Remove selective attribute writeback; always synchronize all attributes.

The reasons are:
  1. Shadow memory manipulation added ~12 instructions to TTLOut.pulse
     (without inlining), and it's already barely fast enough.
  2. More importantly, code such as self.ts[1] did not trigger
     attribute writeback, and there seems to be no easy way to fix
     that.

artiq/compiler/transforms/llvm_ir_generator.py

@@ -418,17 +418,9 @@ class LLVMIRGenerator:
         return self.llmodule
 
     def emit_attribute_writeback(self):
-        llobjects = []
+        llobjects = defaultdict(lambda: [])
-        shadow_memory_dim = defaultdict(lambda: 0)
 
         for obj_id in self.object_map:
-            while len(llobjects) <= obj_id:
-                llobjects.append(ll.Constant(llptr, None))
-
-            llobject = self.llmodule.get_global("object.{}".format(obj_id))
-            if llobject is not None:
-                llobjects[obj_id] = llobject.bitcast(llptr)
-
             obj_ref = self.object_map.retrieve(obj_id)
             if isinstance(obj_ref, (pytypes.FunctionType, pytypes.MethodType)):
                 continue
@@ -437,19 +429,20 @@ class LLVMIRGenerator:
             else:
                 typ, _ = self.type_map[type(obj_ref)]
 
-            if shadow_memory_dim[typ] <= obj_id:
+            llobject = self.llmodule.get_global("object.{}".format(obj_id))
-                shadow_memory_dim[typ] = obj_id + 1
+            if llobject is not None:
+                llobjects[typ].append(llobject.bitcast(llptr))
 
         lldatalayout = llvm.create_target_data(self.llmodule.data_layout)
 
-        llrpcattrty = self.llcontext.get_identified_type("shadow.attr")
+        llrpcattrty = self.llcontext.get_identified_type("attr_desc")
         llrpcattrty.elements = [lli32, llptr, llptr]
 
-        lldescty = self.llcontext.get_identified_type("shadow.desc")
+        lldescty = self.llcontext.get_identified_type("type_desc")
-        lldescty.elements = [llrpcattrty.as_pointer().as_pointer(), lli32, llptr]
+        lldescty.elements = [llrpcattrty.as_pointer().as_pointer(), llptr.as_pointer()]
 
         lldescs = []
-        for typ in shadow_memory_dim:
+        for typ in llobjects:
             if "__objectid__" not in typ.attributes:
                 continue
 
@@ -458,44 +451,25 @@ class LLVMIRGenerator:
             else:
                 type_name = "instance.{}".format(typ.name)
 
-            shadowname = "shadow.{}".format(type_name)
-            llshadow = self.llmodule.get_global(shadowname)
-            if llshadow is None:
-                continue
-
-            llshadowlen = shadow_memory_dim[typ] * len(typ.attributes)
-            llshadowty = ll.ArrayType(lli8, llshadowlen)
-            llshadow.gtype = llshadowty
-            llshadow.type = llshadowty.as_pointer()
-            llshadow.initializer = ll.Constant(llshadowty, None)
-
             def llrpcattr_of_attr(name, typ):
-                llty = self.llty_of_type(typ)
+                size = self.llty_of_type(typ).get_abi_size(lldatalayout, context=self.llcontext)
-                if isinstance(llty, ll.PointerType):
-                    # Work around llvmlite bug where it is unable to get a C++
-                    # object for a type if it includes an identified type in a context
-                    # other than the default.
-                    size = llptr.get_abi_size(lldatalayout)
-                else:
-                    size = llty.get_abi_size(lldatalayout)
 
                 def rpc_tag_error(typ):
                     print(typ)
                     assert False
 
