On 09/14/2015 04:11 AM, Richard Biener wrote:
On Wed, Sep 9, 2015 at 11:07 PM, Jeff Law <l...@redhat.com> wrote:
On 08/31/2015 05:30 AM, Richard Biener wrote:
On Mon, Aug 31, 2015 at 7:49 AM, Mikhail Maltsev <malts...@gmail.com>
wrote:
Hi, all!
This patch removes some conditional compilation from GCC. In this patch I
define
a macro CHECKING_P, which is equal to 1 when ENABLE_CHECKING is defined
and 0
otherwise. The reason for using a new name is the following: currently in
GCC
there are many places where ENABLE_CHECKING is checked using #ifdef, and
it is a
common way to do such checks (though #if would also work and is used in
several
places). If we change it in such way that it is always defined,
accidentally
using "#ifdef" instead of "#if" will lead to subtle errors: some
expensive
checks intended only for development stage will be enabled in release
build and
cause performance degradation.
This patch removes all uses of ENABLE_CHECKING (I also tried poisoning
this
identifier in system.h, and the build succeeded, but I don't know how
will this
affect, e.g. merging feature branches, so I think such decisions should
be made
by maintainers).
I think we want to keep ENABLE_CHECKING for macro use and for some
selected
cases.
Can you outline which cases you want to keep? My general feeling is to
avoid conditionally compiled code as much as we can.
I guess I was merely looking for the patch to be split up to see the motivation
of a always-defined CHECKING_P macro.
Ah. I suspect the motivation is that was the easiest way forward and
roughly what was initially suggested.
With the suggestion to have
a runtime flag_checking variable I wonder if there is any real code that
is guarded by ENABLE_CHECKING now that can't use flag_checking
I wouldn't expect to see any in the .c files. There'll likely be
stragglers (like tree/rtl checking). But even flushing all the stuff
out of the .c files is a major win.
Do you have a preference on whether or not to make flag_checking a pre,
post or integrated patch? I can see arguments for any of those three
choices.
jeff
