core, eth/tracers: separate dynamic gas reporting

this is in preperation of merging memoryFunc/dynamicGasFunc into
executionFuncs

Author: omerfirmak

cmd/evm/internal/t8ntool/file_tracer.go

@@ -148,5 +148,10 @@ func (l *fileWritingTracer) hooks() *tracing.Hooks {
 				l.inner.OnSystemCallEnd()
 			}
 		},
+		OnGasChange: func(old, new uint64, reason tracing.GasChangeReason) {
+			if l.inner.OnGasChange != nil {
+				l.inner.OnGasChange(old, new, reason)
+			}
+		},
 	}
 }

cmd/evm/testdata/32/trace-0-0x47806361c0fa084be3caa18afe8c48156747c01dbdfc1ee11b5aecdbe4fcf23e.jsonl

@@ -44,8 +44,7 @@
 {"pc":38,"op":82,"gas":"0x65ee4","gasCost":"0x6","memSize":0,"stack":["0x10","0x0"],"depth":2,"refund":0,"opName":"MSTORE"}
 {"pc":39,"op":96,"gas":"0x65ede","gasCost":"0x3","memSize":32,"stack":[],"depth":2,"refund":0,"opName":"PUSH1"}
 {"pc":41,"op":96,"gas":"0x65edb","gasCost":"0x3","memSize":32,"stack":["0x20"],"depth":2,"refund":0,"opName":"PUSH1"}
-{"pc":43,"op":253,"gas":"0x65ed8","gasCost":"0x0","memSize":32,"stack":["0x20","0x0"],"depth":2,"refund":0,"opName":"REVERT"}
-{"pc":43,"op":253,"gas":"0x65ed8","gasCost":"0x0","memSize":32,"stack":[],"depth":2,"refund":0,"opName":"REVERT","error":"execution reverted"}
+{"pc":43,"op":253,"gas":"0x65ed8","gasCost":"0x0","memSize":32,"stack":["0x20","0x0"],"depth":2,"refund":0,"opName":"REVERT","error":"execution reverted"}
 {"output":"0000000000000000000000000000000000000000000000000000000000000010","gasUsed":"0x2e44","error":"execution reverted"}
 {"pc":69,"op":96,"gas":"0x67976","gasCost":"0x3","memSize":0,"stack":["0x0"],"depth":1,"refund":0,"opName":"PUSH1"}
 {"pc":71,"op":85,"gas":"0x67973","gasCost":"0x1388","memSize":0,"stack":["0x0","0x2"],"depth":1,"refund":4800,"opName":"SSTORE"}

core/tracing/gen_gas_change_reason_stringer.go

@@ -339,6 +339,9 @@ const (
 	// GasChangeTxDataFloor is the amount of extra gas the transaction has to pay to reach the minimum gas requirement for the
 	// transaction data. This change will always be a negative change.
 	GasChangeTxDataFloor GasChangeReason = 19
+	// GasChangeCallOpCodeDynamic is the amount of dynamic gas that will be charged for an opcode executed by the EVM.
+	// It will be emitted after the `OnOpcode` callback. So the cost should be attributed to the last instance of `OnOpcode`.
+	GasChangeCallOpCodeDynamic GasChangeReason = 20
 
 	// GasChangeIgnored is a special value that can be used to indicate that the gas change should be ignored as
 	// it will be "manually" tracked by a direct emit of the gas change event.

core/tracing/hooks.go

@@ -195,8 +195,8 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 		// For optimisation reason we're using uint64 as the program counter.
 		// It's theoretically possible to go above 2^64. The YP defines the PC
 		// to be uint256. Practically much less so feasible.
-		pc   = uint64(0) // program counter
-		cost uint64
+		pc                = uint64(0) // program counter
+		cost, dynamicCost uint64
 		// copies used by tracer
 		pcCopy  uint64 // needed for the deferred EVMLogger
 		gasCopy uint64 // for EVMLogger to log gas remaining before execution
@@ -234,7 +234,7 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 	for {
 		if debug {
 			// Capture pre-execution values for tracing.
-			logged, pcCopy, gasCopy = false, pc, contract.Gas
+			logged, pcCopy, gasCopy, dynamicCost = false, pc, contract.Gas, 0
 		}
 
