diff --git a/src/etc/platform-intrinsics/generator.py b/src/etc/platform-intrinsics/generator.py
new file mode 100644
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+++ b/src/etc/platform-intrinsics/generator.py
@@ -0,0 +1,482 @@
+# Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+# file at the top-level directory of this distribution and at
+# http://rust-lang.org/COPYRIGHT.
+#
+# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+# option. This file may not be copied, modified, or distributed
+# except according to those terms.
+
+from __future__ import division, print_function
+import json
+import argparse
+import sys
+import re
+import textwrap
+
+SPEC = re.compile(
+    r'^(?:(?P<id>[iusfIUSF])(?:\((?P<start>\d*)-(?P<end>\d*)\)|(?P<width>\d*))' +
+    r'|(?P<reference>\d+)(?P<modifiers>[vShdnwus]*)(?P<force_width>x\d+)?)$'
+)
+
+class IntrinsicSet(object):
+    def __init__(self, json):
+        self._platform = json['platform']
+        self._intrinsic_prefix = json['intrinsic_prefix']
+        self._llvm_prefix = json['llvm_prefix']
+        self._intrinsics = json['intrinsics']
+        self._type_info = json['number_info']
+        self._widths = json['widths']
+
+    def intrinsics(self):
+        for raw in self._intrinsics:
+            yield GenericIntrinsic(self,
+                                   raw['intrinsic'], raw['width'], raw['llvm'],
+                                   raw['ret'], raw['args'])
+    def llvm_prefix(self):
+        return self._llvm_prefix
+    def intrinsic_prefix(self):
+        return self._intrinsic_prefix
+
+    def width_name(self, bitwidth):
+        return self._widths[str(bitwidth)]
+
+    def number_type_info(self, value):
+        data = self._type_info[value.__class__.__name__.lower()]
+        bitwidth = value.bitwidth()
+        raw_dtype = data['data_type']
+        try:
+            dtype = raw_dtype[str(bitwidth)]
+        except KeyError:
+            dtype = raw_dtype['pattern'].format(bitwidth = bitwidth)
+        return PlatformTypeInfo(data['kind'],
+                                dtype,
+                                value.llvm_name())
+
+class PlatformTypeInfo(object):
+    def __init__(self, kind, data_type, llvm_name, width = None):
+        self.kind = kind
+        self.data_type = data_type
+        self.llvm_name = llvm_name
+        if width is not None:
+            self.width = width
+    def vectorize(self, length, width):
+        return PlatformTypeInfo(self.kind, self.data_type,
+                                'v{}{}'.format(length, self.llvm_name),
+                                width)
+
+class Type(object):
+    def __init__(self, bitwidth):
+        self._bitwidth = bitwidth
+
+    def bitwidth(self):
+        return self._bitwidth
+    def modify(self, spec, width):
+        raise NotImplementedError()
+
+class Number(Type):
+    def __init__(self, bitwidth):
+        Type.__init__(self, bitwidth)
+    def modify(self, spec, width):
+        if spec == 'w':
+            return self.__class__(self.bitwidth() * 2)
+        elif spec == 'n':
+            return self.__class__(self.bitwidth() // 2)
+        elif spec == 'v':
+            return Vector(self, width // self.bitwidth())
+        else:
+            raise ValueError('unknown modification spec {}', spec)
+
+    def type_info(self, platform_info):
+        return platform_info.number_type_info(self)
+
+class Signed(Number):
+    def __init__(self, bitwidth):
+        Number.__init__(self, bitwidth)
+    def modify(self, spec, width):
+        if spec == 'u':
+            return Unsigned(self.bitwidth())
+        elif spec == 's':
+            return Signed(self.bitwidth())
+        else:
+            return Number.modify(self, spec, width)
+    def compiler_ctor(self):
+        return 'i({})'.format(self.bitwidth())
+    def llvm_name(self):
+        return 'i{}'.format(self.bitwidth())
+    def rust_name(self):
+        return 'i{}'.format(self.bitwidth())
+
+class Unsigned(Number):
+    def __init__(self, bitwidth):
+        Number.__init__(self, bitwidth)
+    def modify(self, spec, width):
+        if spec == 'u':
+            return Unsigned(self.bitwidth())
+        elif spec == 's':
+            return Signed(self.bitwidth())
+        else:
+            return Number.modify(self, spec, width)
+    def compiler_ctor(self):
+        return 'u({})'.format(self.bitwidth())
+    def llvm_name(self):
+        return 'i{}'.format(self.bitwidth())
+    def rust_name(self):
