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Re: [PATCH][4.8] C++ memory model bitfield handling rewrite
On Tue, 7 Feb 2012, Richard Guenther wrote:
> That would be nice. I suppose that doing
> if (DECL_INITIAL (x))
> unsigned HOST_WIDE_INT width = tree_low_cst (DECL_INITIAL (x),
> DECL_SIZE (x) = bitsize_int (width);
> DECL_BIT_FIELD (x) = 1;
> SET_DECL_C_BIT_FIELD (x);
> at the time we set DECL_INITIAL to the width is not possible
> for some weird reason? At least the struct-layout-1.exp tests
> seem to be happy with
I don't know, but given how many ABI variations there are it would need a
lot of testing and understanding how DECL_SIZE and DECL_BIT_FIELD may be
used. Just setting DECL_C_BIT_FIELD early, and keeping the width
somewhere separate, seems safer (although uses still need to be checked).
For C++ the width may depend on a template parameter so the integer value
can't be determined immediately at parse time.
Joseph S. Myers