https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71310
--- Comment #8 from Segher Boessenkool <segher at gcc dot gnu.org> --- Author: segher Date: Fri Jun 10 23:58:09 2016 New Revision: 237319 URL: https://gcc.gnu.org/viewcvs?rev=237319&root=gcc&view=rev Log: fold-const: Don't access bit fields with too big mode (PR71310) Currently, optimize_bit_field_compare reads the bitfield in word_mode if it can. If the bit field is normally accessed in a smaller mode, this might be a violation of the memory model, although the "extra" part of the read is not used. But also, previous stores to the bit field will have been done in the smaller mode, and then bigger loads from it cause a LHS problem. PR middle-end/71310 * fold-const.c (optimize_bit_field_compare): Don't try to use word_mode unconditionally for reading the bit field, look at DECL_BIT_FIELD_REPRESENTATIVE instead. gcc/testsuite/ PR middle-end/71310 * gcc.target/powerpc/pr71310.c: New testcase. Added: trunk/gcc/testsuite/gcc.target/powerpc/pr71310.c Modified: trunk/gcc/ChangeLog trunk/gcc/fold-const.c trunk/gcc/testsuite/ChangeLog
