecewise":
sign_vx = Select(cond,
-1,
1,
precision=self.precision,
tag="sign_vx",
debug=debug_multi)
cst_sign = Select(sign_cond,
-1,
1,
precision=self.precision,
tag="cst_sign",
debug=debug_multi)
cst = cst_sign * Select(
bound_cond, sollya.pi / 2, 0, precision=self.precision)
cst.set_attributes(tag="cst", debug=debug_multi)
bound_low = 0.0
bound_high = 1.0
num_intervals = self.num_sub_intervals
error_threshold = S2**-(self.precision.get_mantissa_size() + 8)
approx, eval_error = piecewise_approximation(
approx_fct,
red_vx,
self.precision,
bound_low=bound_low,
bound_high=bound_high,
max_degree=None,
num_intervals=num_intervals,
error_threshold=error_threshold,
odd=True)
result = cst + sign_vx * approx
result.set_attributes(tag="result",
precision=self.precision,
debug=debug_multi)
elif self.method == "single":
approx_interval = Interval(0, 1.0)
# determining the degree of the polynomial approximation
poly_degree_range = sollya.guessdegree(
approx_fct / sollya.x, approx_interval,
S2**-(self.precision.get_field_size() + 2))
poly_degree = int(sollya.sup(poly_degree_range)) + 4
Log.report(Log.Info, "poly_degree={}".format(poly_degree))
# arctan is an odd function, so only odd coefficient must be non-zero
poly_degree_list = list(range(1, poly_degree + 1, 2))
poly_object, poly_error = Polynomial.build_from_approximation_with_error(
approx_fct, poly_degree_list,
[1] + [self.precision.get_sollya_object()] *
(len(poly_degree_list) - 1), approx_interval)
odd_predicate = lambda index, _: ((index - 1) % 4 != 0)
even_predicate = lambda index, _: (index != 1 and
(index - 1) % 4 == 0)
poly_odd_object = poly_object.sub_poly_cond(odd_predicate,
offset=1)
poly_even_object = poly_object.sub_poly_cond(even_predicate,
offset=1)
sollya.settings.display = sollya.hexadecimal
Log.report(Log.Info, "poly_error: {}".format(poly_error))
Log.report(Log.Info, "poly_odd: {}".format(poly_odd_object))
Log.report(Log.Info, "poly_even: {}".format(poly_even_object))
poly_odd = PolynomialSchemeEvaluator.generate_horner_scheme(
poly_odd_object, abs_vx)
poly_odd.set_attributes(tag="poly_odd", debug=debug_multi)
poly_even = PolynomialSchemeEvaluator.generate_horner_scheme(
poly_even_object, abs_vx)
poly_even.set_attributes(tag="poly_even", debug=debug_multi)
exact_sum = poly_odd + poly_even
exact_sum.set_attributes(tag="exact_sum", debug=debug_multi)
# poly_even should be (1 + poly_even)
result = vx + vx * exact_sum
result.set_attributes(tag="result",
precision=self.precision,
debug=debug_multi)
else:
raise NotImplementedError
if not offset is None:
result = result + offset
std_scheme = Statement(Return(result))
scheme = std_scheme
return scheme
def generate_scalar_scheme(self, vx, n):
# fixing inputs' node tag
vx.set_attributes(tag="x")
n.set_attributes(tag="n")
int_precision = self.precision.get_integer_format()
# assuming x = m.2^e (m in [1, 2[)
# n, positive or null integers
#
# rootn(x, n) = x^(1/n)
# = exp(1/n * log(x))
# = 2^(1/n * log2(x))
# = 2^(1/n * (log2(m) + e))
#
# approximation log2(m)
# retrieving processor inverse approximation table
dummy_var = Variable("dummy", precision=self.precision)
dummy_div_seed = ReciprocalSeed(dummy_var, precision=self.precision)
inv_approx_table = self.processor.get_recursive_implementation(
dummy_div_seed,
language=None,
table_getter=lambda self: self.approx_table_map)
log_f = sollya.log(sollya.x) # /sollya.log(self.basis)
