3 """A shuffle vector fuzz tester.
5 This is a python program to fuzz test the LLVM shufflevector instruction. It
6 generates a function with a random sequnece of shufflevectors, maintaining the
7 element mapping accumulated across the function. It then generates a main
8 function which calls it with a different value in each element and checks that
9 the result matches the expected mapping.
11 Take the output IR printed to stdout, compile it to an executable using whatever
12 set of transforms you want to test, and run the program. If it crashes, it found
22 parser = argparse.ArgumentParser(description=__doc__)
23 parser.add_argument('seed',
24 help='A string used to seed the RNG')
25 parser.add_argument('-v', '--verbose', action='store_true',
26 help='Show verbose output')
27 parser.add_argument('--max-shuffle-height', type=int, default=16,
28 help='Specify a fixed height of shuffle tree to test')
29 parser.add_argument('--no-blends', dest='blends', action='store_false',
30 help='Include blends of two input vectors')
31 parser.add_argument('--fixed-bit-width', type=int, choices=[128, 256],
32 help='Specify a fixed bit width of vector to test')
33 parser.add_argument('--triple',
34 help='Specify a triple string to include in the IR')
35 args = parser.parse_args()
37 random.seed(args.seed)
39 if args.fixed_bit_width is not None:
40 if args.fixed_bit_width == 128:
41 (width, element_type) = random.choice(
42 [(2, 'i64'), (4, 'i32'), (8, 'i16'), (16, 'i8'),
43 (2, 'f64'), (4, 'f32')])
44 elif args.fixed_bit_width == 256:
45 (width, element_type) = random.choice([
46 (4, 'i64'), (8, 'i32'), (16, 'i16'), (32, 'i8'),
47 (4, 'f64'), (8, 'f32')])
49 sys.exit(1) # Checked above by argument parsing.
51 width = random.choice([2, 4, 8, 16, 32, 64])
52 element_type = random.choice(['i8', 'i16', 'i32', 'i64', 'f32', 'f64'])
55 'i8': 1 << 8, 'i16': 1 << 16, 'i32': 1 << 32, 'i64': 1 << 64,
56 'f32': 1 << 32, 'f64': 1 << 64}[element_type]
58 shuffle_range = (2 * width) if args.blends else width
59 shuffle_indices = [-1] + range(shuffle_range)
61 shuffle_tree = [[[random.choice(shuffle_indices)
62 for _ in itertools.repeat(None, width)]
63 for _ in itertools.repeat(None, args.max_shuffle_height - i)]
64 for i in xrange(args.max_shuffle_height)]
67 # Print out the shuffle sequence in a compact form.
68 print >>sys.stderr, ('Testing shuffle sequence "%s" (v%d%s):' %
69 (args.seed, width, element_type))
70 for i, shuffles in enumerate(shuffle_tree):
71 print >>sys.stderr, ' tree level %d:' % (i,)
72 for j, s in enumerate(shuffles):
73 print >>sys.stderr, ' shuffle %d: %s' % (j, s)
74 print >>sys.stderr, ''
76 # Symbolically evaluate the shuffle tree.
77 inputs = [[int(j % element_modulus)
78 for j in xrange(i * width + 1, (i + 1) * width + 1)]
79 for i in xrange(args.max_shuffle_height + 1)]
81 for shuffles in shuffle_tree:
82 results = [[((results[i] if j < width else results[i + 1])[j % width]
85 for i, s in enumerate(shuffles)]
87 print >>sys.stderr, 'ERROR: Bad results: %s' % (results,)
92 print >>sys.stderr, 'Which transforms:'
93 print >>sys.stderr, ' from: %s' % (inputs,)
94 print >>sys.stderr, ' into: %s' % (result,)
95 print >>sys.stderr, ''
97 # The IR uses silly names for floating point types. We also need a same-size
99 integral_element_type = element_type
100 if element_type == 'f32':
101 integral_element_type = 'i32'
102 element_type = 'float'
103 elif element_type == 'f64':
104 integral_element_type = 'i64'
105 element_type = 'double'
107 # Now we need to generate IR for the shuffle function.
