core: vm: refactor vm config and context

To support multiple VMs, there must be a shared execution environment for each VM,
so this pull request moved some shared component to vm.Context and
implemented the vm.ExecPack to hold the list of VM, list of VM configures,
context and some shared resources.

The adjustment includes:
* Move NoRecursion, Depth, ReadOnly, RandCallIndex, IntPool and CallGasTemp to Context.
* Adjust VM enumeration from byte to uint8, and the VMList from map to
array.
* Register VM constructor in each VM package's init function.
* Initialize all VM instance in NewExecPack.
* Remove EVMImplement, and modify EVM, such that EVM can do the same
functions with EVMImplement.

1 files changed, 4 insertions, 3 deletions

diff --git a/core/evm.go b/core/evm.go
index a2b61c535..6adf59881 100644
--- a/core/evm.go
+++ b/core/evm.go
@@ -45,8 +45,8 @@ type ChainContext interface {
 	GetRoundHeight(uint64) (uint64, bool)
 }
 
-// NewEVMContext creates a new context for use in the EVM.
-func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author *common.Address) vm.Context {
+// NewVMContext creates a new context for use in the EVM.
+func NewVMContext(msg Message, header *types.Header, chain ChainContext, author *common.Address) *vm.Context {
 	// If we don't have an explicit author (i.e. not mining), extract from the header
 	var beneficiary common.Address
 	if author == nil {
@@ -55,7 +55,7 @@ func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author
 		beneficiary = *author
 	}
 
-	return vm.Context{
+	return &vm.Context{
 		CanTransfer:    CanTransfer,
 		Transfer:       Transfer,
 		GetHash:        GetHashFn(header, chain),
@@ -70,6 +70,7 @@ func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author
 		Round:          new(big.Int).SetUint64(header.Round),
 		GasLimit:       header.GasLimit,
 		GasPrice:       new(big.Int).Set(msg.GasPrice()),
+		IntPool:        vm.NewIntPool(),
 	}
 }