use Instr as GetCost argument for more information

compiler/gas.go

@@ -7,7 +7,7 @@ func (c *SSAFunctionCompiler) InsertGasCounters(gp GasPolicy) {
 		blk := &cfg.Blocks[i]
 		totalCost := int64(1)
 		for _, ins := range blk.Code {
-			totalCost += gp.GetCost(ins.Op)
+			totalCost += gp.GetCost(ins)
 			if totalCost < 0 {
 				panic("total cost overflow")
 			}

compiler/gas_policy.go

@@ -1,13 +1,13 @@
 package compiler
 
 type GasPolicy interface {
-	GetCost(key string) int64
+	GetCost(key Instr) int64
 }
 
 type SimpleGasPolicy struct {
 	GasPerInstruction int64
 }
 
-func (p *SimpleGasPolicy) GetCost(key string) int64 {
+func (p *SimpleGasPolicy) GetCost(key Instr) int64 {
 	return p.GasPerInstruction
 }