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Re: [Qemu-devel] [PULL 12/51] build-sys: compile with -Og or -O1 when --
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PULL 12/51] build-sys: compile with -Og or -O1 when --enable-debug |
Date: |
Fri, 02 Mar 2018 21:04:59 +0000 |
User-agent: |
mu4e 1.1.0; emacs 26.0.91 |
Peter Maydell <address@hidden> writes:
> On 16 January 2018 at 14:16, Paolo Bonzini <address@hidden> wrote:
>> From: Marc-André Lureau <address@hidden>
>>
>> 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