add else

lvtrun/README.md

@@ -32,17 +32,21 @@
 
 # ----------------------- 2 -----------------------
 
-02
+02 24
 # 02 is the id of the import section
-24 01 16 77
-61 73 69 5f
-73 6e 61 70
-73 68 6f 74
-5f 70 72 65
-76 69 65 77
-31 09 70 72
-6f 63 5f 65
-78 69 74 00
+# 1 vector
+01
+# name is 16hex = 22dec bytes long
+16
+# name = "wasi_snapshot_preview1"
+77 61 73 69 5f 73 6e 61 70 73 68 6f 74 5f 70 72 65 76 69 65 77 31
+# name is 09
+09
+# name = "proct_exit"
+70 72 6f 63 5f 65 78 69 74
+# 00 = func = function
+00
+# 00 = typeidx = 0
 02
 
 # ----------------------- 3 -----------------------

lvtrun/src/OpCodes.hs

@@ -57,6 +57,7 @@ extractOpCode' (0x4a:rest) = ([0x4a], BSL.pack rest)
 extractOpCode' (0x4c:rest) = ([0x4c], BSL.pack rest)
 extractOpCode' (0x4e:rest) = ([0x4e], BSL.pack rest)
 extractOpCode' (0x47:rest) = ([0x47], BSL.pack rest)
+extractOpCode' (0x05:rest) = ([0x05], BSL.pack rest)
 extractOpCode' (0x3f:0x00:rest) = ([0x3f, 0x00], BSL.pack rest)
 extractOpCode' (0x40:0x00:rest) = ([0x40, 0x00], BSL.pack rest)
 extractOpCode' (0x04:0x40:rest) = ([0x04, 0x40], BSL.pack rest)
@@ -72,6 +73,7 @@ createInstruction [0x00] bytes = (Unreachable, bytes)
 createInstruction [0x01] bytes = (Nop, bytes)
 createInstruction [0x02] bytes = (Block EmptyType, bytes)
 createInstruction [0x0b] bytes = (End, bytes)
+createInstruction [0x05] bytes = (Else, bytes)
 createInstruction [0x48] bytes = (I32Lts, bytes)
 createInstruction [0x0f] bytes = (Return, bytes)
 createInstruction [0x4b] bytes = (I32Gtu, bytes)

lvtrun/src/Run/Vm.hs

@@ -102,10 +102,32 @@ execCall vm cEx funcIdx = cEx { ceStack = newStack }
     currentStack = ceStack cEx
     res = ceResults (currentExec newVm)
 
+doesElseExist' :: [Instruction] -> Bool
+doesElseExist' [] = False
+doesElseExist' (Else:_) = True
+doesElseExist' (_:rest) = doesElseExist' rest
+
+doesElseExist :: CurrentExec -> Bool
+doesElseExist cEx = doesElseExist' (drop (ceInstIdx cEx) (ceInstructions cEx))
+
+getElseIndex' :: [Instruction] -> Int -> Int
+getElseIndex' [] _ = throw $ RuntimeError "getElseIndex: missing else"
+getElseIndex' (Else:_) idx = idx
+getElseIndex' (_:rest) idx = getElseIndex' rest (idx + 1)
+
+getElseIndex :: CurrentExec -> Int
+getElseIndex cEx = getElseIndex' (drop (ceInstIdx cEx) (ceInstructions cEx)) 0
+
+executeElse :: CurrentExec -> CurrentExec
+executeElse cEx@(CurrentExec {ceStack = stack}) =
+  case doesElseExist cEx of
+    False -> cEx
+    True -> cEx { ceInstIdx = getElseIndex cEx }
+
 execIf :: CurrentExec -> CurrentExec
 execIf cEx@(CurrentExec {ceStack = stack}) = case stackTop stack of
   I_32 0 -> goToEndInstruction cEx
-  I_32 1 -> addLabel (cEx { crBlockIndents = (crBlockIndents cEx) + 1 })
+  I_32 1 -> executeElse (addLabel (cEx { crBlockIndents = (crBlockIndents cEx) + 1 }))
   I_32 _ -> throw $ RuntimeError "execIf: bad if statement"
   _ -> throw $ RuntimeError "execIf: bad type"
 
@@ -175,7 +197,8 @@ execOpCode _ cEx (I32Gtu) = execI32GtU cEx
 execOpCode _ cEx (Block _) = incrementBlockIndent (addLabel cEx)
 execOpCode _ cEx (Br labelIdx) = execBr cEx labelIdx
 execOpCode _ cEx (Loop) = incrementBlockIndent (addLabel cEx)
-execOpCode _ cEx _ = cEx
+execOpCode _ cEx (Else) = throw $ RuntimeError "elseWithoutIf"
+execOpCode _ cEx _ = throw $ RuntimeError "execOpCode: not implemented"
 
 execOpCodes :: VM -> [Instruction] -> CurrentExec
 execOpCodes vm [] = currentExec vm

lvtrun/src/Types.hs

@@ -117,6 +117,7 @@ data Instruction =
   | I32Leu
   | I32Eq
   | I32Lts
+  | Else
   | I32Gts
   | I32Les
   | I32Ges