From 25ce6261a69302a19446660ec66875b4774ade52 Mon Sep 17 00:00:00 2001
From: Stefan Karpinski <stefan@karpinski.org>
Date: Tue, 5 Dec 2017 16:21:33 -0500
Subject: [PATCH] Revert "improvements to accuracy/performance for
 float^integer (#24500)"

This reverts commit 8fa23eda5fb79ebe52354b389c09e6d8998954e9.
---
 base/intfuncs.jl | 6 ------
 base/math.jl     | 6 +++---
 test/numbers.jl  | 9 ---------
 3 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/base/intfuncs.jl b/base/intfuncs.jl
index abc1fd95b3e6a3..b7303977f7a495 100644
--- a/base/intfuncs.jl
+++ b/base/intfuncs.jl
@@ -234,12 +234,6 @@ const HWNumber = Union{HWReal, Complex{<:HWReal}, Rational{<:HWReal}}
 @inline literal_pow(::typeof(^), x::HWNumber, ::Val{2}) = x*x
 @inline literal_pow(::typeof(^), x::HWNumber, ::Val{3}) = x*x*x
 
-# don't use the inv(x) transformation here since float^p is slightly more accurate
-@inline literal_pow(::typeof(^), x::AbstractFloat, ::Val{p}) where {p} = x^p
-@inline literal_pow(::typeof(^), x::AbstractFloat, ::Val{-1}) = inv(x)
-
-# for other types, define x^-n as inv(x)^n so that negative literal powers can
-# be computed in a type-stable way even for e.g. integers.
 @inline @generated function literal_pow(f::typeof(^), x, ::Val{p}) where {p}
     if p < 0
         :(literal_pow(^, inv(x), $(Val{-p}())))
diff --git a/base/math.jl b/base/math.jl
index 068dd5d0e0ffa0..fcf46e69475056 100644
--- a/base/math.jl
+++ b/base/math.jl
@@ -732,9 +732,9 @@ end
     end
     z
 end
-@inline ^(x::Float64, y::Integer) = ccall("llvm.pow.f64", llvmcall, Float64, (Float64, Float64), x, Float64(y))
-@inline ^(x::Float32, y::Integer) = ccall("llvm.pow.f32", llvmcall, Float32, (Float32, Float32), x, Float32(y))
-@inline ^(x::Float16, y::Integer) = Float16(Float32(x) ^ y)
+@inline ^(x::Float64, y::Integer) = x ^ Float64(y)
+@inline ^(x::Float32, y::Integer) = x ^ Float32(y)
+@inline ^(x::Float16, y::Integer) = Float16(Float32(x) ^ Float32(y))
 @inline literal_pow(::typeof(^), x::Float16, ::Val{p}) where {p} = Float16(literal_pow(^,Float32(x),Val(p)))
 
 function angle_restrict_symm(theta)
diff --git a/test/numbers.jl b/test/numbers.jl
index 6228baec311739..c917a61e2bf9a1 100644
--- a/test/numbers.jl
+++ b/test/numbers.jl
@@ -2965,15 +2965,6 @@ module M20889 # do we get the expected behavior without importing Base.^?
     Test.@test PR20889(2)^3 == 5
 end
 
-@testset "literal negative power accuracy" begin
-    # a few cases chosen to maximize the error for inv(x)^+n:
-    @test 0.7130409001548401^-2 === 1.9668494399322154
-    @test 0.09496527f0^-2 === 110.88438f0
-    @test 0.20675883960662367^-100 === 2.841786121808917e68
-    @test 0.6123676f0^-100 === 1.9896729f21
-    @test 0.004155780785470562^-1 === 240.6286692253353
-end
-
 @testset "iszero & isone" begin
     # Numeric scalars
     for T in [Float16, Float32, Float64, BigFloat,