def main():
hl.load_plugin("autoschedule_li2018")
x = hl.Var('x')
f_in = hl.Func('in')
f_in[x] = hl.f32(x) # Cast to float 32
f_0 = hl.Func('f_0')
f_0[x] = 2 * f_in[x]
f_1 = hl.Func('f_1')
f_1[x] = hl.sin(f_0[x])
f_2 = hl.Func('f_2')
f_2[x] = f_1[x] * f_1[x]
# Setup
f_2.set_estimate(x, 0, 1000)
p = hl.Pipeline(f_2)
target = hl.Target()
# Only first parameter is used (number of cores on CPU)
params = hl.MachineParams(32, 0, 0)
result = p.auto_schedule('Li2018', target, params)
print('Schedule:')
print(result.schedule_source)
p.compile_jit() # compile
buf = p.realize(1000) # compute and get the buffer
def test_generate_halide(self):
zone = self.define_original_twoel()
decomposed = zone.split_recursive()
self.vars = {k: hl.Var(k) for k in "ijkl"}
i, j, k, l = [self.vars[k] for k in "ijkl"]
g_dens = hl.Func("g_dens")
g_dens[i,j] = i * j
g = hl.Func("g")
g[i,j,k,l] = hl.cos(i*j) * hl.sin(k*l)
self.inputs = {"g": g, "g_dens": g_dens}
self.clamps = {"g": g, "g_dens": g_dens}
self.funcs = {"g": g, "g_dens": g_dens}
self.loopnest_funcs = {}
func = decomposed.generate_halide(self, [8, 8, 8, 8])
def contrast(input, strength, black_point):
output = hl.Func("contrast_output")
x, y, c = hl.Var("x"), hl.Var("y"), hl.Var("c")
scale = strength
inner_constant = math.pi / (2 * scale)
sin_constant = hl.sin(inner_constant)
slope = 65535 / (2 * sin_constant)
constant = slope * sin_constant
factor = math.pi / (scale * 65535)
val = factor * hl.cast(hl.Float(32), input[x, y, c])
output[x, y, c] = hl.u16_sat(slope * hl.sin(val - inner_constant) + constant)
white_scale = 65535 / (65535 - black_point)
output[x, y, c] = hl.u16_sat((hl.cast(hl.Int(32), output[x, y, c]) - black_point) * white_scale)
output.compute_root().parallel(y).vectorize(x, 16)
return output
def main():
# So far Funcs (such as the one below) have evaluated to a single
# scalar value for each point in their domain.
single_valued = hl.Func()
x, y = hl.Var("x"), hl.Var("y")
single_valued[x, y] = x + y
# One way to write a hl.Func that returns a collection of values is
# to add an additional dimension which indexes that
# collection. This is how we typically deal with color. For
# example, the hl.Func below represents a collection of three values
# for every x, y coordinate indexed by c.
color_image = hl.Func()
c = hl.Var("c")
color_image[x, y, c] = hl.select(
c == 0,
245, # Red value
c == 1,
42, # Green value
132) # Blue value
# Since this pattern appears quite often, Halide provides a
# syntatic sugar to write the code above as the following,
# using the "mux" function.
# color_image[x, y, c] = hl.mux(c, [245, 42, 132]);
# This method is often convenient because it makes it easy to
# operate on this hl.Func in a way that treats each item in the
# collection equally:
brighter = hl.Func()
