From 99dca532f65fab3589c167a8961cb9bc9d83a98f Mon Sep 17 00:00:00 2001
From: ValKmjolnir <lhk101lhk101@qq.com>
Date: Sat, 21 May 2022 14:22:54 +0800
Subject: [PATCH] :memo: add notes in nasal_codegen.h and nasal_vm.h. add
 register_info() in debugger.

---
 nasal_codegen.h |  8 ++++++++
 nasal_dbg.h     | 25 +++++++++++++-----------
 nasal_vm.h      | 51 +++++++++++++++++++++++++++----------------------
 3 files changed, 50 insertions(+), 34 deletions(-)

diff --git a/nasal_codegen.h b/nasal_codegen.h
index 3240e7b..463f006 100644
--- a/nasal_codegen.h
+++ b/nasal_codegen.h
@@ -540,6 +540,14 @@ void nasal_codegen::call_func(const nasal_ast& ast)
     }
 }
 
+/* mcall should run after calc_gen because this operation may trigger gc.
+*  to avoid gc incorrectly collecting values that include the memory space(which will cause SIGSEGV),
+*  we must run ast[1] then we run ast[0] to get the memory space.
+*  at this time the value including the memory space can must be found alive.
+*  BUT in fact this method does not make much safety.
+*  so we use another way to avoid gc-caused SIGSEGV: reserve m-called value on stack.
+*  you could see the notes in `nasal_vm::opr_mcallv()`.
+*/
 void nasal_codegen::mcall(const nasal_ast& ast)
 {
     if(ast.type()==ast_id)
diff --git a/nasal_dbg.h b/nasal_dbg.h
index a0e0703..f78c096 100644
--- a/nasal_dbg.h
+++ b/nasal_dbg.h
@@ -65,18 +65,19 @@ void nasal_dbg::help()
 {
     std::cout
     <<"<option>\n"
-    <<"\th,    help      | get help\n"
-    <<"\tbt,   backtrace | get function call trace\n"
-    <<"\tc,    continue  | run program until break point or exit\n"
-    <<"\tf,    file      | see all the compiled files\n"
-    <<"\tg,    global    | see global values\n"
-    <<"\tl,    local     | see local values\n"
-    <<"\tu,    upval     | see upvalue\n"
-    <<"\ta,    all       | show global,local and upvalue\n"
-    <<"\tn,    next      | execute next bytecode\n"
-    <<"\tq,    exit      | exit debugger\n"
+    <<"\th,   help      | get help\n"
+    <<"\tbt,  backtrace | get function call trace\n"
+    <<"\tc,   continue  | run program until break point or exit\n"
+    <<"\tf,   file      | see all the compiled files\n"
+    <<"\tg,   global    | see global values\n"
+    <<"\tl,   local     | see local values\n"
+    <<"\tu,   upval     | see upvalue\n"
+    <<"\tr,   register  | show vm register detail\n"
+    <<"\ta,   all       | show global,local and upvalue\n"
+    <<"\tn,   next      | execute next bytecode\n"
+    <<"\tq,   exit      | exit debugger\n"
     <<"<option> <filename> <line>\n"
-    <<"\tbk,   break     | set break point\n";
+    <<"\tbk,  break     | set break point\n";
 }
 