use_reciprocal = False
# non-scaled vx used to compute vx^1
unmodified_vx = vx
is_subnormal = Test(vx, specifier=Test.IsSubnormal, tag="is_subnormal")
exp_correction_factor = self.precision.get_mantissa_size()
mantissa_factor = Constant(2**exp_correction_factor,
tag="mantissa_factor")
vx = Select(is_subnormal, vx * mantissa_factor, vx, tag="corrected_vx")
m = MantissaExtraction(vx, tag="m", precision=self.precision)
e = ExponentExtraction(vx, tag="e", precision=int_precision)
e = Select(is_subnormal,
e - exp_correction_factor,
e,
tag="corrected_e")
ml_log_args = ML_GenericLog.get_default_args(precision=self.precision,
basis=2)
ml_log = ML_GenericLog(ml_log_args)
log_table, log_table_tho, table_index_range = ml_log.generate_log_table(
log_f, inv_approx_table)
log_approx = ml_log.generate_reduced_log_split(
Abs(m, precision=self.precision), log_f, inv_approx_table,
log_table)
# floating-point version of n
n_f = Conversion(n, precision=self.precision, tag="n_f")
inv_n = Division(Constant(1, precision=self.precision), n_f)
log_approx = Select(Equal(vx, 0), FP_MinusInfty(self.precision),
log_approx)
log_approx.set_attributes(tag="log_approx", debug=debug_multi)
if use_reciprocal:
r = Multiplication(log_approx, inv_n, tag="r", debug=debug_multi)
else:
r = Division(log_approx, n_f, tag="r", debug=debug_multi)
# e_n ~ e / n
e_f = Conversion(e, precision=self.precision, tag="e_f")
if use_reciprocal:
e_n = Multiplication(e_f, inv_n, tag="e_n")
else:
e_n = Division(e_f, n_f, tag="e_n")
error_e_n = FMA(e_n, -n_f, e_f, tag="error_e_n")
e_n_int = NearestInteger(e_n, precision=self.precision, tag="e_n_int")
pre_e_n_frac = e_n - e_n_int
pre_e_n_frac.set_attributes(tag="pre_e_n_frac")
e_n_frac = pre_e_n_frac + error_e_n * inv_n
e_n_frac.set_attributes(tag="e_n_frac")
ml_exp2_args = ML_Exp2.get_default_args(precision=self.precision)
ml_exp2 = ML_Exp2(ml_exp2_args)
exp2_r = ml_exp2.generate_scalar_scheme(r, inline_select=True)
exp2_r.set_attributes(tag="exp2_r", debug=debug_multi)
exp2_e_n_frac = ml_exp2.generate_scalar_scheme(e_n_frac,
inline_select=True)
exp2_e_n_frac.set_attributes(tag="exp2_e_n_frac", debug=debug_multi)
exp2_e_n_int = ExponentInsertion(Conversion(e_n_int,
precision=int_precision),
precision=self.precision,
tag="exp2_e_n_int")
n_is_even = Equal(Modulo(n, 2), 0, tag="n_is_even", debug=debug_multi)
n_is_odd = LogicalNot(n_is_even, tag="n_is_odd")
result_sign = Select(
n_is_odd, CopySign(vx, Constant(1.0, precision=self.precision)), 1)
# managing n == -1
if self.expand_div:
ml_division_args = ML_Division.get_default_args(
precision=self.precision, input_formats=[self.precision] * 2)
ml_division = ML_Division(ml_division_args)
self.division_implementation = ml_division.implementation
self.division_implementation.set_scheme(
ml_division.generate_scheme())
ml_division_fct = self.division_implementation.get_function_object(
)
else:
ml_division_fct = Division
# manage n=1 separately to avoid catastrophic propagation of errors
# between log2 and exp2 to eventually compute the identity function
# test-case #3
result = ConditionBlock(
LogicalOr(LogicalOr(Test(vx, specifier=Test.IsNaN), Equal(n, 0)),
LogicalAnd(n_is_even, vx < 0)),
Return(FP_QNaN(self.precision)),
Statement(
ConditionBlock(
Equal(n, -1, tag="n_is_mone"),
#Return(Division(Constant(1, precision=self.precision), unmodified_vx, tag="div_res", precision=self.precision)),
