def generate_scheme(self):
self.var_mapping = {}
for var_index in range(self.arity):
# FIXME: maximal arity is 4
var_tag = ["x", "y", "z", "t"][var_index]
self.var_mapping[var_tag] = self.implementation.add_input_variable(
var_tag,
self.get_input_precision(var_index),
interval=self.input_intervals[var_index])
self.function_expr = function_parser(self.function_expr_str,
self.var_mapping)
Log.report(Log.Info, "evaluating function range")
evaluate_range(self.function_expr, update_interval=True)
Log.report(
LOG_VERBOSE_FUNCTION_EXPR, "scheme is: \n{}",
self.function_expr.get_str(depth=None, display_interval=True))
# defined copy map to avoid copying input Variables
copy_map = dict((var, var) for var in self.var_mapping.items())
function_expr_copy = self.function_expr.copy(copy_map)
result, scheme = self.instanciate_graph(function_expr_copy,
expand_div=self.expand_div)
scheme.add(Return(result, precision=self.precision))
return scheme
def generate_scheme(self):
# map of expected interval values
expected_interval = {}
vx_interval = Interval(-1, 1)
vx = self.implementation.add_input_variable("x",
self.precision,
interval=vx_interval)
expected_interval[vx] = vx_interval
cst = Constant(7, tag="cst")
cst_interval = Interval(7)
expected_interval[cst] = cst_interval
shl = BitLogicLeftShift(NearestInteger(vx),
2,
interval=2 * vx_interval,
tag="shl")
shl_interval = 2 * vx_interval
expected_interval[shl] = shl_interval
r = vx + cst * vx + shl - cst
r.set_attributes(tag="r")
r_interval = vx_interval + cst_interval * vx_interval + shl_interval - cst_interval
expected_interval[r] = r_interval
# NOTES: implicit interval eval is no longer enforced: explicit call
# to evaluate_range is required
evaluate_range(r, update_interval=True)
for var in [vx, cst, r, shl]:
if var.get_interval() != expected_interval[var]:
Log.report(
Log.Error,
"unexpected interval for {}: got {}, expected {}".format(
var.get_str(display_precision=True),
var.get_interval(), expected_interval[var]))
else:
Log.report(
Log.Info,
"node {}: {} vs {}".format(var.get_tag(),
var.get_interval(),
expected_interval[var]))
return Statement()
def evaluate_set_range(self, optree, memoization_map=None):
""" check if all precision-instantiated operation are supported by the processor """
# memoization map is used to store node's range/interval
memoization_map = {} if memoization_map is None else memoization_map
if optree in memoization_map:
return optree
else:
if not is_leaf_node(optree):
for op in optree.inputs:
_ = self.evaluate_set_range(op, memoization_map=memoization_map)
if optree.get_interval() is None:
op_range = evaluate_range(optree, update_interval=True)
else:
op_range = optree.get_interval()
if not op_range is None:
Log.report(LOG_VERBOSE_EVALUATE_RANGE, "range for {} has been evaluated to {}", optree, op_range)
# memoization
memoization_map[optree] = op_range
return optree
def generate_scheme(self):
## convert @p value from an input floating-point precision
# @p in_precision to an output support format @p out_precision
io_precision = self.precision
# declaring main input variable
vx = self.implementation.add_input_signal("x", io_precision)
# rounding mode input
rnd_mode = self.implementation.add_input_signal(
"rnd_mode", rnd_mode_format)
# size of most significant table index (for linear slope tabulation)
alpha = self.alpha # 6
# size of medium significant table index (for initial value table index LSB)
beta = self.beta # 5
# size of least significant table index (for linear offset tabulation)
gamma = self.gamma # 5
guard_bits = self.guard_bits # 3
vx.set_interval(self.interval)
range_hi = sollya.sup(self.interval)
range_lo = sollya.inf(self.interval)
f_hi = self.function(range_hi)
