PR tree-optimization/45144 shows an issue that SRA causes. I used 
arm-none-eabi target as an example in PR tree-optimization/45144. But 
the same issue can also been seen on x86_64-linux-gnu target using the 
same test case in the PR.

SRA completely scalarizes a small record. But when the record is used 
later as a whole, GCC has to make the record out of the scalar parts. 
When the record contains bit-fields, GCC generates ugly code to assemble 
the scalar parts into a record.

Until the aggregates copy propagation is implemented, I think it would 
better to disable full scalarization for such records. The patch is 
attached. It's bootstrapped on x86_64-linux-gnu and regression tested.

Is it OK for now? We can remove it after aggregates copy propagation is 
implemented.

Will it be better to add bit-field check in type_consists_of_records_p 
instead of using a new function "type_contains_bit_field_p"?


Regards,
-- 
Jie Zhang
CodeSourcery