diff options
| -rw-r--r-- | src/compiler/nir/nir_opt_algebraic.py | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index bf5c69314c5..40f718e5ae2 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -224,7 +224,31 @@ optimizations = [ # (a * #b) << #c # a * (#b << #c) (('ishl', ('imul', a, '#b'), '#c'), ('imul', a, ('ishl', b, c))), +] + +# Care must be taken here. Shifts in NIR uses only the lower log2(bitsize) +# bits of the second source. These replacements must correctly handle the +# case where (b % bitsize) + (c % bitsize) >= bitsize. +for s in [8, 16, 32, 64]: + mask = (1 << s) - 1 + + ishl = "ishl@{}".format(s) + ishr = "ishr@{}".format(s) + ushr = "ushr@{}".format(s) + + in_bounds = ('ult', ('iadd', ('iand', b, mask), ('iand', c, mask)), s) + + optimizations.extend([ + ((ishl, (ishl, a, '#b'), '#c'), ('bcsel', in_bounds, (ishl, a, ('iadd', b, c)), 0)), + ((ushr, (ushr, a, '#b'), '#c'), ('bcsel', in_bounds, (ushr, a, ('iadd', b, c)), 0)), + # To get get -1 for large shifts of negative values, ishr must instead + # clamp the shift count to the maximum value. + ((ishr, (ishr, a, '#b'), '#c'), + (ishr, a, ('imin', ('iadd', ('iand', b, mask), ('iand', c, mask)), s - 1))), + ]) + +optimizations.extend([ # This is common for address calculations. Reassociating may enable the # 'a<<c' to be CSE'd. It also helps architectures that have an ISHLADD # instruction or a constant offset field for in load / store instructions. @@ -859,7 +883,7 @@ optimizations = [ (('ishr', 'a@32', 24), ('extract_i8', a, 3), '!options->lower_extract_byte'), (('ishr', 'a@64', 56), ('extract_i8', a, 7), '!options->lower_extract_byte'), (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte') -] +]) # After the ('extract_u8', a, 0) pattern, above, triggers, there will be # patterns like those below. |