Add branches manually in MulAddMul constructor

This is suggested by chethega in: JuliaLang#29634 (comment)
tkf · Jan 29, 2020 · ec824ad · ec824ad
1 parent 9274757
commit ec824ad
Showing 1 changed file with 15 additions and 2 deletions.
diff --git a/stdlib/LinearAlgebra/src/generic.jl b/stdlib/LinearAlgebra/src/generic.jl
@@ -25,8 +25,21 @@ struct MulAddMul{ais1, bis0, TA, TB}
     beta::TB
 end
 
-MulAddMul(alpha::TA, beta::TB) where {TA, TB} =
-    MulAddMul{isone(alpha), iszero(beta), TA, TB}(alpha, beta)
+@inline function MulAddMul(alpha::TA, beta::TB) where {TA,TB}
+    if isone(alpha)
+        if iszero(beta)
+            return MulAddMul{true,true,TA,TB}(alpha, beta)
+        else
+            return MulAddMul{true,false,TA,TB}(alpha, beta)
+        end
+    else
+        if iszero(beta)
+            return MulAddMul{false,true,TA,TB}(alpha, beta)
+        else
+            return MulAddMul{false,false,TA,TB}(alpha, beta)
+        end
+    end
+end
 
 MulAddMul() = MulAddMul(true, false)