If a loop is followed by a barrier, the ordering between a load inside
the loop and other memory operations after the barrier may have to be
preserved depending on the type of memory involved. This is relevant
when the memory is writeable by other invocations. In such case, it
is not valid to completely eliminate the loop.
This commit doesn't attempt to precisely catch the barrier case, as
analysis could become too complex. It simply assumes it can't drop
the loops that contain certain types of loads unless those are known
to be safe to reorder (via the access flag).
Fixes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4475
Acked-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9938>
This commit replaces the new_src parameter of nir_ssa_def_rewrite_uses()
with an SSA def, removes nir_ssa_def_rewrite_uses_ssa(), and rewrites
all the users as needed.
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Acked-by: Alyssa Rosenzweig <alyssa@collabora.com>
Acked-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9383>
Halt is like a return for the entire shader or exit() if you prefer to
think of it that way. Once an invocation hits a halt, it's 100% dead.
Any writes to output variables which happened before the halt do,
however, still apply.
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7356>
And after discard-only loops. Otherwise we end up with dead code
which confuses nir_repair_ssa into adding a whole bunch of uses
of undefined. However, for derefs, we sometimes always expect to
get a variable instead of undefined.
Fixes dEQP-VK.graphicsfuzz.write-red-in-loop-nest on radv.
Fixes: c832820ce9 "nir/dead_cf: Repair SSA if the pass makes progress"
Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/1928
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
The dead_cf pass calls into the CF manipulation helpers which attempt to
keep NIR's SSA form sane. However, when the only break is removed from
a loop, dominance gets messed up anyway because the CF SSA clean-up code
only looks at phis and doesn't consider the case of code becoming
unreachable. One solution to this would be to put the loop into LCSSA
form before we modify any of its contents. Another (and the approach
taken by this pass) is to just run the repair_ssa pass afterwards
because the CF manipulation helpers are smart enough to keep all the
use/def stuff sane; they just don't always preserve dominance
properties.
While we're here, we clean up some bogus indentation.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111405
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111069
Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
When we inlined cf_node_has_side_effects into node_is_dead, all the
conditions flipped and we forgot to flip one. Fortunately, it doesn't
matter right now because no one uses this pass on shaders with more than
one function.
Fixes: b50465d197 "nir/dead_cf: Inline cf_node_has_side_effects"
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Commit 08bfd710a2. (nir/dead_cf: Stop
relying on liveness analysis) introduced a new check that iterated
through a SSA def's uses, to see if it's used. But it only checked
normal uses, and not uses which are part of an 'if' condition. This
led to it thinking more nodes were dead than possible.
Fixes Piglit's variable-indexing/tcs-output-array-float-index-wr test
(and related tests) with the out-of-tree Iris driver.
Fixes: 08bfd710a2 nir/dead_cf: Stop relying on liveness analysis
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This was probably useful when it was first written, however it
looks to be no longer necessary.
As far as I can tell these days dce is smart enough to remove useless
instructions from if branches. Once this is done
nir_opt_peephole_select() will end up removing the empty if.
Removing this support reduces the dolphin uber shader compilation
time spent in nir_opt_dead_cf() by a little over 7x.
No shader-db changes on i965 or radeonsi.
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
The liveness analysis pass is fairly expensive because it has to build
large bit-sets and run a fix-point algorithm on them. Instead of
requiring liveness for detecting if values escape a CF node, just take
advantage of the structured nature of NIR and use block indices instead.
This only requires the block index metadata which is the fastest we have
metadata to generate.
No shader-db changes on Kaby Lake
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
We want to handle live SSA values differently and it's going to involve
walking the instructions. We can make it a single instruction walk if
we combine it with cf_node_has_side_effects.
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
NIR metadata validation verifies that the debug bit was unset (by a call
to nir_metadata_preserve) if a NIR optimization pass made progress on
the shader. With the expectation that the NIR shader consists of only a
single main function, it has been safe to call nir_metadata_preserve()
iff progress was made.
However, most optimization passes calculate progress per-function and
then return the union of those calculations. In the case that an
optimization pass makes progress only on a subset of the functions in
the shader metadata validation will detect the debug bit is still set on
any unchanged functions resulting in a failed assertion.
This patch offers a quick solution (short of a larger scale refactoring
which I do not wish to undertake as part of this series) that simply
unsets the debug bit on unchanged functions.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Generalize the code for remove dead loops to also remove dead if
nodes. The conditions are the same in both cases, if the node (and
it's children) don't have side-effects AND the nodes after it don't
use the values produced by the node.
The only difference is when evaluating side effects: loops consider
only return jumps as a side-effect -- they can stop execution of nodes
after it; 'if' nodes outside loops should consider all kinds of
jumps (return, break, continue) since all of them can cause execution
of nodes after it to be skipped.
After this patch, empty ifs (those which both then and else blocks are
empty) will be removed by nir_opt_dead_cf.
It caused no change to shader-db, in part because the removal of empty
ifs is currently covered by nir_opt_peephole_select.
v2: Improve the identification of cases where break/continue can cause
side-effects. (Jason)
v3: Move code comment changes to a different patch. (Jason)
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
One of NIR's invariants is that control flow lists always start and end
with blocks. There's no good reason why we should return a cf_node from
these functions since we know that it's always a block. Making it a block
lets us remove a bunch of code.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>
Clean up misrepetitions ('if if', 'the the' etc) found throughout the
comments. This has been done manually, after grepping
case-insensitively for duplicate if, is, the, then, do, for, an,
plus a few other typos corrected in fly-by
v2:
* proper commit message and non-joke title;
* replace two 'as is' followed by 'is' to 'as-is'.
v3:
* 'a integer' => 'an integer' and similar (originally spotted by
Jason Ekstrand, I fixed a few other similar ones while at it)
Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Reviewed-by: Chad Versace <chad.versace@intel.com>
Parenthesis are needed here as ! takes precedence over the &. The
check had the opposite effect than intended.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This matches the "foreach x in container" pattern found in many other
programming languages. Generated by the following regular expression:
s/nir_foreach_function(\([^,]*\),\s*\([^,]*\))/nir_foreach_function(\2, \1)/
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This matches the "foreach x in container" pattern found in many other
programming languages. Generated by the following regular expression:
s/nir_foreach_phi_src(\([^,]*\),\s*\([^,]*\))/nir_foreach_phi_src(\2, \1)/
and a similar expression for nir_foreach_phi_src_safe.
Reviewed-by: Eduardo Lima Mitev <elima@igalia.com>
This matches the "foreach x in container" pattern found in many other
programming languages. Generated by the following regular expression:
s/nir_foreach_instr(\([^,]*\),\s*\([^,]*\))/nir_foreach_instr(\2, \1)/
and similar expressions for nir_foreach_instr_safe etc.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
