Make all blas ops attempt to reuse the previous output buffer.

theano/sandbox/gpuarray/blas.py

@@ -27,6 +27,26 @@ class BlasOp(HideC):
     def c_init_code(self):
         return ['import_pygpu__blas();']
 
+    def c_support_code(self):
+        return """
+PyGpuArray *gpublas_try_copy(PyGpuArray *out, PyGpuArray *y)
+  if (out &&
+      GpuArray_CHKFLAGS(&out->ga, GA_CARRAY) &&
+      theano_size_check(out, PyGpuArray_NDIM(y),
+                        PyGpuArray_DIMS(y),
+                        y->ga.typecode)) {
+    if (pygpu_move(out, y)) {
+      Py_XDECREF(%(out)s)
+      return NULL;
+    }
+  } else {
+    Py_XDECREF(out);
+    out = pygpu_copy(y, GA_ANY_ORDER);
+  }
+  return out;
+}
+"""
+
 
 class GpuGemv(BlasOp, Gemv):
     def make_node(self, y, alpha, A, x, beta):
@@ -50,21 +70,20 @@ class GpuGemv(BlasOp, Gemv):
                     beta=inp[4], fail=sub['fail'], name=name)
         if self.inplace:
             code = """
-                   Py_XDECREF(%(out)s);
                    if (%(y)s->ga.strides[0] <= 0) {
-                     %(out)s = pygpu_copy(%(y)s, GA_ANY_ORDER);
+                     %(out)s = gpublas_try_copy(%(out)s, %(y)s);
                      if (%(out)s == NULL) {
                        %(fail)s
                      }
                    } else {
+                     Py_XDECREF(%(out)s);
                      %(out)s = %(y)s;
                      Py_INCREF(%(out)s);
                    }
                    """ % vars
         else:
             code = """
-                   Py_XDECREF(%(out)s);
-                   %(out)s = pygpu_copy(%(y)s, GA_ANY_ORDER);
+                   %(out)s = gpublas_try_copy(%(out)s, %(y)s);
                    if (%(out)s == NULL) {
                        %(fail)s
                    }
@@ -85,7 +104,7 @@ class GpuGemv(BlasOp, Gemv):
         return code
 
     def c_code_cache_version(self):
-        return (2,)
+        return (3,)
 
 gpugemv_no_inplace = GpuGemv(inplace=False)
 gpugemv_inplace = GpuGemv(inplace=True)
@@ -113,13 +132,13 @@ class GpuGemm(BlasOp, Gemm):
                     beta=inp[4], fail=sub['fail'], name=name)
         if self.inplace:
             code = """
-                   Py_XDECREF(%(out)s);
                    if (!GpuArray_ISONESEGMENT(&%(C)s->ga)) {
-                     %(out)s = pygpu_copy(%(C)s, GA_ANY_ORDER);
+                     %(out)s = gpublas_try_copy(%(out)s, %(C)s);
                      if (%(out)s == NULL) {
                        %(fail)s
                      }
                    } else {
+                     Py_XDECREF(%(out)s);
                      %(out)s = %(C)s;
                      Py_INCREF(%(out)s);
                    }
@@ -127,7 +146,7 @@ class GpuGemm(BlasOp, Gemm):
         else:
             code = """
                    Py_XDECREF(%(out)s);
-                   %(out)s = pygpu_copy(%(C)s, GA_ANY_ORDER);
+                   %(out)s = gpublas_try_copy(%(out)s, %(C)s);
                    if (%(out)s == NULL) {
                        %(fail)s
                    }
@@ -148,7 +167,7 @@ class GpuGemm(BlasOp, Gemm):
         return code
 
     def c_code_cache_version(self):
-        return (2,)
+        return (3,)
 
 
 gpugemm_no_inplace = GpuGemm(inplace=False)
@@ -177,21 +196,20 @@ class GpuGer(BlasOp, Ger):
                     fail=sub['fail'], name=name)
         if self.destructive:
             code = """
-                   Py_XDECREF(%(out)s);
                    if (!GpuArray_ISONESEGMENT(&%(A)s->ga)) {
-                     %(out)s = pygpu_copy(%(A)s, GA_ANY_ORDER);
+                     %(out)s = gpublas_try_copy(%(out)s, %(A)s);
                      if (%(out)s == NULL) {
                        %(fail)s
                      }
                    } else {
+                     Py_XDECREF(%(out)s);
                      %(out)s = %(A)s;
                      Py_INCREF(%(out)s);
                    }
                    """ % vars
         else:
             code = """
-                   Py_XDECREF(%(out)s);
-                   %(out)s = pygpu_copy(%(A)s, GA_ANY_ORDER);
+                   %(out)s = gpublas_try_copy(%(out)s, %(A)s);
                    if (%(out)s == NULL) {
                        %(fail)s
                    }
@@ -209,7 +227,7 @@ class GpuGer(BlasOp, Ger):
         return code
 
     def c_code_cache_version(self):
-        return (1,)
+        return (2,)
 
 
 gpuger_no_inplace = GpuGer(destructive=False)