attr: do not attempt to expand when we know it's not a macro

Keep track of all recognized macros in the new "maybe_macro" field.
If this field is true, it _may_ be a macro (depending on what's in the
current attr stack). But if the field is false, it's definitely not a
macro, no need to go through the whole attr stack in macroexpand_one()
to search for one.

Without this, "git grep abcdefghi" on git.git hits the inner loop in
macroexpand_one() 2481 times. With this, it's 66 times.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions