LFVM: move addressInAccessList to getAccessCost (#730)

* rerwork addressInAccessList into calculateAccessCost

* remove calculateAccessCost function and move it into genericCall

* add tests for account access cost in generic call

* move access cost calculation to a function

* add comments, move revision check before checking access status

* adjust berlin stati costs to not account for warm access

* add test ensuring genericCall charges for warm/cold access

* fix call ops static costs

go/interpreter/lfvm/gas.go

@@ -67,13 +67,13 @@ func getBerlinGasPriceInternal(op OpCode) tosca.Gas {
 	case BALANCE:
 		gp = 100
 	case CALL:
-		gp = 100
+		gp = 0
 	case CALLCODE:
-		gp = 100
+		gp = 0
 	case STATICCALL:
-		gp = 100
+		gp = 0
 	case DELEGATECALL:
-		gp = 100
+		gp = 0
 	case SELFDESTRUCT:
 		gp = 5000
 	}
@@ -223,11 +223,11 @@ func getStaticGasPriceInternal(op OpCode) tosca.Gas {
 	case CREATE2:
 		return 32000
 	case CALL:
-		return 700 // Should be 100 according to evm.code
+		return 700
 	case CALLCODE:
 		return 700
 	case STATICCALL:
-		return 700 // Should be 100 according to evm.code
+		return 700
 	case RETURN:
 		return 0
 	case STOP:
@@ -237,7 +237,7 @@ func getStaticGasPriceInternal(op OpCode) tosca.Gas {
 	case INVALID:
 		return 0
 	case DELEGATECALL:
-		return 700 // Should be 100 according to evm.code
+		return 700
 	case SELFDESTRUCT:
 		return 0 // should be 5000 according to evm.code
 	}
@@ -343,28 +343,6 @@ func gasEip2929AccountCheck(c *context, address tosca.Address) error {
 	return nil
 }
 
-func addressInAccessList(c *context) (warmAccess bool, coldCost tosca.Gas, err error) {
-	warmAccess = true
-	if c.isAtLeast(tosca.R09_Berlin) {
-		addr := tosca.Address(c.stack.peekN(1).Bytes20())
-		// Check slot presence in the access list
-		//lint:ignore SA1019 deprecated functions to be migrated in #616
-		warmAccess = c.context.IsAddressInAccessList(addr)
-		// The WarmStorageReadCostEIP2929 (100) is already deducted in the form of a constant cost, so
-		// the cost to charge for cold access, if any, is Cold - Warm
-		coldCost = ColdAccountAccessCostEIP2929 - WarmStorageReadCostEIP2929
-		if !warmAccess {
-			c.context.AccessAccount(addr)
-			// Charge the remaining difference here already, to correctly calculate available
-			// gas for call
-			if !c.useGas(coldCost) {
-				return false, 0, errOutOfGas
-			}
-		}
-	}
-	return warmAccess, coldCost, nil
-}
-
 func gasSelfdestruct(c *context) tosca.Gas {
 	gas := SelfdestructGasEIP150
 	var address = tosca.Address(c.stack.peekN(0).Bytes20())

go/interpreter/lfvm/instructions.go

@@ -1082,11 +1082,16 @@ func neededMemorySize(c *context, offset, size *uint256.Int) (uint64, error) {
 	return offset.Uint64() + size.Uint64(), nil
 }
 
-func genericCall(c *context, kind tosca.CallKind) {
-	warmAccess, coldCost, err := addressInAccessList(c)
-	if err != nil {
-		return
+func getAccessCost(accessStatus tosca.AccessStatus) tosca.Gas {
+	// EIP-2929 says that cold access cost is 2600 and warm is 100.
+	// (https://eips.ethereum.org/EIPS/eip-2929)
+	if accessStatus == tosca.ColdAccess {
+		return tosca.Gas(2600)
 	}
+	return tosca.Gas(100)
+}
+
+func genericCall(c *context, kind tosca.CallKind) {
 	stack := c.stack
 	value := uint256.NewInt(0)
 
