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vm: handle negative arguments in SHL/SHR #827

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merged 1 commit into from
Apr 6, 2020
Merged

vm: handle negative arguments in SHL/SHR #827

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11 changes: 10 additions & 1 deletion pkg/vm/vm.go
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Original file line number Diff line number Diff line change
Expand Up @@ -806,8 +806,17 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
a := v.estack.Pop().BigInt()
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
if op == opcode.SHL {
if newOp == opcode.SHL {
item.Lsh(a, uint(b))
} else {
item.Rsh(a, uint(b))
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15 changes: 14 additions & 1 deletion pkg/vm/vm_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -844,7 +844,7 @@ func TestMULBigResult(t *testing.T) {
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) {
return func(t *testing.T) {
vm := load(makeProgram(op))
Expand All @@ -869,6 +869,19 @@ func TestDivMod(t *testing.T) {
t.Run("negative/negative", runCase(opcode.MOD, -5, -2, -1))
})

t.Run("SHR", func(t *testing.T) {
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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) {
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