Gidi Nave <gidi.nav...@gmail.com> writes: > I have a question regarding Plus reload situation I ran into in my > port (which was taken from branch 4.6): > > I got the following insn: Set d1 (plus r1 -96). > d1 and r1 are 2 registers from different classes. > > The reload (which take place at: reload1.c , gen_reload(out = d1, in = > (plus r1 -96)) try 3 options: > > 1. switch the plus operands: > set d1 (plus -96 r1) > > 2. split into 2 insns - reload the const to d1 and then add r1: > set d1 -96 > set d1 (plus d1 r1) > > 3. split into 2 insns - copy r1 to d1 and then add the const: > set d1 r1 > set d1 (plus d1 -96) > > GCC tries generating the 1st option - and fails since no valid pattern is > found. > Then it tries generating the 2nd option and fails once again, since no > valid pattern is found. > Then it tries generating the 3rd option without constraint validity > check(emit_insn_if_valid_for_reload) like the first 2 attempts, > and creates a new insn which will later fail since it's not satisfying > it's constraints. > > My question is: why is GCC certain that one of those 3 attempts must work? > In my case, all 3 resulted insns are not supported by the architecture.
What instructions are supported by your processor here? Ian
