https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61912
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
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CC| |law at redhat dot com
--- Comment #2 from Jeffrey A. Law <law at redhat dot com> ---
So testing this with my improvements to DSE, we discover that the first 12
bytes and the last 4 bytes of the CONSTRUCTOR assignment are dead. Leaving
just 4 bytes to be handled by the CONSTRUCTOR assignment. Prior to DSE this
looked like:
info = {};
info.prec = prec_11(D);
[ ... more explicit assignments ... ]
With the DSE improvements it turns into;
MEM[(char[4] *)&info + 12B] = {};
info.prec = prec_11(D);
[ more explicit assignment follow. ]
Note how we turned the full CONSTRUCTOR into one that starts at byte offset 12
and just writes 4 bytes.
We could have started the CONSTRUCTOR at byte 13 instead of byte 12, as the
first 8 single bit fields are assigned explicitly. The code detects this
properly, but explicitly avoids trimming to an odd start byte so as not to
totally muck up alignments.
