chore(gnovm): remove unused Machine.MaxCycles (#3744)

The logic to manage the CPU limit is already handled by the gasmeter,
which has the ability to panic the gnovm if a cpu limit is reached.

It's simpler and faster to have only one path of failure.

No other changes in CPU cycles accounting, still performed in gnovm.

Author: mvertes

gnovm/pkg/gnolang/machine.go

@@ -43,7 +43,6 @@ type Machine struct {
 	// Configuration
 	PreprocessorMode bool // this is used as a flag when const values are evaluated during preprocessing
 	ReadOnly         bool
-	MaxCycles        int64
 	Output           io.Writer
 	Store            Store
 	Context          interface{}
@@ -87,7 +86,6 @@ type MachineOptions struct {
 	Context          interface{}
 	Alloc            *Allocator // or see MaxAllocBytes.
 	MaxAllocBytes    int64      // or 0 for no limit.
-	MaxCycles        int64      // or 0 for no limit.
 	GasMeter         store.GasMeter
 }
 
@@ -112,7 +110,6 @@ var machinePool = sync.Pool{
 func NewMachineWithOptions(opts MachineOptions) *Machine {
 	preprocessorMode := opts.PreprocessorMode
 	readOnly := opts.ReadOnly
-	maxCycles := opts.MaxCycles
 	vmGasMeter := opts.GasMeter
 
 	output := opts.Output
@@ -145,7 +142,6 @@ func NewMachineWithOptions(opts MachineOptions) *Machine {
 	mm.Alloc = alloc
 	mm.PreprocessorMode = preprocessorMode
 	mm.ReadOnly = readOnly
-	mm.MaxCycles = maxCycles
 	mm.Output = output
 	mm.Store = store
 	mm.Context = context
@@ -1025,13 +1021,9 @@ const GasFactorCPU int64 = 1
 func (m *Machine) incrCPU(cycles int64) {
 	if m.GasMeter != nil {
 		gasCPU := overflow.Mul64p(cycles, GasFactorCPU)
-		m.GasMeter.ConsumeGas(gasCPU, "CPUCycles")
+		m.GasMeter.ConsumeGas(gasCPU, "CPUCycles") // May panic if out of gas.
 	}
-
 	m.Cycles += cycles
-	if m.MaxCycles != 0 && m.Cycles > m.MaxCycles {
-		panic("CPU cycle overrun")
-	}
 }
 
 const (