Replace calls to core::arch intrinsics with assembly

crates/libm-test/src/precision.rs

@@ -13,6 +13,7 @@ use crate::{BaseName, CheckBasis, CheckCtx, Float, Identifier, Int, TestResult};
 pub struct SpecialCase;
 
 /// ULP allowed to differ from the results returned by a test basis.
+#[allow(clippy::single_match)]
 pub fn default_ulp(ctx: &CheckCtx) -> u32 {
     // ULP compared to the infinite (MPFR) result.
     let mut ulp = match ctx.base_name {

src/math/arch/i686.rs

@@ -1,22 +1,27 @@
 //! Architecture-specific support for x86-32 and x86-64 with SSE2
 
-#[cfg(target_arch = "x86")]
-use core::arch::x86::*;
-#[cfg(target_arch = "x86_64")]
-use core::arch::x86_64::*;
-
-pub fn sqrtf(x: f32) -> f32 {
+pub fn sqrtf(mut x: f32) -> f32 {
+    // SAFETY: `sqrtss` is part of `sse2`, which this module is gated behind. It has no memory
+    // access or side effects.
     unsafe {
-        let m = _mm_set_ss(x);
-        let m_sqrt = _mm_sqrt_ss(m);
-        _mm_cvtss_f32(m_sqrt)
-    }
+        core::arch::asm!(
+            "sqrtss {x}, {x}",
+            x = inout(xmm_reg) x,
+            options(nostack, nomem, pure),
+        )
+    };
+    x
 }
 
-pub fn sqrt(x: f64) -> f64 {
+pub fn sqrt(mut x: f64) -> f64 {
+    // SAFETY: `sqrtsd` is part of `sse2`, which this module is gated behind. It has no memory
+    // access or side effects.
     unsafe {
-        let m = _mm_set_sd(x);
-        let m_sqrt = _mm_sqrt_pd(m);
-        _mm_cvtsd_f64(m_sqrt)
-    }
+        core::arch::asm!(
+            "sqrtsd {x}, {x}",
+            x = inout(xmm_reg) x,
+            options(nostack, nomem, pure),
+        )
+    };
+    x
 }

src/math/support/env.rs

@@ -70,7 +70,6 @@ impl Status {
     /// The default result for division is +/-inf based on operand sign. For `logB`, the default
     /// result is -inf.
     /// `x / y` when `x != 0.0` and `y == 0.0`,
-
     #[cfg_attr(not(feature = "unstable-public-internals"), allow(dead_code))]
     pub const DIVIDE_BY_ZERO: Self = Self(1 << 2);