Added support for EXIT op (#397)

* EXIT op

* changelog

* docs

* Update CHANGELOG.md

CHANGELOG.md

@@ -6,6 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- Added support for `EXIT` opcode via `exit : (string) => 'a` function (behaves same as `ABORT`, but consumes all gas).
 - Compiler warnings for the follwing: shadowing, negative spends, division by zero, unused functions, unused includes, unused stateful annotations, unused variables, unused parameters, unused user-defined type, dead return value.
 - The pipe operator |>
   ```

docs/sophia_features.md

@@ -862,6 +862,16 @@ function require(b : bool, err : string) =
     if(!b) abort(err)
 ```
 
+Aside from that, there is an almost equivalent function `exit`
+
+```sophia
+exit(reason : string) : 'a
+```
+
+Just like `abort`, it breaks the execution with the given reason. The difference
+however is in the gas consumption — while `abort` returns unused gas, a call to
+`exit` burns it all.
+
 ## Delegation signature
 
 Some chain operations (`Oracle.<operation>` and `AENS.<operation>`) have an

src/aeso_ast_infer_types.erl

@@ -539,8 +539,9 @@ global_env() ->
                      %% TTL constructors
                      {"RelativeTTL", Fun1(Int, TTL)},
                      {"FixedTTL",    Fun1(Int, TTL)},
-                     %% Abort
+                     %% Abort/exit
                      {"abort", Fun1(String, A)},
+                     {"exit", Fun1(String, A)},
                      {"require", Fun([Bool, String], Unit)}])
         , types = MkDefs(
                     [{"int", 0}, {"bool", 0}, {"char", 0}, {"string", 0}, {"address", 0},

src/aeso_ast_to_fcode.erl

@@ -242,7 +242,7 @@ builtins() ->
     MkName = fun(NS, Fun) ->
                 list_to_atom(string:to_lower(string:join(NS ++ [Fun], "_")))
              end,
-    Scopes = [{[],           [{"abort", 1}, {"require", 2}]},
+    Scopes = [{[],           [{"abort", 1}, {"require", 2}, {"exit", 1}]},
               {["Chain"],    [{"spend", 2}, {"balance", 1}, {"block_hash", 1}, {"coinbase", none},
                               {"timestamp", none}, {"block_height", none}, {"difficulty", none},
                               {"gas_limit", none}, {"bytecode_hash", 1}, {"create", variable}, {"clone", variable}]},

src/aeso_fcode_to_fate.erl

@@ -507,6 +507,8 @@ builtin_to_scode(Env, bytes_split, [_, _] = Args) ->
     call_to_scode(Env, aeb_fate_ops:bytes_split(?a, ?a, ?a), Args);
 builtin_to_scode(Env, abort, [_] = Args) ->
     call_to_scode(Env, aeb_fate_ops:abort(?a), Args);
+builtin_to_scode(Env, exit, [_] = Args) ->
+    call_to_scode(Env, aeb_fate_ops:exit(?a), Args);
 builtin_to_scode(Env, chain_spend, [_, _] = Args) ->
     call_to_scode(Env, [aeb_fate_ops:spend(?a, ?a),
                         tuple(0)], Args);
@@ -1486,6 +1488,7 @@ r_write_to_dead_var({i, Ann, I}, Code) ->
 r_write_to_dead_var(_, _) -> false.
 
 op_view({'ABORT', R}) -> {'ABORT', none, [R]};
+op_view({'EXIT', R}) -> {'EXIT', none, [R]};
 op_view(T) when is_tuple(T) ->
     [Op, R | As] = tuple_to_list(T),
     CheckReads = fun(Rs, X) -> case [] == Rs -- [dst, src] of true -> X; false -> false end end,

test/contracts/all_syntax.aes

@@ -80,3 +80,4 @@ contract AllSyntax =
      let sh : shakespeare(shakespeare(int)) =
        {wolfgang = state}
      sh{wolfgang.wolfgang = sh.wolfgang} // comment
+     exit("hope you had fun reading this")