Re: [MIPS r5900] libgcc floating point fixes

[Woon yung Liu <ysai187 at yahoo dot com>]

Hi Matt,

Thank you for your feedback.

New changes in this updated version:

gcc/config/mips/mips.c:added a check against the use of both -mips16 and -march=r5900.
libgcc/configure.ac:added a check for the support of -mips16 by the target.
libgcc/config.host: replaced all explicit checks for the r5900 arch with a test for libgcc_cv_mips16, when checking for whether the MIPS16 ASE is supported.



I have tested the mechanism by replacing the test for -mips16 with -mno-mips16, and I can see the test result for libgcc_cv_mips16 within config.host getting changed.


Please feel free to give further comments.

Thanks and regards,
-W Y


On Tuesday, February 23, 2016 5:09 PM, Matthew Fortune <Matthew.Fortune@imgtec.com> wrote:
Woon yung Liu <ysai187@yahoo.com> wries
> Bump! Sorry, but could I please get an answer? I'm willing to update the patch without
> credit, if necessary.

Hi WY,

Apologies for exceptionally slow response.

The patch you referenced is mostly OK but I would like to get the MIPS16 check
changed to a configure time check for MIPS16 support rather than checking for
r5900. I.e. I think we should have GCC raise an error for -march=r5900 -mips16
and then a configure time check using just -mips16 would fail. That can then
be used to choose whether to build the mips16 code instead of this:

+    if test x$with_arch != xr5900; then
+        tmake_file="$tmake_file mips/t-mips16"
+    fi

This change should also make it possible to have mips.exp simply skip the mips16
tests for r5900 without having to tell it explicitly about r5900.

Thanks,
Matthew


> The patch is working for the R5900 hard-fp mode. I've also used the same, patched copy of
> GCC, to build the toolchain for the IOP (MIPS R3000A, 32-bit MIPS I with no FPU) and it
> also builds correctly.
> 
> If I should be writing to someone else specifically, could someone please tell me who I
> should be writing to instead?
> 
> 
> Thanks and regards,
> -W Y
> 
> 
> 
> On Tuesday, January 26, 2016 5:41 PM, Woon yung Liu <ysai187@yahoo.com> wrote:
> Hi,
> 
> I refer to the previous message by Juergen, regarding his patch to libgcc.
> https://gcc.gnu.org/ml/gcc-patches/2014-08/msg01725.html
> 
> As of now, libgcc (of GCC v5.3.0) still has the problem of building support for both soft
> and hard floats, when there is no support for hard floats by the R5900 (and hence
> resulting in the generation of recursive functions like extendsfdf2).
> 
> That patch doesn't seem to have been committed. I would very much like to help to see it
> get committed because GCC's support for the R5900 is currently not suitable for
> PlayStation 2 development; software-floating point emulation is severely detrimental to
> performance.
> What else needs to be done first, before it can be accepted?
> 
> Thanks and regards,
> -W Y

Attachment: gcc-5.3.0-libgcc-160224.patch
Description: Binary data