Rollup merge of #113534 - oli-obk:simd_shuffle_dehackify, r=workingjubilee

Forbid old-style `simd_shuffleN` intrinsics

Don't merge before https://github.com/rust-lang/packed_simd/pull/350 has made its way to crates.io

We used to support specifying the lane length of simd_shuffle ops by attaching the lane length to the name of the intrinsic (like `simd_shuffle16`). After this PR, you cannot do that anymore, and need to instead either rely on inference of the `idx` argument type or specify it as `simd_shuffle::<_, [u32; 16], _>`.

r? `@workingjubilee`

1 files changed, 13 insertions, 21 deletions

diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index 86c39ab5e94..6f1e4c5178a 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -1020,28 +1020,20 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
         ));
     }
 
-    if let Some(stripped) = name.as_str().strip_prefix("simd_shuffle") {
-        // If this intrinsic is the older "simd_shuffleN" form, simply parse the integer.
-        // If there is no suffix, use the index array length.
-        let n: u64 = if stripped.is_empty() {
-            // Make sure this is actually an array, since typeck only checks the length-suffixed
-            // version of this intrinsic.
-            match args[2].layout.ty.kind() {
-                ty::Array(ty, len) if matches!(ty.kind(), ty::Uint(ty::UintTy::U32)) => {
-                    len.try_eval_target_usize(bx.cx.tcx, ty::ParamEnv::reveal_all()).unwrap_or_else(
-                        || span_bug!(span, "could not evaluate shuffle index array length"),
-                    )
-                }
-                _ => return_error!(InvalidMonomorphization::SimdShuffle {
-                    span,
-                    name,
-                    ty: args[2].layout.ty
-                }),
+    if name == sym::simd_shuffle {
+        // Make sure this is actually an array, since typeck only checks the length-suffixed
+        // version of this intrinsic.
+        let n: u64 = match args[2].layout.ty.kind() {
+            ty::Array(ty, len) if matches!(ty.kind(), ty::Uint(ty::UintTy::U32)) => {
+                len.try_eval_target_usize(bx.cx.tcx, ty::ParamEnv::reveal_all()).unwrap_or_else(
+                    || span_bug!(span, "could not evaluate shuffle index array length"),
+                )
             }
-        } else {
-            stripped.parse().unwrap_or_else(|_| {
-                span_bug!(span, "bad `simd_shuffle` instruction only caught in codegen?")
-            })
+            _ => return_error!(InvalidMonomorphization::SimdShuffle {
+                span,
+                name,
+                ty: args[2].layout.ty
+            }),
         };
 
         require_simd!(ret_ty, InvalidMonomorphization::SimdReturn { span, name, ty: ret_ty });