Return(
ml_division_fct(Constant(1, precision=self.precision),
unmodified_vx,
tag="div_res",
precision=self.precision)),
),
ConditionBlock(
# rootn( ±inf, n) is +∞ for even n< 0.
Test(vx, specifier=Test.IsInfty),
Statement(
ConditionBlock(
n < 0,
#LogicalAnd(n_is_odd, n < 0),
Return(
Select(Test(vx,
specifier=Test.IsPositiveInfty),
Constant(FP_PlusZero(self.precision),
precision=self.precision),
Constant(FP_MinusZero(self.precision),
precision=self.precision),
precision=self.precision)),
Return(vx),
), ),
),
ConditionBlock(
# rootn(±0, n) is ±∞ for odd n < 0.
LogicalAnd(LogicalAnd(n_is_odd, n < 0),
Equal(vx, 0),
tag="n_is_odd_and_neg"),
Return(
Select(Test(vx, specifier=Test.IsPositiveZero),
Constant(FP_PlusInfty(self.precision),
precision=self.precision),
Constant(FP_MinusInfty(self.precision),
precision=self.precision),
precision=self.precision)),
),
ConditionBlock(
# rootn( ±0, n) is +∞ for even n< 0.
LogicalAnd(LogicalAnd(n_is_even, n < 0), Equal(vx, 0)),
Return(FP_PlusInfty(self.precision))),
ConditionBlock(
# rootn(±0, n) is +0 for even n > 0.
LogicalAnd(n_is_even, Equal(vx, 0)),
Return(vx)),
ConditionBlock(
Equal(n, 1), Return(unmodified_vx),
Return(result_sign * exp2_r * exp2_e_n_int *
exp2_e_n_frac))))
return result
def generate_scheme(self):
# declaring target and instantiating optimization engine
vx = self.implementation.add_input_variable("x", self.precision)
vx.set_attributes(precision=self.precision,
tag="vx",
debug=debug_multi)
Log.set_dump_stdout(True)
Log.report(Log.Info,
"\033[33;1m Generating implementation scheme \033[0m")
if self.debug_flag:
Log.report(Log.Info, "\033[31;1m debug has been enabled \033[0;m")
C0 = Constant(0, precision=self.precision)
C0_plus = Constant(FP_PlusZero(self.precision))
C0_minus = Constant(FP_MinusZero(self.precision))
def local_test(specifier, tag):
""" Local wrapper to generate Test operations """
return Test(vx,
specifier=specifier,
likely=False,
debug=debug_multi,
tag="is_%s" % tag,
precision=ML_Bool)
test_NaN = local_test(Test.IsNaN, "is_NaN")
test_inf = local_test(Test.IsInfty, "is_Inf")
test_NaN_or_Inf = local_test(Test.IsInfOrNaN, "is_Inf_Or_Nan")
test_negative = Comparison(vx,
C0,
specifier=Comparison.Less,
debug=debug_multi,
tag="is_Negative",
precision=ML_Bool,
likely=False)
test_NaN_or_Neg = LogicalOr(test_NaN, test_negative, precision=ML_Bool)
test_std = LogicalNot(LogicalOr(test_NaN_or_Inf,
test_negative,
precision=ML_Bool,
likely=False),
precision=ML_Bool,
likely=True)
test_zero = Comparison(vx,
C0,
specifier=Comparison.Equal,
likely=False,
debug=debug_multi,
tag="Is_Zero",
precision=ML_Bool)
return_NaN_or_neg = Statement(Return(FP_QNaN(self.precision)))
return_inf = Statement(Return(FP_PlusInfty(self.precision)))
return_PosZero = Return(C0_plus)
return_NegZero = Return(C0_minus)
NR_init = ReciprocalSquareRootSeed(vx,
precision=self.precision,
tag="sqrt_seed",
debug=debug_multi)
result = compute_sqrt(vx,
NR_init,
int(self.num_iter),
precision=self.precision)
return_non_std = ConditionBlock(
test_NaN_or_Neg, return_NaN_or_neg,
ConditionBlock(
test_inf, return_inf,
ConditionBlock(test_zero, return_PosZero, return_NegZero)))
return_std = Return(result)
scheme = ConditionBlock(test_std, return_std, return_non_std)
return scheme
