https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110305
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Michael Morrell from comment #6) > I'm curious why this transformation is being done by both > fold_real_zero_addition_p AND simplify_binary_operation_1. The answer there involves the history of GCC and the history of how optimizations were done in GCC. Basically fold_real_zero_addition_p (fold) would only act a statement while simplify_binary_operation_1 could happen between statements (while doing CSE and combine, etc.). That changed with the merge of tree-ssa in r0-58166-g6de9cd9a886ea6 (2004). simplify_binary_operation_1 had the optimization since the begining of git (though it moved from cse.c to simplify-rtx in r0-24738-g0cedb36cbd7e0c and the HONOR_SIGNED_ZEROS was done by r0-41258-g71925bc04f24a4, in 2002 before it was just checking ieee float format and unsafe-math). fold had it since the begining of git also (and changed in a similar fashion as simplify-rtx for the HONOR_SIGNED_ZEROS).
