Rollup merge of #125266 - workingjubilee:stream-plastic-love, r=RalfJung,nikic

compiler: add simd_ctpop intrinsic

Fairly straightforward addition.

cc `@rust-lang/opsem` new (extremely boring) intrinsic

Author: matthiaskrgr

src/intrinsics/simd.rs

@@ -42,6 +42,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             | "flog2"
             | "flog10"
             | "ctlz"
+            | "ctpop"
             | "cttz"
             | "bswap"
             | "bitreverse"
@@ -68,6 +69,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                     "round" => Op::Round(rustc_apfloat::Round::NearestTiesToAway),
                     "trunc" => Op::Round(rustc_apfloat::Round::TowardZero),
                     "ctlz" => Op::Numeric(sym::ctlz),
+                    "ctpop" => Op::Numeric(sym::ctpop),
                     "cttz" => Op::Numeric(sym::cttz),
                     "bswap" => Op::Numeric(sym::bswap),
                     "bitreverse" => Op::Numeric(sym::bitreverse),

tests/pass/intrinsics/portable-simd.rs

@@ -505,6 +505,21 @@ fn simd_intrinsics() {
         assert!(simd_reduce_all(i32x4::splat(-1)));
         assert!(!simd_reduce_all(i32x2::from_array([0, -1])));
 
+        assert_eq!(
+            simd_ctlz(i32x4::from_array([0, i32::MAX, i32::MIN, -1_i32])),
+            i32x4::from_array([32, 1, 0, 0])
+        );
+
+        assert_eq!(
+            simd_ctpop(i32x4::from_array([0, i32::MAX, i32::MIN, -1_i32])),
+            i32x4::from_array([0, 31, 1, 32])
+        );
+
+        assert_eq!(
+            simd_cttz(i32x4::from_array([0, i32::MAX, i32::MIN, -1_i32])),
+            i32x4::from_array([32, 0, 31, 0])
+        );
+
         assert_eq!(
             simd_select(i8x4::from_array([0, -1, -1, 0]), a, b),
             i32x4::from_array([1, 10, 10, 4])