From 59329154b71669ede57c579e23251962ca7df771 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 14 Feb 2026 13:33:03 +0100
Subject: [PATCH] minor tweaks

---
 src/tools/miri/src/shims/aarch64.rs              | 16 ++++++----------
 .../shims/aarch64/intrinsics-aarch64-neon.rs     | 11 ++++++-----
 2 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/src/tools/miri/src/shims/aarch64.rs b/src/tools/miri/src/shims/aarch64.rs
index 2aca71819e5e..d06b02a41334 100644
--- a/src/tools/miri/src/shims/aarch64.rs
+++ b/src/tools/miri/src/shims/aarch64.rs
@@ -1,4 +1,4 @@
-use rustc_abi::{CanonAbi, Size};
+use rustc_abi::CanonAbi;
 use rustc_middle::mir::BinOp;
 use rustc_middle::ty::Ty;
 use rustc_span::Symbol;
@@ -60,8 +60,8 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             }
             // Vector table lookup: each index selects a byte from the 16-byte table, out-of-range -> 0.
             // Used to implement vtbl1_u8 function.
-            // LLVM does not have a portable shuffle that takes non-const indices.
-            // So we need to implement this ourselves
+            // LLVM does not have a portable shuffle that takes non-const indices
+            // so we need to implement this ourselves.
             // https://developer.arm.com/architectures/instruction-sets/intrinsics/vtbl1_u8
             "neon.tbl1.v16i8" => {
                 let [table, indices] =
@@ -73,15 +73,11 @@ pub(super) trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 assert_eq!(table_len, 16);
                 assert_eq!(idx_len, dest_len);
 
-                let table_len = u128::from(table_len);
-                let elem_size = Size::from_bytes(1);
                 for i in 0..dest_len {
                     let idx = this.read_immediate(&this.project_index(&indices, i)?)?;
-                    let idx_u = idx.to_scalar().to_uint(elem_size)?;
-                    let val = if idx_u < table_len {
-                        let t = this.read_immediate(
-                            &this.project_index(&table, idx_u.try_into().unwrap())?,
-                        )?;
+                    let idx_u = idx.to_scalar().to_u8()?;
+                    let val = if u64::from(idx_u) < table_len {
+                        let t = this.read_immediate(&this.project_index(&table, idx_u.into())?)?;
                         t.to_scalar()
                     } else {
                         Scalar::from_u8(0)
diff --git a/src/tools/miri/tests/pass/shims/aarch64/intrinsics-aarch64-neon.rs b/src/tools/miri/tests/pass/shims/aarch64/intrinsics-aarch64-neon.rs
index b1132fcaabcd..6d3f153e194f 100644
--- a/src/tools/miri/tests/pass/shims/aarch64/intrinsics-aarch64-neon.rs
+++ b/src/tools/miri/tests/pass/shims/aarch64/intrinsics-aarch64-neon.rs
@@ -10,13 +10,13 @@ fn main() {
     assert!(is_aarch64_feature_detected!("neon"));
 
     unsafe {
-        test_neon();
-        tbl1_v16i8_basic();
+        test_vpmaxq_u8();
+        test_tbl1_v16i8_basic();
     }
 }
 
 #[target_feature(enable = "neon")]
-unsafe fn test_neon() {
+unsafe fn test_vpmaxq_u8() {
     // Adapted from library/stdarch/crates/core_arch/src/aarch64/neon/mod.rs
     unsafe fn test_vpmaxq_u8() {
         let a = vld1q_u8([1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8].as_ptr());
@@ -42,18 +42,19 @@ unsafe fn test_neon() {
 }
 
 #[target_feature(enable = "neon")]
-fn tbl1_v16i8_basic() {
+fn test_tbl1_v16i8_basic() {
     unsafe {
         // table = 0..15
         let table: uint8x16_t =
             transmute::<[u8; 16], _>([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
-        // indices: include in-range, 15 (last), 16 and 255 (out-of-range → 0)
+        // indices
         let idx: uint8x16_t =
             transmute::<[u8; 16], _>([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
         let got = vqtbl1q_u8(table, idx);
         let got_arr: [u8; 16] = transmute(got);
         assert_eq!(got_arr, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
 
+        // Also try different order and out-of-range indices (16, 255).
         let idx2: uint8x16_t =
             transmute::<[u8; 16], _>([15, 16, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
         let got2 = vqtbl1q_u8(table, idx2);