f_lo = self.function(range_lo)
# fixed by format used for reduced_x
range_size = range_hi - range_lo
range_size_log2 = int(sollya.log2(range_size))
assert 2**range_size_log2 == range_size
print("range_size_log2={}".format(range_size_log2))
reduced_x = Conversion(BitLogicRightShift(vx - range_lo,
range_size_log2),
precision=fixed_point(0,
alpha + beta + gamma,
signed=False),
tag="reduced_x",
debug=debug_fixed)
alpha_index = get_fixed_slice(reduced_x,
0,
alpha - 1,
align_hi=FixedPointPosition.FromMSBToLSB,
align_lo=FixedPointPosition.FromMSBToLSB,
tag="alpha_index",
debug=debug_std)
gamma_index = get_fixed_slice(reduced_x,
gamma - 1,
0,
align_hi=FixedPointPosition.FromLSBToLSB,
align_lo=FixedPointPosition.FromLSBToLSB,
tag="gamma_index",
debug=debug_std)
beta_index = get_fixed_slice(reduced_x,
alpha,
gamma,
align_hi=FixedPointPosition.FromMSBToLSB,
align_lo=FixedPointPosition.FromLSBToLSB,
tag="beta_index",
debug=debug_std)
# Assuming monotonic function
f_absmax = max(abs(f_hi), abs(f_lo))
f_absmin = min(abs(f_hi), abs(f_lo))
f_msb = int(sollya.ceil(sollya.log2(f_absmax))) + 1
f_lsb = int(sollya.floor(sollya.log2(f_absmin)))
storage_lsb = f_lsb - io_precision.get_bit_size() - guard_bits
f_int_size = f_msb
f_frac_size = -storage_lsb
storage_format = fixed_point(f_int_size, f_frac_size, signed=False)
Log.report(Log.Info, "storage_format is {}".format(storage_format))
# table of initial value index
tiv_index = Concatenation(alpha_index,
beta_index,
tag="tiv_index",
debug=debug_std)
# table of offset value index
to_index = Concatenation(alpha_index,
gamma_index,
tag="to_index",
debug=debug_std)
tiv_index_size = alpha + beta
to_index_size = alpha + gamma
Log.report(Log.Info, "initial table structures")
table_iv = ML_NewTable(dimensions=[2**tiv_index_size],
storage_precision=storage_format,
tag="tiv")
table_offset = ML_NewTable(dimensions=[2**to_index_size],
storage_precision=storage_format,
tag="to")
slope_table = [None] * (2**alpha)
slope_delta = 1.0 / sollya.SollyaObject(2**alpha)
delta_u = range_size * slope_delta * 2**-15
Log.report(Log.Info, "computing slope value")
for i in range(2**alpha):
# slope is computed at the middle of range_size interval
slope_x = range_lo + (i + 0.5) * range_size * slope_delta
# TODO: gross approximation of derivatives
f_xpu = self.function(slope_x + delta_u / 2)
f_xmu = self.function(slope_x - delta_u / 2)
slope = (f_xpu - f_xmu) / delta_u
slope_table[i] = slope
range_rcp_steps = 1.0 / sollya.SollyaObject(2**tiv_index_size)
Log.report(Log.Info, "computing value for initial-value table")
for i in range(2**tiv_index_size):
slope_index = i / 2**beta
iv_x = range_lo + i * range_rcp_steps * range_size
offset_x = 0.5 * range_rcp_steps * range_size
# initial value is computed so that the piecewise linear
# approximation intersects the function at iv_x + offset_x
iv_y = self.function(
iv_x + offset_x) - offset_x * slope_table[int(slope_index)]
initial_value = storage_format.round_sollya_object(iv_y)
table_iv[i] = initial_value
# determining table of initial value interval
tiv_min = table_iv[0]
tiv_max = table_iv[0]
for i in range(1, 2**tiv_index_size):
tiv_min = min(tiv_min, table_iv[i])
tiv_max = max(tiv_max, table_iv[i])
table_iv.set_interval(Interval(tiv_min, tiv_max))
offset_step = range_size / S2**(alpha + beta + gamma)
for i in range(2**alpha):
Log.report(Log.Info,
"computing offset value for sub-table {}".format(i))
for j in range(2**gamma):
to_i = i * 2**gamma + j
offset = slope_table[i] * j * offset_step
table_offset[to_i] = offset
# determining table of offset interval
to_min = table_offset[0]
to_max = table_offset[0]
for i in range(1, 2**(alpha + gamma)):
to_min = min(to_min, table_offset[i])
