Regressions on arm926 target with some GCC tests

[Christophe Lyon]

Hi,

After trying qemu master:
commit 474f3938d79ab36b9231c9ad3b5a9314c2aeacde
Merge: 68d7ff0 14f5d87
Author: Peter Maydell <email address hidden>
Date: Fri Jun 21 15:40:50 2019 +0100

even with the fix for https://bugs.launchpad.net/qemu/+bug/1834496,
I've noticed several regressions compared to qemu-3.1 when running the GCC testsuite, with GCC configured to generate arm10tdmi code by default, and using qemu's --cpu arm926.

I'm attaching a tarball containing one of the GCC tests (binaries), needed shared libs, and a short script to run the test.

This was noticed with GCC master configured with
--target arm-none-linux-gnueabi
--with-cpu arm10tdmi
--with-fpu vfp

Thanks

[Peter Maydell (pmaydell)]

We didn't spot that armv5 CPUs don't have mvfr0, so now the vfp refactor is looking at mvfr0 fields to gate feature presence we need to initialize cpu->isar.mvfr0 specifically to a value that indicates the right thing even on the armv5 CPUs which don't have a guest-visible mvfr0. This specifically affects just arm926 and arm1026, which have accidentally lost short-vector support and double-precision support.

[Christophe Lyon (christophe-lyon)]

I confirm this patch fixes the problem I reported. Thanks!

[Thomas Huth (th-huth)]

https://git.qemu.org/?p=qemu.git;a=commitdiff;h=cb7cef8b32033f6284a47d797