 void nasal_dbg::stepinfo()
@@ -140,6 +141,8 @@ void nasal_dbg::interact()
             }
             else if(res[0]=="u" || res[0]=="upval")
                 upval_state();
+            else if(res[0]=="r" || res[0]=="register")
+                register_info();
             else if(res[0]=="a" || res[0]=="all")
                 detail();
             else if(res[0]=="n" || res[0]=="next")
diff --git a/nasal_vm.h b/nasal_vm.h
index 39b41fe..8fac746 100644
--- a/nasal_vm.h
+++ b/nasal_vm.h
@@ -35,6 +35,7 @@ protected:
     void bytecodeinfo(const char*,const uint32_t);
     void traceback();
     void stackinfo(const uint32_t);
+    void register_info();
     void global_state();
     void local_state();
     void upval_state();
@@ -281,6 +282,28 @@ void nasal_vm::stackinfo(const uint32_t limit=10)
         valinfo(t[0]);
     }
 }
+void nasal_vm::register_info()
+{
+    printf("registers(%s):\n",gc.coroutine?"coroutine":"main");
+    printf("  [ pc     ]    | pc   | 0x%.x\n",pc);
+    printf("  [ global ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)global);
+    printf("  [ localr ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)localr);
+    printf("  [ memr   ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)memr);
+    if(funcr.type==vm_nil)
+        printf("  [ funcr  ]    | nil  |\n");
+    else
+        printf("  [ funcr  ]    | func | <0x" PRTHEX64 "> entry:0x%x\n",
+            (uint64_t)funcr.value.gcobj,
+            funcr.func().entry);
+    if(upvalr.type==vm_nil)
+        printf("  [ upvalr ]    | nil  |\n");
+    else
+        printf("  [ upvalr ]    | upval| <0x" PRTHEX64 "> [%u val]\n",
+            (uint64_t)upvalr.value.gcobj,
+            upvalr.upval().size);
+    printf("  [ canary ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)canary);
+    printf("  [ top    ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)top);
+}
 void nasal_vm::global_state()
 {
     if(!bytecode[0].num || gc.stack[0].type==vm_none) // bytecode[0].op is op_intg
@@ -323,25 +346,7 @@ void nasal_vm::upval_state()
 }
 void nasal_vm::detail()
 {
-    printf("registers(%s):\n",gc.coroutine?"coroutine":"main");
-    printf("  [ pc     ]    | pc   | 0x%.x\n",pc);
-    printf("  [ global ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)global);
-    printf("  [ localr ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)localr);
-    printf("  [ memr   ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)memr);
-    if(funcr.type==vm_nil)
-        printf("  [ funcr  ]    | nil  |\n");
-    else
-        printf("  [ funcr  ]    | func | <0x" PRTHEX64 "> entry:0x%x\n",
-            (uint64_t)funcr.value.gcobj,
-            funcr.func().entry);
-    if(upvalr.type==vm_nil)
-        printf("  [ upvalr ]    | nil  |\n");
-    else
-        printf("  [ upvalr ]    | upval| <0x" PRTHEX64 "> [%u val]\n",
-            (uint64_t)upvalr.value.gcobj,
-            upvalr.upval().size);
-    printf("  [ canary ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)canary);
-    printf("  [ top    ]    | addr | 0x" PRTHEX64 "\n",(uint64_t)top);
+    register_info();
     global_state();
     local_state();
     upval_state();
@@ -910,15 +915,15 @@ inline void nasal_vm::opr_mupval()
 }
 inline void nasal_vm::opr_mcallv()
 {
-    nasal_ref val=top[0];
-    nasal_ref vec=(--top)[0];
+    nasal_ref val=top[0];     // index
+    nasal_ref vec=(--top)[0]; // mcall vector, reserved on stack to avoid gc
     if(vec.type==vm_vec)
     {
         memr=vec.vec().get_mem(val.to_number());
         if(!memr)
             die("mcallv: index out of range:"+std::to_string(val.to_number()));
     }
-    else if(vec.type==vm_hash)
+    else if(vec.type==vm_hash) // special call of hash, this do mcallh but use the mcallv way
     {
         if(val.type!=vm_str)
             die("mcallv: must use string as the key");
@@ -936,7 +941,7 @@ inline void nasal_vm::opr_mcallv()
 }
 inline void nasal_vm::opr_mcallh()
 {
-    nasal_ref hash=top[0];
+    nasal_ref hash=top[0]; // mcall hash, reserved on stack to avoid gc
     if(hash.type!=vm_hash)
         die("mcallh: must call a hash");
     nasal_hash& ref=hash.hash();