Optimize native call if statically bound (bug 5842, r=ds,fyren f=dvander).

Original patch written by David Anderson (original r from Fyren).
- Updated to function with the current JIT compiler.
- Took in clean-ups from later-dated patches.

core/logic/ShareSys.cpp

@@ -331,6 +331,13 @@ void ShareSystem::BindNativeToPlugin(CPlugin *pPlugin, sp_native_t *native, uint
 	native->status = SP_NATIVE_BOUND;
 	native->pfn = pEntry->func();
 
+	if (pEntry->fake)
+	{
+		/* This native is not necessarily optional, but we don't guarantee
+		 * that its address is long-lived. */
+		native->flags |= SP_NTVFLAG_EPHEMERAL;
+	}
+
 	/* We don't bother with dependency crap if the owner is Core. */
 	if (pEntry->owner != &g_CoreNatives)
 	{

public/sourcepawn/sp_vm_types.h

@@ -148,6 +148,7 @@ typedef struct sp_pubvar_s
 #define SP_NATIVE_BOUND			(1)		/**< Native is bound */
 
 #define SP_NTVFLAG_OPTIONAL		(1<<0)	/**< Native is optional */
+#define SP_NTVFLAG_EPHEMERAL		(1<<1)	/**< Native can be unbound */
 
 /** 
  * @brief Native lookup table, by default names point back to the sp_plugin_infotab_t structure.

sourcepawn/jit/BaseRuntime.cpp

@@ -355,6 +355,12 @@ BaseRuntime::GetNativeByIndex(uint32_t index, sp_native_t **native)
   return SP_ERROR_NONE;
 }
 
+sp_native_t *
+BaseRuntime::GetNativeByIndex(uint32_t index)
+{
+  assert(index < m_plugin.num_natives);
+  return &m_plugin.natives[index];
+}
 
 uint32_t
 BaseRuntime::GetNativesNum()

sourcepawn/jit/BaseRuntime.h

@@ -49,6 +49,7 @@ class BaseRuntime
   virtual IPluginDebugInfo *GetDebugInfo();
   virtual int FindNativeByName(const char *name, uint32_t *index);
   virtual int GetNativeByIndex(uint32_t index, sp_native_t **native);
+  virtual sp_native_t *GetNativeByIndex(uint32_t index);
   virtual uint32_t GetNativesNum();
   virtual int FindPublicByName(const char *name, uint32_t *index);
   virtual int GetPublicByIndex(uint32_t index, sp_public_t **publicptr);

sourcepawn/jit/interpreter.cpp

@@ -167,6 +167,29 @@ NativeCallback(sp_context_t *ctx, ucell_t native_idx, cell_t *params)
   return result;
 }
 
+cell_t
+BoundNativeCallback(sp_context_t *ctx, SPVM_NATIVE_FUNC pfn, cell_t *params)
+{
+  cell_t save_sp = ctx->sp;
+  cell_t save_hp = ctx->hp;
+
+  cell_t result = pfn(ctx->basecx, params);
+
+  if (ctx->n_err != SP_ERROR_NONE)
+    return result;
+
+  if (save_sp != ctx->sp) {
+    ctx->n_err = SP_ERROR_STACKLEAK;
+    return result;
+  }
+  if (save_hp != ctx->hp) {
+    ctx->n_err = SP_ERROR_HEAPLEAK;
+    return result;
+  }
+
+  return result;
+}
+
 static inline bool
 GenerateArray(BaseRuntime *rt, sp_context_t *ctx, cell_t dims, cell_t *stk, bool autozero)
 {

sourcepawn/jit/interpreter.h

@@ -33,6 +33,7 @@ int Interpret(BaseRuntime *rt, uint32_t aCodeStart, cell_t *rval);
 
 int GenerateFullArray(BaseRuntime *rt, uint32_t argc, cell_t *argv, int autozero);
 cell_t NativeCallback(sp_context_t *ctx, ucell_t native_idx, cell_t *params);
+cell_t BoundNativeCallback(sp_context_t *ctx, SPVM_NATIVE_FUNC pfn, cell_t *params);
 int PopTrackerAndSetHeap(BaseRuntime *rt);
 int PushTracker(sp_context_t *ctx, size_t amount);
 

sourcepawn/jit/x86/jit_x86.cpp

@@ -1579,9 +1579,8 @@ Compiler::emitNativeCall(OPCODE op)
   // Save registers.
   __ push(edx);
 
-  // Push the parameters for the C++ function.
+  // Push the last parameter for the C++ function.
   __ push(stk);
-  __ push(native_index);
 
   // Relocate our absolute stk to be dat-relative, and update the context's
   // view.
@@ -1589,9 +1588,23 @@ Compiler::emitNativeCall(OPCODE op)
   __ subl(stk, dat);
   __ movl(Operand(eax, offsetof(sp_context_t, sp)), stk);
 
-  // Push context and make the call.
+  __ movl(Operand(eax, offsetof(sp_context_t, n_idx)), native_index);
+
+  sp_native_t *native = rt_->GetNativeByIndex(native_index);
+  if ((native->status != SP_NATIVE_BOUND) ||
+      (native->flags & (SP_NTVFLAG_OPTIONAL | SP_NTVFLAG_EPHEMERAL)))
+  {
+    // The native is either unbound, or it could become unbound in the
+    // future. Invoke the slower native callback.
+    __ push(native_index);
     __ push(eax);
     __ call(ExternalAddress((void *)NativeCallback));
+  } else {
+    // The native is bound so we have a few more guarantees.
+    __ push(intptr_t(native->pfn));
+    __ push(eax);
+    __ call(ExternalAddress((void *)BoundNativeCallback));
+  }
 
   // Check for errors.
   __ movl(ecx, intptr_t(rt_->GetBaseContext()->GetCtx()));