108 subst = {'N': width, 'T': element_type, 'IT': integral_element_type}
110 define internal fastcc <%(N)d x %(T)s> @test(%(arguments)s) noinline nounwind {
111 entry:""" % dict(subst,
113 ['<%(N)d x %(T)s> %%s.0.%(i)d' % dict(subst, i=i)
114 for i in xrange(args.max_shuffle_height + 1)]))
116 for i, shuffles in enumerate(shuffle_tree):
117 for j, s in enumerate(shuffles):
119 %%s.%(next_i)d.%(j)d = shufflevector <%(N)d x %(T)s> %%s.%(i)d.%(j)d, <%(N)d x %(T)s> %%s.%(i)d.%(next_j)d, <%(N)d x i32> <%(S)s>
120 """.strip('\n') % dict(subst, i=i, next_i=i + 1, j=j, next_j=j + 1,
121 S=', '.join(['i32 ' + (str(si) if si != -1 else 'undef')
125 ret <%(N)d x %(T)s> %%s.%(i)d.0
127 """ % dict(subst, i=len(shuffle_tree))
129 # Generate some string constants that we can use to report errors.
130 for i, r in enumerate(result):
132 s = ('FAIL(%(seed)s): lane %(lane)d, expected %(result)d, found %%d\\0A' %
133 {'seed': args.seed, 'lane': i, 'result': r})
134 s += ''.join(['\\00' for _ in itertools.repeat(None, 128 - len(s) + 2)])
136 @error.%(i)d = private unnamed_addr global [128 x i8] c"%(s)s"
137 """.strip() % {'i': i, 's': s}
139 # Define a wrapper function which is marked 'optnone' to prevent
140 # interprocedural optimizations from deleting the test.
142 define internal fastcc <%(N)d x %(T)s> @test_wrapper(%(arguments)s) optnone noinline {
143 %%result = call fastcc <%(N)d x %(T)s> @test(%(arguments)s)
144 ret <%(N)d x %(T)s> %%result
147 arguments=', '.join(['<%(N)d x %(T)s> %%s.%(i)d' % dict(subst, i=i)
148 for i in xrange(args.max_shuffle_height + 1)]))
150 # Finally, generate a main function which will trap if any lanes are mapped
151 # incorrectly (in an observable way).
155 ; Create a scratch space to print error messages.
156 %%str = alloca [128 x i8]
157 %%str.ptr = getelementptr inbounds [128 x i8]* %%str, i32 0, i32 0
159 ; Build the input vector and call the test function.
160 %%v = call fastcc <%(N)d x %(T)s> @test_wrapper(%(inputs)s)
161 ; We need to cast this back to an integer type vector to easily check the
163 %%v.cast = bitcast <%(N)d x %(T)s> %%v to <%(N)d x %(IT)s>
167 [('<%(N)d x %(T)s> bitcast '
168 '(<%(N)d x %(IT)s> <%(input)s> to <%(N)d x %(T)s>)' %
169 dict(subst, input=', '.join(['%(IT)s %(i)d' % dict(subst, i=i)
171 for input in inputs]))
173 # Test that each non-undef result lane contains the expected value.
174 for i, r in enumerate(result):
178 ; Skip this lane, its value is undef.
179 br label %%test.%(next_i)d
180 """ % dict(subst, i=i, next_i=i + 1)
184 %%v.%(i)d = extractelement <%(N)d x %(IT)s> %%v.cast, i32 %(i)d
185 %%cmp.%(i)d = icmp ne %(IT)s %%v.%(i)d, %(r)d
186 br i1 %%cmp.%(i)d, label %%die.%(i)d, label %%test.%(next_i)d
189 ; Capture the actual value and print an error message.
190 %%tmp.%(i)d = zext %(IT)s %%v.%(i)d to i2048
191 %%bad.%(i)d = trunc i2048 %%tmp.%(i)d to i32
192 call i32 (i8*, i8*, ...)* @sprintf(i8* %%str.ptr, i8* getelementptr inbounds ([128 x i8]* @error.%(i)d, i32 0, i32 0), i32 %%bad.%(i)d)
193 %%length.%(i)d = call i32 @strlen(i8* %%str.ptr)
194 %%size.%(i)d = add i32 %%length.%(i)d, 1
195 call i32 @write(i32 2, i8* %%str.ptr, i32 %%size.%(i)d)
196 call void @llvm.trap()
198 """ % dict(subst, i=i, next_i=i + 1, r=r)
205 declare i32 @strlen(i8*)
206 declare i32 @write(i32, i8*, i32)
207 declare i32 @sprintf(i8*, i8*, ...)
208 declare void @llvm.trap() noreturn nounwind
211 if __name__ == '__main__':