to_max = max(to_max, table_offset[i])
offset_interval = Interval(to_min, to_max)
table_offset.set_interval(offset_interval)
initial_value = TableLoad(table_iv,
tiv_index,
precision=storage_format,
tag="initial_value",
debug=debug_fixed)
offset_precision = get_fixed_type_from_interval(offset_interval, 16)
print("offset_precision is {} ({} bits)".format(
offset_precision, offset_precision.get_bit_size()))
table_offset.get_precision().storage_precision = offset_precision
# rounding table value
for i in range(1, 2**(alpha + gamma)):
table_offset[i] = offset_precision.round_sollya_object(
table_offset[i])
offset_value = TableLoad(table_offset,
to_index,
precision=offset_precision,
tag="offset_value",
debug=debug_fixed)
Log.report(
Log.Verbose,
"initial_value's interval: {}, offset_value's interval: {}".format(
evaluate_range(initial_value), evaluate_range(offset_value)))
final_add = initial_value + offset_value
round_bit = final_add # + FixedPointPosition(final_add, io_precision.get_bit_size(), align=FixedPointPosition.FromMSBToLSB)
vr_out = Conversion(initial_value + offset_value,
precision=io_precision,
tag="vr_out",
debug=debug_fixed)
self.implementation.add_output_signal("vr_out", vr_out)
# Approximation error evaluation
approx_error = 0.0
for i in range(2**alpha):
for j in range(2**beta):
tiv_i = (i * 2**beta + j)
# = range_lo + tiv_i * range_rcp_steps * range_size
iv = table_iv[tiv_i]
for k in range(2**gamma):
to_i = i * 2**gamma + k
offset = table_offset[to_i]
approx_value = offset + iv
table_x = range_lo + range_size * (
(i * 2**beta + j) * 2**gamma + k) / S2**(alpha + beta +
gamma)
local_error = abs(1 / (table_x) - approx_value)
approx_error = max(approx_error, local_error)
error_log2 = float(sollya.log2(approx_error))
print("approx_error is {}, error_log2 is {}".format(
float(approx_error), error_log2))
# table size
table_iv_size = 2**(alpha + beta)
table_offset_size = 2**(alpha + gamma)
print("tables' size are {} entries".format(table_iv_size +
table_offset_size))
return [self.implementation]
def generate_scheme(self):
""" main scheme generation """
int_size = 3
frac_size = self.width - int_size
input_precision = fixed_point(int_size, frac_size)
output_precision = fixed_point(int_size, frac_size)
expected_interval = {}
# declaring main input variable
var_x = self.implementation.add_input_signal("x", input_precision)
x_interval = Interval(-10.3,10.7)
var_x.set_interval(x_interval)
expected_interval[var_x] = x_interval
var_y = self.implementation.add_input_signal("y", input_precision)
y_interval = Interval(-17.9,17.2)
var_y.set_interval(y_interval)
expected_interval[var_y] = y_interval
var_z = self.implementation.add_input_signal("z", input_precision)
z_interval = Interval(-7.3,7.7)
var_z.set_interval(z_interval)
expected_interval[var_z] = z_interval
cst = Constant(42.5, tag = "cst")
expected_interval[cst] = Interval(42.5)
conv_ceil = Ceil(var_x, tag = "ceil")
expected_interval[conv_ceil] = sollya.ceil(x_interval)
conv_floor = Floor(var_y, tag = "floor")
expected_interval[conv_floor] = sollya.floor(y_interval)
mult = var_z * var_x
mult.set_tag("mult")
mult_interval = z_interval * x_interval
expected_interval[mult] = mult_interval
large_add = (var_x + var_y) - mult
large_add.set_attributes(tag = "large_add")
large_add_interval = (x_interval + y_interval) - mult_interval
expected_interval[large_add] = large_add_interval
var_x_lzc = CountLeadingZeros(var_x, tag="var_x_lzc")
expected_interval[var_x_lzc] = Interval(0, input_precision.get_bit_size())
reduced_result = Max(0, Min(large_add, 13))
reduced_result.set_tag("reduced_result")
reduced_result_interval = interval_max(
Interval(0),
interval_min(
