From 0bcb970842735f2ea5d52ec719245389ff84e111 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sat, 22 Mar 2014 20:47:27 +0900
Subject: [PATCH 1/3] handle grefs at analyzing stage

---
 src/codegen.c | 55 +++++++++++++++++++++++++++------------------------
 1 file changed, 29 insertions(+), 26 deletions(-)

diff --git a/src/codegen.c b/src/codegen.c
index 10aeeda7..61a7d01b 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -16,6 +16,7 @@
 #endif
 
 typedef struct analyze_scope {
+  int depth;
   bool varg;
   xvect args, locals, captures; /* rest args variable is counted as a local */
   struct analyze_scope *up;
@@ -29,7 +30,7 @@ typedef struct analyze_state {
   pic_sym rEQ, rLT, rLE, rGT, rGE, rNOT;
   pic_sym rVALUES, rCALL_WITH_VALUES;
   pic_sym sCALL, sTAILCALL, sCALL_WITH_VALUES, sTAILCALL_WITH_VALUES;
-  pic_sym sREF, sRETURN;
+  pic_sym sREF, sGREF, sRETURN;
 } analyze_state;
 
 static bool push_scope(analyze_state *, pic_value);
@@ -83,6 +84,7 @@ new_analyze_state(pic_state *pic)
   register_symbol(pic, state, sCALL_WITH_VALUES, "call-with-values");
   register_symbol(pic, state, sTAILCALL_WITH_VALUES, "tailcall-with-values");
   register_symbol(pic, state, sREF, "ref");
+  register_symbol(pic, state, sGREF, "gref");
   register_symbol(pic, state, sRETURN, "return");
 
   /* push initial scope */
@@ -144,6 +146,7 @@ push_scope(analyze_state *state, pic_value formals)
   if (analyze_args(pic, formals, &varg, &args, &locals)) {
     scope = (analyze_scope *)pic_alloc(pic, sizeof(analyze_scope));
     scope->up = state->scope;
+    scope->depth = scope->up ? scope->up->depth + 1 : 0;
     scope->varg = varg;
     scope->args = args;
     scope->locals = locals;
@@ -282,6 +285,26 @@ analyze(analyze_state *state, pic_value obj, bool tailpos)
   return res;
 }
 
+static pic_value
+analyze_global_var(analyze_state *state, pic_sym sym)
+{
+  pic_state *pic = state->pic;
+  xh_entry *e;
+  size_t i;
+
+  if ((e = xh_get_int(pic->global_tbl, sym))) {
+    i = e->val;
+  }
+  else {
+    i = pic->glen++;
+    if (i >= pic->gcapa) {
+      pic_error(pic, "global table overflow");
+    }
+    xh_put_int(pic->global_tbl, sym, i);
+  }
+  return pic_list2(pic, pic_symbol_value(state->sGREF), pic_int_value(i));
+}
+
 static pic_value
 analyze_var(analyze_state *state, pic_value obj)
 {
@@ -293,6 +316,10 @@ analyze_var(analyze_state *state, pic_value obj)
   if ((depth = find_var(state, sym)) == -1) {
     pic_errorf(pic, "unbound variable %s", pic_symbol_name(pic, sym));
   }
+
+  if (depth == state->scope->depth) {
+    return analyze_global_var(state, sym);
+  }
   return new_ref(state, depth, sym);
 }
 
@@ -871,26 +898,6 @@ is_closed(resolver_state *state, pic_sym sym)
   return xh_get_int(state->scope->cvs, sym) != NULL;
 }
 
-static pic_value
-resolve_gref(resolver_state *state, pic_sym sym)
-{
-  pic_state *pic = state->pic;
-  xh_entry *e;
-  size_t i;
-
-  if ((e = xh_get_int(pic->global_tbl, sym))) {
-    i = e->val;
-  }
-  else {
-    i = pic->glen++;
-    if (i >= pic->gcapa) {
-      pic_error(pic, "global table overflow");
-    }
-    xh_put_int(pic->global_tbl, sym, i);
-  }
-  return pic_list2(pic, pic_symbol_value(state->sGREF), pic_int_value(i));
-}
-
 static pic_value
 resolve_lref(resolver_state *state, pic_sym sym)
 {
@@ -940,7 +947,6 @@ static pic_value
 resolve_reference_node(resolver_state *state, pic_value obj)
 {
   pic_state *pic = state->pic;
-  resolver_scope *scope = state->scope;
   pic_sym tag;
 
   if (! pic_pair_p(obj))
@@ -953,10 +959,7 @@ resolve_reference_node(resolver_state *state, pic_value obj)
 
     depth = pic_int(pic_list_ref(pic, obj, 1));
     sym = pic_sym(pic_list_ref(pic, obj, 2));
-    if (depth == scope->depth) {
-      return resolve_gref(state, sym);
-    }
-    else if (depth == 0 && ! is_closed(state, sym)) {
+    if (depth == 0 && ! is_closed(state, sym)) {
       return resolve_lref(state, sym);
     }
     else {

