EIP-4750: EOF - Functions

Author: jangko

nimbus/evm/code_stream.nim

@@ -119,6 +119,12 @@ proc parseEOF*(c: CodeStream): Result[void, EOFV1Error] =
 func hasEOFCode*(c: CodeStream): bool =
   hasEOFMagic(c.legacyCode)
 
+func getType*(c: CodeStream, idx: int): FunctionMetaData =
+  c.container.types[idx]
+
+func section*(c: CodeStream): int =
+  c.section
+
 proc next*(c: var CodeStream): Op =
   if c.pc != c.codeLen:
     result = Op(c.codeView[c.pc])

nimbus/evm/computation.nim

@@ -226,7 +226,8 @@ proc newComputation*(vmState: BaseVMState, sysCall: bool, message: Message,
   result.msg = message
   result.memory = Memory()
   result.stack = newStack()
-  result.returnStack = @[]
+  # disable EIP-2315
+  # result.returnStack = @[]
   result.gasMeter.init(message.gas)
   result.sysCall = sysCall
 
@@ -238,18 +239,29 @@ proc newComputation*(vmState: BaseVMState, sysCall: bool, message: Message,
     result.code = newCodeStream(
       vmState.readOnlyStateDB.getCode(message.codeAddress))
 
+  # EIP-4750
+  result.returnStack = @[
+    ReturnContext(section: 0, pc: 0, stackHeight: 0)
+  ]
+
 proc newComputation*(vmState: BaseVMState, sysCall: bool,
                      message: Message, code: seq[byte]): Computation =
   new result
   result.vmState = vmState
   result.msg = message
   result.memory = Memory()
   result.stack = newStack()
-  result.returnStack = @[]
+  # disable EIP-2315
+  # result.returnStack = @[]
   result.gasMeter.init(message.gas)
   result.code = newCodeStream(code)
   result.sysCall = sysCall
 
+  # EIP-4750
+  result.returnStack = @[
+    ReturnContext(section: 0, pc: 0, stackHeight: 0)
+  ]
+
 template gasCosts*(c: Computation): untyped =
   c.vmState.gasCosts
 

nimbus/evm/interpreter/gas_costs.nim

@@ -722,6 +722,10 @@ template gasCosts(fork: EVMFork, prefix, ResultGasCostsName: untyped) =
           Log3:           memExpansion `prefix gasLog3`,
           Log4:           memExpansion `prefix gasLog4`,
 
+          # b0s: Function Operations
+          CallF:          fixed GasLow,
+          RetF:           fixed GasVeryLow,
+
           # e0s: Static jumps
           RJump:          fixed GasBase,
           RJumpI:         fixed GasMidLow,

nimbus/evm/interpreter/op_codes.nim

@@ -176,8 +176,12 @@ type
     Log4 =           0xa4, ## Append log record with four topics.
 
     Nop0xA5, Nop0xA6, Nop0xA7, Nop0xA8, Nop0xA9, Nop0xAA,
-    Nop0xAB, Nop0xAC, Nop0xAD, Nop0xAE, Nop0xAF, Nop0xB0,
-    Nop0xB1, Nop0xB2, Nop0xB3, Nop0xB4, Nop0xB5, Nop0xB6,
+    Nop0xAB, Nop0xAC, Nop0xAD, Nop0xAE, Nop0xAF,
+
+    CallF =          0xb0, ## call a function (EIP4750)
+    RetF =           0xb1, ## return from a function (EIP4750)
+
+    Nop0xB2, Nop0xB3, Nop0xB4, Nop0xB5, Nop0xB6,
     Nop0xB7, Nop0xB8, Nop0xB9, Nop0xBA, Nop0xBB, Nop0xBC,
     Nop0xBD, Nop0xBE, Nop0xBF, Nop0xC0, Nop0xC1, Nop0xC2,
     Nop0xC3, Nop0xC4, Nop0xC5, Nop0xC6, Nop0xC7, Nop0xC8,

nimbus/evm/interpreter/op_dispatcher.nim

@@ -105,6 +105,14 @@ proc toCaseStmt(forkArg, opArg, k: NimNode): NimNode =
         quote do:
           `forkCaseSubExpr`
           break
+      of RetF:
+        quote do:
+          `forkCaseSubExpr`
+          # EIP-4750: If returning from top frame, exit cleanly.
+          let c = `k`.cpt
+          if c.fork >= FkEOF and
+             c.returnStack.len == 0:
+            break
       else:
         # FIXME-manyOpcodesNowRequireContinuations
         # We used to have another clause in this case statement for various
@@ -150,6 +158,11 @@ template genLowMemDispatcher*(fork: EVMFork; op: Op; k: Vm2Ctx) =
   case c.instr
   of Return, Revert, SelfDestruct:
     break
+  of RetF:
+    # EIP-4750: If returning from top frame, exit cleanly.
+    if fork >= FkEOF and
+       k.cpt.returnStack.len == 0:
+      break
   else:
     # FIXME-manyOpcodesNowRequireContinuations
     if not k.cpt.continuation.isNil:

nimbus/evm/interpreter/op_handlers.nim

@@ -24,7 +24,7 @@ import
   ./op_handlers/[oph_defs,
                  oph_arithmetic, oph_hash, oph_envinfo, oph_blockdata,
                  oph_memory, oph_push, oph_dup, oph_swap, oph_log,
-                 oph_create, oph_call, oph_sysops]
+                 oph_create, oph_call, oph_sysops, oph_function]
 
 const
   allHandlersList = @[
@@ -40,7 +40,8 @@ const
     (vm2OpExecLog,        "Log"),
     (vm2OpExecCreate,     "Create"),
     (vm2OpExecCall,       "Call"),
-    (vm2OpExecSysOp,      "SysOp")]
+    (vm2OpExecSysOp,      "SysOp"),
+    (vm2OpExecFunction,   "Function")]
 
