Refactor GC trace generation in the compiler

- Add a new trace pattern, static tracing. This is used when tracing a
nominal type in order to trace it in the most efficient way possible
(type in the sending context and capability in the receiving context).
- Enhance dynamic tracing of nominal types with that same
type/capability logic.
- Trace boxed tuples correctly.

src/libponyc/codegen/gencall.c

@@ -359,8 +359,8 @@ LLVMValueRef gen_funptr(compile_t* c, ast_t* ast)
   return funptr;
 }
 
-void gen_send_message(compile_t* c, reach_method_t* m, LLVMValueRef args[],
-  ast_t* args_ast)
+void gen_send_message(compile_t* c, reach_method_t* m, LLVMValueRef orig_args[],
+  LLVMValueRef cast_args[], ast_t* args_ast)
 {
   // Allocate the message, setting its size and ID.
   size_t msg_size = (size_t)LLVMABISizeOfType(c->target_data, m->msg_type);
@@ -376,7 +376,7 @@ void gen_send_message(compile_t* c, reach_method_t* m, LLVMValueRef args[],
   for(unsigned int i = 0; i < m->param_count; i++)
   {
     LLVMValueRef arg_ptr = LLVMBuildStructGEP(c->builder, msg_ptr, i + 3, "");
-    LLVMBuildStore(c->builder, args[i+1], arg_ptr);
+    LLVMBuildStore(c->builder, cast_args[i+1], arg_ptr);
   }
 
   // Trace while populating the message contents.
@@ -407,7 +407,8 @@ void gen_send_message(compile_t* c, reach_method_t* m, LLVMValueRef args[],
 
     for(size_t i = 0; i < m->param_count; i++)
     {
-      gentrace(c, ctx, args[i+1], ast_type(arg_ast), ast_type(param));
+      gentrace(c, ctx, orig_args[i+1], cast_args[i+1], ast_type(arg_ast),
+        ast_type(param));
       param = ast_sibling(param);
       arg_ast = ast_sibling(arg_ast);
     }
@@ -417,7 +418,7 @@ void gen_send_message(compile_t* c, reach_method_t* m, LLVMValueRef args[],
 
   // Send the message.
   msg_args[0] = ctx;
-  msg_args[1] = LLVMBuildBitCast(c->builder, args[0], c->object_ptr, "");
+  msg_args[1] = LLVMBuildBitCast(c->builder, cast_args[0], c->object_ptr, "");
   msg_args[2] = msg;
   gencall_runtime(c, "pony_sendv", msg_args, 3, "");
 }
@@ -688,9 +689,11 @@ LLVMValueRef gen_call(compile_t* c, ast_t* ast)
   {
     // If we're sending a message, trace and send here instead of calling the
     // sender to trace the most specific types possible.
+    LLVMValueRef* cast_args = (LLVMValueRef*)ponyint_pool_alloc_size(buf_size);
+    cast_args[0] = args[0];
     while(arg != NULL)
     {
-      args[i] = gen_assign_cast(c, params[i], args[i], ast_type(arg));
+      cast_args[i] = gen_assign_cast(c, params[i], args[i], ast_type(arg));
       arg = ast_sibling(arg);
       i++;
     }
@@ -699,7 +702,7 @@ LLVMValueRef gen_call(compile_t* c, ast_t* ast)
     reach_method_t* m = reach_method(t, cap, method_name, typeargs);
 
     codegen_debugloc(c, ast);
-    gen_send_message(c, m, args, positional);
+    gen_send_message(c, m, args, cast_args, positional);
     codegen_debugloc(c, NULL);
     switch(ast_id(postfix))
     {
@@ -712,6 +715,7 @@ LLVMValueRef gen_call(compile_t* c, ast_t* ast)
         r = c->none_instance;
         break;
     }
+    ponyint_pool_free_size(buf_size, cast_args);
   } else {
     while(arg != NULL)
     {

src/libponyc/codegen/gencall.h

@@ -6,8 +6,8 @@
 
 PONY_EXTERN_C_BEGIN
 
-void gen_send_message(compile_t* c, reach_method_t* m, LLVMValueRef args[],
-  ast_t* args_ast);
+void gen_send_message(compile_t* c, reach_method_t* m, LLVMValueRef orig_args[],
+  LLVMValueRef cast_args[], ast_t* args_ast);
 
 LLVMValueRef gen_funptr(compile_t* c, ast_t* ast);
 

src/libponyc/codegen/genfun.c

@@ -257,7 +257,8 @@ static void add_dispatch_case(compile_t* c, reach_type_t* t, ast_t* params,
 
   while(param != NULL)
   {
-    if(gentrace_needed(c, ast_type(param), NULL))
+    ast_t* param_type = ast_type(param);
+    if(gentrace_needed(c, param_type, param_type))
     {
       need_trace = true;
       break;
@@ -273,7 +274,8 @@ static void add_dispatch_case(compile_t* c, reach_type_t* t, ast_t* params,
 
     for(int i = 1; i < count; i++)
     {
-      gentrace(c, ctx, args[i], ast_type(param), NULL);
+      ast_t* param_type = ast_type(param);
+      gentrace(c, ctx, args[i], args[i], param_type, param_type);
       param = ast_sibling(param);
     }
 
@@ -387,7 +389,7 @@ static bool genfun_be(compile_t* c, reach_type_t* t, reach_method_t* m)
   LLVMGetParams(m->func, param_vals);
 
   // Send the arguments in a message to 'this'.
-  gen_send_message(c, m, param_vals, params);
+  gen_send_message(c, m, param_vals, param_vals, params);
 
   // Return None.
   LLVMBuildRet(c->builder, c->none_instance);
@@ -462,7 +464,7 @@ static bool genfun_newbe(compile_t* c, reach_type_t* t, reach_method_t* m)
   LLVMGetParams(m->func, param_vals);
 
   // Send the arguments in a message to 'this'.
-  gen_send_message(c, m, param_vals, params);
+  gen_send_message(c, m, param_vals, param_vals, params);
 
   // Return 'this'.
   LLVMBuildRet(c->builder, param_vals[0]);

src/libponyc/codegen/genprim.c

@@ -665,7 +665,7 @@ static void trace_array_elements(compile_t* c, reach_type_t* t,
   ast_t* typeargs = ast_childidx(t->ast, 2);
   ast_t* typearg = ast_child(typeargs);
 
-  if(!gentrace_needed(c, typearg, NULL))
+  if(!gentrace_needed(c, typearg, typearg))
     return;
 
   reach_type_t* t_elem = reach_type(c->reach, typearg);
@@ -695,7 +695,7 @@ static void trace_array_elements(compile_t* c, reach_type_t* t,
   LLVMValueRef elem_ptr = LLVMBuildInBoundsGEP(c->builder, pointer, &phi, 1,
     "");
   LLVMValueRef elem = LLVMBuildLoad(c->builder, elem_ptr, "");
-  gentrace(c, ctx, elem, typearg, NULL);
+  gentrace(c, ctx, elem, elem, typearg, typearg);
 
   // Add one to the phi node and branch back to the cond block.
   LLVMValueRef one = LLVMConstInt(c->intptr, 1, false);