VM: the delete_context() and reset_context() api functions can be

simplified a bit

The functions always operates on parent->ctx, so passing a context*
parameter is redundant. This enables shorter assembly code for
the (start-context-and-delete) and (set-context-and-delete) primitives.

basis/bootstrap/assembler/ppc.factor

@@ -820,7 +820,6 @@ IN: bootstrap.ppc
 : jit-delete-current-context ( -- )
     jit-load-context
     3 vm-reg MR
-    4 ctx-reg MR
     "delete_context" jit-call ;
 
 [
@@ -831,7 +830,6 @@ IN: bootstrap.ppc
 : jit-start-context-and-delete ( -- )
     jit-load-context
     3 vm-reg MR
-    4 ctx-reg MR
     "reset_context" jit-call
     jit-pop-quot-and-param
     ctx-reg jit-switch-context

basis/bootstrap/assembler/x86.32.factor

@@ -344,7 +344,7 @@ IN: bootstrap.x86
 : jit-delete-current-context ( -- )
     jit-load-vm
     jit-load-context
-    vm-reg ctx-reg "delete_context" jit-call-2arg ;
+    vm-reg "delete_context" jit-call-1arg ;
 
 [
     jit-delete-current-context
@@ -354,7 +354,7 @@ IN: bootstrap.x86
 : jit-start-context-and-delete ( -- )
     jit-load-vm
     jit-load-context
-    vm-reg ctx-reg "reset_context" jit-call-2arg
+    vm-reg "reset_context" jit-call-1arg
 
     jit-save-quot-and-param
     ctx-reg jit-switch-context

basis/bootstrap/assembler/x86.64.factor

@@ -62,6 +62,7 @@ IN: bootstrap.x86
     ctx-reg context-datastack-offset [+] ds-reg MOV
     ctx-reg context-retainstack-offset [+] rs-reg MOV ;
 
+! ctx-reg must already have been loaded
 : jit-restore-context ( -- )
     ds-reg ctx-reg context-datastack-offset [+] MOV
     rs-reg ctx-reg context-retainstack-offset [+] MOV ;
@@ -298,8 +299,7 @@ IN: bootstrap.x86
 [ jit-start-context ] \ (start-context) define-sub-primitive
 
 : jit-delete-current-context ( -- )
-    jit-load-context
-    vm-reg ctx-reg "delete_context" jit-call-2arg ;
+    vm-reg "delete_context" jit-call-1arg ;
 
 [
     jit-delete-current-context
@@ -307,9 +307,9 @@ IN: bootstrap.x86
 ] \ (set-context-and-delete) define-sub-primitive
 
 : jit-start-context-and-delete ( -- )
-    jit-load-context
-    vm-reg ctx-reg "reset_context" jit-call-2arg
 
+    jit-load-context
+    vm-reg "reset_context" jit-call-1arg
     jit-pop-quot-and-param
     ctx-reg jit-switch-context
     jit-push-param

vm/contexts.cpp

@@ -100,15 +100,15 @@ void factor_vm::init_context(context* ctx) {
 }
 
 /* Allocates memory (init_context(), but not parent->new_context() */
-context* new_context(factor_vm* parent) {
+VM_C_API context* new_context(factor_vm* parent) {
   context* new_context = parent->new_context();
   parent->init_context(new_context);
   return new_context;
 }
 
-void factor_vm::delete_context(context* old_context) {
-  unused_contexts.push_back(old_context);
-  active_contexts.erase(old_context);
+void factor_vm::delete_context() {
+  unused_contexts.push_back(ctx);
+  active_contexts.erase(ctx);
 
   while (unused_contexts.size() > 10) {
     context* stale_context = unused_contexts.front();
@@ -117,14 +117,14 @@ void factor_vm::delete_context(context* old_context) {
   }
 }
 
-VM_C_API void delete_context(factor_vm* parent, context* old_context) {
-  parent->delete_context(old_context);
+VM_C_API void delete_context(factor_vm* parent) {
+  parent->delete_context();
 }
 
 /* Allocates memory (init_context()) */
-VM_C_API void reset_context(factor_vm* parent, context* ctx) {
-  ctx->reset();
-  parent->init_context(ctx);
+VM_C_API void reset_context(factor_vm* parent) {
+  parent->ctx->reset();
+  parent->init_context(parent->ctx);
 }
 
 /* Allocates memory */
@@ -147,7 +147,7 @@ cell begin_callback(factor_vm* parent, cell quot) {
 
 void factor_vm::end_callback() {
   callback_ids.pop_back();
-  delete_context(ctx);
+  delete_context();
 }
 
 void end_callback(factor_vm* parent) { parent->end_callback(); }

vm/contexts.hpp

@@ -66,8 +66,8 @@ struct context {
 };
 
 VM_C_API context* new_context(factor_vm* parent);
-VM_C_API void delete_context(factor_vm* parent, context* old_context);
-VM_C_API void reset_context(factor_vm* parent, context* ctx);
+VM_C_API void delete_context(factor_vm* parent);
+VM_C_API void reset_context(factor_vm* parent);
 VM_C_API cell begin_callback(factor_vm* parent, cell quot);
 VM_C_API void end_callback(factor_vm* parent);
 

vm/vm.hpp

@@ -154,7 +154,7 @@ struct factor_vm {
   // contexts
   context* new_context();
   void init_context(context* ctx);
-  void delete_context(context* old_context);
+  void delete_context();
   void init_contexts(cell datastack_size_, cell retainstack_size_,
                      cell callstack_size_);
   void delete_contexts();