 		if in.evm.chainRules.IsEIP4762 && !contract.IsDeployment && !contract.IsSystemCall {
@@ -286,7 +286,6 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 			}
 			// Consume the gas and return an error if not enough gas is available.
 			// cost is explicitly set so that the capture state defer method can get the proper cost
-			var dynamicCost uint64
 			dynamicCost, err = operation.dynamicGas(in.evm, contract, stack, mem, memorySize)
 			cost += dynamicCost // for tracing
 			if err != nil {
@@ -303,10 +302,15 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 		// Do tracing before potential memory expansion
 		if debug {
 			if in.evm.Config.Tracer.OnGasChange != nil {
-				in.evm.Config.Tracer.OnGasChange(gasCopy, gasCopy-cost, tracing.GasChangeCallOpCode)
+				// Trace the constant cost only
+				in.evm.Config.Tracer.OnGasChange(gasCopy, gasCopy-operation.constantGas, tracing.GasChangeCallOpCode)
 			}
 			if in.evm.Config.Tracer.OnOpcode != nil {
-				in.evm.Config.Tracer.OnOpcode(pc, byte(op), gasCopy, cost, callContext, in.returnData, in.evm.depth, VMErrorFromErr(err))
+				in.evm.Config.Tracer.OnOpcode(pc, byte(op), gasCopy, operation.constantGas, callContext, in.returnData, in.evm.depth, VMErrorFromErr(err))
+				// If any, trace the dynamic cost as well
+				if in.evm.Config.Tracer.OnGasChange != nil && dynamicCost > 0 {
+					in.evm.Config.Tracer.OnGasChange(gasCopy-operation.constantGas, gasCopy-cost, tracing.GasChangeCallOpCodeDynamic)
+				}
 				logged = true
 			}
 		}

core/vm/interpreter.go

@@ -667,6 +667,11 @@ func TestColdAccountAccessCost(t *testing.T) {
 		Execute(tc.code, nil, &Config{
 			EVMConfig: vm.Config{
 				Tracer: &tracing.Hooks{
+					OnGasChange: func(old, new uint64, reason tracing.GasChangeReason) {
+						if step-1 == tc.step && reason == tracing.GasChangeCallOpCodeDynamic {
+							have += old - new
+						}
+					},
 					OnOpcode: func(pc uint64, op byte, gas, cost uint64, scope tracing.OpContext, rData []byte, depth int, err error) {
 						// Uncomment to investigate failures:
 						//t.Logf("%d: %v %d", step, vm.OpCode(op).String(), cost)
@@ -700,10 +705,15 @@ func TestRuntimeJSTracer(t *testing.T) {
 		this.exits++;
 		this.gasUsed = res.getGasUsed();
 	}}`,
-		`{enters: 0, exits: 0, enterGas: 0, gasUsed: 0, steps:0,
+		`{enters: 0, exits: 0, enterGas: 0, gasUsed: 0, steps:0, dynamicGas:0,
 	fault: function() {},
 	result: function() {
-		return [this.enters, this.exits,this.enterGas,this.gasUsed, this.steps].join(",")
+		return [this.enters, this.exits,this.enterGas,this.gasUsed, this.steps, this.dynamicGas].join(",")
+	},
+	gas: function(change) {
+		if (change.getReason() == "CallOpCodeDynamic") {
+			this.dynamicGas += change.getOld() - change.getNew();
+		}
 	},
 	enter: function(frame) {
 		this.enters++;
@@ -726,7 +736,7 @@ func TestRuntimeJSTracer(t *testing.T) {
 				Push(0).                  // value
 				Op(vm.CREATE).
 				Op(vm.POP).Bytes(),
-			results: []string{`"1,1,952853,6,12"`, `"1,1,952853,6,0"`},
+			results: []string{`"1,1,952853,6,12"`, `"1,1,952853,6,0,5"`},
 		},
 		{ // CREATE2
 			code: program.New().MstoreSmall(initcode, 0).
@@ -736,27 +746,27 @@ func TestRuntimeJSTracer(t *testing.T) {
 				Push(0).                  // value
 				Op(vm.CREATE2).
 				Op(vm.POP).Bytes(),
-			results: []string{`"1,1,952844,6,13"`, `"1,1,952844,6,0"`},
+			results: []string{`"1,1,952844,6,13"`, `"1,1,952844,6,0,11"`},
 		},
 		{ // CALL
 			code:    program.New().Call(nil, 0xbb, 0, 0, 0, 0, 0).Op(vm.POP).Bytes(),
-			results: []string{`"1,1,981796,6,13"`, `"1,1,981796,6,0"`},
+			results: []string{`"1,1,981796,6,13"`, `"1,1,981796,6,0,984296"`},
 		},
 		{ // CALLCODE
 			code:    program.New().CallCode(nil, 0xcc, 0, 0, 0, 0, 0).Op(vm.POP).Bytes(),
-			results: []string{`"1,1,981796,6,13"`, `"1,1,981796,6,0"`},
+			results: []string{`"1,1,981796,6,13"`, `"1,1,981796,6,0,984296"`},
 		},
 		{ // STATICCALL
 			code:    program.New().StaticCall(nil, 0xdd, 0, 0, 0, 0).Op(vm.POP).Bytes(),
-			results: []string{`"1,1,981799,6,12"`, `"1,1,981799,6,0"`},
+			results: []string{`"1,1,981799,6,12"`, `"1,1,981799,6,0,984299"`},
 		},
 		{ // DELEGATECALL
 			code:    program.New().DelegateCall(nil, 0xee, 0, 0, 0, 0).Op(vm.POP).Bytes(),
-			results: []string{`"1,1,981799,6,12"`, `"1,1,981799,6,0"`},
+			results: []string{`"1,1,981799,6,12"`, `"1,1,981799,6,0,984299"`},
 		},
 		{ // CALL self-destructing contract
 			code:    program.New().Call(nil, 0xff, 0, 0, 0, 0, 0).Op(vm.POP).Bytes(),
-			results: []string{`"2,2,0,5003,12"`, `"2,2,0,5003,0"`},
+			results: []string{`"2,2,0,5003,12"`, `"2,2,0,5003,0,984296"`},
 		},
 	}
 	calleeCode := []byte{
@@ -921,6 +931,11 @@ func TestDelegatedAccountAccessCost(t *testing.T) {
 			State:       statedb,
 			EVMConfig: vm.Config{
 				Tracer: &tracing.Hooks{
+					OnGasChange: func(old, new uint64, reason tracing.GasChangeReason) {
+						if step-1 == tc.step && reason == tracing.GasChangeCallOpCodeDynamic {
+							have += old - new
+						}
+					},
 					OnOpcode: func(pc uint64, op byte, gas, cost uint64, scope tracing.OpContext, rData []byte, depth int, err error) {
 						// Uncomment to investigate failures:
 						t.Logf("%d: %v %d", step, vm.OpCode(op).String(), cost)

