compiler: do not generate specific virtual method if compatible with the original

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/compiler/separate_compiler.nit b/src/compiler/separate_compiler.nit
index 0ad35b9..9988a4e 100644 (file)
--- a/src/compiler/separate_compiler.nit
+++ b/src/compiler/separate_compiler.nit
@@ -560,7 +560,7 @@ class SeparateCompiler
                                var r = pd.separate_runtime_function
                                r.compile_to_c(self)
                                var r2 = pd.virtual_runtime_function
-                               r2.compile_to_c(self)
+                               if r2 != r then r2.compile_to_c(self)
                        end
                end
                self.mainmodule = old_module
@@ -1802,7 +1802,20 @@ redef class MMethodDef
                        # Because the function is virtual, the signature must match the one of the original class
                        var intromclassdef = mproperty.intro.mclassdef
                        var recv = intromclassdef.bound_mtype
+
+                       res = separate_runtime_function
+                       if res.called_recv == recv then
+                               self.virtual_runtime_function_cache = res
+                               return res
+                       end
+
                        var msignature = mproperty.intro.msignature.resolve_for(recv, recv, intromclassdef.mmodule, true)
+
+                       if recv.ctype == res.called_recv.ctype and msignature.c_equiv(res.called_signature) then
+                               self.virtual_runtime_function_cache = res
+                               return res
+                       end
+
                        res = new SeparateRuntimeFunction(self, recv, msignature, "VIRTUAL_{c_name}")
                        self.virtual_runtime_function_cache = res
                        res.is_thunk = true
@@ -1812,6 +1825,23 @@ redef class MMethodDef
        private var virtual_runtime_function_cache: nullable SeparateRuntimeFunction
 end
 
+redef class MSignature
+       # Does the C-version of `self` the same than the C-version of `other`?
+       fun c_equiv(other: MSignature): Bool
+       do
+               if self == other then return true
+               if arity != other.arity then return false
+               for i in [0..arity[ do
+                       if mparameters[i].mtype.ctype != other.mparameters[i].mtype.ctype then return false
+               end
+               if return_mtype != other.return_mtype then
+                       if return_mtype == null or other.return_mtype == null then return false
+                       if return_mtype.ctype != other.return_mtype.ctype then return false
+               end
+               return true
+       end
+end
+
 # The C function associated to a methoddef separately compiled
 class SeparateRuntimeFunction
        super AbstractRuntimeFunction