def booth_radix4_multiply(lhs, rhs, pos_bit_heap, neg_bit_heap):
""" Compute the multiplication @p lhs x @p rhs using radix 4 Booth
recoding and drop the generated partial product in @p
pos_bit_heap and @p neg_bit_heap based on their sign """
# booth recoded partial product for n-th digit
# is based on digit from n-1 to n+1
# (n+1) | (n) | (n-1) | PP |
# ------|-----|-------|------|
# 0 | 0 | 0 | +0 |
# 0 | 0 | 1 | +X |
# 0 | 1 | 0 | +X |
# 0 | 1 | 1 | +2x |
# 1 | 0 | 0 | -2X |
# 1 | 0 | 1 | -X |
# 1 | 1 | 0 | -X |
# 1 | 1 | 1 | +0 |
# ------|-----|-------|------|
assert lhs.get_precision().get_bit_size() >= 2
# lhs is the recoded operand
# RECODING DIGITS
# first recoded digit is padded right by 0
first_digit = Concatenation(SubSignalSelection(
lhs, 0, 1, precision=ML_StdLogicVectorFormat(2)),
Constant(0, precision=ML_StdLogic),
precision=ML_StdLogicVectorFormat(3),
debug=debug_std,
tag="booth_digit_0")
digit_list = [(first_digit, 0)]
for digit_index in range(2, lhs.get_precision().get_bit_size(), 2):
if digit_index + 1 < lhs.get_precision().get_bit_size():
# digits exist completely in lhs
digit = SubSignalSelection(lhs,
digit_index - 1,
digit_index + 1,
tag="booth_digit_%d" % digit_index,
debug=debug_std)
else:
# MSB padding required
sign_ext = Constant(0, precision=ML_StdLogic) if not (
lhs.get_precision().get_signed()) else BitSelection(
lhs,
lhs.get_precision().get_bit_size() - 1)
digit = Concatenation(sign_ext,
SubSignalSelection(lhs, digit_index - 1,
digit_index),
precision=ML_StdLogicVectorFormat(3),
debug=debug_std,
tag="booth_digit_%d" % digit_index)
digit_list.append((digit, digit_index))
# if lhs size is a mutiple of two and it is unsigned
# than an extra digit must be generated to ensure a positive result
if lhs.get_precision().get_bit_size() % 2 == 0 and not (
lhs.get_precision().get_signed()):
digit_index = lhs.get_precision().get_bit_size() - 1
digit = Concatenation(Constant(0,
precision=ML_StdLogicVectorFormat(2)),
BitSelection(lhs, digit_index),
precision=ML_StdLogicVectorFormat(3),
debug=debug_std,
tag="booth_digit_%d" % (digit_index + 1))
digit_list.append((digit, digit_index + 1))
def DCV(value):
""" Digit Constante Value """
return Constant(value, precision=ML_StdLogicVectorFormat(3))
# PARTIAL PRODUCT GENERATION
# Radix-4 booth recoding requires the following Partial Products
# -2.rhs, -rhs, 0, rhs and 2.rhs
# Negative PP are obtained by 1's complement of the value correctly shifted
# adding a positive one to the LSB (inserted separately) and assuming
# MSB digit has a negative weight
for digit, index in digit_list:
pp_zero = LogicalOr(Equal(digit, DCV(0), precision=ML_Bool),
Equal(digit, DCV(7), precision=ML_Bool),
precision=ML_Bool)
pp_shifted = LogicalOr(Equal(digit, DCV(3), precision=ML_Bool),
Equal(digit, DCV(4), precision=ML_Bool),
precision=ML_Bool)
# excluding zero case
pp_neg_bit = BitSelection(digit, 2)
pp_neg = equal_to(pp_neg_bit, 1)
pp_neg_lsb_carryin = Select(LogicalAnd(pp_neg, LogicalNot(pp_zero)),
Constant(1, precision=ML_StdLogic),
Constant(0, precision=ML_StdLogic),
tag="pp_%d_neg_lsb_carryin" % index,
debug=debug_std)
# LSB digit
lsb_pp_digit = Select(pp_shifted,
Constant(0, precision=ML_StdLogic),
BitSelection(rhs, 0),
precision=ML_StdLogic)
lsb_local_pp = Select(pp_zero,