From 312c977c17cac4c3ff8df52a8ddde83cfcddbc7b Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sun, 23 Mar 2014 11:28:11 +0900
Subject: [PATCH 2/3] distinguish lref and cref at analysis stage

---
 src/codegen.c | 57 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 36 insertions(+), 21 deletions(-)

diff --git a/src/codegen.c b/src/codegen.c
index 61a7d01b..a3c8866c 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -30,7 +30,7 @@ typedef struct analyze_state {
   pic_sym rEQ, rLT, rLE, rGT, rGE, rNOT;
   pic_sym rVALUES, rCALL_WITH_VALUES;
   pic_sym sCALL, sTAILCALL, sCALL_WITH_VALUES, sTAILCALL_WITH_VALUES;
-  pic_sym sREF, sGREF, sRETURN;
+  pic_sym sGREF, sLREF, sCREF, sRETURN;
 } analyze_state;
 
 static bool push_scope(analyze_state *, pic_value);
@@ -83,8 +83,9 @@ new_analyze_state(pic_state *pic)
   register_symbol(pic, state, sTAILCALL, "tail-call");
   register_symbol(pic, state, sCALL_WITH_VALUES, "call-with-values");
   register_symbol(pic, state, sTAILCALL_WITH_VALUES, "tailcall-with-values");
-  register_symbol(pic, state, sREF, "ref");
   register_symbol(pic, state, sGREF, "gref");
+  register_symbol(pic, state, sLREF, "lref");
+  register_symbol(pic, state, sCREF, "cref");
   register_symbol(pic, state, sRETURN, "return");
 
   /* push initial scope */
@@ -249,15 +250,6 @@ define_var(analyze_state *state, pic_sym sym)
   xv_push(&scope->locals, &sym);
 }
 
-static pic_value
-new_ref(analyze_state *state, int depth, pic_sym sym)
-{
-  return pic_list3(state->pic,
-                   pic_symbol_value(state->sREF),
-                   pic_int_value(depth),
-                   pic_symbol_value(sym));
-}
-
 static pic_value analyze_node(analyze_state *, pic_value, bool);
 
 static pic_value
@@ -305,6 +297,22 @@ analyze_global_var(analyze_state *state, pic_sym sym)
   return pic_list2(pic, pic_symbol_value(state->sGREF), pic_int_value(i));
 }
 
+static pic_value
+analyze_local_var(analyze_state *state, pic_sym sym)
+{
+  pic_state *pic = state->pic;
+
+  return pic_list2(pic, pic_symbol_value(state->sLREF), pic_sym_value(sym));
+}
+
+static pic_value
+analyze_free_var(analyze_state *state, pic_sym sym, int depth)
+{
+  pic_state *pic = state->pic;
+
+  return pic_list3(pic, pic_symbol_value(state->sCREF), pic_int_value(depth), pic_sym_value(sym));
+}
+
 static pic_value
 analyze_var(analyze_state *state, pic_value obj)
 {
@@ -319,8 +327,11 @@ analyze_var(analyze_state *state, pic_value obj)
 
   if (depth == state->scope->depth) {
     return analyze_global_var(state, sym);
+  } else if (depth == 0) {
+    return analyze_local_var(state, sym);
+  } else {
+    return analyze_free_var(state, sym, depth);
   }
-  return new_ref(state, depth, sym);
 }
 
 static pic_value
@@ -810,7 +821,6 @@ typedef struct resolver_scope {
 typedef struct resolver_state {
   pic_state *pic;
   resolver_scope *scope;
-  pic_sym sREF;
   pic_sym sGREF, sCREF, sLREF;
 } resolver_state;
 
@@ -826,7 +836,6 @@ new_resolver_state(pic_state *pic)
   state->pic = pic;
   state->scope = NULL;
 
