core/state: rename Delete/IsDeleted to Suicide/HasSuicided

The delete/remove naming has caused endless confusion in the past.

core/vm/environment.go

@@ -105,9 +105,12 @@ type Database interface {
 	GetState(common.Address, common.Hash) common.Hash
 	SetState(common.Address, common.Hash, common.Hash)
 
-	Delete(common.Address) bool
+	Suicide(common.Address) bool
+	HasSuicided(common.Address) bool
+
+	// Exist reports whether the given account exists in state.
+	// Notably this should also return true for suicided accounts.
 	Exist(common.Address) bool
-	IsDeleted(common.Address) bool
 }
 
 // Account represents a contract or basic ethereum account.

core/vm/instructions.go

@@ -614,7 +614,7 @@ func opSuicide(instr instruction, pc *uint64, env Environment, contract *Contrac
 	balance := env.Db().GetBalance(contract.Address())
 	env.Db().AddBalance(common.BigToAddress(stack.pop()), balance)
 
-	env.Db().Delete(contract.Address())
+	env.Db().Suicide(contract.Address())
 }
 
 // following functions are used by the instruction jump  table

core/vm/jit.go

@@ -425,7 +425,7 @@ func jitCalculateGasAndSize(env Environment, contract *Contract, instr instructi
 		}
 		gas.Set(g)
 	case SUICIDE:
-		if !statedb.IsDeleted(contract.Address()) {
+		if !statedb.HasSuicided(contract.Address()) {
 			statedb.AddRefund(params.SuicideRefundGas)
 		}
 	case MLOAD:

core/vm/vm.go

@@ -303,7 +303,7 @@ func calculateGasAndSize(env Environment, contract *Contract, caller ContractRef
 		}
 		gas.Set(g)
 	case SUICIDE:
-		if !statedb.IsDeleted(contract.Address()) {
+		if !statedb.HasSuicided(contract.Address()) {
 			statedb.AddRefund(params.SuicideRefundGas)
 		}
 	case MLOAD: