fixes #236

nimbus/vm/computation.nim

@@ -333,11 +333,11 @@ proc getGasRemaining*(c: BaseComputation): GasInt =
 proc tracingEnabled*(c: BaseComputation): bool =
   c.vmState.tracingEnabled
 
-proc traceOpCodeStarted*(c: BaseComputation, op: Op) =
+proc traceOpCodeStarted*(c: BaseComputation, op: Op): int =
   c.vmState.tracer.traceOpCodeStarted(c, op)
 
-proc traceOpCodeEnded*(c: BaseComputation, op: Op) =
-  c.vmState.tracer.traceOpCodeEnded(c, op)
+proc traceOpCodeEnded*(c: BaseComputation, op: Op, lastIndex: int) =
+  c.vmState.tracer.traceOpCodeEnded(c, op, lastIndex)
 
 proc traceError*(c: BaseComputation) =
   c.vmState.tracer.traceError(c)

nimbus/vm/interpreter_dispatch.nim

@@ -196,20 +196,22 @@ proc opTableToCaseStmt(opTable: array[Op, NimNode], computation: NimNode): NimNo
         let asOp = quote do: Op(`op`) # TODO: unfortunately when passing to runtime, ops are transformed into int
         if BaseGasCosts[op].kind == GckFixed:
           quote do:
+            var lastOpIndex: int
             if `computation`.tracingEnabled:
-              `computation`.traceOpCodeStarted(`asOp`)
+              lastOpIndex = `computation`.traceOpCodeStarted(`asOp`)
             `computation`.gasMeter.consumeGas(`computation`.gasCosts[`asOp`].cost, reason = $`asOp`)
             `opImpl`(`computation`)
             if `computation`.tracingEnabled:
-              `computation`.traceOpCodeEnded(`asOp`)
+              `computation`.traceOpCodeEnded(`asOp`, lastOpIndex)
             `instr` = `computation`.code.next()
         else:
           quote do:
+            var lastOpIndex: int
             if `computation`.tracingEnabled:
-              `computation`.traceOpCodeStarted(`asOp`)
+              lastOpIndex = `computation`.traceOpCodeStarted(`asOp`)
             `opImpl`(`computation`)
             if `computation`.tracingEnabled:
-              `computation`.traceOpCodeEnded(`asOp`)
+              `computation`.traceOpCodeEnded(`asOp`, lastOpIndex)
             when `asOp` in {Return, Revert, SelfDestruct}:
               break
             else:

nimbus/vm/transaction_tracer.nim

@@ -38,7 +38,7 @@ iterator storage(tracer: TransactionTracer, compDepth: int): Uint256 =
   for key in tracer.storageKeys[compDepth]:
     yield key
 
-proc traceOpCodeStarted*(tracer: var TransactionTracer, c: BaseComputation, op: Op) =
+proc traceOpCodeStarted*(tracer: var TransactionTracer, c: BaseComputation, op: Op): int =
   if unlikely tracer.trace.isNil:
     tracer.initTracer()
 
@@ -49,7 +49,6 @@ proc traceOpCodeStarted*(tracer: var TransactionTracer, c: BaseComputation, op:
   j["pc"] = %(c.code.pc - 1)
   j["depth"] = %(c.msg.depth + 1)
   j["gas"] = %c.gasMeter.gasRemaining
-  tracer.gasRemaining = c.gasMeter.gasRemaining
 
   # log stack
   if TracerFlags.DisableStack notin tracer.flags:
@@ -83,8 +82,10 @@ proc traceOpCodeStarted*(tracer: var TransactionTracer, c: BaseComputation, op:
       assert(c.stack.values.len > 1)
       tracer.rememberStorageKey(c.msg.depth, c.stack[^1, Uint256])
 
-proc traceOpCodeEnded*(tracer: var TransactionTracer, c: BaseComputation, op: Op) =
-  let j = tracer.trace["structLogs"].elems[^1]
+  result = tracer.trace["structLogs"].len - 1
+
+proc traceOpCodeEnded*(tracer: var TransactionTracer, c: BaseComputation, op: Op, lastIndex: int) =
+  let j = tracer.trace["structLogs"].elems[lastIndex]
 
   # TODO: figure out how to get storage
   # when contract execution interrupted by exception
@@ -97,7 +98,8 @@ proc traceOpCodeEnded*(tracer: var TransactionTracer, c: BaseComputation, op: Op
         storage[key.dumpHex] = %(value.dumpHex)
       j["storage"] = storage
 
-  j["gasCost"] = %(tracer.gasRemaining - c.gasMeter.gasRemaining)
+  let gasRemaining = j["gas"].getInt()
+  j["gasCost"] = %(gasRemaining - c.gasMeter.gasRemaining)
 
   if op in {Return, Revert}:
     let returnValue = %("0x" & toHex(c.rawOutput, true))

nimbus/vm_types.nim

@@ -40,7 +40,6 @@ type
 
   TransactionTracer* = object
     trace*: JsonNode
-    gasRemaining*: GasInt
     flags*: set[TracerFlags]
     accounts*: HashSet[EthAddress]
     storageKeys*: seq[HashSet[Uint256]]

premix/premixcore.nim

@@ -13,8 +13,10 @@ proc fakeAlloc(n: JsonNode) =
     let
       prevMem = n[i-1]["memory"]
       currMem = n[i]["memory"]
-
-    if currMem.len > prevMem.len:
+      prevPc = n[i-1]["pc"].getInt()
+      currPc = n[i]["pc"].getInt()
+      
+    if currMem.len > prevMem.len and prevPc == currPc - 1:
       let diff = currMem.len - prevMem.len
       for _ in 0 ..< diff:
         prevMem.add %chunk