Re: [Qemu-devel] [PULL 12/51] build-sys: compile with -Og or -O1 when --enable-debug

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> On 16 January 2018 at 14:16, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> From: Marc-André Lureau <marcandre.lureau@redhat.com>
>>
>> When --enable-debug is turned on, configure doesn't set -O level, and
>> uses default compiler -O0 level, which is slow.
>>
>> Instead, use -Og if supported by the compiler (optimize debugging
>> experience), or -O1 (keeps code somewhat debuggable and works around
>> compiler bugs).
>
> This gives me a noticeably worse debug experience (using -Og),
> because gdb shows a lot more "<optimised out>" variables and
> function arguments. (I've been mildly irritated by this for
> the last few weeks and only just figured out why this was
> happening.)

I was wondering why my:

   ./configure --enable-debug --enable-debug-tcg --extra-cflags="-O0 -g3" --target-list=aarch64-linux-user

builds where showing that.

> Can we go back to the previous behaviour, please ? I don't
> care if the build is slow if I'm debugging, but I really do
> care that I don't have my variables and arguments all
> optimised away by the compiler so I can't tell what's going on.

+1

There is a lot of other stuff enabled when debugging which slows stuff
down anyway.

--
Alex Bennée