From da29332c5f4c368ff03ec4e7132eefac48fed1ae Mon Sep 17 00:00:00 2001
From: Guillaume Ballet <gballet@gmail.com>
Date: Thu, 20 Sep 2018 09:44:35 +0200
Subject: core/vm: add switches to select evm+ewasm interpreters (#17687)

Interpreter initialization is left to the PRs implementing them.
Options for external interpreters are passed after a colon in the
`--vm.ewasm` and `--vm.evm` switches.
---
 core/vm/evm.go         | 22 ++++++++++++++++++++--
 core/vm/interpreter.go |  5 +++++
 2 files changed, 25 insertions(+), 2 deletions(-)

(limited to 'core/vm')

diff --git a/core/vm/evm.go b/core/vm/evm.go
index 58618f811..fc040c621 100644
--- a/core/vm/evm.go
+++ b/core/vm/evm.go
@@ -136,10 +136,28 @@ func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmCon
 		vmConfig:     vmConfig,
 		chainConfig:  chainConfig,
 		chainRules:   chainConfig.Rules(ctx.BlockNumber),
-		interpreters: make([]Interpreter, 1),
+		interpreters: make([]Interpreter, 0, 1),
 	}
 
-	evm.interpreters[0] = NewEVMInterpreter(evm, vmConfig)
+	if chainConfig.IsEWASM(ctx.BlockNumber) {
+		// to be implemented by EVM-C and Wagon PRs.
+		// if vmConfig.EWASMInterpreter != "" {
+		//  extIntOpts := strings.Split(vmConfig.EWASMInterpreter, ":")
+		//  path := extIntOpts[0]
+		//  options := []string{}
+		//  if len(extIntOpts) > 1 {
+		//    options = extIntOpts[1..]
+		//  }
+		//  evm.interpreters = append(evm.interpreters, NewEVMVCInterpreter(evm, vmConfig, options))
+		// } else {
+		// 	evm.interpreters = append(evm.interpreters, NewEWASMInterpreter(evm, vmConfig))
+		// }
+		panic("No supported ewasm interpreter yet.")
+	}
+
+	// vmConfig.EVMInterpreter will be used by EVM-C, it won't be checked here
+	// as we always want to have the built-in EVM as the failover option.
+	evm.interpreters = append(evm.interpreters, NewEVMInterpreter(evm, vmConfig))
 	evm.interpreter = evm.interpreters[0]
 
 	return evm
diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index 0f1b07342..8e934f60e 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -39,6 +39,11 @@ type Config struct {
 	// may be left uninitialised and will be set to the default
 	// table.
 	JumpTable [256]operation
+
+	// Type of the EWASM interpreter
+	EWASMInterpreter string
+	// Type of the EVM interpreter
+	EVMInterpreter string
 }
 
 // Interpreter is used to run Ethereum based contracts and will utilise the
-- 
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