On Fri, Nov 08, 2013 at 06:26:53PM +0400, Andrey Turetskiy wrote:
> Thanks.
> And a few questions about compiler options:
> 1) You've mentioned two options for offloading:
> -foffload-target=<set of targets> - to specify targets for offloading
> -foffload-target-<target name>=<set of options> - to specify
> compiler options for different targets
> Do we really need two options to set up offloading?
> What do you think about, in my opinion, more compact way:
> -foffload-<target name> - if I want to offload for 'target name',
> but I don't want to specify any options
> -foffload-<target-name>=<set of options> - enable offloading for
> 'target name' and set options
> And compilation for several targets would look like:
> gcc -fopenmp -foffload-mic="-O3 -msse -m64" -foffload-ptx
> -foffload-hsail="-O2 -m32" file.c
I don't think it is a good idea to include the target name before =
in the name of the option, but perhaps you can use two =s:
-foffloat-target=x86_64-k1om-linux="-O2 -mtune=foobar' -foffloat-target=ptx-none
> 2) If user doesn't specify target options directly, is target
> compilation done without any option or compiler uses those host
> options which are suitable for target?
I think I've said that earlier, non-target specific options from original
compilation should be copied over, target specific options discarded,
and the command line supplied overrides appended to that.
> 3) Am I understand right, that options for different targets should be
> stored in different sections in fat object file, and than lto frontend
> should read theese options and run target compilation with them?
No, I'd store in the LTO target IL only the original host compilation
options that weren't target specific (opt* has some flags what is target
specific and what is not), so say -O2 -ftree-vrp would go there,
but say -march=corei7-avx would not. And the -foffload-target= options
would only matter during linking.
Jakub