large_add_interval,
Interval(13)
)
)
expected_interval[reduced_result] = reduced_result_interval
select_result = Select(
var_x > var_y,
reduced_result,
var_z,
tag = "select_result"
)
select_interval = interval_union(reduced_result_interval, z_interval)
expected_interval[select_result] = select_interval
# floating-point operation on mantissa and exponents
fp_x_range = Interval(-0.01, 100)
unbound_fp_var = Variable("fp_x", precision=ML_Binary32, interval=fp_x_range)
mant_fp_x = MantissaExtraction(unbound_fp_var, tag="mant_fp_x", precision=ML_Binary32)
exp_fp_x = ExponentExtraction(unbound_fp_var, tag="exp_fp_x", precision=ML_Int32)
ins_exp_fp_x = ExponentInsertion(exp_fp_x, tag="ins_exp_fp_x", precision=ML_Binary32)
expected_interval[unbound_fp_var] = fp_x_range
expected_interval[exp_fp_x] = Interval(
sollya.floor(sollya.log2(sollya.inf(abs(fp_x_range)))),
sollya.floor(sollya.log2(sollya.sup(abs(fp_x_range))))
)
expected_interval[mant_fp_x] = Interval(1, 2)
expected_interval[ins_exp_fp_x] = Interval(
S2**sollya.inf(expected_interval[exp_fp_x]),
S2**sollya.sup(expected_interval[exp_fp_x])
)
# checking interval evaluation
for var in [var_x_lzc, exp_fp_x, unbound_fp_var, mant_fp_x, ins_exp_fp_x, cst, var_x, var_y, mult, large_add, reduced_result, select_result, conv_ceil, conv_floor]:
interval = evaluate_range(var)
expected = expected_interval[var]
print("{}: {}".format(var.get_tag(), interval))
print(" vs expected {}".format(expected))
assert not interval is None
assert interval == expected
return [self.implementation]
def generate_scheme(self):
""" main scheme generation """
int_size = 3
frac_size = self.width - int_size
input_precision = fixed_point(int_size, frac_size)
output_precision = fixed_point(int_size, frac_size)
expected_interval = {}
# declaring main input variable
var_x = self.implementation.add_input_signal("x", input_precision)
x_interval = Interval(-10.3, 10.7)
var_x.set_interval(x_interval)
expected_interval[var_x] = x_interval
var_y = self.implementation.add_input_signal("y", input_precision)
y_interval = Interval(-17.9, 17.2)
var_y.set_interval(y_interval)
expected_interval[var_y] = y_interval
var_z = self.implementation.add_input_signal("z", input_precision)
z_interval = Interval(-7.3, 7.7)
var_z.set_interval(z_interval)
expected_interval[var_z] = z_interval
cst = Constant(42.5, tag="cst")
expected_interval[cst] = Interval(42.5)
conv_ceil = Ceil(var_x, tag="ceil")
expected_interval[conv_ceil] = sollya.ceil(x_interval)
conv_floor = Floor(var_y, tag="floor")
expected_interval[conv_floor] = sollya.floor(y_interval)
mult = var_z * var_x
mult.set_tag("mult")
mult_interval = z_interval * x_interval
expected_interval[mult] = mult_interval
large_add = (var_x + var_y) - mult
large_add.set_attributes(tag="large_add")
large_add_interval = (x_interval + y_interval) - mult_interval
expected_interval[large_add] = large_add_interval
reduced_result = Max(0, Min(large_add, 13))
reduced_result.set_tag("reduced_result")
reduced_result_interval = interval_max(
Interval(0), interval_min(large_add_interval, Interval(13)))
expected_interval[reduced_result] = reduced_result_interval
select_result = Select(var_x > var_y,
reduced_result,
var_z,
tag="select_result")
select_interval = interval_union(reduced_result_interval, z_interval)
expected_interval[select_result] = select_interval
# checking interval evaluation
for var in [
cst, var_x, var_y, mult, large_add, reduced_result,
select_result, conv_ceil, conv_floor
]:
interval = evaluate_range(var)
expected = expected_interval[var]
print("{}: {} vs expected {}".format(var.get_tag(), interval,
expected))
assert not interval is None
assert interval == expected
return [self.implementation]