-  register_symbol(pic, state, sREF, "ref");
   register_symbol(pic, state, sGREF, "gref");
   register_symbol(pic, state, sLREF, "lref");
   register_symbol(pic, state, sCREF, "cref");
@@ -953,18 +962,24 @@ resolve_reference_node(resolver_state *state, pic_value obj)
     return obj;
 
   tag = pic_sym(pic_car(pic, obj));
-  if (tag == state->sREF) {
+  if (tag == state->sLREF) {
+    pic_sym sym;
+
+    sym = pic_sym(pic_list_ref(pic, obj, 1));
+    if (! is_closed(state, sym)) {
+      return resolve_lref(state, sym);
+    }
+    else {
+      return resolve_cref(state, 0, sym);
+    }
+  }
+  else if (tag == state->sCREF) {
     int depth;
     pic_sym sym;
 
     depth = pic_int(pic_list_ref(pic, obj, 1));
     sym = pic_sym(pic_list_ref(pic, obj, 2));
-    if (depth == 0 && ! is_closed(state, sym)) {
-      return resolve_lref(state, sym);
-    }
-    else {
-      return resolve_cref(state, depth, sym);
-    }
+    return resolve_cref(state, depth, sym);
   }
   else if (tag == pic->sLAMBDA) {
     pic_value args, locals, closes, body;

From 74294c819f79e8717279e738ab2178e23daa9de0 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sun, 23 Mar 2014 11:55:06 +0900
Subject: [PATCH 3/3] remove resolver pass

---
 src/codegen.c | 308 ++++++++++++--------------------------------------
 1 file changed, 73 insertions(+), 235 deletions(-)

diff --git a/src/codegen.c b/src/codegen.c
index a3c8866c..9946fa4b 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -809,226 +809,6 @@ pic_analyze(pic_state *pic, pic_value obj)
   return obj;
 }
 