+        return 'u{}'.format(self.bitwidth())
+class Float(Number):
+    def __init__(self, bitwidth):
+        assert bitwidth in (32, 64)
+        Number.__init__(self, bitwidth)
+    def compiler_ctor(self):
+        return 'f({})'.format(self.bitwidth())
+    def llvm_name(self):
+        return 'f{}'.format(self.bitwidth())
+    def rust_name(self):
+        return 'f{}'.format(self.bitwidth())
+
+class Vector(Type):
+    def __init__(self, elem, length):
+        assert isinstance(elem, Type) and not isinstance(elem, Vector)
+        Type.__init__(self,
+                      elem.bitwidth() * length)
+        self._length = length
+        self._elem = elem
+    def modify(self, spec, width):
+        if spec == 'h':
+            return Vector(self._elem, self._length // 2)
+        elif spec == 'd':
+            return Vector(self._elem, self._length * 2)
+        elif spec.startswith('x'):
+            new_bitwidth = int(spec[1:])
+            return Vector(self._elem, new_bitwidth // self._elem.bitwidth())
+        else:
+            return Vector(self._elem.modify(spec, width), self._length)
+    def compiler_ctor(self):
+        return 'v({}, {})'.format(self._elem.compiler_ctor(), self._length)
+    def rust_name(self):
+        return '{}x{}'.format(self._elem.rust_name(), self._length)
+    def type_info(self, platform_info):
+        elem_info = self._elem.type_info(platform_info)
+        return elem_info.vectorize(self._length,
+                                   platform_info.width_name(self.bitwidth()))
+
+class Aggregate(Type):
+    def __init__(self, flatten, elems):
+        self._flatten = flatten
+        self._elems = elems
+        Type.__init__(self,
+                      sum(elem.bitwidth() for elem in elems))
+    def __repr__(self):
+        return '<Aggregate {}>'.format(self._elems)
+    def compiler_ctor(self):
+        return 'agg({}, vec![{}])'.format('true' if self._flatten else 'false',
+                                          ', '.join(elem.compiler_ctor() for elem in self._elems))
+    def rust_name(self):
+        return '({})'.format(', '.join(elem.rust_name() for elem in self._elems))
+    def type_info(self, platform_info):
+        #return PlatformTypeInfo(None, None, self._llvm_name)
+        return None
+
+
+TYPE_ID_LOOKUP = {'i': [Signed, Unsigned],
+                  's': [Signed],
+                  'u': [Unsigned],
+                  'f': [Float]}
+
+class TypeSpec(object):
+    def __init__(self, spec):
+        if not isinstance(spec, list):
+            spec = [spec]
+
+        self.spec = spec
+    def enumerate(self, width):
+        for spec in self.spec:
+            match = SPEC.match(spec)
+            if match:
+                id = match.group('id')
+                is_vector = id.islower()
+                type_ctors = TYPE_ID_LOOKUP[id.lower()]
+                start = match.group('start')
+                if start is not None:
+                    end = match.group('end')
+                else:
+                    start = end = match.group('width')
+                start = int(start)
+                end = int(end)
+
+                bitwidth = start
+                while bitwidth <= end:
+                    for ctor in type_ctors:
+                        scalar = ctor(bitwidth)
+                        if is_vector:
+
+                            yield Vector(scalar, width // bitwidth)
+                        else:
+                            yield scalar
+                    bitwidth *= 2
+            else:
+                print('Failed to parse: {}'.format(spec), file=sys.stderr)
+    def resolve(self, width, zero):
+        assert len(self.spec) == 1
+        spec = self.spec[0]
+        match = SPEC.match(spec)
+        if match:
+            id  = match.group('id')
+            if id is not None:
+                options = list(self.enumerate(width))
+                assert len(options) == 1
+                return options[0]
+            reference = match.group('reference')
+            if reference != '0':
+                raise NotImplementedError('only argument 0 (return value) references are supported')
+            ret = zero
+            for x in match.group('modifiers') or []:
+                ret = ret.modify(x, width)
+            force = match.group('force_width')
+            if force is not None:
+                ret = ret.modify(force, width)
+            return ret
+        elif spec.startswith('('):
+            if spec.endswith(')'):
+                raise NotImplementedError()
