The use of vector.end()[-1] seems to generate warnings in Coverity about
not allowing a negative argument to a parameter. The intention with the
code snippet is just to access the last element of the vector. The
vector.back() call acheives the same thing, is clearer and will
hopefully fix the Coverity warning.
I’m not exactly sure why Coverity thinks the array index can’t be
negative. cplusplus.com says that vector::end() returns a random access
iterator and that the type of the array index operator argument to that
should be the difference type for the container. It then also says that
difference_type for a vector is "a signed integral type".
Reviewed-by: Eric Anholt <eric@anholt.net>
When an ir_call is encountered that invokes a builtin, it will now try
to generate a lowered version of the builtin. This only happens if all
of the arguments to the function are lowerable. Previously the builtin
would be inlined before the lowering pass is invoked and then the
implementation would be lowered as a consequence of the pass. However
this causes problems if the builtin has multiple arguments and the
implementation has operations on only a few of the arguments before
combining it with the others. In that case the entire builtin should
only be lowered if all of the arguments are lower precision. The
previous approach would end up lowering only parts of the
implementation.
The lowered implementations are cached in a hash table in case they can
be reused.
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3885>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3885>
This works by finding the first rvalue that it can lower using an
ir_rvalue_visitor. In that case it adds a conversion to float16
after each rvalue and a conversion back to float before storing
the assignment.
Also it uses a set to keep track of rvalues that have been
lowred already. The handle_rvalue method of the rvalue visitor doesn’t
provide any way to stop iteration. If we handle a value in
find_precision_visitor we want to be able to stop it from descending into
the lowered rvalue again.
Additionally this pass disallows converting nodes containing non-float.
The can_lower_rvalue function explicitly excludes any branches
that have non-float types except bools. This avoids the need to have
special handling for functions that convert to int or double.
Co-authored-by: Hyunjun Ko <zzoon@igalia.com>
v2. Adds lowering for texture samples
v3. Instead of checking whether each node can be lowered while walking the
tree, a separate tree walk is now done to check all of the nodes in a
single pass. The lowerable nodes are added to a set which is checked
during find_precision_visitor instead of calling can_lower_rvalue.
v4. Move the special case for temporaries to find_lowerable_rvalues. This
needs to be handled while checking for lowerable rvalues so that any
later dereferences of the variable will see the right precision.
v5. Add an override to visit ir_call instructions and apply the same
technique to override the precision of the temporary variable in the
same way as done for builtin temporaries and ir_assignment calls.
v6. Changes the pass so that it doesn’t need to lower an entire subtree in
order do perform a lowering. Instead, certain instructions can be
marked as being indepedent of their child instructions. For example,
this is the case with array dereferences. The precision of the array
index doesn’t have any bearing on whether things using the result of
the array deref can be lowered.
Now, only toplevel lowerable nodes are added to the lowerable_rvalues
instead instead of additionally adding all of the subnodes.
It now also only needs one hash table instead of two.
v7. Don’t try to lower sampler types. Instead, the sample instruction is
now treated as an independent point where the result of the sample can
be used in a lowered section. The precision of the sampler type
determines the precision of the sample instruction. This also means
the coordinates to the sampler can be lowered.
v8. Use f2fmp instead of f2f16.
v9. Disable lowering derivatives calcualtions, which might not work
properly on some hw backends.
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3885>
