Edit docs to explain mask type discrepancy in _mm_shuffle_ps between Rust and Intel's Intrinsics Guide
diff --git a/crates/core_arch/src/x86/sse.rs b/crates/core_arch/src/x86/sse.rs
index 551da76..7ca8326 100644
--- a/crates/core_arch/src/x86/sse.rs
+++ b/crates/core_arch/src/x86/sse.rs
@@ -992,6 +992,12 @@
/// `b`. Mask is split to 2 control bits each to index the element from inputs.
///
/// [Intel's documentation](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_shuffle_ps)
+///
+/// Note that there appears to be a mistake within Intel's Intrinsics Guide.
+/// `_mm_shuffle_ps` is supposed to take an `i32` instead of an `u32`
+/// as is the case for [other shuffle intrinsics](https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mm_shuffle_).
+/// Performing an implicit type conversion between an unsigned integer and a signed integer
+/// does not cause a problem in C, however Rust's commitment to safety does not allow this.
#[inline]
#[target_feature(enable = "sse")]
#[cfg_attr(test, assert_instr(shufps, mask = 3))]
