Auto merge of #1067 - Aaron1011:feature/inverse-trig, r=RalfJung

Add acos, asin, and atan foreign functions

I copied the tests from the docs pages

Author: bors

src/shims/foreign_items.rs

@@ -496,14 +496,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
 
             // math functions
-            "cbrtf" | "coshf" | "sinhf" | "tanf" => {
+            "cbrtf" | "coshf" | "sinhf" | "tanf" | "acosf" | "asinf" | "atanf" => {
                 // FIXME: Using host floats.
                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
                 let f = match link_name {
                     "cbrtf" => f.cbrt(),
                     "coshf" => f.cosh(),
                     "sinhf" => f.sinh(),
                     "tanf" => f.tan(),
+                    "acosf" => f.acos(),
+                    "asinf" => f.asin(),
+                    "atanf" => f.atan(),
                     _ => bug!(),
                 };
                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
@@ -521,14 +524,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
             }
 
-            "cbrt" | "cosh" | "sinh" | "tan" => {
+            "cbrt" | "cosh" | "sinh" | "tan" | "acos" | "asin" | "atan" => {
                 // FIXME: Using host floats.
                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
                 let f = match link_name {
                     "cbrt" => f.cbrt(),
                     "cosh" => f.cosh(),
                     "sinh" => f.sinh(),
                     "tan" => f.tan(),
+                    "acos" => f.acos(),
+                    "asin" => f.asin(),
+                    "atan" => f.atan(),
                     _ => bug!(),
                 };
                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;

tests/run-pass/intrinsics-math.rs

@@ -92,6 +92,15 @@ pub fn main() {
     assert_approx_eq!(1.0f32.tan(), 1.557408f32);
     assert_approx_eq!(1.0f64.tan(), 1.557408f64);
 
+    assert_approx_eq!(f32::consts::FRAC_PI_4.cos().acos(), f32::consts::FRAC_PI_4);
+    assert_approx_eq!(f64::consts::FRAC_PI_4.cos().acos(), f64::consts::FRAC_PI_4);
+
+    assert_approx_eq!(f32::consts::FRAC_PI_4.sin().asin(), f32::consts::FRAC_PI_4);
+    assert_approx_eq!(f64::consts::FRAC_PI_4.sin().asin(), f64::consts::FRAC_PI_4);
+
+    assert_approx_eq!(1.0_f32, 1.0_f32.tan().atan());
+    assert_approx_eq!(1.0_f64, 1.0_f64.tan().atan());
+
     assert_eq!(3.3_f32.round(), 3.0);
     assert_eq!(3.3_f64.round(), 3.0);