diff options
Diffstat (limited to 'src/compiler/nir/nir_opt_algebraic.py')
| -rw-r--r-- | src/compiler/nir/nir_opt_algebraic.py | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index aa55e203ffd..d7577c5a2ac 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -148,6 +148,7 @@ optimizations = [ # If a < 0: fsign(a)*a*a => -1*a*a => -a*a => abs(a)*a # If a > 0: fsign(a)*a*a => 1*a*a => a*a => abs(a)*a # If a == 0: fsign(a)*a*a => 0*0*0 => abs(0)*0 + # If a != a: fsign(a)*a*a => 0*NaN*NaN => abs(NaN)*NaN (('fmul', ('fsign', a), ('fmul', a, a)), ('fmul', ('fabs', a), a)), (('fmul', ('fmul', ('fsign', a), a), a), ('fmul', ('fabs', a), a)), (('~ffma', 0.0, a, b), b), @@ -583,6 +584,7 @@ optimizations.extend([ # SignedZeroInfNanPreserve is set, but we don't currently have any way of # representing this in the optimizations other than the usual ~. (('~fmax', ('fmin', a, 0.0), -1.0), ('fneg', ('fsat', ('fneg', a))), '!options->lower_fsat'), + # fsat(fsign(NaN)) = fsat(0) = 0, and b2f(0 < NaN) = b2f(False) = 0. (('fsat', ('fsign', a)), ('b2f', ('flt', 0.0, a))), (('fsat', ('b2f', a)), ('b2f', a)), (('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'), @@ -666,6 +668,11 @@ for s in [16, 32, 64]: # The (i2f32, ...) part is an open-coded fsign. When that is combined with # the bcsel, it's basically copysign(1.0, a). There is no copysign in NIR, # so emit an open-coded version of that. + # + # If 'a' is NaN, bcsel(False, 1.0, i2f(b2i(False) - b2i(False))) = 0, but + # the replacement will produce ±1. + # + # The replacement will also produce a different value for -0: -1 vs +1. (('bcsel@{}'.format(s), ('feq', a, 0.0), 1.0, ('i2f{}'.format(s), ('iadd', ('b2i{}'.format(s), ('flt', 0.0, 'a@{}'.format(s))), ('ineg', ('b2i{}'.format(s), ('flt', 'a@{}'.format(s), 0.0)))))), ('ior', fp_one, ('iand', a, 1 << (s - 1)))), @@ -1564,6 +1571,7 @@ optimizations.extend([ (('isign', a), ('imin', ('imax', a, -1), 1), 'options->lower_isign'), (('imin', ('imax', a, -1), 1), ('isign', a), '!options->lower_isign'), (('imax', ('imin', a, 1), -1), ('isign', a), '!options->lower_isign'), + # float(0 < NaN) - float(NaN < 0) = float(False) - float(False) = 0 - 0 = 0 (('fsign', a), ('fsub', ('b2f', ('flt', 0.0, a)), ('b2f', ('flt', a, 0.0))), 'options->lower_fsign'), # Address/offset calculations: |