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vm: handle negative arguments in SHL/SHR

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Do it as in reference implementation: a >> -b == a << b.
This commit is contained in:
Evgenii Stratonikov 2020-04-06 10:14:26 +03:00
parent 83a02f42f7
commit 96806262bf
2 changed files with 24 additions and 2 deletions
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11
pkg/vm/vm.go
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@ -806,8 +806,17 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
a := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt()
v.checkBigIntSize(a) v.checkBigIntSize(a)
newOp := op
if b < 0 {
b = -b
if op == opcode.SHR {
newOp = opcode.SHL
} else {
newOp = opcode.SHR
}
}
var item big.Int var item big.Int
if op == opcode.SHL { if newOp == opcode.SHL {
item.Lsh(a, uint(b)) item.Lsh(a, uint(b))
} else { } else {
item.Rsh(a, uint(b)) item.Rsh(a, uint(b))

15
pkg/vm/vm_test.go
View file

@ -844,7 +844,7 @@ func TestMULBigResult(t *testing.T) {
checkVMFailed(t, vm) checkVMFailed(t, vm)
} }
func TestDivMod(t *testing.T) { func TestArithNegativeArguments(t *testing.T) {
runCase := func(op opcode.Opcode, p, q, result int64) func(t *testing.T) { runCase := func(op opcode.Opcode, p, q, result int64) func(t *testing.T) {
return func(t *testing.T) { return func(t *testing.T) {
vm := load(makeProgram(op)) vm := load(makeProgram(op))
@ -869,6 +869,19 @@ func TestDivMod(t *testing.T) {
t.Run("negative/negative", runCase(opcode.MOD, -5, -2, -1)) t.Run("negative/negative", runCase(opcode.MOD, -5, -2, -1))
}) })
t.Run("SHR", func(t *testing.T) {
t.Run("positive/positive", runCase(opcode.SHR, 5, 2, 1))
t.Run("positive/negative", runCase(opcode.SHR, 5, -2, 20))
t.Run("negative/positive", runCase(opcode.SHR, -5, 2, -2))
t.Run("negative/negative", runCase(opcode.SHR, -5, -2, -20))
})
t.Run("SHL", func(t *testing.T) {
t.Run("positive/positive", runCase(opcode.SHL, 5, 2, 20))
t.Run("positive/negative", runCase(opcode.SHL, 5, -2, 1))
t.Run("negative/positive", runCase(opcode.SHL, -5, 2, -20))
t.Run("negative/negative", runCase(opcode.SHL, -5, -2, -2))
})
} }
func TestSub(t *testing.T) { func TestSub(t *testing.T) {