optimise string-to-something comparisons also when we know that the result is...

optimise string-to-something comparisons also when we know that the result is boolean (the cmp functions have a proper fallback for non-strings)

Cython/Compiler/ExprNodes.py

@@ -9930,11 +9930,11 @@ class CmpNode(object):
             return (container_type.is_ptr or container_type.is_array) \
                 and not container_type.is_string
 
-    def find_special_bool_compare_function(self, env, operand1):
+    def find_special_bool_compare_function(self, env, operand1, result_is_bool=False):
         # note: currently operand1 must get coerced to a Python object if we succeed here!
         if self.operator in ('==', '!='):
             type1, type2 = operand1.type, self.operand2.type
-            if type1.is_builtin_type and type2.is_builtin_type:
+            if result_is_bool or (type1.is_builtin_type and type2.is_builtin_type):
                 if type1 is Builtin.unicode_type or type2 is Builtin.unicode_type:
                     self.special_bool_cmp_utility_code = UtilityCode.load_cached("UnicodeEquals", "StringTools.c")
                     self.special_bool_cmp_function = "__Pyx_PyUnicode_Equals"
@@ -10184,6 +10184,7 @@ class PrimaryCmpNode(ExprNode, CmpNode):
         else:
             self.operand1 = self.operand1.coerce_to(func_type.args[0].type, env)
             self.operand2 = self.operand2.coerce_to(func_type.args[1].type, env)
+        self.is_pycmp = False
         self.type = func_type.return_type
 
     def analyse_memoryviewslice_comparison(self, env):
@@ -10199,6 +10200,23 @@ class PrimaryCmpNode(ExprNode, CmpNode):
 
         return False
 
+    def coerce_to_boolean(self, env):
+        if self.is_pycmp:
+            # coercing to bool => may allow for more efficient comparison code
+            if self.find_special_bool_compare_function(
+                    env, self.operand1, result_is_bool=True):
+                self.is_pycmp = False
+                self.type = PyrexTypes.c_bint_type
+                self.is_temp = 1
+                if self.cascade:
+                    operand2 = self.cascade.optimise_comparison(
+                        self.operand2, env, result_is_bool=True)
+                    if operand2 is not self.operand2:
+                        self.coerced_operand2 = operand2
+                return self
+        # TODO: check if we can optimise parts of the cascade here
+        return ExprNode.coerce_to_boolean(self, env)
+
     def has_python_operands(self):
         return (self.operand1.type.is_pyobject
             or self.operand2.type.is_pyobject)
@@ -10320,12 +10338,14 @@ class CascadedCmpNode(Node, CmpNode):
     def has_python_operands(self):
         return self.operand2.type.is_pyobject
 
-    def optimise_comparison(self, operand1, env):
-        if self.find_special_bool_compare_function(env, operand1):
+    def optimise_comparison(self, operand1, env, result_is_bool=False):
+        if self.find_special_bool_compare_function(env, operand1, result_is_bool):
+            self.is_pycmp = False
+            self.type = PyrexTypes.c_bint_type
             if not operand1.type.is_pyobject:
                 operand1 = operand1.coerce_to_pyobject(env)
         if self.cascade:
-            operand2 = self.cascade.optimise_comparison(self.operand2, env)
+            operand2 = self.cascade.optimise_comparison(self.operand2, env, result_is_bool)
             if operand2 is not self.operand2:
                 self.coerced_operand2 = operand2
         return operand1