brighter[x, y, c] = color_image[x, y, c] + 10
# However this method is also inconvenient for three reasons.
#
# 1) Funcs are defined over an infinite domain, so users of this
# hl.Func can for example access color_image(x, y, -17), which is
# not a meaningful value and is probably indicative of a bug.
#
# 2) It requires a hl.select, which can impact performance if not
# bounded and unrolled:
# brighter.bound(c, 0, 3).unroll(c)
#
# 3) With this method, all values in the collection must have the
# same type. While the above two issues are merely inconvenient,
# this one is a hard limitation that makes it impossible to
# express certain things in this way.
# It is also possible to represent a collection of values as a
# collection of Funcs:
func_array = [hl.Func() for i in range(3)]
func_array[0][x, y] = x + y
func_array[1][x, y] = hl.sin(x)
func_array[2][x, y] = hl.cos(y)
# This method avoids the three problems above, but introduces a
# new annoyance. Because these are separate Funcs, it is
# difficult to schedule them so that they are all computed
# together inside a single loop over x, y.
# A third alternative is to define a hl.Func as evaluating to a
# Tuple instead of an hl.Expr. A Tuple is a fixed-size collection of
# Exprs which may have different type. The following function
# evaluates to an integer value (x+y), and a floating point value
# (hl.sin(x*y)).
multi_valued = hl.Func("multi_valued")
multi_valued[x, y] = (x + y, hl.sin(x * y))
# Realizing a tuple-valued hl.Func returns a collection of
# Buffers. We call this a Realization. It's equivalent to a
# std::vector of hl.Buffer/Image objects:
if True:
im1, im2 = multi_valued.realize([80, 60])
assert im1.type() == hl.Int(32)
assert im2.type() == hl.Float(32)
assert im1[30, 40] == 30 + 40
assert np.isclose(im2[30, 40], math.sin(30 * 40))
# You can also pass a tuple of pre-allocated buffers to realize()
# rather than having new ones created. (The Buffers must have the correct
# types and have identical sizes.)
if True:
im1, im2 = hl.Buffer(hl.Int(32),
[80, 60]), hl.Buffer(hl.Float(32), [80, 60])
multi_valued.realize((im1, im2))
assert im1[30, 40] == 30 + 40
assert np.isclose(im2[30, 40], math.sin(30 * 40))
# All Tuple elements are evaluated together over the same domain
# in the same loop nest, but stored in distinct allocations. The
# equivalent C++ code to the above is:
if True:
multi_valued_0 = np.empty((80 * 60), dtype=np.int32)
multi_valued_1 = np.empty((80 * 60), dtype=np.int32)
for yy in range(80):
for xx in range(60):
multi_valued_0[xx + 60 * yy] = xx + yy
multi_valued_1[xx + 60 * yy] = math.sin(xx * yy)
# When compiling ahead-of-time, a Tuple-valued hl.Func evaluates
# into multiple distinct output halide_buffer_t structs. These appear in
# order at the end of the function signature:
# int multi_valued(...input buffers and params..., halide_buffer_t
# *output_1, halide_buffer_t *output_2)
# You can construct a Tuple by passing multiple Exprs to the
# Tuple constructor as we did above. Perhaps more elegantly, you
# can also take advantage of initializer lists and just
# enclose your Exprs in braces:
multi_valued_2 = hl.Func("multi_valued_2")
multi_valued_2[x, y] = (x + y, hl.sin(x * y))
# Calls to a multi-valued hl.Func cannot be treated as Exprs. The
# following is a syntax error:
# hl.Func consumer
# consumer[x, y] = multi_valued_2[x, y] + 10
# Instead you must index the returned object with square brackets
# to retrieve the individual Exprs:
integer_part = multi_valued_2[x, y][0]
floating_part = multi_valued_2[x, y][1]
assert type(integer_part) is hl.FuncTupleElementRef
assert type(floating_part) is hl.FuncTupleElementRef
consumer = hl.Func()
consumer[x, y] = (integer_part + 10, floating_part + 10.0)
# Tuple reductions.
if True:
# Tuples are particularly useful in reductions, as they allow
# the reduction to maintain complex state as it walks along
# its domain. The simplest example is an argmax.
# First we create an Image to take the argmax over.
input_func = hl.Func()
input_func[x] = hl.sin(x)
input = input_func.realize([100])
assert input.type() == hl.Float(32)
# Then we defined a 2-valued Tuple which tracks the maximum value
# its index.
arg_max = hl.Func()
