From 55e55826ee3b763be8805dcdef0468a179619ba1 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Fri, 2 Jan 2015 17:35:55 +0100
Subject: [PATCH] Changed JUMP(I) behaviour.

* All jumps must land on a JUMPDEST instruction byte.
* The byte may not be part of a PUSH*
---
 tests/vm/gh_test.go |  8 +++++++-
 vm/analysis.go      | 26 ++++++--------------------
 vm/vm_debug.go      | 20 ++------------------
 3 files changed, 15 insertions(+), 39 deletions(-)

diff --git a/tests/vm/gh_test.go b/tests/vm/gh_test.go
index f1e4d1acc..698b0aefc 100644
--- a/tests/vm/gh_test.go
+++ b/tests/vm/gh_test.go
@@ -78,6 +78,12 @@ func RunVmTest(p string, t *testing.T) {
 	helper.CreateFileTests(t, p, &tests)
 
 	for name, test := range tests {
+		/*
+			helper.Logger.SetLogLevel(5)
+			if name != "jump0_jumpdest2" {
+				continue
+			}
+		*/
 		statedb := state.New(helper.NewTrie())
 		for addr, account := range test.Pre {
 			obj := StateObjectFromAccount(addr, account)
@@ -127,7 +133,7 @@ func RunVmTest(p string, t *testing.T) {
 
 		if isVmTest {
 			if len(test.Gas) == 0 && err == nil {
-				t.Errorf("%s's gas unspecified, indicating an error. VM returned (incorrectly) successfull")
+				t.Errorf("%s's gas unspecified, indicating an error. VM returned (incorrectly) successfull", name)
 			} else {
 				gexp := ethutil.Big(test.Gas)
 				if gexp.Cmp(gas) != 0 {
diff --git a/vm/analysis.go b/vm/analysis.go
index fef448b7b..501fbfc4a 100644
--- a/vm/analysis.go
+++ b/vm/analysis.go
@@ -1,34 +1,20 @@
 package vm
 
-import (
-	"math/big"
+import "gopkg.in/fatih/set.v0"
 
-	"github.com/ethereum/go-ethereum/ethutil"
-)
+func analyseJumpDests(code []byte) (dests *set.Set) {
+	dests = set.New()
 
-func analyseJumpDests(code []byte) (dests map[uint64]*big.Int) {
-	dests = make(map[uint64]*big.Int)
-
-	lp := false
-	var lpv *big.Int
 	for pc := uint64(0); pc < uint64(len(code)); pc++ {
 		var op OpCode = OpCode(code[pc])
 		switch op {
 		case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16, PUSH17, PUSH18, PUSH19, PUSH20, PUSH21, PUSH22, PUSH23, PUSH24, PUSH25, PUSH26, PUSH27, PUSH28, PUSH29, PUSH30, PUSH31, PUSH32:
 			a := uint64(op) - uint64(PUSH1) + 1
-			if uint64(len(code)) > pc+1+a {
-				lpv = ethutil.BigD(code[pc+1 : pc+1+a])
-			}
 
 			pc += a
-			lp = true
-		case JUMP, JUMPI:
-			if lp {
-				dests[pc] = lpv
-			}
-
-		default:
-			lp = false
+			//lp = true
+		case JUMPDEST:
+			dests.Add(pc)
 		}
 	}
 	return
diff --git a/vm/vm_debug.go b/vm/vm_debug.go
index 1b9c480f8..6ad385fd0 100644
--- a/vm/vm_debug.go
+++ b/vm/vm_debug.go
@@ -83,29 +83,13 @@ func (self *DebugVm) Run(me, caller ContextRef, code []byte, value, gas, price *
 		jump = func(from uint64, to *big.Int) {
 			p := to.Uint64()
 
-			self.Printf(" ~> %v", to)
-			/* NOTE: new model. Will change soon
 			nop := OpCode(context.GetOp(p))
-			if nop != JUMPDEST {
+			if !destinations.Has(p) {
 				panic(fmt.Sprintf("invalid jump destination (%v) %v", nop, p))
 			}
 
+			self.Printf(" ~> %v", to)
 			pc = to.Uint64()
-			*/
-			// Return to start
-			if p == 0 {
-				pc = 0
-			} else {
-				nop := OpCode(context.GetOp(p))
-				if !(nop == JUMPDEST || destinations[from] != nil) {
-					panic(fmt.Sprintf("invalid jump destination (%v) %v", nop, p))
-				} else if nop == JUMP || nop == JUMPI {
-					panic(fmt.Sprintf("not allowed to JUMP(I) in to JUMP"))
-				}
-
-				pc = to.Uint64()
-
-			}
 
 			self.Endl()
 		}