[cfe-dev] Bitwidth attribute

ihusar ihusar at fit.vutbr.cz
Wed Jan 12 03:13:48 PST 2011


   I would like to ask, whether there are any plan to support the bitwidth attribute.

In llvm-test-2.8 in SingleSource/UnitTests/Integer/bits.h, there is the attribute used:

typedef unsigned int __attribute__((bitwidth(1))) uint1;

However, when I try to compile it with clang 2.8, I get this message:

test.c:2:37: warning: unknown attribute 'bitwidth' ignored [-Wunknown-attributes]

   I did not try the latest llvm-gcc, but last time i tried, it did not work either.
So, I would like to ask, whether you plan to include support for the bitwidth attribute in the close future, or if
you would be willing to accept a patch that implements this support.

   We need this to describe hardware using C and I think that we are not the only ones that
would find this useful.

Thank you
   Adam Husar

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