Issue error for nogil Py->C conversion & support runtime num_threads

Cython/Compiler/Code.py

@@ -986,11 +986,13 @@ class CCodeWriter(object):
         if create_from is not None:
             # Use same global state
             self.globalstate = create_from.globalstate
+            self.funcstate = create_from.funcstate
             # Clone formatting state
             if copy_formatting:
                 self.level = create_from.level
                 self.bol = create_from.bol
                 self.call_level = create_from.call_level
+
         if emit_linenums is None and self.globalstate:
             self.emit_linenums = self.globalstate.emit_linenums
         else:
@@ -1000,7 +1002,8 @@ class CCodeWriter(object):
     def create_new(self, create_from, buffer, copy_formatting):
         # polymorphic constructor -- very slightly more versatile
         # than using __class__
-        result = CCodeWriter(create_from, buffer, copy_formatting, c_line_in_traceback=self.c_line_in_traceback)
+        result = CCodeWriter(create_from, buffer, copy_formatting,
+                             c_line_in_traceback=self.c_line_in_traceback)
         return result
 
     def copyto(self, f):

Cython/Compiler/ExprNodes.py

@@ -7814,6 +7814,9 @@ class CoerceFromPyTypeNode(CoercionNode):
         if self.type.is_pyobject:
             code.put_gotref(self.py_result())
 
+    def nogil_check(self, env):
+        error(self.pos, "Coercion from Python not allowed without the GIL")
+
 
 class CoerceToBooleanNode(CoercionNode):
     #  This node is used when a result needs to be used

Cython/Compiler/Nodes.py

@@ -5929,7 +5929,7 @@ class ParallelStatNode(StatNode, ParallelNode):
                                 construct (replaced by its compile time value)
     """
 
-    child_attrs = ['body']
+    child_attrs = ['body', 'num_threads']
 
     body = None
 
@@ -5937,6 +5937,8 @@ class ParallelStatNode(StatNode, ParallelNode):
 
     error_label_used = False
 
+    num_threads = None
+
     parallel_exc = (
         Naming.parallel_exc_type,
         Naming.parallel_exc_value,
@@ -5977,7 +5979,15 @@ class ParallelStatNode(StatNode, ParallelNode):
     def analyse_declarations(self, env):
         self.body.analyse_declarations(env)
 
+        self.num_threads = None
+
         if self.kwargs:
+            for idx, dictitem in enumerate(self.kwargs.key_value_pairs[:]):
+                if dictitem.key.value == 'num_threads':
+                    self.num_threads = dictitem.value
+                    del self.kwargs.key_value_pairs[idx]
+                    break
+
             try:
                 self.kwargs = self.kwargs.compile_time_value(env)
             except Exception, e:
@@ -5993,6 +6003,8 @@ class ParallelStatNode(StatNode, ParallelNode):
                 setattr(self, kw, val)
 
     def analyse_expressions(self, env):
+        if self.num_threads:
+            self.num_threads.analyse_expressions(env)
         self.body.analyse_expressions(env)
         self.analyse_sharing_attributes(env)
 
@@ -6000,13 +6012,18 @@ class ParallelStatNode(StatNode, ParallelNode):
             if self.parent and self.parent.num_threads is not None:
                 error(self.pos,
                       "num_threads already declared in outer section")
-            elif not isinstance(self.num_threads, (int, long)):
+            elif self.parent:
                 error(self.pos,
-                      "Invalid value for num_threads argument, expected an int")
-            elif self.num_threads <= 0:
+                      "num_threads must be declared in the parent parallel section")
+            elif (self.num_threads.type.is_int and
+                  self.num_threads.is_literal and
+                  self.num_threads.compile_time_value(env) <= 0):
                 error(self.pos,
                       "argument to num_threads must be greater than 0")
 
+            self.num_threads = self.num_threads.coerce_to(
+                                PyrexTypes.c_int_type, env).coerce_to_temp(env)
+
     def analyse_sharing_attributes(self, env):
         """
         Analyse the privates for this block and set them in self.privates.
@@ -6146,7 +6163,16 @@ class ParallelStatNode(StatNode, ParallelNode):
         Write self.num_threads if set as the num_threads OpenMP directive
         """
         if self.num_threads is not None:
-            code.put(" num_threads(%d)" % (self.num_threads,))
+            c = self.begin_of_parallel_control_block_point
+            # we need to set the owner to ourselves temporarily, as
+            # allocate_temp may generate a comment in the middle of our pragma
+            # otherwise when DebugFlags.debug_temp_code_comments is in effect
+            owner = c.funcstate.owner
+            c.funcstate.owner = c
+            self.num_threads.generate_evaluation_code(c)
+            c.funcstate.owner = owner
+
+            code.put(" num_threads(%s)" % (self.num_threads.result(),))
 
 
     def declare_closure_privates(self, code):
@@ -6511,8 +6537,6 @@ class ParallelWithBlockNode(ParallelStatNode):
     This node represents a 'with cython.parallel.parallel():' block
     """
 
-    nogil_check = None
-
     valid_keyword_arguments = ['num_threads']
 
     num_threads = None

tests/errors/e_invalid_num_threads.pyx

@@ -19,8 +19,17 @@ with nogil, parallel(num_threads=2):
     for i in prange(10, num_threads=2):
         pass
 
+with nogil, parallel():
+    for i in prange(10, num_threads=2):
+        pass
+
+# this one is valid
+for i in prange(10, nogil=True, num_threads=2):
+    pass
+
 _ERRORS = u"""
+e_invalid_num_threads.pyx:8:33: Coercion from Python not allowed without the GIL
 e_invalid_num_threads.pyx:12:20: argument to num_threads must be greater than 0
-e_invalid_num_threads.pyx:15:20: Invalid value for num_threads argument, expected an int
 e_invalid_num_threads.pyx:19:19: num_threads already declared in outer section
+e_invalid_num_threads.pyx:23:19: num_threads must be declared in the parent parallel section
 """

tests/run/parallel.pyx

@@ -26,10 +26,18 @@ def test_parallel():
 
     free(buf)
 
+cdef int get_num_threads() with gil:
+    print "get_num_threads called"
+    return 3
+
 def test_num_threads():
     """
     >>> test_num_threads()
     1
+    get_num_threads called
+    3
+    get_num_threads called
+    3
     """
     cdef int dyn = openmp.omp_get_dynamic()
     cdef int num_threads
@@ -40,6 +48,19 @@ def test_num_threads():
     with nogil, cython.parallel.parallel(num_threads=1):
         p[0] = openmp.omp_get_num_threads()
 
+    print num_threads
+
+    with nogil, cython.parallel.parallel(num_threads=get_num_threads()):
+        p[0] = openmp.omp_get_num_threads()
+
+    print num_threads
+
+    cdef int i
+    num_threads = 0xbad
+    for i in prange(1, nogil=True, num_threads=get_num_threads()):
+        p[0] = openmp.omp_get_num_threads()
+        break
+
     openmp.omp_set_dynamic(dyn)
 
     return num_threads

tests/run/sequential_parallel.pyx

@@ -729,6 +729,6 @@ def test_num_threads_compile():
     with nogil, cython.parallel.parallel(num_threads=2):
         pass
 
-    with nogil, cython.parallel.parallel():
-        for i in prange(10, num_threads=2):
+    with nogil, cython.parallel.parallel(num_threads=2):
+        for i in prange(10):
             pass