Replace magic constants and test all floats

Author: kshyatt

src/device/intrinsics/math.jl

@@ -174,7 +174,7 @@ end
 @device_override function Base.exp(h::Float16)
     # perform computation in Float32 domain
     f = Float32(h)
-    f = fma(f, reinterpret(Float32, 0x3fb8aa3b), reinterpret(Float32, Base.sign_mask(Float32)))
+    f = fma(f, reinterpret(Float32, reinterpret(UInt32, log2(Float32(ℯ)))), -0.0f0)
     f = @fastmath exp2(f)
     r = Float16(f)
 
@@ -217,7 +217,7 @@ end
 @device_override function Base.exp10(h::Float16)
     # perform computation in Float32 domain
     f = Float32(h)
-    f = fma(f, reinterpret(Float32, 0x40549A78), reinterpret(Float32, Base.sign_mask(Float32)))
+    f = fma(f, reinterpret(Float32, reinterpret(UInt32, log2(10.f0))), reinterpret(Float32, Base.sign_mask(Float32)))
     f = @fastmath exp2(f)
     r = Float16(f)
 

test/core/device/intrinsics/math.jl

@@ -112,8 +112,9 @@ using SpecialFunctions
     end
 
     @testset "Float16 - $op" for op in (log,exp,exp2,exp10,log2,log10)
-        @testset "$T" for T in (Float16, )
-            @test testf(x->op.(x), rand(T, 1))
+        all_float_16 = collect(reinterpret(Float16, pattern) for pattern in  UInt16(0):UInt16(1):typemax(UInt16))
+        for each_float in all_float_16
+            @test testf(x->op.(x), Float16[each_float])
         end
     end