# Pure definition.
# (using [()] for zero-dimensional Funcs is a convention of this python interface)
arg_max[()] = (0, input[0])
# Update definition.
r = hl.RDom([(1, 99)])
old_index = arg_max[()][0]
old_max = arg_max[()][1]
new_index = hl.select(old_max > input[r], r, old_index)
new_max = hl.max(input[r], old_max)
arg_max[()] = (new_index, new_max)
# The equivalent C++ is:
arg_max_0 = 0
arg_max_1 = float(input[0])
for r in range(1, 100):
old_index = arg_max_0
old_max = arg_max_1
new_index = r if (old_max > input[r]) else old_index
new_max = max(input[r], old_max)
# In a tuple update definition, all loads and computation
# are done before any stores, so that all Tuple elements
# are updated atomically with respect to recursive calls
# to the same hl.Func.
arg_max_0 = new_index
arg_max_1 = new_max
# Let's verify that the Halide and C++ found the same maximum
# value and index.
if True:
r0, r1 = arg_max.realize()
assert r0.type() == hl.Int(32)
assert r1.type() == hl.Float(32)
assert arg_max_0 == r0[()]
assert np.isclose(arg_max_1, r1[()])
# Halide provides argmax and hl.argmin as built-in reductions
# similar to sum, product, maximum, and minimum. They return
# a Tuple consisting of the point in the reduction domain
# corresponding to that value, and the value itself. In the
# case of ties they return the first value found. We'll use
# one of these in the following section.
# Tuples for user-defined types.
if True:
# Tuples can also be a convenient way to represent compound
# objects such as complex numbers. Defining an object that
# can be converted to and from a Tuple is one way to extend
# Halide's type system with user-defined types.
class Complex:
def __init__(self, r, i=None):
if type(r) is float and type(i) is float:
self.real = hl.Expr(r)
self.imag = hl.Expr(i)
elif i is not None:
self.real = r
self.imag = i
else:
self.real = r[0]
self.imag = r[1]
def as_tuple(self):
"Convert to a Tuple"
return (self.real, self.imag)
def __add__(self, other):
"Complex addition"
return Complex(self.real + other.real, self.imag + other.imag)
def __mul__(self, other):
"Complex multiplication"
return Complex(self.real * other.real - self.imag * other.imag,
self.real * other.imag + self.imag * other.real)
def __getitem__(self, idx):
return (self.real, self.imag)[idx]
def __len__(self):
return 2
def magnitude(self):
"Complex magnitude"
return (self.real * self.real) + (self.imag * self.imag)
# Other complex operators would go here. The above are
# sufficient for this example.
# Let's use the Complex struct to compute a Mandelbrot set.
mandelbrot = hl.Func()
# The initial complex value corresponding to an x, y coordinate
# in our hl.Func.
initial = Complex(x / 15.0 - 2.5, y / 6.0 - 2.0)
# Pure definition.
t = hl.Var("t")
mandelbrot[x, y, t] = Complex(0.0, 0.0)
# We'll use an update definition to take 12 steps.
r = hl.RDom([(1, 12)])
current = Complex(mandelbrot[x, y, r - 1])
# The following line uses the complex multiplication and
# addition we defined above.
mandelbrot[x, y, r] = (Complex(current * current) + initial)
# We'll use another tuple reduction to compute the iteration
# number where the value first escapes a circle of radius 4.
# This can be expressed as an hl.argmin of a boolean - we want
# the index of the first time the given boolean expression is
# false (we consider false to be less than true). The argmax
# would return the index of the first time the expression is
# true.
escape_condition = Complex(mandelbrot[x, y, r]).magnitude() < 16.0
first_escape = hl.argmin(escape_condition)
assert type(first_escape) is tuple
# We only want the index, not the value, but hl.argmin returns
# both, so we'll index the hl.argmin Tuple expression using
# square brackets to get the hl.Expr representing the index.
escape = hl.Func()
escape[x, y] = first_escape[0]
# Realize the pipeline and print the result as ascii art.
result = escape.realize([61, 25])
assert result.type() == hl.Int(32)
code = " .:-~*={&%#@"
for yy in range(result.height()):
for xx in range(result.width()):
index = result[xx, yy]
if index < len(code):
print("%c" % code[index], end="")
else:
pass # is lesson 13 cpp version buggy ?
print("")
print("Success!")
