vm: some optimizations.

* vm.c (vm_getz): Manual CSE: calculate address of location,
then conditionally set to zero.
(vm_set_nil_error): New static function.
(vm_set, vm_sm_set): Call zero-argument vm_set_nil_error
instead of three_argument uw_throwf.
(vm_stab_slowpath): New function.
(vm_stab): Function marked inline. The slow path when the
binding is not cached goes through vm_stab_slowpath which is
not inlined.

1 files changed, 27 insertions, 11 deletions

diff --git a/vm.c b/vm.c
index 4413faef..7aa463c9 100644
--- a/vm.c
+++ b/vm.c
@@ -366,9 +366,8 @@ INLINE val vm_get(struct vm_env *dspl, unsigned ref)
 INLINE val vm_getz(struct vm_env *dspl, unsigned ref)
 {
   unsigned lev = vm_lev(ref);
-  if (lev == 0)
-    return z(dspl[0].mem[vm_idx(ref)]);
-  return dspl[lev].mem[vm_idx(ref)];
+  val *addr = &dspl[lev].mem[vm_idx(ref)];
+  return (lev == 0) ? z(*addr) : *addr;
 }
 
 INLINE val vm_sm_get(struct vm_env *dspl, unsigned ref)
@@ -376,6 +375,11 @@ INLINE val vm_sm_get(struct vm_env *dspl, unsigned ref)
   return dspl[vm_sm_lev(ref)].mem[vm_sm_idx(ref)];
 }
 
+NOINLINE static void vm_set_nil_error(void)
+{
+    uw_throwf(error_s, lit("modification of t00/nil"), nao);
+}
+
 INLINE void vm_set(struct vm_env *dspl, unsigned ref, val newval)
 {
   unsigned d = vm_lev(ref);
@@ -383,7 +387,7 @@ INLINE void vm_set(struct vm_env *dspl, unsigned ref, val newval)
   struct vm_env *env = &dspl[d];
 
   if (ref == 0)
-    uw_throwf(error_s, lit("modification of t00/nil"), nao);
+    vm_set_nil_error();
 
   env->mem[i] = newval;
 
@@ -398,7 +402,7 @@ INLINE void vm_sm_set(struct vm_env *dspl, unsigned ref, val newval)
   struct vm_env *env = &dspl[d];
 
   if (ref == 0)
-    uw_throwf(error_s, lit("modification of t00/nil"), nao);
+    vm_set_nil_error();
 
   env->mem[i] = newval;
 
@@ -522,24 +526,36 @@ NOINLINE static void vm_apply(struct vm *vm, vm_word_t insn)
   vm_set(vm->dspl, dest, result);
 }
 
-static loc vm_stab(struct vm *vm, unsigned fun,
-                   val (*lookup_fn)(val env, val sym), val kind_str)
+
+NOINLINE static loc vm_stab_slowpath(struct vm *vm, unsigned fun,
+                                     val (*lookup_fn)(val env, val sym),
+                                     val kind_str)
 {
   struct vm_desc *vd = vm->vd;
   struct vm_stent *fe = &vd->stab[fun];
-  loc bindloc = fe->bindloc;
-
-  if (!nullocp(bindloc))
-    return bindloc;
 
   if (nilp(fe->bind = lookup_fn(nil, vecref(vd->symvec, num_fast(fun)))))
     eval_error(vd->bytecode,
                lit("~a ~s is not defined"), kind_str,
                vecref(vd->symvec, num(fun)), nao);
   setcheck(vd->self, fe->bind);
+
   return (fe->bindloc = cdr_l(fe->bind));
 }
 
+INLINE loc vm_stab(struct vm *vm, unsigned fun,
+                   val (*lookup_fn)(val env, val sym), val kind_str)
+{
+  struct vm_desc *vd = vm->vd;
+  struct vm_stent *fe = &vd->stab[fun];
+  loc bindloc = fe->bindloc;
+
+  if (!nullocp(bindloc))
+    return bindloc;
+
+  return vm_stab_slowpath(vm, fun, lookup_fn, kind_str);
+}
+
 NOINLINE static void vm_gcall(struct vm *vm, vm_word_t insn)
 {
   unsigned nargs = vm_insn_extra(insn);