Dan Horák
2017-04-25 18:20:25 UTC
forwarding to the ARM list for better visibility by the ARM team
Dan
On Tue, 25 Apr 2017 12:55:47 -0500
you have any idea what would be needed in order to do so?
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Dan
On Tue, 25 Apr 2017 12:55:47 -0500
Hi!
A severe ABI bug on AArch64 and especially on ARM 32-bit has been
recently discovered and GCC 7.1 is going to have that ABI change in.
For details see http://gcc.gnu.org/PR77728
gcc-7.1.1-0.16.fc{26,27} which I'll build tomorrow will contain the
ABI changes as well as a -Wpsabi diagnostics (note:) on code that is
changing the ABI.
The ABI change should affect primarily just C++ code passing PODs
by value where all the non-static data members and base classes are
at most
word aligned, but there are some static data members with doubleword
or bigger alignment or there are typedefs or other nested types in
the class/struct which are doubleword or bigger aligned, and are
passed
in certain positions in the argument list (passing them in even
registers
is fine, passing them in odd ones changes ABI, on the stack at odd
positions
might change the ABI too). For the typedefs, the broken ABI of GCC
5.2 to 7.0.1
has been actually not even self-consitent in some templates, earlier
instantiation vs. lack thereof could affect the ABI. GCC 5.1 and
earlier
for structs used to match earlier AAPCS version and had different
rules and
issues.
Could somebody from rel-eng perform a test mass rebuild on armv7hl
and aarch64 of F26 to determine which packages are affected by the
ABI changes so that we could rebuild only those that actually need
changing?
We do not currently have resources or tooling to do test rebuilds. DoA severe ABI bug on AArch64 and especially on ARM 32-bit has been
recently discovered and GCC 7.1 is going to have that ABI change in.
For details see http://gcc.gnu.org/PR77728
gcc-7.1.1-0.16.fc{26,27} which I'll build tomorrow will contain the
ABI changes as well as a -Wpsabi diagnostics (note:) on code that is
changing the ABI.
The ABI change should affect primarily just C++ code passing PODs
by value where all the non-static data members and base classes are
at most
word aligned, but there are some static data members with doubleword
or bigger alignment or there are typedefs or other nested types in
the class/struct which are doubleword or bigger aligned, and are
passed
in certain positions in the argument list (passing them in even
registers
is fine, passing them in odd ones changes ABI, on the stack at odd
positions
might change the ABI too). For the typedefs, the broken ABI of GCC
5.2 to 7.0.1
has been actually not even self-consitent in some templates, earlier
instantiation vs. lack thereof could affect the ABI. GCC 5.1 and
earlier
for structs used to match earlier AAPCS version and had different
rules and
issues.
Could somebody from rel-eng perform a test mass rebuild on armv7hl
and aarch64 of F26 to determine which packages are affected by the
ABI changes so that we could rebuild only those that actually need
changing?
you have any idea what would be needed in order to do so?
If grepping for note: is not good enough for the test mass rebuild,
I could
hack up a test compiler that does something different when it
encounters
this (say abort if it encounters this and some special env var is
set,
or writes something into some /tmp/ file and let some brp script
collect
info from there, etc.).
DennisI could
hack up a test compiler that does something different when it
encounters
this (say abort if it encounters this and some special env var is
set,
or writes something into some /tmp/ file and let some brp script
collect
info from there, etc.).
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