From: Ian Romanick <ian.d.roman...@intel.com>
BFM is (((1u << a) - 1) << b). Recognize a couple patterns that look
like this, and replace them with BFM.
NOTE: Using lower_bitfield_insert is definitely not the right way to
flag this optimization... so, I'm looking for some advice as to what the
right way is.
Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
---
src/compiler/nir/nir_opt_algebraic.py | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/src/compiler/nir/nir_opt_algebraic.py
b/src/compiler/nir/nir_opt_algebraic.py
index e3d83d4..06ebdbf 100644
--- a/src/compiler/nir/nir_opt_algebraic.py
+++ b/src/compiler/nir/nir_opt_algebraic.py
@@ -315,6 +315,11 @@ optimizations = [
('bfi', ('bfm', 'bits', 'offset'), 'insert', 'base')),
'options->lower_bitfield_insert'),
+ (('ishl@32', ('iadd', ('ishl', 1, a), -1), b), ('bfm', a, b),
+ 'options->lower_bitfield_insert'),
+ (('iadd@32', ('ishl', 1, a), -1), ('bfm', a, 0),
+ 'options->lower_bitfield_insert'),
+
(('ibitfield_extract', 'value', 'offset', 'bits'),
('bcsel', ('ilt', 31, 'bits'), 'value',
('ibfe', 'value', 'offset', 'bits')),
--
2.5.5
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