SI-9403 fix ICodeReader for negative BIPUSH / SIPUSH values

The byte value of a BIPUSH instruction and the (byte1 << 8) | byte2
value of a SIPUSH instruction are signed, see [1] and [2].

Similar for the increment value of IINC [3].

[1] https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html#jvms-6.5.bipush
[2] https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html#jvms-6.5.sipush
[3] https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html#jvms-6.5.iinc

2 files changed, 34 insertions, 0 deletions

diff --git a/test/files/run/t9403/C_1.scala b/test/files/run/t9403/C_1.scala
new file mode 100644
index 0000000000..439af1a386
--- /dev/null
+++ b/test/files/run/t9403/C_1.scala
@@ -0,0 +1,5 @@
+package p
+class C {
+  @inline final def f(x: Int): Long = 10L / (if (x < 0) -2 else 2)
+  @inline final def g(x: Int): Long = 3000L / (if (x < 0) -300 else 300)
+}
diff --git a/test/files/run/t9403/Test_2.scala b/test/files/run/t9403/Test_2.scala
new file mode 100644
index 0000000000..fb2777b9a8
--- /dev/null
+++ b/test/files/run/t9403/Test_2.scala
@@ -0,0 +1,29 @@
+import p.C
+import scala.tools.asm.Opcodes
+import scala.tools.partest.BytecodeTest
+import scala.tools.partest.ASMConverters._
+
+
+object Test extends BytecodeTest {
+  def foo(c: C, x: Int) = c.f(x)
+  def goo(c: C, x: Int) = c.g(x)
+
+  def has(i: Instruction, c: String, m: String) = {
+    val cls = loadClassNode(c)
+    val mth = convertMethod(getMethod(cls, m))
+    assert(mth.instructions.contains(i))
+  }
+
+  def show(): Unit = {
+    assert(foo(new C, -2) == -5L)
+    assert(goo(new C, -2) == -10L)
+
+    val bipush2 = IntOp(Opcodes.BIPUSH, -2)
+    has(bipush2, "p.C", "f")
+    has(bipush2, "Test$", "foo")
+
+    val sipush300 = IntOp(Opcodes.SIPUSH, -300)
+    has(sipush300, "p.C", "g")
+    has(sipush300, "Test$", "goo")
+  }
+}