Initiliaze private variables to maximum values or NaNs

Cython/Compiler/ModuleNode.py

@@ -499,8 +499,19 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
   #define DL_EXPORT(t) t
 #endif
 
-#ifndef PY_LONG_LONG
-  #define PY_LONG_LONG LONG_LONG
+#ifdef PY_LONG_LONG
+    #define %(LONG_LONG_MAX)s PY_LLONG_MAX
+    #define %(ULONG_LONG_MAX)s PY_ULLONG_MAX
+#else
+    #define PY_LONG_LONG LONG_LONG
+
+    #if defined(LLONG_MAX)
+        #define %(LONG_LONG_MAX)s LLONG_MAX
+        #define %(ULONG_LONG_MAX)s ULLONG_MAX
+    #else
+        #define %(LONG_LONG_MAX)s LONG_MAX
+        #define %(ULONG_LONG_MAX)s ULONG_MAX
+    #endif
 #endif
 
 #if PY_VERSION_HEX < 0x02040000
@@ -637,7 +648,7 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
   #define __Pyx_PyInt_AsHash_t   PyInt_AsSsize_t
 #endif
 
-""")
+""" % vars(Naming))
 
         code.put("""
 #if PY_MAJOR_VERSION >= 3
@@ -699,10 +710,52 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         code.putln("")
         self.generate_extern_c_macro_definition(code)
         code.putln("")
+
         code.putln("#if defined(WIN32) || defined(MS_WINDOWS)")
         code.putln("#define _USE_MATH_DEFINES")
         code.putln("#endif")
-        code.putln("#include <math.h>")
+
+        code.putln("""
+/* Define NAN */
+#ifdef Py_NAN
+    #include <math.h>
+    #define %(pyx_nan)s Py_NAN
+#else
+    #if defined(__GNUC__)
+        #define _GNU_SOURCE
+    #endif
+
+    #include <math.h>
+
+    #ifdef NAN
+        #define %(pyx_nan)s NAN
+    #else
+        #if defined(HUGE_VALL)
+            #define %(pyx_nan)s HUGE_VALL
+        #elif defined(__STDC__) && __STDC_VERSION__ >= 199901L
+            /* C99 or greater */
+            #include <float.h>
+            #define %(pyx_nan)s LDBL_MAX
+        #else
+            static PY_LONG_LONG __pyx__nan = PY_LLONG_MAX;
+            #define %(pyx_nan)s (*(double*) &__pyx__nan)
+        #endif
+    #endif
+#endif
+
+#ifdef PY_LONG_LONG
+    #define __PYX_LONG_LONG_MAX PY_LLONG_MAX
+    #define __PYX_ULONG_LONG_MAX PY_ULLONG_MAX
+#elif defined(LLONG_MAX)
+    #define __PYX_LONG_LONG_MAX LLONG_MAX
+    #define __PYX_ULONG_LONG_MAX ULLONG_MAX
+#else
+    /* This should probably suffice, even if not strictly the largest value */
+    #define __PYX_LONG_LONG_MAX LONG_MAX
+    #define __PYX_ULONG_LONG_MAX ULONG_MAX
+#endif
+""" % {'pyx_nan': Naming.NAN})
+
         code.putln("#define %s" % Naming.h_guard_prefix + self.api_name(env))
         code.putln("#define %s" % Naming.api_guard_prefix + self.api_name(env))
         self.generate_includes(env, cimported_modules, code)
@@ -711,6 +764,7 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         code.putln("#define CYTHON_WITHOUT_ASSERTIONS")
         code.putln("#endif")
         code.putln("")
+
         if env.directives['ccomplex']:
             code.putln("")
             code.putln("#if !defined(CYTHON_CCOMPLEX)")

Cython/Compiler/Naming.py

@@ -116,5 +116,10 @@ h_guard_prefix   = "__PYX_HAVE__"
 api_guard_prefix = "__PYX_HAVE_API__"
 api_func_guard   = "__PYX_HAVE_API_FUNC_"
 
+NAN              = "__PYX_NAN"
+HUGE_VAL         = "Py_HUGE_VAL"
+LONG_LONG_MAX    = "__PYX_LONG_LONG_MAX"
+ULONG_LONG_MAX   = "__PYX_ULONG_LONG_MAX"
+
 def py_version_hex(major, minor=0, micro=0, release_level=0, release_serial=0):
     return (major << 24) | (minor << 16) | (micro << 8) | (release_level << 4) | (release_serial)

Cython/Compiler/Nodes.py

@@ -6007,6 +6007,9 @@ class ParallelStatNode(StatNode, ParallelNode):
             for i in prange(10, nogil=True):
                 var = x # error, x is private and read before assigned
                 x = i
+
+        Fortunately, it doesn't need to be perfect, as we still initialize
+        private variables to maximum values, NULL or NaN whenever possible.
         """
         from Cython.Compiler import ParseTreeTransforms
 
@@ -6022,6 +6025,17 @@ class ParallelStatNode(StatNode, ParallelNode):
                 if not op and pos < assignment_pos:
                     error(pos, "Private variable referenced before assignment")
 
