On 09/18/14 04:07, Richard Sandiford wrote:
This series is a cleaned-up version of:https://gcc.gnu.org/ml/gcc/2014-03/msg00163.html The underlying problem is that the semantics of subregs depend on the word size. You can't have a subreg for byte 2 of a 4-byte word, say, but you can have a subreg for word 2 of a 4-word value (as well as lowpart subregs of that word, etc.). This causes problems when an architecture has wider-than-word registers, since the addressability of a word can then depend on which register class is used. The register allocators need to fix up cases where a subreg turns out to be invalid for a particular class. This is really an extension of what we need to do for CANNOT_CHANGE_MODE_CLASS. Tested on x86_64-linux-gnu, powerpc64-linux-gnu and aarch64_be-elf.
I thought we fixed these problems long ago with the change to subreg_byte?!? Clearly I missed something. jeff
