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| author | Ian Romanick <ian.d.romanick@intel.com> | 2019-08-26 13:28:09 -0700 |
|---|---|---|
| committer | Dylan Baker <dylan@pnwbakers.com> | 2019-09-04 11:56:08 -0700 |
| commit | 91fa24a6869b14a6e1c3a1c6af9fc567ac284051 (patch) | |
| tree | 8a8d093f5b09f23c25e92db343904926e30124d2 | |
| parent | c96de002b77e64c85f7e98daba2566a593ee8f92 (diff) | |
| download | mesa-91fa24a6869b14a6e1c3a1c6af9fc567ac284051.tar.gz | |
nir/algrbraic: Don't optimize open-coded bitfield reverse when lowering is enabled
This caused a problem on Sandybridge where an open-coded
bitfieldReverse() function could be optimized to a
nir_op_bitfield_reverse that would generate an unsupported BFREV
instruction in the backend. This was encountered in some Unreal4 tech
demos in shader-db. The bug was not previously noticed because we don't
actually try to run those demos on Sandybridge.
The fixes tag is a bit a lie. The actual bug was introduced about
26,000 commits earlier in 371c4b3c48f ("nir: Recognize open-coded
bitfield_reverse."). Without the NIR lowering pass, the flag needed to
avoid the optimization does not exist. Hopefully nobody will care to
fix this on an earlier Mesa release.
Reviewed-by: Matt Turner <mattst88@gmail.com>
Fixes: 7afa26d4e39 ("nir: Add lowering for nir_op_bitfield_reverse.")
(cherry picked from commit d3fd1c761aab01e06665180ab86c9528c0b285b2)
| -rw-r--r-- | src/compiler/nir/nir_opt_algebraic.py | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index 26e2fc346ed..35255204133 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -1316,7 +1316,7 @@ def bitfield_reverse(u): return step5 -optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'))] +optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'), '!options->lower_bitfield_reverse')] # For any float comparison operation, "cmp", if you have "a == a && a cmp b" # then the "a == a" is redundant because it's equivalent to "a is not NaN" |