-typedef struct resolver_scope {
-  int depth;
-  bool varg;
-  int argc, localc, capturec;
-  xhash *cvs, *lvs;
-
-  struct resolver_scope *up;
-} resolver_scope;
-
-typedef struct resolver_state {
-  pic_state *pic;
-  resolver_scope *scope;
-  pic_sym sGREF, sCREF, sLREF;
-} resolver_state;
-
-static void push_resolver_scope(resolver_state *, pic_value, pic_value, bool, pic_value);
-static void pop_resolver_scope(resolver_state *);
-
-static resolver_state *
-new_resolver_state(pic_state *pic)
-{
-  resolver_state *state;
-
-  state = (resolver_state *)pic_alloc(pic, sizeof(resolver_state));
-  state->pic = pic;
-  state->scope = NULL;
-
-  register_symbol(pic, state, sGREF, "gref");
-  register_symbol(pic, state, sLREF, "lref");
-  register_symbol(pic, state, sCREF, "cref");
-
-  push_resolver_scope(state, pic_nil_value(), pic_nil_value(), false, pic_nil_value());
-
-  return state;
-}
-
-static void
-destroy_resolver_state(resolver_state *state)
-{
-  pop_resolver_scope(state);
-  pic_free(state->pic, state);
-}
-
-static void
-push_resolver_scope(resolver_state *state, pic_value args, pic_value locals, bool varg, pic_value captures)
-{
-  pic_state *pic = state->pic;
-  resolver_scope *scope;
-  int i;
-
-  scope = (resolver_scope *)pic_alloc(pic, sizeof(resolver_scope));
-  scope->up = state->scope;
-  scope->depth = scope->up ? scope->up->depth + 1 : 0;
-  scope->lvs = xh_new_int();
-  scope->cvs = xh_new_int();
-  scope->argc = pic_length(pic, args) + 1;
-  scope->localc = pic_length(pic, locals);
-  scope->capturec = pic_length(pic, captures);
-  scope->varg = varg;
-
-  /* arguments */
-  for (i = 1; i < scope->argc; ++i) {
-    xh_put_int(scope->lvs, pic_sym(pic_list_ref(pic, args, i - 1)), i);
-  }
-
-  /* locals */
-  for (i = 0; i < scope->localc; ++i) {
-    xh_put_int(scope->lvs, pic_sym(pic_list_ref(pic, locals, i)), scope->argc + i);
-  }
-
-  /* closed variables */
-  for (i = 0; i < scope->capturec; ++i) {
-    xh_put_int(scope->cvs, pic_sym(pic_list_ref(pic, captures, i)), i);
-  }
-
-  state->scope = scope;
-}
-
-static void
-pop_resolver_scope(resolver_state *state)
-{
-  resolver_scope *scope;
-
-  scope = state->scope;
-  xh_destroy(scope->cvs);
-  xh_destroy(scope->lvs);
-
-  scope = scope->up;
-  pic_free(state->pic, state->scope);
-  state->scope = scope;
-}
-
-static bool
-is_closed(resolver_state *state, pic_sym sym)
-{
-  return xh_get_int(state->scope->cvs, sym) != NULL;
-}
-
-static pic_value
-resolve_lref(resolver_state *state, pic_sym sym)
-{
-  pic_state *pic = state->pic;
-  int i;
-
-  i = xh_get_int(state->scope->lvs, sym)->val;
-
-  return pic_list2(pic, pic_symbol_value(state->sLREF), pic_int_value(i));
-}
-
-static pic_value
-resolve_cref(resolver_state *state, int depth, pic_sym sym)
-{
-  pic_state *pic = state->pic;
-  resolver_scope *scope = state->scope;
-  int i, d;
-
-  d = depth;
-  while (d-- > 0) {
-    scope = scope->up;
-  }
-
-  i = xh_get_int(scope->cvs, sym)->val;
-
-  return pic_list3(pic,
-                   pic_symbol_value(state->sCREF),
-                   pic_int_value(depth),
-                   pic_int_value(i));
-}
-
-static pic_value resolve_reference_node(resolver_state *state, pic_value obj);
-
-static pic_value
-resolve_reference(resolver_state *state, pic_value obj)
-{
-  int ai = pic_gc_arena_preserve(state->pic);
-
-  obj = resolve_reference_node(state, obj);
-
-  pic_gc_arena_restore(state->pic, ai);
-  pic_gc_protect(state->pic, obj);
-  return obj;
-}
-
-static pic_value
-resolve_reference_node(resolver_state *state, pic_value obj)
-{
-  pic_state *pic = state->pic;
-  pic_sym tag;
-
-  if (! pic_pair_p(obj))
-    return obj;
-
-  tag = pic_sym(pic_car(pic, obj));
-  if (tag == state->sLREF) {
-    pic_sym sym;
-
-    sym = pic_sym(pic_list_ref(pic, obj, 1));
-    if (! is_closed(state, sym)) {
-      return resolve_lref(state, sym);
-    }
-    else {
-      return resolve_cref(state, 0, sym);
-    }
-  }
-  else if (tag == state->sCREF) {
-    int depth;
-    pic_sym sym;
-
-    depth = pic_int(pic_list_ref(pic, obj, 1));
-    sym = pic_sym(pic_list_ref(pic, obj, 2));
-    return resolve_cref(state, depth, sym);
-  }
-  else if (tag == pic->sLAMBDA) {
-    pic_value args, locals, closes, body;
-    bool varg;
-
-    args = pic_list_ref(pic, obj, 1);
-    locals = pic_list_ref(pic, obj, 2);
-    varg = pic_true_p(pic_list_ref(pic, obj, 3));
-    closes = pic_list_ref(pic, obj, 4);
-    body = pic_list_ref(pic, obj, 5);
-
-    push_resolver_scope(state, args, locals, varg, closes);
-    {
-      body = resolve_reference(state, body);
-    }
-    pop_resolver_scope(state);
-
-    return pic_list6(pic, pic_symbol_value(pic->sLAMBDA), args, locals, pic_bool_value(varg), closes, body);
-  }
-  else if (tag == pic->sQUOTE) {
-    return obj;
-  }
-  else {
-    int ai = pic_gc_arena_preserve(pic);
-    pic_value seq = pic_list1(pic, pic_symbol_value(tag)), elt;
-
-    pic_for_each (elt, pic_cdr(pic, obj)) {
-      seq = pic_cons(pic, resolve_reference(state, elt), seq);
-
-      pic_gc_arena_restore(pic, ai);
-      pic_gc_protect(pic, seq);
-    }
-    return pic_reverse(pic, seq);
-  }
-}
-
-static pic_value
-pic_resolve(pic_state *pic, pic_value obj)
-{
-  resolver_state *state;
-
-  state = new_resolver_state(pic);
-
-  obj = resolve_reference(state, obj);
-
-  destroy_resolver_state(state);
-  return obj;
-}
-
 /**
  * scope object
  */
@@ -1210,6 +990,47 @@ pop_codegen_context(codegen_state *state)
   return irep;
 }
 