+            elif spec.endswith(')f'):
+                true_spec = spec[1:-2]
+                flatten = True
+            elems = [TypeSpec(subspec).resolve(width, zero) for subspec in true_spec.split(',')]
+            return Aggregate(flatten, elems)
+
+class GenericIntrinsic(object):
+    def __init__(self, platform, intrinsic, widths, llvm_name, ret, args):
+        self._platform = platform
+        self.intrinsic = intrinsic
+        self.widths = map(int, widths)
+        self.llvm_name = llvm_name
+        self.ret = TypeSpec(ret)
+        self.args = list(map(TypeSpec, args))
+
+    def monomorphise(self):
+        for width in self.widths:
+            assert width in (64, 128)
+            for ret in self.ret.enumerate(width):
+                args = [arg.resolve(width, ret) for arg in self.args]
+                yield MonomorphicIntrinsic(self._platform, self.intrinsic, width, self.llvm_name,
+                                           ret, args)
+
+class MonomorphicIntrinsic(object):
+    def __init__(self, platform, intrinsic, width, llvm_name, ret, args):
+        self._platform = platform
+        self._intrinsic = intrinsic
+        self._width = '' if width == 64 else 'q'
+        self._llvm_name = llvm_name
+        self._ret_raw = ret
+        self._ret = ret.type_info(platform)
+        self._args_raw = args
+        self._args = [arg.type_info(platform) for arg in args]
+    def llvm_name(self):
+        if self._llvm_name.startswith('!'):
+            return self._llvm_name[1:].format(self._ret, *self._args)
+        else:
+            return self._platform.llvm_prefix() + self._llvm_name.format(self._ret, *self._args)
+    def intrinsic_suffix(self):
+        return self._intrinsic.format(self._ret,
+                                      *self._args,
+                                      width = self._width)
+    def intrinsic_name(self):
+        return self._platform.intrinsic_prefix() + self.intrinsic_suffix()
+    def compiler_args(self):
+        return ', '.join(arg.compiler_ctor() for arg in self._args_raw)
+    def compiler_ret(self):
+        return self._ret_raw.compiler_ctor()
+    def compiler_signature(self):
+        return '({}) -> {}'.format(self.compiler_args(), self.compiler_ret())
+    def intrinsic_signature(self):
+        names = 'xyzwabcdef'
+        return '({}) -> {}'.format(', '.join('{}: {}'.format(name, arg.rust_name())
+                                             for name, arg in zip(names, self._args_raw)),
+                                   self._ret.rust_name())
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        formatter_class = argparse.RawDescriptionHelpFormatter,
+        description = 'Render an intrinsic definition JSON to various formats.',
+        epilog = textwrap.dedent('''\
+        An intrinsic definition consists of a map with fields:
+        - intrinsic: pattern for the name(s) of the vendor's C intrinsic(s)
+        - llvm: pattern for the name(s) of the internal llvm intrinsic(s)
+        - width: a vector of vector bit-widths the pattern works with
+        - ret: type specifier for the return value
+        - arguments: vector of type specifiers for arguments
+
+        The width and types describe a range of possible intrinsics,
+        and these are fed back into the intrinsic and llvm patterns to
+        create the appropriate definitions.
+
+        ## Type specifier grammar
+
+        ```
+        type := vector | scalar | aggregate | reference
+
+        vector := vector_elem width |
+        vector_elem := 'i' | 'u' | 's' | 'f'
+
+        scalar := scalar_type number
+        scalar_type := 'U' | 'S' | 'F'
+
+        aggregate := '(' (type),* ')' 'f'?
+
+        reference := number modifiers*
+        modifiers := 'v' | 'h' | 'd' | 'n' | 'w' | 'u' | 's' |
+                     'x' number
+
+
+        width = number | '(' number '-' number ')'
+
+        number = [0-9]+
+        ```
+
+        ## Vectors
+
+        The vector grammar is a pattern describing many possibilities
+        for arguments/return value. The `vector_elem` describes the
+        types of elements to use, and the `width` describes the (range
+        of) widths for those elements, which are then placed into a
+        vector with the `width` bitwidth. E.g. if an intrinsic has a
+        `width` that includes 128, and the return value is `i(8-32)`,
+        then some instantiation of that intrinsic will be `u8x16`,
+        `u32x4`, `i32x4`, etc.
