On 2016-01-08 11:03, Sedat Dilek wrote:

On Mon, Jan 4, 2016 at 11:37 PM, Michal Marek [off-list ref] wrote:

quoted

Dne 4.1.2016 v 12:47 Sedat Dilek napsal(a):

quoted

But I think you did not get my problem - to have two different
optimization-levels for a compiler in *one* make-line makes no sense
to me.

That we sometimes have -O2 ... -Os on the command line is not a problem,
since any same unix tool parses its options so that the last one of
mutually exclusive options wins.

That is new to me and I haven't tested this by dropping arguments in
my make-line(s).

From where do have this information - sort of "business-life-experience" :-)?
Is that documented somewhere in the Linux-sources?

You override a previously set option by appending one with different value:

$ yes | head -n 10 -n 999 -n 2
y
y
$

This pattern is used all over in Makefiles.

Do you agree that it is confusing to have two optlevel arguments in
one make-line?

It probably is, but fixing this problem would make the Makefiles unreadable.

Linus suggested me to use a wrapper-script in case of using two
different compiler and passing arguments...

[  /usr/bin/mycompiler ]
#!/bin/bash

gcc-4.9 "$@"
- EOF -

According to your statement passing an optlevel here in this script
will never-ever be recognized - as it is at the begin-of-(make)-line.

Pass it as the last argument.

So how should someone change the Linux-sources to test a different
optlevel than -O2?

make KCFLAGS=-O3

However, per-directory and per-file cflags set in Makefiles will take
precedence. If you want to override these as well, use the wrapper.

Michal