+static int
+index_capture(codegen_state *state, pic_sym sym, int depth)
+{
+  codegen_context *cxt = state->cxt;
+  size_t i;
+  pic_sym *var;
+
+  while (depth-- > 0) {
+    cxt = cxt->up;
+  }
+
+  for (i = 0; i < cxt->captures.size; ++i) {
+    var = xv_get(&cxt->captures, i);
+    if (*var == sym)
+      return i;
+  }
+  return -1;
+}
+
+static int
+index_local(codegen_state *state, pic_sym sym)
+{
+  codegen_context *cxt = state->cxt;
+  size_t i, offset;
+  pic_sym *var;
+
+  offset = 1;
+  for (i = 0; i < cxt->args.size; ++i) {
+    var = xv_get(&cxt->args, i);
+    if (*var == sym)
+      return i + offset;
+  }
+  offset += i;
+  for (i = 0; i < cxt->locals.size; ++i) {
+    var = xv_get(&cxt->locals, i);
+    if (*var == sym)
+      return i + offset;
+  }
+  return -1;
+}
+
 static struct pic_irep *codegen_lambda(codegen_state *, pic_value);
 
 static void
@@ -1226,14 +1047,27 @@ codegen(codegen_state *state, pic_value obj)
     cxt->clen++;
     return;
   } else if (sym == state->sCREF) {
+    pic_sym name;
+    int depth;
+
+  CREF:
+    depth = pic_int(pic_list_ref(pic, obj, 1));
+    name  = pic_sym(pic_list_ref(pic, obj, 2));
     cxt->code[cxt->clen].insn = OP_CREF;
-    cxt->code[cxt->clen].u.r.depth = pic_int(pic_list_ref(pic, obj, 1));
-    cxt->code[cxt->clen].u.r.idx = pic_int(pic_list_ref(pic, obj, 2));
+    cxt->code[cxt->clen].u.r.depth = depth;
+    cxt->code[cxt->clen].u.r.idx = index_capture(state, name, depth);
     cxt->clen++;
     return;
   } else if (sym == state->sLREF) {
+    pic_sym name;
+
+    name = pic_sym(pic_list_ref(pic, obj, 1));
+    if (index_capture(state, name, 0) != -1) {
+      obj = pic_list3(pic, pic_sym_value(state->sCREF), pic_int_value(0), pic_sym_value(name));
+      goto CREF;
+    }
     cxt->code[cxt->clen].insn = OP_LREF;
-    cxt->code[cxt->clen].u.i = pic_int(pic_list_ref(pic, obj, 1));
+    cxt->code[cxt->clen].u.i = index_local(state, name);
     cxt->clen++;
     return;
   } else if (sym == pic->sSETBANG) {
@@ -1254,17 +1088,30 @@ codegen(codegen_state *state, pic_value obj)
       return;
     }
     else if (type == state->sCREF) {
+      pic_sym name;
+      int depth;
+
+    CSET:
+      depth = pic_int(pic_list_ref(pic, var, 1));
+      name  = pic_sym(pic_list_ref(pic, var, 2));
       cxt->code[cxt->clen].insn = OP_CSET;
-      cxt->code[cxt->clen].u.r.depth = pic_int(pic_list_ref(pic, var, 1));
-      cxt->code[cxt->clen].u.r.idx = pic_int(pic_list_ref(pic, var, 2));
+      cxt->code[cxt->clen].u.r.depth = depth;
+      cxt->code[cxt->clen].u.r.idx = index_capture(state, name, depth);
       cxt->clen++;
       cxt->code[cxt->clen].insn = OP_PUSHNONE;
       cxt->clen++;
       return;
     }
     else if (type == state->sLREF) {
+      pic_sym name;
+
+      name = pic_sym(pic_list_ref(pic, var, 1));
+      if (index_capture(state, name, 0) != -1) {
+        var = pic_list3(pic, pic_sym_value(state->sCREF), pic_int_value(0), pic_sym_value(name));
+        goto CSET;
+      }
       cxt->code[cxt->clen].insn = OP_LSET;
-      cxt->code[cxt->clen].u.i = pic_int(pic_list_ref(pic, var, 1));
+      cxt->code[cxt->clen].u.i = index_local(state, name);
       cxt->clen++;
       cxt->code[cxt->clen].insn = OP_PUSHNONE;
       cxt->clen++;
@@ -1568,15 +1415,6 @@ pic_compile(pic_state *pic, pic_value obj)
   fprintf(stdout, "ai = %d\n", pic_gc_arena_preserve(pic));
 #endif
 
-  /* resolution */
-  obj = pic_resolve(pic, obj);
-#if DEBUG
-  fprintf(stdout, "## resolver completed\n");
-  pic_debug(pic, obj);
-  fprintf(stdout, "\n");
-  fprintf(stdout, "ai = %d\n", pic_gc_arena_preserve(pic));
-#endif
-
   /* codegen */
   irep = pic_codegen(pic, obj);
 #if DEBUG