Re: [GIT PULL 2/2] Kconfig updates for v5.10-rc1

[Linus Torvalds]

On Fri, Nov 27, 2020 at 11:05 PM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>
> As for the cc1plus cost, I got a similar result.
>
> Running scripts/gcc-plugin.sh directly
> took me 0.5 sec, which is a fourth
> of the allmodconfig run-time.
>
> Actually, I did not know this shell script
> was so expensive to run...

So it turns out that one reason it's so expensive to run is that it
does a *lot* more than it claims to do.

It says "we need a c++ compiler that supports the designated
initializer GNU extension", but then it actually includes a header
file from hell, rather than just test designated initializers.

This patch makes the cc1plus overhead go down a lot. That said, I'm
doubtful we really want gcc plugins at all, considering that the only
real users have all apparently migrated to clang builtin functionality
instead.

        Linus
 scripts/gcc-plugin.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/gcc-plugin.sh b/scripts/gcc-plugin.sh
index b79fd0bea838..59db87bff456 100755
--- a/scripts/gcc-plugin.sh
+++ b/scripts/gcc-plugin.sh
@@ -8,8 +8,8 @@ srctree=$(dirname "$0")
 gccplugins_dir=$($* -print-file-name=plugin)
 
 # we need a c++ compiler that supports the designated initializer GNU extension
+test -e "$gccplugins_dir/include/plugin-version.h" &&
 $HOSTCC -c -x c++ -std=gnu++98 - -fsyntax-only -I $srctree/gcc-plugins -I $gccplugins_dir/include 2>/dev/null <<EOF
-#include "gcc-common.h"
 class test {
 public:
 	int test;