 # ------------------------------------------------------------------------------
 # Helper

nimbus/evm/interpreter/op_handlers/oph_function.nim

@@ -0,0 +1,78 @@
+# Nimbus
+# Copyright (c) 2018 Status Research & Development GmbH
+# Licensed under either of
+#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+#    http://www.apache.org/licenses/LICENSE-2.0)
+#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
+#    http://opensource.org/licenses/MIT)
+# at your option. This file may not be copied, modified, or distributed except
+# according to those terms.
+
+## EVM Opcode Handlers: Function Operations
+## ======================================
+##
+
+import
+  ../../../errors,
+  ../../code_stream,
+  ../../stack,
+  ../../types,
+  ../op_codes,
+  ./oph_defs
+
+# ------------------------------------------------------------------------------
+# Private, op handlers implementation
+# ------------------------------------------------------------------------------
+
+const
+  callfOp: Vm2OpFn = proc (k: var Vm2Ctx) =
+    ## 0xb0, Call a function.
+    let
+      idx = k.cpt.code.readInt16()
+      typ = k.cpt.code.getType(idx)
+
+    if k.cpt.stack.len + typ.maxStackHeight.int >= 1024:
+      raise newException(
+        StackDepthError, "CallF stack overflow")
+
+    k.cpt.returnStack.add ReturnContext(
+      section    : k.cpt.code.section,
+      pc         : k.cpt.code.pc,
+      stackHeight: k.cpt.stack.len - typ.input.int
+    )
+
+    k.cpt.code.setSection(idx)
+    k.cpt.code.pc = 0
+
+  retfOp: Vm2OpFn = proc (k: var Vm2Ctx) =
+    ## 0x50, Return from a function.
+    let ctx = k.cpt.returnStack.pop()
+    k.cpt.code.setSection(ctx.section)
+    k.cpt.code.pc = ctx.pc
+
+# ------------------------------------------------------------------------------
+# Public, op exec table entries
+# ------------------------------------------------------------------------------
+
+const
+  vm2OpExecFunction*: seq[Vm2OpExec] = @[
+
+    (opCode: CallF,    ## 0xb0, Call a function
+     forks: Vm2OpEOFAndLater,
+     name: "CallF",
+     info: "Create a new account with associated code",
+     exec: (prep: vm2OpIgnore,
+            run: callfOp,
+            post: vm2OpIgnore)),
+
+    (opCode: RetF,     ## 0xb1, Return from a function
+     forks: Vm2OpEOFAndLater,
+     name: "RetF",
+     info: "Behaves identically to CREATE, except using keccak256",
+     exec: (prep: vm2OpIgnore,
+            run: retfOp,
+            post: vm2OpIgnore))]
+
+# ------------------------------------------------------------------------------
+# End
+# ------------------------------------------------------------------------------

nimbus/evm/interpreter/op_handlers/oph_memory.nim

@@ -488,23 +488,23 @@ const
             post: vm2OpIgnore)),
 
     (opCode: Jump,      ## 0x56, Jump
-     forks: Vm2OpAllForks,
+     forks: Vm2OpAllForks - Vm2OpEOFAndLater,
      name: "jump",
      info: "Alter the program counter",
      exec: (prep: vm2OpIgnore,
             run:  jumpOp,
             post: vm2OpIgnore)),
 
     (opCode: JumpI,     ## 0x57, Conditional jump
-     forks: Vm2OpAllForks,
+     forks: Vm2OpAllForks - Vm2OpEOFAndLater,
      name: "jumpI",
      info: "Conditionally alter the program counter",
      exec: (prep: vm2OpIgnore,
             run:  jumpIOp,
             post: vm2OpIgnore)),
 
     (opCode: Pc,        ## 0x58, Program counter prior to instruction
-     forks: Vm2OpAllForks,
+     forks: Vm2OpAllForks - Vm2OpEOFAndLater,
      name: "pc",
      info: "Get the value of the program counter prior to the increment "&
            "corresponding to this instruction",

nimbus/evm/types.nim

@@ -72,13 +72,20 @@ type
     gasCosts*         : GasCosts
     asyncFactory*     : AsyncOperationFactory
 
+  # EIP-4750
+  ReturnContext* = object
+    section*: int
+    pc*: int
+    stackHeight*: int
+
   Computation* = ref object
     # The execution computation
     vmState*:               BaseVMState
     msg*:                   Message
     memory*:                Memory
     stack*:                 Stack
-    returnStack*:           seq[int]
+    # disable EIP-2315
+    # returnStack*:           seq[int]
     gasMeter*:              GasMeter
     code*:                  CodeStream
     output*:                seq[byte]
@@ -97,6 +104,7 @@ type
     continuation*:          proc() {.gcsafe, raises: [CatchableError].}
     sysCall*:               bool
     initcodeEOF*:           bool
+    returnStack*:           seq[ReturnContext]
 
   Error* = ref object
     statusCode*: evmc_status_code

nimbus/vm_types.nim

@@ -23,7 +23,8 @@ export
   vmt.TracerRef,
   vmt.VMFlag,
   vmt.BlockContext,
-  vmt.TxContext
+  vmt.TxContext,
+  vmt.ReturnContext
 
 when defined(evmc_enabled):
   import