Introduce math::arch::intrinsics

This module provides implementations of basic functions that defer to
LLVM for what to do, rather than either using a builtin operation or
calling another function in this library.

`math::arch` will become the home of anything architecture-specific in
the future.

library/compiler-builtins/libm/src/math/arch/intrinsics.rs

@@ -0,0 +1,52 @@
+// Config is needed for times when this module is available but we don't call everything
+#![allow(dead_code)]
+
+pub fn ceil(x: f64) -> f64 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::ceilf64(x) }
+}
+
+pub fn ceilf(x: f32) -> f32 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::ceilf32(x) }
+}
+
+pub fn fabs(x: f64) -> f64 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::fabsf64(x) }
+}
+
+pub fn fabsf(x: f32) -> f32 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::fabsf32(x) }
+}
+
+pub fn floor(x: f64) -> f64 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::floorf64(x) }
+}
+
+pub fn floorf(x: f32) -> f32 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::floorf32(x) }
+}
+
+pub fn sqrt(x: f64) -> f64 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::sqrtf64(x) }
+}
+
+pub fn sqrtf(x: f32) -> f32 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::sqrtf32(x) }
+}
+
+pub fn trunc(x: f64) -> f64 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::truncf64(x) }
+}
+
+pub fn truncf(x: f32) -> f32 {
+    // SAFETY: safe intrinsic with no preconditions
+    unsafe { core::intrinsics::truncf32(x) }
+}

library/compiler-builtins/libm/src/math/arch/mod.rs

@@ -0,0 +1,9 @@
+//! Architecture-specific routines and operations.
+//!
+//! LLVM will already optimize calls to some of these in cases that there are hardware
+//! instructions. Providing an implementation here just ensures that the faster implementation
+//! is used when calling the function directly. This helps anyone who uses `libm` directly, as
+//! well as improving things when these routines are called as part of other implementations.
+
+#[cfg(intrinsics_enabled)]
+pub mod intrinsics;

library/compiler-builtins/libm/src/math/mod.rs

@@ -302,6 +302,7 @@ pub use self::trunc::trunc;
 pub use self::truncf::truncf;
 
 // Private modules
+mod arch;
 mod expo2;
 mod fenv;
 mod k_cos;