The GCC manual has a whole section on signedness of bitfields with the
ultimate conclusion that the property really isn't an ABI issue, but
instead a C dialect issue (agreed). Furthermore it concludes that all
targets should behave the same by default.
So it was a mistake for the mcore port to force bitfields to be unsigned
and that never should have been included. This patch rectifies that
problem.
I should have remembered this -- I went down this path once in the 90s.
I don't recall which port anymore, but once Joseph mentioned this policy
bits and pieces did start to come back to me.
Restoring the proper default happens to also fix 170 tests in the GCC
testsuite, some of which would go into infinite loops when bitfields
were treated as signed values (pr88621 for example). Essentially the
testing time cuts in half, which was actually the point of digging into
pr88621 to begin with.
Pushed to the trunk.
Jeff
commit 6c22779dfb09f9691c2893c5cabfe35187e1b9f6
Author: Jeff Law <j...@ventanamicro.com>
Date: Tue Dec 19 21:05:25 2023 -0700
[committed] Stop forcing unsigned bitfields on mcore
The GCC manual has a whole section on signedness of bitfields with the
ultimate
conclusion that the property really isn't an ABI issue, but instead a C
dialect
issue (agreed). Furthermore it concludes that all targets should behave the
same by default.
So it was a mistake for the mcore port to force bitfields to be unsigned and
that never should have been included. This patch rectifies that problem.
I should have remembered this -- I went down this path once in the 90s. I
don't recall which port anymore, but once Joseph mentioned this policy bits
and
pieces did start to come back to me.
Restoring the proper default happens to also fix 170 tests in the GCC
testsuite, some of which would go into infinite loops when bitfields were
treated as signed values (pr88621 for example). Essentially the testing
time
cuts in half, which was actually the point of digging into pr88621 to begin
with.
gcc/
* config/mcore/mcore.h (CC1_SPEC): Do not set -funsigned-bitfields.
diff --git a/gcc/config/mcore/mcore.h b/gcc/config/mcore/mcore.h
index 3de4f0b336a..c732dc014c6 100644
--- a/gcc/config/mcore/mcore.h
+++ b/gcc/config/mcore/mcore.h
@@ -81,9 +81,6 @@
extern char * mcore_current_function_name;
-/* The MCore ABI says that bitfields are unsigned by default. */
-#define CC1_SPEC "-funsigned-bitfields"
-
/* Target machine storage Layout. */
#define PROMOTE_MODE(MODE,UNSIGNEDP,TYPE) \