From 0b840c71c1d05734bd9b66e8b9f1dace80943485 Mon Sep 17 00:00:00 2001
From: Oscar Smith <oscardssmith@gmail.com>
Date: Fri, 26 Aug 2022 05:11:05 -0400
Subject: [PATCH] fix bug when error is infinite (#46436)

(cherry picked from commit c491e7912603facb0adfc04592c88b17d3e281c2)
---
 base/math.jl | 4 ++--
 test/math.jl | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/base/math.jl b/base/math.jl
index eb69c555d985b5..3b5465bc86e192 100644
--- a/base/math.jl
+++ b/base/math.jl
@@ -1068,8 +1068,8 @@ end
         xnlo += err
         n >>>= 1
     end
-    !isfinite(x) && return x*y
-    return muladd(x, y, muladd(y, xnlo, x*ynlo))
+    err = muladd(y, xnlo, x*ynlo)
+    return ifelse(isfinite(x) & isfinite(err), muladd(x, y, err), x*y)
 end
 
 function ^(x::Float32, n::Integer)
diff --git a/test/math.jl b/test/math.jl
index 56d97562ca0abb..1946e73829eb68 100644
--- a/test/math.jl
+++ b/test/math.jl
@@ -1362,6 +1362,7 @@ end
     end
     # test for large negative exponent where error compensation matters
     @test 0.9999999955206014^-1.0e8 == 1.565084574870928
+    @test 3e18^20 == Inf
 end
 
 # Test that sqrt behaves correctly and doesn't exhibit fp80 double rounding.