Constant(0, precision=ML_StdLogic),
Select(pp_neg,
BitLogicNegate(lsb_pp_digit),
lsb_pp_digit,
precision=ML_StdLogic),
debug=debug_std,
tag="lsb_local_pp_%d" % index,
precision=ML_StdLogic)
pos_bit_heap.insert_bit(index, lsb_local_pp)
pos_bit_heap.insert_bit(index, pp_neg_lsb_carryin)
# other digits
rhs_size = rhs.get_precision().get_bit_size()
for k in range(1, rhs_size):
pp_digit = Select(pp_shifted,
BitSelection(rhs, k - 1),
BitSelection(rhs, k),
precision=ML_StdLogic)
local_pp = Select(pp_zero,
Constant(0, precision=ML_StdLogic),
Select(pp_neg,
BitLogicNegate(pp_digit),
pp_digit,
precision=ML_StdLogic),
debug=debug_std,
tag="local_pp_%d_%d" % (index, k),
precision=ML_StdLogic)
pos_bit_heap.insert_bit(index + k, local_pp)
# MSB digit
msb_pp_digit = pp_digit = Select(
pp_shifted,
BitSelection(rhs, rhs_size - 1),
# TODO: fix for signed rhs
Constant(0, precision=ML_StdLogic)
if not (rhs.get_precision().get_signed()) else BitSelection(
rhs, rhs_size - 1),
precision=ML_StdLogic)
msb_pp = Select(pp_zero,
Constant(0, precision=ML_StdLogic),
Select(pp_neg,
BitLogicNegate(msb_pp_digit),
msb_pp_digit,
precision=ML_StdLogic),
debug=debug_std,
tag="msb_pp_%d" % (index),
precision=ML_StdLogic)
if rhs.get_precision().get_signed():
neg_bit_heap.insert_bit(index + rhs_size, msb_pp)
else:
pos_bit_heap.insert_bit(index + rhs_size, msb_pp)
# MSB negative digit,
# 'rhs_size + index) is the position of the MSB digit of rhs shifted by 1
# we add +1 to get to the sign position
neg_bit_heap.insert_bit(index + rhs_size + 1, pp_neg_lsb_carryin)
def LogicalXor(a, b):
return LogicalOr(LogicalAnd(a, LogicalNot(b)), LogicalAnd(LogicalNot(a), b))
def generate_scheme(self):
int_precision = self.precision.get_integer_format()
# We wish to compute vx / vy
vx = self.implementation.add_input_variable("x", self.precision, interval=self.input_intervals[0])
vy = self.implementation.add_input_variable("y", self.precision, interval=self.input_intervals[1])
if self.mode is FULL_MODE:
quo = self.implementation.add_input_variable("quo", ML_Pointer_Format(int_precision))
i = Variable("i", precision=int_precision, var_type=Variable.Local)
q = Variable("q", precision=int_precision, var_type=Variable.Local)
CI = lambda v: Constant(v, precision=int_precision)
CF = lambda v: Constant(v, precision=self.precision)
vx_subnormal = Test(vx, specifier=Test.IsSubnormal, tag="vx_subnormal")
vy_subnormal = Test(vy, specifier=Test.IsSubnormal, tag="vy_subnormal")
DELTA_EXP = self.precision.get_mantissa_size()
scale_factor = Constant(2.0**DELTA_EXP, precision=self.precision)
inv_scale_factor = Constant(2.0**-DELTA_EXP, precision=self.precision)
normalized_vx = Select(vx_subnormal, vx * scale_factor, vx, tag="scaled_vx")
normalized_vy = Select(vy_subnormal, vy * scale_factor, vy, tag="scaled_vy")
real_ex = ExponentExtraction(vx, tag="real_ex", precision=int_precision)
real_ey = ExponentExtraction(vy, tag="real_ey", precision=int_precision)
# if real_e<x/y> is +1023 then it may Overflow in -real_ex for ExponentInsertion
# which only supports downto -1022 before falling into subnormal numbers (which are
# not supported by ExponentInsertion)
real_ex_h0 = real_ex / 2
real_ex_h1 = real_ex - real_ex_h0
real_ey_h0 = real_ey / 2
real_ey_h1 = real_ey - real_ey_h0