return 0
def main():
# So far Funcs (such as the one below) have evaluated to a single
# scalar value for each point in their domain.
single_valued = hl.Func()
x, y = hl.Var("x"), hl.Var("y")
single_valued[x, y] = x + y
# One way to write a hl.Func that returns a collection of values is
# to add an additional dimension which indexes that
# collection. This is how we typically deal with color. For
# example, the hl.Func below represents a collection of three values
# for every x, y coordinate indexed by c.
color_image = hl.Func()
c = hl.Var("c")
color_image[x, y, c] = hl.select(c == 0, 245, # Red value
c == 1, 42, # Green value
132) # Blue value
# This method is often convenient because it makes it easy to
# operate on this hl.Func in a way that treats each item in the
# collection equally:
brighter = hl.Func()
brighter[x, y, c] = color_image[x, y, c] + 10
# However this method is also inconvenient for three reasons.
#
# 1) Funcs are defined over an infinite domain, so users of this
# hl.Func can for example access color_image(x, y, -17), which is
# not a meaningful value and is probably indicative of a bug.
#
# 2) It requires a hl.select, which can impact performance if not
# bounded and unrolled:
# brighter.bound(c, 0, 3).unroll(c)
#
# 3) With this method, all values in the collection must have the
# same type. While the above two issues are merely inconvenient,
# this one is a hard limitation that makes it impossible to
# express certain things in this way.
# It is also possible to represent a collection of values as a
# collection of Funcs:
func_array = [hl.Func() for i in range(3)]
func_array[0][x, y] = x + y
func_array[1][x, y] = hl.sin(x)
func_array[2][x, y] = hl.cos(y)
# This method avoids the three problems above, but introduces a
# new annoyance. Because these are separate Funcs, it is
# difficult to schedule them so that they are all computed
# together inside a single loop over x, y.
# A third alternative is to define a hl.Func as evaluating to a
# Tuple instead of an hl.Expr. A Tuple is a fixed-size collection of
# Exprs which may have different type. The following function
# evaluates to an integer value (x+y), and a floating point value
# (hl.sin(x*y)).
multi_valued = hl.Func("multi_valued")
multi_valued[x, y] = (x + y, hl.sin(x * y))
# Realizing a tuple-valued hl.Func returns a collection of
# Buffers. We call this a Realization. It's equivalent to a
# std::vector of hl.Buffer/Image objects:
if True:
(im1, im2) = multi_valued.realize(80, 60)
assert type(im1) is hl.Buffer_int32
assert type(im2) is hl.Buffer_float32
assert im1(30, 40) == 30 + 40
assert numpy.isclose(im2(30, 40), math.sin(30 * 40))
# All Tuple elements are evaluated together over the same domain
# in the same loop nest, but stored in distinct allocations. The
# equivalent C++ code to the above is:
if True:
multi_valued_0 = numpy.empty((80*60), dtype=numpy.int32)
multi_valued_1 = numpy.empty((80*60), dtype=numpy.int32)
for yy in range(80):
for xx in range(60):
multi_valued_0[xx + 60*yy] = xx + yy
multi_valued_1[xx + 60*yy] = math.sin(xx*yy)
# When compiling ahead-of-time, a Tuple-valued hl.Func evaluates
# into multiple distinct output buffer_t structs. These appear in
# order at the end of the function signature:
# int multi_valued(...input buffers and params..., buffer_t *output_1, buffer_t *output_2)
# You can construct a Tuple by passing multiple Exprs to the
# Tuple constructor as we did above. Perhaps more elegantly, you
# can also take advantage of C++11 initializer lists and just
# enclose your Exprs in braces:
multi_valued_2 = hl.Func("multi_valued_2")
multi_valued_2[x, y] = (x + y, hl.sin(x * y))
# Calls to a multi-valued hl.Func cannot be treated as Exprs. The
# following is a syntax error:
# hl.Func consumer
# consumer[x, y] = multi_valued_2[x, y] + 10
# Instead you must index the returned object with square brackets
# to retrieve the individual Exprs:
integer_part = multi_valued_2[x, y][0]
floating_part = multi_valued_2[x, y][1]
assert type(integer_part) is hl.FuncTupleElementRef
assert type(floating_part) is hl.FuncTupleElementRef
consumer = hl.Func()
consumer[x, y] = (integer_part + 10, floating_part + 10.0)
# Tuple reductions.
if True:
