In 144cbf8 ("nir: Make nir_opt_remove_phis see through moves."), Ken
made nir_opt_remove_phis able to coalesce phi nodes whose sources are
all moves with the same swizzle. However, he didn't add the logic
necessary for handling the fact that the phi may now have multiple
different sources, even though the sources point to the same thing. For
example, if we had something like:
if (...)
a1 = b.yx;
else
a2 = b.yx;
a = phi(a1, a2)
... = a
then we would rewrite it to
if (...)
a1 = b.yx;
else
a2 = b.yx;
... = a1
by picking a random phi source, which in this case is invalid because
the source doesn't dominate the phi. Instead, we need to change it to:
if (...)
a1 = b.yx;
else
a2 = b.yx;
a3 = b.yx;
... = a3;
Fixes 12 CTS tests:
ES31-CTS.functional.tessellation.invariance.outer_edge_symmetry.quads*
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
I found a shader in Tales of Maj'Eyal that contains:
if ssa_21 {
block block_1:
/* preds: block_0 */
...instructions that prevent the select peephole...
vec1 32 ssa_23 = imov ssa_4
vec1 32 ssa_24 = imov ssa_4.y
vec1 32 ssa_25 = imov ssa_4.z
/* succs: block_3 */
} else {
block block_2:
/* preds: block_0 */
vec1 32 ssa_26 = imov ssa_4
vec1 32 ssa_27 = imov ssa_4.y
vec1 32 ssa_28 = imov ssa_4.z
/* succs: block_3 */
}
block block_3:
/* preds: block_1 block_2 */
vec1 32 ssa_29 = phi block_1: ssa_23, block_2: ssa_26
vec1 32 ssa_30 = phi block_1: ssa_24, block_2: ssa_27
vec1 32 ssa_31 = phi block_1: ssa_25, block_2: ssa_28
Here, copy propagation will bail because phis cannot perform swizzles,
and CSE won't do anything because there is no dominance relationship
between the imovs. By making nir_opt_remove_phis handle identical moves,
we can eliminate the phis and rewrite everything to use ssa_4 directly,
so all the moves become dead and get eliminated.
I don't think we need to check "exact" - just the alu sources.
Presumably phi sources should match in their exactness.
On Broadwell:
total instructions in shared programs: 11639872 -> 11638535 (-0.01%)
instructions in affected programs: 134222 -> 132885 (-1.00%)
helped: 338
HURT: 0
v2: Fix return value to be NULL, not false (caught by Iago).
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Iago Toral Quiroga <itoral@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_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>
