Auto merge of #125358 - matthiaskrgr:rollup-mx841tg, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #124570 (Miscellaneous cleanups)
 - #124772 (Refactor documentation for Apple targets)
 - #125011 (Add opt-for-size core lib feature flag)
 - #125218 (Migrate `run-make/no-intermediate-extras` to new `rmake.rs`)
 - #125225 (Use functions from `crt_externs.h` on iOS/tvOS/watchOS/visionOS)
 - #125266 (compiler: add simd_ctpop intrinsic)
 - #125348 (Small fixes to `std::path::absolute` docs)

Failed merges:

 - #125296 (Fix `unexpected_cfgs` lint on std)

r? `@ghost`
`@rustbot` modify labels: rollup

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])