return_call extension (#60)

* support tail call in grammar & extract function calling logics

* when tail call, we can share a continuation for returning

* tweak

* ignore grammar/.antlr/

* should use `return_call`

Author: butterunderflow

.gitignore

@@ -23,3 +23,4 @@ project/.bloop/bloop.settings.json
 conc_gen/*
 ccbse_gen/*
 headers/gensym/external.hpp
+grammar/.antlr/

benchmarks/wasm/sum.wat

@@ -0,0 +1,24 @@
+(module
+  (type (;0;) (func (param i32)))
+  (import "console" "log" (func (type 0)))
+  (func (param i32 i32) (result i32)
+    local.get 0
+    i32.eqz
+    if (result i32)
+      local.get 1
+    else
+      local.get 0
+      i32.const 1
+      i32.sub
+      local.get 1
+      local.get 0
+      i32.add
+      (return_call 1)
+    end
+  )
+  (func (result i32)
+    i32.const 10
+    i32.const 0
+    (return_call 1))
+  (export "sum10" (func 2))
+)

grammar/WatLexer.g4

@@ -68,6 +68,8 @@ ELSE: 'else' ;
 SELECT: '.select' ;
 CALL: 'call' ;
 CALL_INDIRECT: 'call_indirect' ;
+RETURN_CALL: 'return_call' ;
+RETURN_CALL_INDIRECT: 'return_call_indirect' ;
 
 LOCAL_GET: 'local.get' ;
 LOCAL_SET: 'local.set' ;

grammar/WatParser.g4

@@ -133,6 +133,7 @@ plainInstr
   | BR_TABLE idx+
   | RETURN
   | CALL idx
+  | RETURN_CALL idx
   | LOCAL_GET idx
   | LOCAL_SET idx
   | LOCAL_TEE idx
@@ -177,6 +178,7 @@ selectInstr
 callIndirectInstr
   /* : CALL_INDIRECT typeUse? callInstrParams */
   : CALL_INDIRECT idx? typeUse
+  | RETURN_CALL_INDIRECT idx? typeUse
   ;
 
 callInstrParams
@@ -220,6 +222,7 @@ foldedInstr
 expr
   : plainInstr expr*
   | CALL_INDIRECT callExprType
+  | RETURN_CALL_INDIRECT callExprType
   | BLOCK bindVar? block
   | LOOP bindVar? block
   // | IF bindVar? ifBlock