I've been promissed in a bug that this will be fixed in a future version of
the header. However, in the interest of my branch building, I'm adding
these changes in myself for the moment.
We don't actually use it to create all the instructions but we do use it
for insertion always. This should make things far more consistent for
implementing extended instructions.
We do control-flow handling as a two-step process. The first step is to
walk the instructions list and record various information about blocks and
functions. This is where the acutal nir_function_overload objects get
created. We also record the start/stop instruction for each block. Then
a second pass walks over each of the functions and over the blocks in each
function in a way that's NIR-friendly and actually parses the instructions.
Instead of having functions to add values and set various things, we just
have a function that does a few asserts and then returns the value. The
caller is then responsible for setting the various fields.
Previously, this case was being handled in match_expression prior to
calling match_value. However, there is really no good reason for this
given that match_value has all of the information it needs. Also, they
weren't being handled properly in the commutative case and putting it in
match_value gives us that for free.
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
This commit switches us from the current setup of using hash sets for
use/def sets to using linked lists. Doing so should save us quite a bit of
memory because we aren't carrying around 3 hash sets per register and 2 per
SSA value. It should also save us CPU time because adding/removing things
from use/def sets is 4 pointer manipulations instead of a hash lookup.
Running shader-db 50 times with USE_NIR=0, NIR, and NIR + use/def lists:
GLSL IR Only: 586.4 +/- 1.653833
NIR with hash sets: 675.4 +/- 2.502108
NIR + use/def lists: 641.2 +/- 1.557043
I also ran a memory usage experiment with Ken's patch to delete GLSL IR and
keep NIR. This patch cuts an aditional 42.9 MiB of ralloc'd memory over
and above what we gained by deleting the GLSL IR on the same dota trace.
On the code complexity side of things, some things are now much easier and
others are a bit harder. One of the operations we perform constantly in
optimization passes is to replace one source with another. Due to the fact
that an instruction can use the same SSA value multiple times, we had to
iterate through the sources of the instruction and determine if the use we
were replacing was the only one before removing it from the set of uses.
With this patch, uses are per-source not per-instruction so we can just
remove it safely. On the other hand, trying to iterate over all of the
instructions that use a given value is more difficult. Fortunately, the
two places we do that are the ffma peephole where it doesn't matter and GCM
where we already gracefully handle duplicates visits to an instruction.
Another aspect here is that using linked lists in this way can be tricky to
get right. With sets, things were quite forgiving and the worst that
happened if you didn't properly remove a use was that it would get caught
in the validator. With linked lists, it can lead to linked list corruption
which can be harder to track. However, we do just as much validation of
the linked lists as we did of the sets so the validator should still catch
these problems. While working on this series, the vast majority of the
bugs I had to fix were caught by assertions. I don't think the lists are
going to be that much worse than the sets.
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
v2: Use LIST_ENTRY instead of container_of in iterators
Acked-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Rob Clark <robclark@freedesktop.org>
The linked list in gallium is pretty much the kernel list and we would like
to have a C-based linked list for all of mesa. Let's not duplicate and
just steal the gallium one.
Acked-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Rob Clark <robclark@freedesktop.org>