EI = lambda v: ExponentInsertion(v, precision=self.precision)
mx = Abs((vx * EI(-real_ex_h0)) * EI(-real_ex_h1), tag="mx")
my = Abs((vy * EI(-real_ey_h0)) * EI(-real_ey_h1), tag="pre_my")
# scale_ey is used to regain the unscaling of mx in the first loop
# if real_ey >= real_ex, the first loop is never executed
# so a different scaling is required
mx_unscaling = Select(real_ey < real_ex, real_ey, real_ex)
ey_half0 = (mx_unscaling) / 2
ey_half1 = (mx_unscaling) - ey_half0
scale_ey_half0 = ExponentInsertion(ey_half0, precision=self.precision, tag="scale_ey_half0")
scale_ey_half1 = ExponentInsertion(ey_half1, precision=self.precision, tag="scale_ey_half1")
# if only vy is subnormal we want to normalize it
#normal_cond = LogicalAnd(vy_subnormal, LogicalNot(vx_subnormal))
normal_cond = vy_subnormal #LogicalAnd(vy_subnormal, LogicalNot(vx_subnormal))
my = Select(normal_cond, Abs(MantissaExtraction(vy * scale_factor)), my, tag="my")
# vx / vy = vx * 2^-ex * 2^(ex-ey) / (vy * 2^-ey)
# vx % vy
post_mx = Variable("post_mx", precision=self.precision, var_type=Variable.Local)
# scaling for half comparison
VY_SCALING = Select(vy_subnormal, 1.0, 0.5, precision=self.precision)
VX_SCALING = Select(vy_subnormal, 2.0, 1.0, precision=self.precision)
def LogicalXor(a, b):
return LogicalOr(LogicalAnd(a, LogicalNot(b)), LogicalAnd(LogicalNot(a), b))
rem_sign = Select(vx < 0, CF(-1), CF(1), precision=self.precision, tag="rem_sign")
quo_sign = Select(LogicalXor(vx <0, vy < 0), CI(-1), CI(1), precision=int_precision, tag="quo_sign")
loop_watchdog = Variable("loop_watchdog", precision=ML_Int32, var_type=Variable.Local)
loop = Statement(
real_ex, real_ey, mx, my, loop_watchdog,
ReferenceAssign(loop_watchdog, 5000),
ReferenceAssign(q, CI(0)),
Loop(
ReferenceAssign(i, CI(0)), i < (real_ex - real_ey),
Statement(
ReferenceAssign(i, i+CI(1)),
ReferenceAssign(q, ((q << 1) + Select(mx >= my, CI(1), CI(0))).modify_attributes(tag="step1_q")),
ReferenceAssign(mx, (CF(2) * (mx - Select(mx >= my, my, CF(0)))).modify_attributes(tag="step1_mx")),
# loop watchdog
ReferenceAssign(loop_watchdog, loop_watchdog - 1),
ConditionBlock(loop_watchdog < 0, Return(-1)),
),
),
# unscaling remainder
ReferenceAssign(mx, ((mx * scale_ey_half0) * scale_ey_half1).modify_attributes(tag="scaled_rem")),
ReferenceAssign(my, ((my * scale_ey_half0) * scale_ey_half1).modify_attributes(tag="scaled_rem_my")),
Loop(
Statement(), (my > Abs(vy)),
Statement(
ReferenceAssign(q, ((q << 1) + Select(mx >= Abs(my), CI(1), CI(0))).modify_attributes(tag="step2_q")),
ReferenceAssign(mx, (mx - Select(mx >= Abs(my), Abs(my), CF(0))).modify_attributes(tag="step2_mx")),
ReferenceAssign(my, (my * 0.5).modify_attributes(tag="step2_my")),
# loop watchdog
ReferenceAssign(loop_watchdog, loop_watchdog - 1),
ConditionBlock(loop_watchdog < 0, Return(-1)),
),
),
ReferenceAssign(q, q << 1),
Loop(
ReferenceAssign(i, CI(0)), mx > Abs(vy),
Statement(
ReferenceAssign(q, (q + Select(mx > Abs(vy), CI(1), CI(0))).modify_attributes(tag="step3_q")),
ReferenceAssign(mx, (mx - Select(mx > Abs(vy), Abs(vy), CF(0))).modify_attributes(tag="step3_mx")),
# loop watchdog
ReferenceAssign(loop_watchdog, loop_watchdog - 1),
ConditionBlock(loop_watchdog < 0, Return(-1)),
),
),
ReferenceAssign(q, q + Select(mx >= Abs(vy), CI(1), CI(0))),
