Don't use f64 shims for f32 cmath functions on none 32-bit x86 MSVC

These shims are only needed on 32-bit x86. Additionally since https://reviews.llvm.org/rL268875 LLVM handles adding the shims itself for the intrinsics.

src/libstd/f32.rs

@@ -44,23 +44,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn floor(self) -> f32 {
-        // On MSVC LLVM will lower many math intrinsics to a call to the
-        // corresponding function. On MSVC, however, many of these functions
-        // aren't actually available as symbols to call, but rather they are all
-        // `static inline` functions in header files. This means that from a C
-        // perspective it's "compatible", but not so much from an ABI
-        // perspective (which we're worried about).
-        //
-        // The inline header functions always just cast to a f64 and do their
-        // operation, so we do that here as well, but only for MSVC targets.
-        //
-        // Note that there are many MSVC-specific float operations which
-        // redirect to this comment, so `floorf` is just one case of a missing
-        // function on MSVC, but there are many others elsewhere.
-        #[cfg(target_env = "msvc")]
-        return (self as f64).floor() as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::floorf32(self) };
+        unsafe { intrinsics::floorf32(self) }
     }
 
     /// Returns the smallest integer greater than or equal to a number.
@@ -78,11 +62,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn ceil(self) -> f32 {
-        // see notes above in `floor`
-        #[cfg(target_env = "msvc")]
-        return (self as f64).ceil() as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::ceilf32(self) };
+        unsafe { intrinsics::ceilf32(self) }
     }
 
     /// Returns the nearest integer to a number. Round half-way cases away from
@@ -348,11 +328,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn powf(self, n: f32) -> f32 {
-        // see notes above in `floor`
-        #[cfg(target_env = "msvc")]
-        return (self as f64).powf(n as f64) as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::powf32(self, n) };
+        unsafe { intrinsics::powf32(self, n) }
     }
 
     /// Takes the square root of a number.
@@ -399,11 +375,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn exp(self) -> f32 {
-        // see notes above in `floor`
-        #[cfg(target_env = "msvc")]
-        return (self as f64).exp() as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::expf32(self) };
+        unsafe { intrinsics::expf32(self) }
     }
 
     /// Returns `2^(self)`.
@@ -447,11 +419,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn ln(self) -> f32 {
-        // see notes above in `floor`
-        #[cfg(target_env = "msvc")]
-        return (self as f64).ln() as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::logf32(self) };
+        unsafe { intrinsics::logf32(self) }
     }
 
     /// Returns the logarithm of the number with respect to an arbitrary base.
@@ -521,11 +489,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn log10(self) -> f32 {
-        // see notes above in `floor`
-        #[cfg(target_env = "msvc")]
-        return (self as f64).log10() as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::log10f32(self) };
+        unsafe { intrinsics::log10f32(self) }
     }
 
     /// The positive difference of two numbers.
@@ -625,11 +589,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn sin(self) -> f32 {
-        // see notes in `core::f32::Float::floor`
-        #[cfg(target_env = "msvc")]
-        return (self as f64).sin() as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::sinf32(self) };
+        unsafe { intrinsics::sinf32(self) }
     }
 
     /// Computes the cosine of a number (in radians).
@@ -649,11 +609,7 @@ impl f32 {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
     pub fn cos(self) -> f32 {
-        // see notes in `core::f32::Float::floor`
-        #[cfg(target_env = "msvc")]
-        return (self as f64).cos() as f32;
-        #[cfg(not(target_env = "msvc"))]
-        return unsafe { intrinsics::cosf32(self) };
+        unsafe { intrinsics::cosf32(self) }
     }
 
     /// Computes the tangent of a number (in radians).

src/libstd/sys/windows/cmath.rs

@@ -27,7 +27,7 @@ extern "C" {
 
 pub use self::shims::*;
 
-#[cfg(not(target_env = "msvc"))]
+#[cfg(not(all(target_env = "msvc", target_arch = "x86")))]
 mod shims {
     use libc::c_float;
 
@@ -43,10 +43,10 @@ mod shims {
     }
 }
 
-// On MSVC these functions aren't defined, so we just define shims which promote
-// everything fo f64, perform the calculation, and then demote back to f32.
-// While not precisely correct should be "correct enough" for now.
-#[cfg(target_env = "msvc")]
+// On 32-bit x86 MSVC these functions aren't defined, so we just define shims
+// which promote everything fo f64, perform the calculation, and then demote
+// back to f32. While not precisely correct should be "correct enough" for now.
+#[cfg(all(target_env = "msvc", target_arch = "x86"))]
 mod shims {
     use libc::c_float;