Fix elemwise on float16 (hopefully).

theano/gpuarray/elemwise.py

@@ -33,6 +33,12 @@ def as_C_string_const(s):
                      for l in s.split('\n'))
 
 
+def get_scal(dt):
+    if dt == 'float16':
+        dt = 'float32'
+    return scalar.get_scalar_type(dt)
+
+
 class GpuElemwise(HideC, Elemwise):
     """
     Elemwise on the GPU.
@@ -60,23 +66,18 @@ class GpuElemwise(HideC, Elemwise):
                    zip(out_info[0], out_info[1])]
         if len(outputs) > 1:
             raise NotImplementedError()
-        node = Apply(self, inputs, outputs)
 
         # Try to generate the kernel to catch SupportCodeErrors
+        scal_ins = [get_scal(i.dtype) for i in inputs]
+        fake_node = self.scalar_op.make_node(*[i() for i in scal_ins])
         try:
-            scal_ins = [scalar.get_scalar_type(i.dtype) for i in node.inputs]
-
-            scal_out = [scalar.get_scalar_type(o.dtype) for o in node.outputs]
-
-            fake_node = Apply(self.scalar_op, [i() for i in scal_ins],
-                              [o() for o in scal_out])
-            code = self.scalar_op.c_support_code_apply(fake_node, "test")
+            code = fake_node.op.c_support_code_apply(fake_node, "test")
             if code:
                 raise SupportCodeError(code)
         except MethodNotDefined:
             pass
         try:
-            support_code = self.scalar_op.c_support_code()
+            support_code = fake_node.op.c_support_code()
             if "struct" in support_code:
                 # The macro is fine, the C++ struct is not.
                 raise SupportCodeError(
@@ -85,6 +86,15 @@ class GpuElemwise(HideC, Elemwise):
         except MethodNotDefined:
             pass
 
+        if fake_node.op != self.scalar_op:
+            # If the new op is different due to type changes, we make a new
+            # op for it.
+            elem = GpuElemwise(fake_node.op, self.inplace_pattern, self.name,
+                               self.nfunc_spec, self.openmp)
+        else:
+            elem = self
+
+        node = Apply(elem, inputs, outputs)
         return node
 
     def get_params(self, node):
@@ -92,59 +102,31 @@ class GpuElemwise(HideC, Elemwise):
 
     def _get_vnames(self, node):
         inps = ['i%d' % (n,) for n, _ in enumerate(node.inputs)]
-        outs = ['o%d' % (n,) for n, _ in enumerate(node.outputs) if n not in self.inplace_pattern]
+        outs = ['o%d' % (n,) if n not in self.inplace_pattern else
+                inps[self.inplace_pattern[n]]
+                for n, _ in enumerate(node.outputs)]
         return inps, outs
 
     def _generate_op_string(self, node):
-        scal_v_ins = [scalar.get_scalar_type(i.dtype) for i in node.inputs]
-        scal_v_outs = [scalar.get_scalar_type(o.dtype) for o in node.outputs]
         inps, outs = self._get_vnames(node)
+        scal_v_ins = [get_scal(i.dtype)() for i in node.inputs]
 
-        fake_node = Apply(self.scalar_op, [i() for i in scal_v_ins],
-                          [o() for o in scal_v_outs])
-
-        scal_in = [i if si.dtype != 'float16' else
-                   'load_half(&' + i + ')' for i, si in zip(inps, scal_v_ins)]
-
-        scal_out = []
-        oi = 0
-        scal_f16 = []
-        for n in range(len(node.outputs)):
-            if n in self.inplace_pattern:
-                arg = inps[self.inplace_pattern[n]]
-            else:
-                arg = outs[oi]
-                oi += 1
-            if node.outputs[n].dtype == 'float16':
-                scal_f16.append(('tmpf16%i' % (len(scal_f16),), arg))
-                scal_out.append(scal_f16[-1][0])
-            else:
-                scal_out.append(arg)
+        fake_node = self.scalar_op.make_node(*scal_v_ins)
+        scal_v_out = fake_node.outputs
+        assert len(scal_v_out) == len(node.outputs)
 
-        kop = self.scalar_op.c_code(fake_node, 'elem_scalar',
-                                    scal_in, scal_out,
+        kop = fake_node.op.c_code(fake_node, 'elem_scalar',
+                                  inps, outs,
                                   dict(fail='return;'))
 
-        if scal_f16:
-            # if we have float16 scalars on output we have to wrap
-            # them and insert a stand-in float32 variable since
-            # float16 arithemtic is not available
-            code = ["{"]
-            for f in scal_f16:
-                code.append('ga_float %s;' % (f[0],))
-            # XXX: The replace is an ugly hack to make sure temp
-            # variables inthe middle are float32
-            code.append(kop.replace('npy_float16', 'ga_float'))
-            for f in scal_f16:
-                code.append('store_half(&%s, %s);' % (f[1], f[0]))
-            code.append('}')
-            kop = '\n'.join(code)
+        # Some ops like cast will reintroduce float16 in the internal graph.
+        kop = kop.replace('npy_float16', 'ga_float')
 
         support_code = ""
         try:
             # We accept only some c_support_code().
             # This filter is done in the make_node()
-            support_code += self.scalar_op.c_support_code()
+            support_code += fake_node.op.c_support_code()
         except MethodNotDefined:
             pass
         for npy, ga in [("npy_uint8", "ga_ubyte"),
@@ -171,7 +153,7 @@ class GpuElemwise(HideC, Elemwise):
 
     def c_init_code_struct(self, node, name, sub):
         inps, outs = self._get_vnames(node)
-        nargs = len(inps) + len(outs)
+        nargs = len(inps) + len(outs) - len(self.inplace_pattern)
         support_code, kop = self._generate_op_string(node)
         res = """
         gpuelemwise_arg args[%(nargs)s] = {{0}};
@@ -202,7 +184,7 @@ class GpuElemwise(HideC, Elemwise):
                            typecode=o.type.typecode)
 
         res += """
-        ge = GpuElemwise_new(%(ctx)s->ctx, %(support)s, %(kop)s, %(nargs)s, args, %(nd)s, 0);
+        ge = GpuElemwise_new(%(ctx)s->ctx, %(support)s, %(kop)s, %(nargs)s, args, %(nd)s, GE_CONVERT_F16);
         if (ge == NULL) {
            PyErr_SetString(PyExc_RuntimeError, "Could not initialize elemwise support");
            %(fail)s
@@ -363,7 +345,7 @@ class GpuElemwise(HideC, Elemwise):
     def c_code_cache_version(self):
         ver = self.scalar_op.c_code_cache_version()
         if ver:
-            return (7, ver)
+            return (8, ver)
         else:
             return ver