From 2bd3d28c52e59075c3c01a1c79dc3404ab28e9fb Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 16 Nov 2018 07:14:41 -0800
Subject: vm: use faster funcall functions in vm_gcall.

* vm.c (vm_gcall): For the 0 to 4 argument cases, use funcall,
funcall1, ..., funcall4 instead of generic_funcall.
---
 vm.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 58 insertions(+), 15 deletions(-)

diff --git a/vm.c b/vm.c
index 9322cba8..8664b804 100644
--- a/vm.c
+++ b/vm.c
@@ -545,28 +545,71 @@ NOINLINE static void vm_gcall(struct vm *vm, vm_word_t insn)
   unsigned nargs = vm_insn_extra(insn);
   unsigned dest = vm_insn_operand(insn);
   vm_word_t argw = vm->code[vm->ip++];
-  unsigned fun = vm_arg_operand_lo(argw);
+  unsigned funidx = vm_arg_operand_lo(argw);
+  val fun = deref(vm_stab(vm, funidx, lookup_fun, lit("function")));
   val result;
-  args_decl (args, max(nargs, ARGS_MIN));
-
-  if (nargs--) {
-    args_add(args, vm_getz(vm->dspl, vm_arg_operand_hi(argw)));
 
-    while (nargs >= 2) {
-      nargs -= 2;
-      argw = vm->code[vm->ip++];
-      args_add(args, vm_getz(vm->dspl, vm_arg_operand_lo(argw)));
-      args_add(args, vm_getz(vm->dspl, vm_arg_operand_hi(argw)));
+  switch (nargs) {
+  case 0:
+    result = funcall(fun);
+    break;
+  case 1:
+    {
+      val arg1 = vm_getz(vm->dspl, vm_arg_operand_hi(argw));
+      result = funcall1(fun, z(arg1));
+    }
+    break;
+  case 2:
+    {
+      vm_word_t argx = vm->code[vm->ip++];
+      val arg1 = vm_getz(vm->dspl, vm_arg_operand_hi(argw));
+      val arg2 = vm_getz(vm->dspl, vm_arg_operand_lo(argx));
+      result = funcall2(fun, z(arg1), z(arg2));
     }
+    break;
+  case 3:
+    {
+      vm_word_t argx = vm->code[vm->ip++];
+      val arg1 = vm_getz(vm->dspl, vm_arg_operand_hi(argw));
+      val arg2 = vm_getz(vm->dspl, vm_arg_operand_lo(argx));
+      val arg3 = vm_getz(vm->dspl, vm_arg_operand_hi(argx));
+      result = funcall3(fun, z(arg1), z(arg2), z(arg3));
+    }
+    break;
+  case 4:
+    {
+      vm_word_t argx = vm->code[vm->ip++];
+      vm_word_t argy = vm->code[vm->ip++];
+      val arg1 = vm_getz(vm->dspl, vm_arg_operand_hi(argw));
+      val arg2 = vm_getz(vm->dspl, vm_arg_operand_lo(argx));
+      val arg3 = vm_getz(vm->dspl, vm_arg_operand_hi(argx));
+      val arg4 = vm_getz(vm->dspl, vm_arg_operand_lo(argy));
+      result = funcall4(fun, z(arg1), z(arg2), z(arg3), z(arg4));
+    }
+    break;
+  default:
+    {
+      args_decl (args, max(nargs, ARGS_MIN));
+      args_add(args, vm_getz(vm->dspl, vm_arg_operand_hi(argw)));
+      nargs--;
 
-    if (nargs) {
-      argw = vm->code[vm->ip++];
-      args_add(args, vm_getz(vm->dspl, vm_arg_operand_lo(argw)));
+      while (nargs >= 2) {
+        nargs -= 2;
+        argw = vm->code[vm->ip++];
+        args_add(args, vm_getz(vm->dspl, vm_arg_operand_lo(argw)));
+        args_add(args, vm_getz(vm->dspl, vm_arg_operand_hi(argw)));
+      }
+
+      if (nargs) {
+        argw = vm->code[vm->ip++];
+        args_add(args, vm_getz(vm->dspl, vm_arg_operand_lo(argw)));
+      }
+
+      result = generic_funcall(fun, args);
     }
+    break;
   }
 
-  result = generic_funcall(deref(vm_stab(vm, fun, lookup_fun,
-                                         lit("function"))), args);
   vm_set(vm->dspl, dest, result);
 }
 
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