+
+        ### Elements
+
+        - i: integer, both signed and unsigned
+        - u: unsigned integer
+        - s: signed integer
+        - f: float
+
+        ## Scalars
+
+        Similar to vectors, but these describe a single concrete type,
+        not a range. The number is the bitwidth.
+
+        ### Types
+
+        - U: unsigned integer
+        - S: signed integer
+        - F: float
+
+        ## Aggregates
+
+        An aggregate is a collection of multiple types; a tuple in
+        Rust terms, or an unnamed struct in LLVM. The `f` modifiers
+        forces the tuple to be flattened in the LLVM
+        intrinsic. E.g. if `llvm.foo` takes `(F32,S32)`:
+
+        - no `f` corresponds to `declare ... @llvm.foo({float, i32})`.
+        - having an `f` corresponds to `declare ... @llvm.foo(float, i32)`.
+
+
+        (Currently aggregates can not contain other aggregates.)
+
+        ## References
+
+        A reference uses the type of another argument, with possible
+        modifications. The number refers to the type to use, starting
+        with 0 == return value, 1 == first argument, 2 == second
+        argument, etc. (Currently only referencing 0, the return
+        value, is supported.)
+
+        ### Modifiers
+
+        - 'v': put a scalar into a vector of the current width (u32 -> u32x4, when width == 128)
+        - 'h': half the length of the vector (u32x4 -> u32x2)
+        - 'd': double the length of the vector (u32x2 -> u32x4)
+        - 'n': narrow the element of the vector (u32x4 -> u16x4)
+        - 'w': widen the element of the vector (u16x4 -> u32x4)
+        - 'u': force an integer (vector or scalar) to be unsigned (i32x4 -> u32x4)
+        - 's': force an integer (vector or scalar) to be signed (u32x4 -> i32x4)
+        - 'x' number: force the type to be a vector of bitwidth `number`.
+        '''))
+    parser.add_argument('--format', choices=FORMATS, required=True,
+                        help = 'Output format.')
+    parser.add_argument('-o', '--out', type=argparse.FileType('w'), default=sys.stdout,
+                        help = 'File to output to (default stdout).')
+    parser.add_argument('in_', metavar="FILE", type=argparse.FileType('r'),
+                        help = 'JSON file to load')
+    return parser.parse_args()
+
+
+class ExternBlock(object):
+    def __init__(self):
+        pass
+    def open(self, platform):
+        return 'extern "platform-intrinsic" {'
+    def render(self, mono):
+        return '    fn {}{};'.format(mono.intrinsic_name(),
+                                     mono.intrinsic_signature())
+    def close(self):
+        return '}'
+
+class CompilerDefs(object):
+    def __init__(self):
+        pass
+    def open(self, platform):
+        return '''\
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// DO NOT EDIT: autogenerated by etc/platform-intrinsics/generator.py
+// ignore-tidy-linelength
+
+use {{Intrinsic, i, u, f, v, agg}};
+use IntrinsicDef::Named;
+use rustc::middle::ty;
+
+pub fn find<'tcx>(_tcx: &ty::ctxt<'tcx>, name: &str) -> Option<Intrinsic> {{
+    if !name.starts_with("{0}") {{ return None }}
+    Some(match &name["{0}".len()..] {{'''.format(platform.intrinsic_prefix())
+
+    def render(self, mono):
+        return '''\
+        "{}" => Intrinsic {{
+            inputs: vec![{}],
+            output: {},
+            definition: Named("{}")
+        }},'''.format(mono.intrinsic_suffix(),
+                      mono.compiler_args(),
+                      mono.compiler_ret(),
+                      mono.llvm_name())
+    def close(self):
+        return '''\
+        _ => return None,
+    })
+}'''
+
+FORMATS = {
+    'extern-block': ExternBlock(),
+    'compiler-defs': CompilerDefs(),
+}
+
+
+def main():
+    args = parse_args()
+    in_ = args.in_
+    out = args.out
+    out_format = FORMATS[args.format]
+
+    intrinsics = IntrinsicSet(json.load(in_))
+
+    print(out_format.open(intrinsics), file=out)
+    for intr in intrinsics.intrinsics():
+        for mono in intr.monomorphise():
+            print(out_format.render(mono), file=out)
+    print(out_format.close(), file=out)
+
+if __name__ == '__main__':
+    main()