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, 8 insertions, 38 deletions

diff --git a/core/vm/gas_table.go b/core/vm/gas_table.go
index 0d8e295a5..ff109af57 100644
--- a/core/vm/gas_table.go
+++ b/core/vm/gas_table.go
@@ -342,19 +342,11 @@ func gasCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem
 		return 0, errGasUintOverflow
 	}
 
-	cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+	evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
 	if err != nil {
 		return 0, err
 	}
-	// Replace the stack item with the new gas calculation. This means that
-	// either the original item is left on the stack or the item is replaced by:
-	// (availableGas - gas) * 63 / 64
-	// We replace the stack item so that it's available when the opCall instruction is
-	// called. This information is otherwise lost due to the dependency on *current*
-	// available gas.
-	stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
-	if gas, overflow = math.SafeAdd(gas, cg); overflow {
+	if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
 		return 0, errGasUintOverflow
 	}
 	return gas, nil
@@ -374,19 +366,11 @@ func gasCallCode(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack,
 		return 0, errGasUintOverflow
 	}
 
-	cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+	evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
 	if err != nil {
 		return 0, err
 	}
-	// Replace the stack item with the new gas calculation. This means that
-	// either the original item is left on the stack or the item is replaced by:
-	// (availableGas - gas) * 63 / 64
-	// We replace the stack item so that it's available when the opCall instruction is
-	// called. This information is otherwise lost due to the dependency on *current*
-	// available gas.
-	stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
-	if gas, overflow = math.SafeAdd(gas, cg); overflow {
+	if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
 		return 0, errGasUintOverflow
 	}
 	return gas, nil
@@ -436,18 +420,11 @@ func gasDelegateCall(gt params.GasTable, evm *EVM, contract *Contract, stack *St
 		return 0, errGasUintOverflow
 	}
 
-	cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+	evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
 	if err != nil {
 		return 0, err
 	}
-	// Replace the stack item with the new gas calculation. This means that
-	// either the original item is left on the stack or the item is replaced by:
-	// (availableGas - gas) * 63 / 64
-	// We replace the stack item so that it's available when the opCall instruction is
-	// called.
-	stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
-	if gas, overflow = math.SafeAdd(gas, cg); overflow {
+	if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
 		return 0, errGasUintOverflow
 	}
 	return gas, nil
@@ -463,18 +440,11 @@ func gasStaticCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stac
 		return 0, errGasUintOverflow
 	}
 
-	cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+	evm.callGasTemp, err = callGas(gt, contract.Gas, gas, stack.Back(0))
 	if err != nil {
 		return 0, err
 	}
-	// Replace the stack item with the new gas calculation. This means that
-	// either the original item is left on the stack or the item is replaced by:
-	// (availableGas - gas) * 63 / 64
-	// We replace the stack item so that it's available when the opCall instruction is
-	// called.
-	stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
-
-	if gas, overflow = math.SafeAdd(gas, cg); overflow {
+	if gas, overflow = math.SafeAdd(gas, evm.callGasTemp); overflow {
 		return 0, errGasUintOverflow
 	}
 	return gas, nil