------- Comment #8 from jakub at gcc dot gnu dot org 2010-06-10 11:36 ------- Don't understand the last comment. If matched constraint can't have side-effects, then this bug is valid and auto-inc-dec.c should just do if (asm_noperands (insn) >= 0) continue; similarly how it refuses to auto-inc into JUMP_INSNs. If this bug is not valid, then even the powerpc specific uses can't be correct, they don't mention many of the "m" or "=m" operands at all. If it would be ok to use "m" constraint only together with matching %U on ppc, use it at least once, but it would be fine to use it more than once, then "lwz%U2%X2 %0,%2 lwz%U2%X2 %1,%2" would increment the reg in "m" operand 2 twice if it contains pre_inc/pre_modify in it.
-- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44492