# Tuples are particularly useful in reductions, as they allow
# the reduction to maintain complex state as it walks along
# its domain. The simplest example is an argmax.
# First we create an Image to take the argmax over.
input_func = hl.Func()
input_func[x] = hl.sin(x)
input = input_func.realize(100)
assert type(input) is hl.Buffer_float32
# Then we defined a 2-valued Tuple which tracks the maximum value
# its index.
arg_max = hl.Func()
# Pure definition.
# (using [()] for zero-dimensional Funcs is a convention of this python interface)
arg_max[()] = (0, input(0))
# Update definition.
r = hl.RDom(1, 99)
old_index = arg_max[()][0]
old_max = arg_max[()][1]
new_index = hl.select(old_max > input[r], r, old_index)
new_max = hl.max(input[r], old_max)
arg_max[()] = (new_index, new_max)
# The equivalent C++ is:
arg_max_0 = 0
arg_max_1 = float(input(0))
for r in range(1, 100):
old_index = arg_max_0
old_max = arg_max_1
new_index = r if (old_max > input(r)) else old_index
new_max = max(input(r), old_max)
# In a tuple update definition, all loads and computation
# are done before any stores, so that all Tuple elements
# are updated atomically with respect to recursive calls
# to the same hl.Func.
arg_max_0 = new_index
arg_max_1 = new_max
# Let's verify that the Halide and C++ found the same maximum
# value and index.
if True:
(r0, r1) = arg_max.realize()
assert type(r0) is hl.Buffer_int32
assert type(r1) is hl.Buffer_float32
assert arg_max_0 == r0(0)
assert numpy.isclose(arg_max_1, r1(0))
# Halide provides argmax and hl.argmin as built-in reductions
# similar to sum, product, maximum, and minimum. They return
# a Tuple consisting of the point in the reduction domain
# corresponding to that value, and the value itself. In the
# case of ties they return the first value found. We'll use
# one of these in the following section.
# Tuples for user-defined types.
if True:
# Tuples can also be a convenient way to represent compound
# objects such as complex numbers. Defining an object that
# can be converted to and from a Tuple is one way to extend
# Halide's type system with user-defined types.
class Complex:
def __init__(self, r, i=None):
if type(r) is float and type(i) is float:
self.real = hl.Expr(r)
self.imag = hl.Expr(i)
elif i is not None:
self.real = r
self.imag = i
else:
self.real = r[0]
self.imag = r[1]
def as_tuple(self):
"Convert to a Tuple"
return (self.real, self.imag)
def __add__(self, other):
"Complex addition"
return Complex(self.real + other.real, self.imag + other.imag)
def __mul__(self, other):
"Complex multiplication"
return Complex(self.real * other.real - self.imag * other.imag,
self.real * other.imag + self.imag * other.real)
def __getitem__(self, idx):
return (self.real, self.imag)[idx]
def __len__(self):
return 2
def magnitude(self):
"Complex magnitude"
return (self.real * self.real) + (self.imag * self.imag)
# Other complex operators would go here. The above are
# sufficient for this example.
# Let's use the Complex struct to compute a Mandelbrot set.
mandelbrot = hl.Func()
# The initial complex value corresponding to an x, y coordinate
# in our hl.Func.
initial = Complex(x/15.0 - 2.5, y/6.0 - 2.0)
# Pure definition.
t = hl.Var("t")
mandelbrot[x, y, t] = Complex(0.0, 0.0)
# We'll use an update definition to take 12 steps.
r = hl.RDom(1, 12)
current = Complex(mandelbrot[x, y, r-1])
# The following line uses the complex multiplication and
# addition we defined above.
mandelbrot[x, y, r] = (Complex(current*current) + initial)
