Merge pull request #18149 from JuliaLang/jb/fasterbitshift

replace branch in bit shift operators, helps #18135

Author: JeffBezanson

base/int.jl

@@ -182,11 +182,11 @@ trailing_ones(x::Integer) = trailing_zeros(~x)
 # note: this early during bootstrap, `>=` is not yet available
 # note: we only define Int shift counts here; the generic case is handled later
 >>(x::BitInteger, y::Int) =
-    0 <= y ? x >> unsigned(y) : x << unsigned(-y)
+    select_value(0 <= y, x >> unsigned(y), x << unsigned(-y))
 <<(x::BitInteger, y::Int) =
-    0 <= y ? x << unsigned(y) : x >> unsigned(-y)
+    select_value(0 <= y, x << unsigned(y), x >> unsigned(-y))
 >>>(x::BitInteger, y::Int) =
-    0 <= y ? x >>> unsigned(y) : x << unsigned(-y)
+    select_value(0 <= y, x >>> unsigned(y), x << unsigned(-y))
 
 ## integer conversions ##