core/vm: track 63/64 call gas off stack (#15563)

* core/vm: track 63/64 call gas off stack

Gas calculations in gasCall* relayed the available gas for calls by
replacing it on the stack. This lead to inconsistent traces, which we
papered over by copying the pre-execution stack in trace mode.

This change relays available gas using a temporary variable, off the
stack, and allows removing the weird copy.

* core/vm: remove stackCopy

* core/vm: pop call gas into pool

* core/vm: to -> addr

1 files changed, 10 insertions, 18 deletions

diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index ea5468f90..ac6000f97 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -138,16 +138,15 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
 		pc   = uint64(0) // program counter
 		cost uint64
 		// copies used by tracer
-		stackCopy = newstack() // stackCopy needed for Tracer since stack is mutated by 63/64 gas rule
-		pcCopy    uint64       // needed for the deferred Tracer
-		gasCopy   uint64       // for Tracer to log gas remaining before execution
-		logged    bool         // deferred Tracer should ignore already logged steps
+		pcCopy  uint64 // needed for the deferred Tracer
+		gasCopy uint64 // for Tracer to log gas remaining before execution
+		logged  bool   // deferred Tracer should ignore already logged steps
 	)
 	contract.Input = input
 
 	defer func() {
 		if err != nil && !logged && in.cfg.Debug {
-			in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stackCopy, contract, in.evm.depth, err)
+			in.cfg.Tracer.CaptureState(in.evm, pcCopy, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
 		}
 	}()
 
@@ -156,21 +155,14 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
 	// the execution of one of the operations or until the done flag is set by the
 	// parent context.
 	for atomic.LoadInt32(&in.evm.abort) == 0 {
-		// Get the memory location of pc
-		op = contract.GetOp(pc)
-
 		if in.cfg.Debug {
-			logged = false
-			pcCopy = pc
-			gasCopy = contract.Gas
-			stackCopy = newstack()
-			for _, val := range stack.data {
-				stackCopy.push(val)
-			}
+			// Capture pre-execution values for tracing.
+			logged, pcCopy, gasCopy = false, pc, contract.Gas
 		}
 
-		// Get the operation from the jump table matching the opcode and validate the
-		// stack and make sure there enough stack items available to perform the operation
+		// Get the operation from the jump table and validate the stack to ensure there are
+		// enough stack items available to perform the operation.
+		op = contract.GetOp(pc)
 		operation := in.cfg.JumpTable[op]
 		if !operation.valid {
 			return nil, fmt.Errorf("invalid opcode 0x%x", int(op))
@@ -211,7 +203,7 @@ func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret
 		}
 
 		if in.cfg.Debug {
-			in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stackCopy, contract, in.evm.depth, err)
+			in.cfg.Tracer.CaptureState(in.evm, pc, op, gasCopy, cost, mem, stack, contract, in.evm.depth, err)
 			logged = true
 		}