# We'll use another tuple reduction to compute the iteration
# number where the value first escapes a circle of radius 4.
# This can be expressed as an hl.argmin of a boolean - we want
# the index of the first time the given boolean expression is
# false (we consider false to be less than true). The argmax
# would return the index of the first time the expression is
# true.
escape_condition = Complex(mandelbrot[x, y, r]).magnitude() < 16.0
first_escape = hl.argmin(escape_condition)
assert type(first_escape) is tuple
# We only want the index, not the value, but hl.argmin returns
# both, so we'll index the hl.argmin Tuple expression using
# square brackets to get the hl.Expr representing the index.
escape = hl.Func()
escape[x, y] = first_escape[0]
# Realize the pipeline and print the result as ascii art.
result = escape.realize(61, 25)
assert type(result) is hl.Buffer_int32
code = " .:-~*={&%#@"
for yy in range(result.height()):
for xx in range(result.width()):
index = result(xx, yy)
if index < len(code):
print("%c" % code[index], end="")
else:
pass # is lesson 13 cpp version buggy ?
print("")
print("Success!")
return 0
def main():
# All Exprs have a scalar type, and all Funcs evaluate to one or
# more scalar types. The scalar types in Halide are unsigned
# integers of various bit widths, signed integers of the same set
# of bit widths, floating point numbers in single and double
# precision, and opaque handles (equivalent to void *). The
# following array contains all the legal types.
valid_halide_types = [
hl.UInt(8), hl.UInt(16), hl.UInt(32), hl.UInt(64),
hl.Int(8), hl.Int(16), hl.Int(32), hl.Int(64),
hl.Float(32), hl.Float(64), hl.Handle() ]
# Constructing and inspecting types.
if True:
# You can programmatically examine the properties of a Halide
# type. This is useful when you write a C++ function that has
# hl.Expr arguments and you wish to check their types:
assert hl.UInt(8).bits() == 8
assert hl.Int(8).is_int()
# You can also programmatically construct Types as a function of other Types.
t = hl.UInt(8)
t = t.with_bits(t.bits() * 2)
assert t == hl.UInt(16)
# Or construct a Type from a C++ scalar type
#assert type_of<float>() == hl.Float(32)
# The Type struct is also capable of representing vector types,
# but this is reserved for Halide's internal use. You should
# vectorize code by using hl.Func::vectorize, not by attempting to
# construct vector expressions directly. You may encounter vector
# types if you programmatically manipulate lowered Halide code,
# but this is an advanced topic (see hl.Func::add_custom_lowering_pass).
# You can query any Halide hl.Expr for its type. An hl.Expr
# representing a hl.Var has type hl.Int(32):
x = hl.Var("x")
assert hl.Expr(x).type() == hl.Int(32)
# Most transcendental functions in Halide hl.cast their inputs to a
# hl.Float(32) and return a hl.Float(32):
assert hl.sin(x).type() == hl.Float(32)
# You can hl.cast an hl.Expr from one Type to another using the hl.cast operator:
assert hl.cast(hl.UInt(8), x).type() == hl.UInt(8)
# This also comes in a template form that takes a C++ type.
#assert hl.cast<uint8_t>(x).type() == hl.UInt(8)
# You can also query any defined hl.Func for the types it produces.
f1 = hl.Func("f1")
f1[x] = hl.cast(hl.UInt(8), x)
assert f1.output_types()[0] == hl.UInt(8)
f2 = hl.Func("f2")
f2[x] = (x, hl.sin(x))
assert f2.output_types()[0] == hl.Int(32) and \
f2.output_types()[1] == hl.Float(32)
# Type promotion rules.
if True:
# When you combine Exprs of different types (e.g. using '+',
# '*', etc), Halide uses a system of type promotion
# rules. These differ to C's rules. To demonstrate these
# we'll make some Exprs of each type.
x = hl.Var("x")
u8 = hl.cast(hl.UInt(8), x)
u16 = hl.cast(hl.UInt(16), x)
u32 = hl.cast(hl.UInt(32), x)
u64 = hl.cast(hl.UInt(64), x)
s8 = hl.cast(hl.Int(8), x)
s16 = hl.cast(hl.Int(16), x)
s32 = hl.cast(hl.Int(32), x)
s64 = hl.cast(hl.Int(64), x)
f32 = hl.cast(hl.Float(32), x)
f64 = hl.cast(hl.Float(64), x)