+    def initialize_privates_to_nan(self, code, exclude=None):
+        code.putln("/* Initialize private variables to invalid values */")
+
+        for entry, op in self.privates.iteritems():
+            if not op and (not exclude or entry != exclude):
+                max_value = entry.type.max_value()
+
+                if max_value:
+                    code.putln("%s = %s;" % (entry.cname,
+                                             entry.type.cast_code(max_value)))
+
     def declare_closure_privates(self, code):
         """
         Set self.privates to a dict mapping C variable names that are to be
@@ -6075,6 +6089,7 @@ class ParallelWithBlockNode(ParallelStatNode):
         code.putln("#endif /* _OPENMP */")
 
         code.begin_block()
+        self.initialize_privates_to_nan(code)
         self.body.generate_execution_code(code)
         code.end_block()
 
@@ -6334,6 +6349,9 @@ class ParallelRangeNode(ParallelStatNode):
         code.put("for (%(i)s = 0; %(i)s < %(nsteps)s; %(i)s++)" % fmt_dict)
         code.begin_block()
         code.putln("%(target)s = %(start)s + %(step)s * %(i)s;" % fmt_dict)
+
+        self.initialize_privates_to_nan(code, exclude=self.target.entry)
+
         self.body.generate_execution_code(code)
         code.end_block()
 

Cython/Compiler/PyrexTypes.py

@@ -27,6 +27,12 @@ class BaseType(object):
         else:
             return base_code
 
+    def max_value(self):
+        """
+        Returns the maximum or most invalid value an object of this type can
+        assume as a C expression string. Returns None if no such value exists.
+        """
+
 class PyrexType(BaseType):
     #
     #  Base class for all Pyrex types.
@@ -378,6 +384,10 @@ class PyObjectType(PyrexType):
         else:
             return cname
 
+    def max_value(self):
+        return "NULL"
+
+
 class BuiltinObjectType(PyObjectType):
     #  objstruct_cname  string           Name of PyObject struct
 
@@ -902,6 +912,8 @@ class CIntType(CNumericType):
     def assignable_from_resolved_type(self, src_type):
         return src_type.is_int or src_type.is_enum or src_type is error_type
 
+    def max_value(self):
+        return typename_to_maxval[rank_to_type_name[self.rank]][not self.signed]
 
 class CAnonEnumType(CIntType):
 
@@ -1109,6 +1121,8 @@ class CFloatType(CNumericType):
     def assignable_from_resolved_type(self, src_type):
         return (src_type.is_numeric and not src_type.is_complex) or src_type is error_type
 
+    def max_value(self):
+        return Naming.NAN
 
 class CComplexType(CNumericType):
 
@@ -1622,6 +1636,8 @@ class CPtrType(CType):
         else:
             return CPtrType(base_type)
 
+    def max_value(self):
+        return "NULL"
 
 class CNullPtrType(CPtrType):
 
@@ -2353,6 +2369,15 @@ rank_to_type_name = (
     "long double",  # 7
 )
 
+typename_to_maxval = {
+    "char" : ("CHAR_MAX", "UCHAR_MAX"),
+    "short": ("SHRT_MAX", "USHRT_MAX"),
+    "int"  : ("INT_MAX", "UINT_MAX"),
+    "long" : ("LONG_MAX", "ULONG_MAX"),
+    "PY_LONG_LONG" : (Naming.LONG_LONG_MAX, Naming.ULONG_LONG_MAX),
+    # CFloatType overrides max_value
+}
+
 RANK_INT  = list(rank_to_type_name).index('int')
 RANK_LONG = list(rank_to_type_name).index('long')
 UNSIGNED = 0

Cython/Shadow.py

@@ -288,7 +288,8 @@ class CythonDotParallel(object):
 
     __all__ = ['parallel', 'prange', 'threadid']
 
-    parallel = nogil
+    def parallel(self, num_threads=None):
+        return nogil
 
     def prange(self, start=0, stop=None, step=1, schedule=None, nogil=False):
         if stop is None:

tests/run/sequential_parallel.pyx

@@ -171,6 +171,53 @@ def test_pure_mode():
     for i in pure_parallel.prange(4, -1, -1, schedule='dynamic', nogil=True):
         print i
 
-    with pure_parallel.parallel:
+    with pure_parallel.parallel():
         print pure_parallel.threadid()
 
+def test_nan_init():
+    """
+    >>> test_nan_init()
+    """
+    cdef int mybool = 0
+    cdef int err = 0
+    cdef int *errp = &err
+
+    cdef signed char a1 = 10
+    cdef unsigned char a2 = 10
+    cdef short b1 = 10
+    cdef unsigned short b2 = 10
+    cdef int c1 = 10
+    cdef unsigned int c2 = 10
+    cdef long d1 = 10
+    cdef unsigned long d2 = 10
+    cdef long long e1 = 10
+    cdef unsigned long long e2 = 10
+
+    cdef float f = 10.0
+    cdef double g = 10.0
+    cdef long double h = 10.0
+
+    cdef void *p = <void *> 10
+
+    with nogil, cython.parallel.parallel():
+        # First, trick the error checking to make it believe these variables
+        # are initialized after this if
+
+        if mybool: # mybool is always false!
+            a1 = a2 = b1 = b2 = c1 = c2 = d1 = d2 = e1 = e2 = 0
+            f = g = h = 0.0
+            p = NULL
+
+        if (a1 == 10 or a2 == 10 or
+            b1 == 10 or b2 == 10 or
+            c1 == 10 or c2 == 10 or
+            d1 == 10 or d2 == 10 or
+            e1 == 10 or e2 == 10 or
+            f == 10.0 or g == 10.0 or h == 10.0 or
+            p != NULL):
+
+            errp[0] = 1
+
+    if err:
+        raise Exception("One of the values was not initiazed to a maximum "
+                        "or NaN value")