On 30 Oct 2013, at 08:16, "Vladimir Makarov" <vmaka...@redhat.com> wrote:
> The following patch fixes: > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58785 > > LRA chooses constraint 'm' for const_int operand. It means that the > const_int should be placed in memory but it does not happen as preferred > reload class hook returns LO_REGS for class NO_REGS which is result of > LRA choosing 'm'. I don't know why reload pass needs such value but it > should be return NO_REGS IMHO as it results in much less reload insns. > > Is this patch ok to commit to the trunk? > > 2013-10-30 Vladimir Makarov <vmaka...@redhat.com> > > PR target/58785 > * config/arm/arm.c (arm_preferred_reload_class): Don't return > LO_REGS for NO_REGS for LRA. > > 2013-10-30 Vladimir Makarov <vmaka...@redhat.com> > > PR target/58785 > * gcc.target/arm/pr58785.c: New. > > <pr58785.patch> We've been suspicious of this hunk of code for a while now. One reading of the manual suggests that p_r_c can only return a subset of rclass, not a different class. On that basis, lo_regs as a result should only be returned when rclass is general_regs, even for traditional reload. R.