core/vm/runtime/runtime_test.go

@@ -129,17 +129,20 @@ type jsTracer struct {
 	step   goja.Callable
 	enter  goja.Callable
 	exit   goja.Callable
+	gas    goja.Callable
 
 	// Underlying structs being passed into JS
 	log         *steplog
 	frame       *callframe
 	frameResult *callframeResult
+	gasChange   *gasChange
 
 	// Goja-wrapping of types prepared for JS consumption
 	logValue         goja.Value
 	dbValue          goja.Value
 	frameValue       goja.Value
 	frameResultValue goja.Value
+	gasChangeValue   goja.Value
 }
 
 // newJsTracer instantiates a new JS tracer instance. code is a
@@ -202,6 +205,7 @@ func newJsTracer(code string, ctx *tracers.Context, cfg json.RawMessage, chainCo
 	if hasEnter != hasExit {
 		return nil, errors.New("trace object must expose either both or none of enter() and exit()")
 	}
+	t.gas, _ = goja.AssertFunction(obj.Get("gas"))
 	t.traceFrame = hasEnter
 	t.obj = obj
 	t.step = step
@@ -230,18 +234,21 @@ func newJsTracer(code string, ctx *tracers.Context, cfg json.RawMessage, chainCo
 	}
 	t.frame = &callframe{vm: vm, toBig: t.toBig, toBuf: t.toBuf}
 	t.frameResult = &callframeResult{vm: vm, toBuf: t.toBuf}
+	t.gasChange = &gasChange{vm: vm}
 	t.frameValue = t.frame.setupObject()
 	t.frameResultValue = t.frameResult.setupObject()
 	t.logValue = t.log.setupObject()
+	t.gasChangeValue = t.gasChange.setupObject()
 
 	return &tracers.Tracer{
 		Hooks: &tracing.Hooks{
-			OnTxStart: t.OnTxStart,
-			OnTxEnd:   t.OnTxEnd,
-			OnEnter:   t.OnEnter,
-			OnExit:    t.OnExit,
-			OnOpcode:  t.OnOpcode,
-			OnFault:   t.OnFault,
+			OnTxStart:   t.OnTxStart,
+			OnTxEnd:     t.OnTxEnd,
+			OnEnter:     t.OnEnter,
+			OnExit:      t.OnExit,
+			OnOpcode:    t.OnOpcode,
+			OnFault:     t.OnFault,
+			OnGasChange: t.OnGasChange,
 		},
 		GetResult: t.GetResult,
 		Stop:      t.Stop,
@@ -329,6 +336,20 @@ func (t *jsTracer) onStart(from common.Address, to common.Address, create bool,
 	t.ctx["value"] = valueBig
 }
 
