Rollup merge of #147534 - sayantn:simd-funnel-shifts, r=RalfJung

Implement SIMD funnel shifts in const-eval/Miri

Split off from rust-lang/rust#147520 with just this change for easier review

r? ```@RalfJung```

Author: matthiaskrgr

tests/fail/intrinsics/simd-funnel_shl-too-far.rs

@@ -0,0 +1,12 @@
+#![feature(core_intrinsics, portable_simd)]
+
+use std::intrinsics::simd::simd_funnel_shl;
+use std::simd::*;
+
+fn main() {
+    unsafe {
+        let x = i32x2::from_array([1, 1]);
+        let y = i32x2::from_array([100, 0]);
+        simd_funnel_shl(x, x, y); //~ERROR: overflowing shift by 100 in `simd_funnel_shl` in lane 0
+    }
+}

tests/fail/intrinsics/simd-funnel_shl-too-far.stderr

@@ -0,0 +1,13 @@
+error: Undefined Behavior: overflowing shift by 100 in `simd_funnel_shl` in lane 0
+  --> tests/fail/intrinsics/simd-funnel_shl-too-far.rs:LL:CC
+   |
+LL |         simd_funnel_shl(x, x, y);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+

tests/fail/intrinsics/simd-funnel_shr-too-far.rs

@@ -0,0 +1,12 @@
+#![feature(core_intrinsics, portable_simd)]
+
+use std::intrinsics::simd::simd_funnel_shr;
+use std::simd::*;
+
+fn main() {
+    unsafe {
+        let x = i32x2::from_array([1, 1]);
+        let y = i32x2::from_array([20, 40]);
+        simd_funnel_shr(x, x, y); //~ERROR: overflowing shift by 40 in `simd_funnel_shr` in lane 1
+    }
+}

tests/fail/intrinsics/simd-funnel_shr-too-far.stderr

@@ -0,0 +1,13 @@
+error: Undefined Behavior: overflowing shift by 40 in `simd_funnel_shr` in lane 1
+  --> tests/fail/intrinsics/simd-funnel_shr-too-far.rs:LL:CC
+   |
+LL |         simd_funnel_shr(x, x, y);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+

tests/pass/intrinsics/portable-simd.rs

@@ -62,7 +62,7 @@ impl<T: Copy, const N: usize> PackedSimd<T, N> {
 #[rustc_nounwind]
 pub unsafe fn simd_shuffle_const_generic<T, U, const IDX: &'static [u32]>(x: T, y: T) -> U;
 
-pub fn simd_ops_f16() {
+fn simd_ops_f16() {
     use intrinsics::*;
 
     // small hack to make type inference better
@@ -273,7 +273,7 @@ fn simd_ops_f64() {
     assert_eq!(f64x2::from_array([f64::NAN, 0.0]).reduce_min(), 0.0);
 }
 
-pub fn simd_ops_f128() {
+fn simd_ops_f128() {
     use intrinsics::*;
 
     // small hack to make type inference better
@@ -454,6 +454,18 @@ fn simd_ops_i32() {
             0x3fffffffu32 as i32
         ])
     );
+
+    // these values are taken from the doctests of `u32::funnel_shl` and `u32::funnel_shr`
+    let c = u32x4::splat(0x010000b3);
+    let d = u32x4::splat(0x2fe78e45);
+
+    unsafe {
+        assert_eq!(intrinsics::simd_funnel_shl(c, d, u32x4::splat(0)), c);
+        assert_eq!(intrinsics::simd_funnel_shl(c, d, u32x4::splat(8)), u32x4::splat(0x0000b32f));
+
+        assert_eq!(intrinsics::simd_funnel_shr(c, d, u32x4::splat(0)), d);
+        assert_eq!(intrinsics::simd_funnel_shr(c, d, u32x4::splat(8)), u32x4::splat(0xb32fe78e));
+    }
 }
 
 fn simd_mask() {