core/vm, tests: implemented semi-jit vm

* changed stack and removed stack ptr. Let go decide on slice reuse.

core/vm/settings.go

@@ -0,0 +1,24 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+package vm
+
+var (
+	DisableJit  bool // Disable the JIT VM
+	ForceJit    bool // Force the JIT, skip byte VM
+	MaxProgSize int  // Max cache size for JIT Programs
+)
+
+const defaultJitMaxCache int = 64