# The rules are as follows, and are applied in the order they are
# written below.
# 1) It is an error to hl.cast or use arithmetic operators on Exprs of type hl.Handle().
# 2) If the types are the same, then no type conversions occur.
for t in valid_halide_types:
# Skip the handle type.
if t.is_handle():
continue
e = hl.cast(t, x)
assert (e + e).type() == e.type()
# 3) If one type is a float but the other is not, then the
# non-float argument is promoted to a float (possibly causing a
# loss of precision for large integers).
assert (u8 + f32).type() == hl.Float(32)
assert (f32 + s64).type() == hl.Float(32)
assert (u16 + f64).type() == hl.Float(64)
assert (f64 + s32).type() == hl.Float(64)
# 4) If both types are float, then the narrower argument is
# promoted to the wider bit-width.
assert (f64 + f32).type() == hl.Float(64)
# The rules above handle all the floating-point cases. The
# following three rules handle the integer cases.
# 5) If one of the expressions is an integer constant, then it is
# coerced to the type of the other expression.
assert (u32 + 3).type() == hl.UInt(32)
assert (3 + s16).type() == hl.Int(16)
# If this rule would cause the integer to overflow, then Halide
# will trigger an error, e.g. uncommenting the following line
# will cause this program to terminate with an error.
# hl.Expr bad = u8 + 257
# 6) If both types are unsigned integers, or both types are
# signed integers, then the narrower argument is promoted to
# wider type.
assert (u32 + u8).type() == hl.UInt(32)
assert (s16 + s64).type() == hl.Int(64)
# 7) If one type is signed and the other is unsigned, both
# arguments are promoted to a signed integer with the greater of
# the two bit widths.
assert (u8 + s32).type() == hl.Int(32)
assert (u32 + s8).type() == hl.Int(32)
# Note that this may silently overflow the unsigned type in the
# case where the bit widths are the same.
assert (u32 + s32).type() == hl.Int(32)
if False: # evaluate<X> not yet exposed to python
# When an unsigned hl.Expr is converted to a wider signed type in
# this way, it is first widened to a wider unsigned type
# (zero-extended), and then reinterpreted as a signed
# integer. I.e. casting the hl.UInt(8) value 255 to an hl.Int(32)
# produces 255, not -1.
#int32_t result32 = evaluate<int>(hl.cast<int32_t>(hl.cast<uint8_t>(255)))
assert result32 == 255
# When a signed type is explicitly converted to a wider unsigned
# type with the hl.cast operator (the type promotion rules will
# never do this automatically), it is first converted to the
# wider signed type (sign-extended), and then reinterpreted as
# an unsigned integer. I.e. casting the hl.Int(8) value -1 to a
# hl.UInt(16) produces 65535, not 255.
#uint16_t result16 = evaluate<uint16_t>(hl.cast<uint16_t>(hl.cast<int8_t>(-1)))
assert result16 == 65535
# The type hl.Handle().
if True:
# hl.Handle is used to represent opaque pointers. Applying
# type_of to any pointer type will return hl.Handle()
#assert type_of<void *>() == hl.Handle()
#assert type_of<const char * const **>() == hl.Handle()
# (not clear what the proper python version would be)
# Handles are always stored as 64-bit, regardless of the compilation
# target.
assert hl.Handle().bits() == 64
# The main use of an hl.Expr of type hl.Handle is to pass
# it through Halide to other external code.
# Generic code.
if True:
# The main explicit use of Type in Halide is to write Halide
# code parameterized by a Type. In C++ you'd do this with
# templates. In Halide there's no need - you can inspect and
# modify the types dynamically at C++ runtime instead. The
# function defined below averages two expressions of any
# equal numeric type.
x = hl.Var("x")
assert average(hl.cast(hl.Float(32), x), 3.0).type() == hl.Float(32)
assert average(x, 3).type() == hl.Int(32)
assert average(hl.cast(hl.UInt(8), x), hl.cast(hl.UInt(8), 3)).type() == hl.UInt(8)
print("Success!")
return 0