+// OnGasChange keeps track of the changes in available gas
+func (t *jsTracer) OnGasChange(old, new uint64, reason tracing.GasChangeReason) {
+	if t.gas == nil {
+		return
+	}
+
+	t.gasChange.old = old
+	t.gasChange.new = new
+	t.gasChange.reason = reason
+	if _, err := t.gas(t.obj, t.gasChangeValue); err != nil {
+		t.onError("gas", err)
+	}
+}
+
 // OnOpcode implements the Tracer interface to trace a single step of VM execution.
 func (t *jsTracer) OnOpcode(pc uint64, op byte, gas, cost uint64, scope tracing.OpContext, rData []byte, depth int, err error) {
 	if !t.traceStep {
@@ -1043,3 +1064,23 @@ func (l *steplog) setupObject() *goja.Object {
 	o.Set("contract", l.contract.setupObject())
 	return o
 }
+
+type gasChange struct {
+	vm *goja.Runtime
+
+	old, new uint64
+	reason   tracing.GasChangeReason
+}
+
+func (g *gasChange) GetOld() uint64    { return g.old }
+func (g *gasChange) GetNew() uint64    { return g.new }
+func (g *gasChange) GetReason() string { return g.reason.String() }
+
+func (g *gasChange) setupObject() *goja.Object {
+	o := g.vm.NewObject()
+	// Setup basic fields.
+	o.Set("getOld", g.vm.ToValue(g.GetOld))
+	o.Set("getNew", g.vm.ToValue(g.GetNew))
+	o.Set("getReason", g.vm.ToValue(g.GetReason))
+	return o
+}

eth/tracers/js/goja.go

@@ -24,8 +24,12 @@
 	// an inner call.
 	descended: false,
 
+	// keeps track of last pushed call to attribute the next dynamic cost with
+	lastPushedCall: undefined,
+
 	// step is invoked for every opcode that the VM executes.
 	step: function(log, db) {
+		this.lastPushedCall = undefined
 		// Capture any errors immediately
 		var error = log.getError();
 		if (error !== undefined) {
@@ -52,6 +56,7 @@
 				value:   '0x' + log.stack.peek(0).toString(16)
 			};
 			this.callstack.push(call);
+			this.lastPushedCall = call
 			this.descended = true
 			return;
 		}
@@ -61,14 +66,16 @@
 			if (this.callstack[left-1].calls === undefined) {
 				this.callstack[left-1].calls = [];
 			}
-			this.callstack[left-1].calls.push({
-				type:    op,
-				from:    toHex(log.contract.getAddress()),
-				to:      toHex(toAddress(log.stack.peek(0).toString(16))),
-				gasIn:   log.getGas(),
+			var call = {
+				type: op,
+				from: toHex(log.contract.getAddress()),
+				to: toHex(toAddress(log.stack.peek(0).toString(16))),
+				gasIn: log.getGas(),
 				gasCost: log.getCost(),
-				value:   '0x' + db.getBalance(log.contract.getAddress()).toString(16)
-			});
+				value: '0x' + db.getBalance(log.contract.getAddress()).toString(16)
+			}
+			this.callstack[left - 1].calls.push(call);
+			this.lastPushedCall = call
 			return
 		}
 		// If a new method invocation is being done, add to the call stack
@@ -98,6 +105,7 @@
 				call.value = '0x' + log.stack.peek(2).toString(16);
 			}
 			this.callstack.push(call);
+			this.lastPushedCall = call
 			this.descended = true
 			return;
 		}
@@ -161,6 +169,13 @@
 		}
 	},
 
+	gas: function(change) {
+		if (this.lastPushedCall !== undefined && change.getReason() == "CallOpCodeDynamic") {
+			this.lastPushedCall.gasCost += change.getOld() - change.getNew();
+			this.lastPushedCall = undefined
+		}
+	},
+
 	// fault is invoked when the actual execution of an opcode fails.
 	fault: function(log, db) {
 		// If the topmost call already reverted, don't handle the additional fault again