Add arithmetic right shift to stdlib

examples/pos/bitshifts.check

@@ -0,0 +1,24 @@
+0
+4
+16
+14
+60
+0
+1
+32
+8
+4
+4
+3
+0
+-2
+-8
+-64
+-1
+-1
+-2
+-2
+-8
+-2
+-32
+-1

examples/pos/bitshifts.effekt

@@ -0,0 +1,33 @@
+def main() = {
+  // + << +
+  println(0.bitwiseShl(1))     // 0
+  println(1.bitwiseShl(2))     // 4
+  println(2.bitwiseShl(3))     // 16
+  println(7.bitwiseShl(1))     // 14
+  println(15.bitwiseShl(2))    // 60
+
+  // + >> +
+  println(1.bitwiseShr(1))     // 0
+  println(8.bitwiseShr(3))     // 1
+  println(1024.bitwiseShr(5))  // 32
+  println(16.bitwiseShr(1))    // 8
+  println(16.bitwiseShr(2))    // 4
+  println(32.bitwiseShr(3))    // 4
+  println(7.bitwiseShr(1))     // 3
+  println(3.bitwiseShr(2))     // 0
+
+  // - >> +
+  println(-1.bitwiseShl(1))    // -2
+  println(-2.bitwiseShl(2))    // -8
+  println(-8.bitwiseShl(3))    // -64
+
+  // - << +
+  println(-1.bitwiseShr(1))    // -1
+  println(-2.bitwiseShr(1))    // -1
+  println(-4.bitwiseShr(1))    // -2
+  println(-8.bitwiseShr(2))    // -2
+  println(-16.bitwiseShr(1))   // -8
+  println(-16.bitwiseShr(3))   // -2
+  println(-1024.bitwiseShr(5)) // -32
+  println(-1.bitwiseShr(30))   // -1
+}

libraries/common/effekt.effekt

@@ -550,11 +550,19 @@ def infixAnd { first: => Bool } { second: => Bool }: Bool =
 
 // Bitwise operations
 // ==================
+
+/// Arithmetic left shift
 extern pure def bitwiseShl(x: Int, y: Int): Int =
   js "(${x} << ${y})"
   chez "(ash ${x} ${y})"
   llvm "%z = shl %Int ${x}, ${y} ret %Int %z"
 
+/// Arithmetic right shift
+extern pure def bitwiseShr(x: Int, y: Int): Int =
+  js "(${x} >> ${y})"
+  chez "(ash ${x} (- ${y}))"
+  llvm "%z = ashr %Int ${x}, ${y} ret %Int %z"
+
 extern pure def bitwiseAnd(x: Int, y: Int): Int =
   js "(${x} & ${y})"
   chez "(logand ${x} ${y})"