ReferenceAssign(mx, (mx - Select(mx >= Abs(vy), Abs(vy), CF(0))).modify_attributes(tag="pre_half_mx")),
ConditionBlock(
# actual comparison is mx > | abs(vy * 0.5) | to avoid rounding effect when
# vy is subnormal we mulitply both side by 2.0**60
((mx * VX_SCALING) > Abs(vy * VY_SCALING)).modify_attributes(tag="half_test"),
Statement(
ReferenceAssign(q, q + CI(1)),
ReferenceAssign(mx, (mx - Abs(vy)))
)
),
ConditionBlock(
# if the remainder is exactly half the dividend
# we need to make sure the quotient is even
LogicalAnd(
Equal(mx * VX_SCALING, Abs(vy * VY_SCALING)),
Equal(Modulo(q, CI(2)), CI(1)),
),
Statement(
ReferenceAssign(q, q + CI(1)),
ReferenceAssign(mx, (mx - Abs(vy)))
)
),
ReferenceAssign(mx, rem_sign * mx),
ReferenceAssign(q,
Modulo(TypeCast(q, precision=self.precision.get_unsigned_integer_format()), Constant(2**self.quotient_size, precision=self.precision.get_unsigned_integer_format()), tag="mod_q")
),
ReferenceAssign(q, quo_sign * q),
)
# NOTES: Warning QuotientReturn must always preceeds RemainderReturn
if self.mode is QUOTIENT_MODE:
#
QuotientReturn = Return
RemainderReturn = lambda _: Statement()
elif self.mode is REMAINDER_MODE:
QuotientReturn = lambda _: Statement()
RemainderReturn = Return
elif self.mode is FULL_MODE:
QuotientReturn = lambda v: ReferenceAssign(Dereference(quo, precision=int_precision), v)
RemainderReturn = Return
else:
raise NotImplemented
# quotient invalid value
QUO_INVALID_VALUE = 0
mod_scheme = Statement(
# x or y is NaN, a NaN is returned
ConditionBlock(
LogicalOr(Test(vx, specifier=Test.IsNaN), Test(vy, specifier=Test.IsNaN)),
Statement(
QuotientReturn(QUO_INVALID_VALUE),
RemainderReturn(FP_QNaN(self.precision))
),
),
#
ConditionBlock(
Test(vy, specifier=Test.IsZero),
Statement(
QuotientReturn(QUO_INVALID_VALUE),
RemainderReturn(FP_QNaN(self.precision))
),
),
ConditionBlock(
Test(vx, specifier=Test.IsZero),
Statement(
QuotientReturn(0),
RemainderReturn(vx)
),
),
ConditionBlock(
Test(vx, specifier=Test.IsInfty),
Statement(
QuotientReturn(QUO_INVALID_VALUE),
RemainderReturn(FP_QNaN(self.precision))
)
),
ConditionBlock(
Test(vy, specifier=Test.IsInfty),
Statement(
QuotientReturn(0),
RemainderReturn(vx),
)
),
ConditionBlock(
Abs(vx) < Abs(vy * 0.5),
Statement(
QuotientReturn(0),
RemainderReturn(vx),
)
),
ConditionBlock(
Equal(vx, vy),
Statement(
QuotientReturn(1),
# 0 with the same sign as x
RemainderReturn(vx - vx),
),
),
ConditionBlock(
Equal(vx, -vy),
Statement(
# quotient is -1
QuotientReturn(-1),
# 0 with the same sign as x
RemainderReturn(vx - vx),
),
),
loop,
QuotientReturn(q),
RemainderReturn(mx),
)
quo_scheme = Statement(
# x or y is NaN, a NaN is returned
ConditionBlock(
LogicalOr(Test(vx, specifier=Test.IsNaN), Test(vy, specifier=Test.IsNaN)),
Return(QUO_INVALID_VALUE),
),
#
ConditionBlock(
Test(vy, specifier=Test.IsZero),
Return(QUO_INVALID_VALUE),
),
ConditionBlock(
Test(vx, specifier=Test.IsZero),
Return(0),
),
ConditionBlock(
Test(vx, specifier=Test.IsInfty),
Return(QUO_INVALID_VALUE),
),
ConditionBlock(
Test(vy, specifier=Test.IsInfty),
Return(QUO_INVALID_VALUE),
),
ConditionBlock(
Abs(vx) < Abs(vy * 0.5),
Return(0),
),
ConditionBlock(
Equal(vx, vy),
Return(1),
),
ConditionBlock(
Equal(vx, -vy),
Return(-1),
),
loop,
Return(q),
)
return mod_scheme