From b6eeb4ee90e31f7846e94e4f639f44bc5f623ca0 Mon Sep 17 00:00:00 2001
From: Jubilee Young <workingjubilee@gmail.com>
Date: Wed, 13 Dec 2023 17:46:46 -0800
Subject: [PATCH] Assume masks are correct

This allows miri to detect when they are not, and
may be exploited by LLVM during optimization.
---
 crates/core_simd/src/lib.rs   | 1 +
 crates/core_simd/src/masks.rs | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/crates/core_simd/src/lib.rs b/crates/core_simd/src/lib.rs
index 64ba9705ef523..e974e7aa25a44 100644
--- a/crates/core_simd/src/lib.rs
+++ b/crates/core_simd/src/lib.rs
@@ -4,6 +4,7 @@
     const_maybe_uninit_as_mut_ptr,
     const_mut_refs,
     convert_float_to_int,
+    core_intrinsics,
     decl_macro,
     inline_const,
     intra_doc_pointers,
diff --git a/crates/core_simd/src/masks.rs b/crates/core_simd/src/masks.rs
index 0623d2bf3d121..b95c070d09c35 100644
--- a/crates/core_simd/src/masks.rs
+++ b/crates/core_simd/src/masks.rs
@@ -175,7 +175,10 @@ where
     #[must_use = "method returns a new mask and does not mutate the original value"]
     pub unsafe fn from_int_unchecked(value: Simd<T, N>) -> Self {
         // Safety: the caller must confirm this invariant
-        unsafe { Self(mask_impl::Mask::from_int_unchecked(value)) }
+        unsafe {
+            core::intrinsics::assume(<T as Sealed>::valid(value));
+            Self(mask_impl::Mask::from_int_unchecked(value))
+        }
     }
 
     /// Converts a vector of integers to a mask, where 0 represents `false` and -1