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[Bug driver/83206] -mfpu=auto does not work on ARM (armv7l-unknown-linux-gnueabihf)
- From: "andrewm.roberts at sky dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 11 Dec 2017 06:19:29 +0000
- Subject: [Bug driver/83206] -mfpu=auto does not work on ARM (armv7l-unknown-linux-gnueabihf)
- Auto-submitted: auto-generated
- References: <bug-83206-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83206
--- Comment #18 from Andrew Roberts <andrewm.roberts at sky dot com> ---
Richard, I'm giving the latest snapshot a test, the armv6 version will be
ready in 16 hrs or so...
Meanwhile a question about consistency with gcc -Q --help=target,
and also what happens if you don't specify -mcpu= with =mfpu=auto
tested with gcc version 8.0.0 20171210 (experimental) (GCC)
/usr/local/gcc/bin/gcc -Q --help=target | grep "mcpu\|mfpu\|march"
-march= armv7-a+fp
-mcpu=
-mfpu= vfpv3-d16
/usr/local/gcc/bin/gcc -march=native -Q --help=target | grep
"mcpu\|mfpu\|march"
-march= armv7ve+vfpv3-d16
-mcpu=
-mfpu= vfpv3-d16
/usr/local/gcc/bin/gcc -march=native -mcpu=native -Q --help=target | grep
"mcpu\|mfpu\|march"
-march= armv7ve+vfpv3-d16
-mcpu= cortex-a7
-mfpu= vfpv3-d16
/usr/local/gcc/bin/gcc -march=native -mcpu=native -mfpu=auto -Q --help=target |
grep "mcpu\|mfpu\|march"
-march= armv7ve
-mcpu= cortex-a7
-mfpu= auto
So without anything specified generic arch is given and also a fpu.
-march=native fills in the arch with the correct one
whereas -mfpu=auto just says auto rather than what was selected
march=native gives different results depending on if -mfpu=auto is set
How does mfpu=auto impact cross compuilers? Will it just not be available? What
will happen in the future when its the default?
This was all on the Big/Little ODROID XU4, so it should really have been:
-mcpu= cortex-a15.cortex-a7
When the patches for that issue land.