From f9a49ffba74e8f741eed973d48355a2c0d233811 Mon Sep 17 00:00:00 2001
From: Daniel Kolesa <dkolesa@igalia.com>
Date: Mon, 22 Mar 2021 22:01:49 +0100
Subject: [PATCH] get rid of emptyblock

---
 src/cs_bcode.cc   | 24 ++++++++++++++++++++++++
 src/cs_bcode.hh   |  9 +++++++++
 src/cs_util.hh    | 11 ++++++++++-
 src/cs_vm.cc      | 17 +++++------------
 src/cubescript.cc |  1 -
 5 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/src/cs_bcode.cc b/src/cs_bcode.cc
index d0bbc2b..c111beb 100644
--- a/src/cs_bcode.cc
+++ b/src/cs_bcode.cc
@@ -110,4 +110,28 @@ void bcode_unref(std::uint32_t *code) {
     }
 }
 
+/* empty fallbacks */
+
+static std::uint32_t emptyrets[CS_VAL_ANY] = {
+    CS_RET_NULL, CS_RET_INT, CS_RET_FLOAT, CS_RET_STRING
+};
+
+empty_block *bcode_init_empty(cs_shared_state *cs) {
+    auto a = cs_allocator<empty_block>{cs};
+    auto *p = a.allocate(CS_VAL_ANY);
+    for (std::size_t i = 0; i < CS_VAL_ANY; ++i) {
+        p[i].init.init = CS_CODE_START + 0x100;
+        p[i].code = CS_CODE_EXIT | emptyrets[i];
+    }
+    return p;
+}
+
+void bcode_free_empty(cs_shared_state *cs, empty_block *empty) {
+    cs_allocator<empty_block>{cs}.deallocate(empty, CS_VAL_ANY);
+};
+
+cs_bcode *bcode_get_empty(empty_block *empty, std::size_t val) {
+    return &empty[val].init + 1;
+}
+
 } /* namespace cscript */
diff --git a/src/cs_bcode.hh b/src/cs_bcode.hh
index 3eda361..7ad32e4 100644
--- a/src/cs_bcode.hh
+++ b/src/cs_bcode.hh
@@ -79,6 +79,15 @@ void bcode_decr(std::uint32_t *code);
 void bcode_ref(std::uint32_t *code);
 void bcode_unref(std::uint32_t *code);
 
+struct empty_block {
+    cs_bcode init;
+    std::uint32_t code;
+};
+
+empty_block *bcode_init_empty(cs_shared_state *cs);
+void bcode_free_empty(cs_shared_state *cs, empty_block *empty);
+cs_bcode *bcode_get_empty(empty_block *empty, std::size_t val);
+
 } /* namespace cscript */
 
 #endif
diff --git a/src/cs_util.hh b/src/cs_util.hh
index bc7ac83..c82e298 100644
--- a/src/cs_util.hh
+++ b/src/cs_util.hh
@@ -5,6 +5,8 @@
 #include <unordered_map>
 #include <vector>
 
+#include "cs_bcode.hh"
+
 namespace cscript {
 
 cs_int cs_parse_int(
@@ -140,6 +142,7 @@ struct cs_shared_state {
 
     cs_vprint_cb varprintf;
     cs_strman *strman;
+    empty_block *empty;
 
     cs_shared_state() = delete;
 
@@ -148,9 +151,15 @@ struct cs_shared_state {
         idents{allocator_type{this}},
         identmap{allocator_type{this}},
         varprintf{},
-        strman{create<cs_strman>(this)}
+        strman{create<cs_strman>(this)},
+        empty{bcode_init_empty(this)}
     {}
 
+    ~cs_shared_state() {
+         bcode_free_empty(this, empty);
+         destroy(strman);
+    }
+
     void *alloc(void *ptr, size_t os, size_t ns) {
         void *p = allocf(aptr, ptr, os, ns);
         if (!p && ns) {
diff --git a/src/cs_vm.cc b/src/cs_vm.cc
index f943908..9288890 100644
--- a/src/cs_vm.cc
+++ b/src/cs_vm.cc
@@ -185,13 +185,6 @@ static inline void forcecond(cs_state &cs, cs_value &v) {
     }
 }
 
-static uint32_t emptyblock[CS_VAL_ANY][2] = {
-    { CS_CODE_START + 0x100, CS_CODE_EXIT | CS_RET_NULL },
-    { CS_CODE_START + 0x100, CS_CODE_EXIT | CS_RET_INT },
-    { CS_CODE_START + 0x100, CS_CODE_EXIT | CS_RET_FLOAT },
-    { CS_CODE_START + 0x100, CS_CODE_EXIT | CS_RET_STRING }
-};
-
 static inline void force_arg(cs_value &v, int type) {
     switch (type) {
         case CS_RET_STRING:
@@ -303,7 +296,7 @@ static inline void callcommand(
                         break;
                     }
                     args[i].set_code(
-                        reinterpret_cast<cs_bcode *>(emptyblock[CS_VAL_NULL] + 1)
+                        bcode_get_empty(cs_get_sstate(cs)->empty, CS_VAL_NULL)
                     );
                     fakeargs++;
                 } else {
@@ -750,22 +743,22 @@ static uint32_t *runcode(cs_state &cs, uint32_t *code, cs_value &result) {
 
             case CS_CODE_EMPTY | CS_RET_NULL:
                 args[numargs++].set_code(
-                    reinterpret_cast<cs_bcode *>(emptyblock[CS_VAL_NULL] + 1)
+                    bcode_get_empty(cs_get_sstate(cs)->empty, CS_VAL_NULL)
                 );
                 break;
             case CS_CODE_EMPTY | CS_RET_STRING:
                 args[numargs++].set_code(
-                    reinterpret_cast<cs_bcode *>(emptyblock[CS_VAL_STRING] + 1)
+                    bcode_get_empty(cs_get_sstate(cs)->empty, CS_VAL_STRING)
                 );
                 break;
             case CS_CODE_EMPTY | CS_RET_INT:
                 args[numargs++].set_code(
-                    reinterpret_cast<cs_bcode *>(emptyblock[CS_VAL_INT] + 1)
+                    bcode_get_empty(cs_get_sstate(cs)->empty, CS_VAL_INT)
                 );
                 break;
             case CS_CODE_EMPTY | CS_RET_FLOAT:
                 args[numargs++].set_code(
-                    reinterpret_cast<cs_bcode *>(emptyblock[CS_VAL_FLOAT] + 1)
+                    bcode_get_empty(cs_get_sstate(cs)->empty, CS_VAL_FLOAT)
                 );
                 break;
             case CS_CODE_BLOCK: {
diff --git a/src/cubescript.cc b/src/cubescript.cc
index 8d959ef..bdc1319 100644
--- a/src/cubescript.cc
+++ b/src/cubescript.cc
@@ -421,7 +421,6 @@ LIBCUBESCRIPT_EXPORT void cs_state::destroy() {
         }
         p_state->destroy(i->p_impl);
     }
-    p_state->destroy(p_state->strman);
     p_state->destroy(static_cast<cs_charbuf *>(p_errbuf));
     p_state->destroy(p_state);
 }