-                rpctag = b"Os"
+                if not (types.is_function(typ) or types.is_method(typ) or
-                if not (types.is_function(typ) or types.is_method(typ)):
+                        name == "__objectid__"):
-                    rpctag += self._rpc_tag(typ, error_handler=rpc_tag_error)
+                    rpctag   = b"Os" + self._rpc_tag(typ, error_handler=rpc_tag_error) + b":n\x00"
-                else:
-                    rpctag += b""
-                rpctag += b":n\x00"
                     llrpctag = self.llstr_of_str(rpctag)
+                else:
+                    llrpctag = ll.Constant(llptr, None)
 
                 llrpcattr = ll.GlobalVariable(self.llmodule, llrpcattrty,
-                                              name="shadow.attr.{}.{}".format(type_name, name))
+                                              name="attr.{}.{}".format(type_name, name))
                 llrpcattr.initializer = ll.Constant(llrpcattrty, [
                     ll.Constant(lli32, size),
-                    self.llstr_of_str(rpctag),
+                    llrpctag,
                     self.llstr_of_str(name)
                 ])
                 llrpcattr.global_constant = True
@@ -509,33 +483,36 @@ class LLVMIRGenerator:
 
             llrpcattraryty = ll.ArrayType(llrpcattrty.as_pointer(), len(llrpcattrs) + 1)
             llrpcattrary = ll.GlobalVariable(self.llmodule, llrpcattraryty,
-                                             name="shadow.attrs.{}".format(type_name))
+                                             name="attrs.{}".format(type_name))
             llrpcattrary.initializer = ll.Constant(llrpcattraryty,
                 llrpcattrs + [ll.Constant(llrpcattrty.as_pointer(), None)])
             llrpcattrary.global_constant = True
             llrpcattrary.unnamed_addr = True
             llrpcattrary.linkage = 'internal'
 
+            llobjectaryty = ll.ArrayType(llptr, len(llobjects[typ]) + 1)
+            llobjectary = ll.GlobalVariable(self.llmodule, llobjectaryty,
+                                            name="objects.{}".format(type_name))
+            llobjectary.initializer = ll.Constant(llobjectaryty,
+                llobjects[typ] + [ll.Constant(llptr, None)])
+            llobjectary.linkage = 'internal'
+
             lldesc = ll.GlobalVariable(self.llmodule, lldescty,
-                                       name="shadow.desc.{}".format(type_name))
+                                       name="desc.{}".format(type_name))
             lldesc.initializer = ll.Constant(lldescty, [
                 llrpcattrary.bitcast(llrpcattrty.as_pointer().as_pointer()),
-                ll.Constant(lli32, shadow_memory_dim[typ]),
+                llobjectary.bitcast(llptr.as_pointer())
-                llshadow.bitcast(llptr)
             ])
             lldesc.global_constant = True
             lldesc.linkage = 'internal'
             lldescs.append(lldesc)
 
         llglobaldescty = ll.ArrayType(lldescty.as_pointer(), len(lldescs) + 1)
-        llglobaldesc = ll.GlobalVariable(self.llmodule, llglobaldescty, name="shadow")
+        llglobaldesc = ll.GlobalVariable(self.llmodule, llglobaldescty,
+                                         name="typeinfo")
         llglobaldesc.initializer = ll.Constant(llglobaldescty,
             lldescs + [ll.Constant(lldescty.as_pointer(), None)])
 
-        llobjectaryty = ll.ArrayType(llptr, len(llobjects))
-        llobjectary = ll.GlobalVariable(self.llmodule, llobjectaryty, name="objects")
-        llobjectary.initializer = ll.Constant(llobjectaryty, llobjects)
-
     def process_function(self, func):
         try:
             self.llfunction = self.llmodule.get_global(func.name)
@@ -695,34 +672,6 @@ class LLVMIRGenerator:
 
     def process_SetAttr(self, insn):
         assert builtins.is_allocated(insn.object().type)
-
-        object_type = insn.object().type.find()
-        value_type = insn.value().type.find()
-        if "__objectid__" in object_type.attributes and \
-                not (types.is_function(value_type) or types.is_method(value_type)):
-            llidptr = self.llbuilder.gep(self.map(insn.object()),
-                                         [self.llindex(0), self.llindex(0)])
-            llid = self.llbuilder.load(llidptr, name="shadow.id")
-            llattrcount = ll.Constant(lli32, len(object_type.attributes))
-            llshadowpos = self.llbuilder.add(
-                self.llbuilder.mul(llid, llattrcount),
-                ll.Constant(lli32, self.attr_index(insn)))
-
-            if types.is_constructor(object_type):
-                shadowname = "shadow.class.{}".format(object_type.name)
-            else:
-                shadowname = "shadow.instance.{}".format(object_type.name)
-
-            llshadow = self.llmodule.get_global(shadowname)
-            if llshadow is None:
-                llshadowty = ll.ArrayType(lli8, 0)
-                llshadow = ll.GlobalVariable(self.llmodule, llshadowty, shadowname)
-                llshadow.linkage = 'internal'
-
-            llshadowptr = self.llbuilder.gep(llshadow, [self.llindex(0), llshadowpos],
-                                             name="shadow.ptr")
-            self.llbuilder.store(ll.Constant(lli8, 1), llshadowptr)
-
         llptr = self.llbuilder.gep(self.map(insn.object()),
                                    [self.llindex(0), self.llindex(self.attr_index(insn))],
                                    name=insn.name)