@@ -1119,6 +1124,10 @@ func genericCall(c *context, kind tosca.CallKind) {
 	}
 
 	baseGas := c.memory.getExpansionCosts(needed_memory_size)
+	// from berlin onwards access cost changes depending on warm/cold access.
+	if c.isAtLeast(tosca.R09_Berlin) {
+		baseGas += getAccessCost(c.context.AccessAccount(toAddr))
+	}
 	checkGas := func(cost tosca.Gas) bool {
 		return 0 <= cost && cost <= c.gas
 	}
@@ -1148,14 +1157,6 @@ func genericCall(c *context, kind tosca.CallKind) {
 	}
 
 	cost := callGas(c.gas, baseGas, provided_gas)
-	if !warmAccess {
-		// In case of a cold access, we temporarily add the cold charge back, and also
-		// add it to the returned gas. By adding it to the return, it will be charged
-		// outside of this function, as part of the dynamic gas, and that will make it
-		// also become correctly reported to tracers.
-		c.gas += coldCost
-		baseGas += coldCost
-	}
 	if !c.useGas(baseGas + cost) {
 		return
 	}

go/interpreter/lfvm/instructions_test.go

@@ -882,3 +882,79 @@ func TestExpansionCostOverflow(t *testing.T) {
 		}
 	}
 }
+
+func TestGetAccessCost_RespondsWithProperGasPrice(t *testing.T) {
+	if want, got := tosca.Gas(100), getAccessCost(tosca.WarmAccess); want != got {
+		t.Errorf("unexpected gas cost, wanted %d, got %d", want, got)
+	}
+	if want, got := tosca.Gas(2600), getAccessCost(tosca.ColdAccess); want != got {
+		t.Errorf("unexpected gas cost, wanted %d, got %d", want, got)
+	}
+}
+
+func TestCall_ChargesNothingForColdAccessBeforeBerlin(t *testing.T) {
+
+	ctrl := gomock.NewController(t)
+	runContext := tosca.NewMockRunContext(ctrl)
+	runContext.EXPECT().Call(tosca.Call, gomock.Any()).Return(tosca.CallResult{}, nil)
+	ctxt := context{
+		params: tosca.Parameters{
+			BlockParameters: tosca.BlockParameters{
+				Revision: tosca.R07_Istanbul,
+			},
+		},
+		stack:   NewStack(),
+		memory:  NewMemory(),
+		context: runContext,
+		gas:     0,
+	}
+
+	ctxt.stack.stackPointer = 8
+
+	genericCall(&ctxt, tosca.Call)
+
+	if ctxt.gas != 0 {
+		t.Errorf("unexpected gas cost, wanted 0, got %v", ctxt.gas)
+	}
+	if ctxt.status != statusRunning {
+		t.Errorf("unexpected status, wanted RUNNING, got %v", ctxt.status)
+	}
+}
+
+func TestCall_ChargesForAccessAfterBerlin(t *testing.T) {
+
+	for _, accessStatus := range []tosca.AccessStatus{tosca.WarmAccess, tosca.ColdAccess} {
+
+		ctrl := gomock.NewController(t)
+		runContext := tosca.NewMockRunContext(ctrl)
+		runContext.EXPECT().AccessAccount(gomock.Any()).Return(accessStatus)
+		runContext.EXPECT().Call(tosca.Call, gomock.Any()).Return(tosca.CallResult{}, nil)
+		delta := tosca.Gas(1)
+		ctxt := context{
+			params: tosca.Parameters{
+				BlockParameters: tosca.BlockParameters{
+					Revision: tosca.R09_Berlin,
+				},
+			},
+			stack:   NewStack(),
+			memory:  NewMemory(),
+			context: runContext,
+			gas:     2600 + delta,
+		}
+		ctxt.stack.stackPointer = 8
+
+		genericCall(&ctxt, tosca.Call)
+
+		want := tosca.Gas(delta)
+		if accessStatus == tosca.WarmAccess {
+			want = 2500 + delta
+		}
+		if ctxt.gas != want {
+			t.Errorf("unexpected gas cost, wanted %v, got %v", want, ctxt.gas)
+		}
+
+		if ctxt.status != statusRunning {
+			t.Errorf("unexpected status, wanted RUNNING, got %v", ctxt.status)
+		}
+	}
+}