Samuel Iglesias Gonsálvez <sigles...@igalia.com> writes: > From: Iago Toral Quiroga <ito...@igalia.com> > > We were not accounting for reg_suboffset in the check for the start > of the region. This meant that would allow copy-propagation even if > the dst wrote to sub_regoffset 4 and our source read from > sub_regoffset 0, which is not correct. This was observed in fp64 code, > since there we use reg_suboffset to select the high 32-bit of a double. > I don't think this paragraph is accurate, copy instructions with non-zero destination subreg offset are currently considered partial writes and should never have been added to the ACP hash table in the first place.
> Also, fs_reg::regs_read() already takes the stride into account, so we > should not multiply its result by the stride again. This was making > copy-propagation fail to copy-propagate cases that would otherwise be > safe to copy-propagate. Again, this was observed in fp64 code, since > there we use stride > 1 often. > > Incidentally, these fixes open up more possibilities for copy propagation > which uncovered new bugs in copy-propagation. The folowing patches address > each of these new issues. Oh man, that sucks... > --- > .../drivers/dri/i965/brw_fs_copy_propagation.cpp | 21 > +++++++++++++-------- > 1 file changed, 13 insertions(+), 8 deletions(-) > > diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp > b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp > index 5fae10f..23df877 100644 > --- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp > +++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp > @@ -329,6 +329,15 @@ can_take_stride(fs_inst *inst, unsigned arg, unsigned > stride, > return true; > } > > +static inline bool > +region_match(fs_reg src, unsigned regs_read, > + fs_reg dst, unsigned regs_written) How about 'region_contained_in(dst, regs_write, src, regs_read)'? (I personally wouldn't mind 'region_match' but 'write_region_contains_read_region' sounds a bit too long for my taste). > +{ > + return src.reg_offset >= dst.reg_offset && > + (src.reg_offset + regs_read) <= (dst.reg_offset + regs_written) && > + src.subreg_offset >= dst.subreg_offset; This works under the assumption that src.subreg_offset is strictly less than the reg_offset unit -- Which *should* be the case unless we've messed up that restriction in some place (we have in the past :P). To be on the safe side you could do something like following, if you like: | return (src.reg_offset * REG_SIZE + src.subreg_offset >= | dst.reg_offset * REG_SIZE + dst.subreg_offset) && | src.reg_offset + regs_read <= dst.reg_offset + regs_written; With the above taken into account: Reviewed-by: Francisco Jerez <curroje...@riseup.net> > +} > + > bool > fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry) > { > @@ -351,10 +360,8 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int arg, > acp_entry *entry) > /* Bail if inst is reading a range that isn't contained in the range > * that entry is writing. > */ > - if (inst->src[arg].reg_offset < entry->dst.reg_offset || > - (inst->src[arg].reg_offset * 32 + inst->src[arg].subreg_offset + > - inst->regs_read(arg) * inst->src[arg].stride * 32) > > - (entry->dst.reg_offset + entry->regs_written) * 32) > + if (!region_match(inst->src[arg], inst->regs_read(arg), > + entry->dst, entry->regs_written)) > return false; > > /* we can't generally copy-propagate UD negations because we > @@ -554,10 +561,8 @@ fs_visitor::try_constant_propagate(fs_inst *inst, > acp_entry *entry) > /* Bail if inst is reading a range that isn't contained in the range > * that entry is writing. > */ > - if (inst->src[i].reg_offset < entry->dst.reg_offset || > - (inst->src[i].reg_offset * 32 + inst->src[i].subreg_offset + > - inst->regs_read(i) * inst->src[i].stride * 32) > > - (entry->dst.reg_offset + entry->regs_written) * 32) > + if (!region_match(inst->src[i], inst->regs_read(i), > + entry->dst, entry->regs_written)) > continue; > > fs_reg val = entry->src; > -- > 2.5.0 > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
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