artiq/runtime/ksupport.c

@@ -20,7 +20,7 @@
 double round(double x);
 
 void ksupport_abort(void);
-static void attribute_writeback(void *, void *);
+static void attribute_writeback(void *);
 
 int64_t now;
 
@@ -247,16 +247,15 @@ int main(void)
             mailbox_send(&load_reply);
             while(1);
         }
+
+        void *__bss_start = dyld_lookup("__bss_start", request->library_info);
+        void *_end = dyld_lookup("_end", request->library_info);
+        memset(__bss_start, 0, _end - __bss_start);
     }
 
     if(request->run_kernel) {
         void (*kernel_run)() = request->library_info->init;
-        void *__bss_start = dyld_lookup("__bss_start", request->library_info);
+        void *typeinfo = dyld_lookup("typeinfo", request->library_info);
-        void *_end = dyld_lookup("_end", request->library_info);
-        void *shadow  = dyld_lookup("shadow", request->library_info);
-        void *objects = dyld_lookup("objects", request->library_info);
-
-        memset(__bss_start, 0, _end - __bss_start);
 
         mailbox_send_and_wait(&load_reply);
 
@@ -264,7 +263,7 @@ int main(void)
         kernel_run();
         now_save(now);
 
-        attribute_writeback(shadow, objects);
+        attribute_writeback(typeinfo);
 
         struct msg_base finished_reply;
         finished_reply.type = MESSAGE_TYPE_FINISHED;
@@ -405,40 +404,36 @@ int recv_rpc(void *slot) {
     }
 }
 
-struct shadow_attr {
+struct attr_desc {
     uint32_t size;
     const char *tag;
     const char *name;
 };
 
-struct shadow_desc {
+struct type_desc {
-    struct shadow_attr **attributes;
+    struct attr_desc **attributes;
-    uint32_t object_count;
+    void **objects;
-    uint8_t *shadow;
 };
 
-void attribute_writeback(void *udescs, void *uobjects) {
+void attribute_writeback(void *utypes) {
-    struct shadow_desc **descs = (struct shadow_desc **)udescs;
+    struct type_desc **types = (struct type_desc **)utypes;
-    void **objects = (void **)uobjects;
+    while(*types) {
-
+        struct type_desc *type = *types++;
-    while(*descs) {
-        struct shadow_desc *desc = *descs++;
 
         size_t attr_count = 0;
-        for(struct shadow_attr **attr = desc->attributes; *attr; attr++)
+        for(struct attr_desc **attr = type->attributes; *attr; attr++)
             attr_count++;
 
-        for(int object_id = 0; object_id < desc->object_count; object_id++) {
+        void **objects = type->objects;
-            uint8_t *shadow = &desc->shadow[object_id * attr_count];
+        while(*objects) {
-            void *object = objects[object_id];
+            void *object = *objects++;
-
-            if(object == NULL) continue;
 
             size_t offset = 0;
-            for(int attr_index = 0; attr_index < attr_count; attr_index++) {
+            struct attr_desc **attrs = type->attributes;
-                struct shadow_attr *attr = desc->attributes[attr_index];
+            while(*attrs) {
+                struct attr_desc *attr = *attrs++;
 
-                if(shadow[attr_index]) {
+                if(attr->tag) {
                     uintptr_t value = (uintptr_t)object + offset;
                     send_rpc(0, attr->tag, &object, &attr->name, value);
                 }