nir/algebraic: Flag inexact optimizations

Many of our optimizations, while great for cutting shaders down to size,
aren't really precision-safe.  This commit tries to flag all of the
inexact floating-point optimizations so they don't get run on values that
are flagged "exact".  It's a bit conservative and maybe flags some safe
optimizations as unsafe but that's better than missing one.

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
This commit is contained in:
Jason Ekstrand 2016-03-17 11:31:48 -07:00
parent ed3a029e80
commit 0dbda153aa

View file

@ -61,19 +61,19 @@ optimizations = [
(('fabs', ('fneg', a)), ('fabs', a)),
(('iabs', ('iabs', a)), ('iabs', a)),
(('iabs', ('ineg', a)), ('iabs', a)),
(('fadd', a, 0.0), a),
(('~fadd', a, 0.0), a),
(('iadd', a, 0), a),
(('usadd_4x8', a, 0), a),
(('usadd_4x8', a, ~0), ~0),
(('fadd', ('fmul', a, b), ('fmul', a, c)), ('fmul', a, ('fadd', b, c))),
(('~fadd', ('fmul', a, b), ('fmul', a, c)), ('fmul', a, ('fadd', b, c))),
(('iadd', ('imul', a, b), ('imul', a, c)), ('imul', a, ('iadd', b, c))),
(('fadd', ('fneg', a), a), 0.0),
(('~fadd', ('fneg', a), a), 0.0),
(('iadd', ('ineg', a), a), 0),
(('iadd', ('ineg', a), ('iadd', a, b)), b),
(('iadd', a, ('iadd', ('ineg', a), b)), b),
(('fadd', ('fneg', a), ('fadd', a, b)), b),
(('fadd', a, ('fadd', ('fneg', a), b)), b),
(('fmul', a, 0.0), 0.0),
(('~fadd', ('fneg', a), ('fadd', a, b)), b),
(('~fadd', a, ('fadd', ('fneg', a), b)), b),
(('~fmul', a, 0.0), 0.0),
(('imul', a, 0), 0),
(('umul_unorm_4x8', a, 0), 0),
(('umul_unorm_4x8', a, ~0), a),
@ -81,29 +81,29 @@ optimizations = [
(('imul', a, 1), a),
(('fmul', a, -1.0), ('fneg', a)),
(('imul', a, -1), ('ineg', a)),
(('ffma', 0.0, a, b), b),
(('ffma', a, 0.0, b), b),
(('ffma', a, b, 0.0), ('fmul', a, b)),
(('~ffma', 0.0, a, b), b),
(('~ffma', a, 0.0, b), b),
(('~ffma', a, b, 0.0), ('fmul', a, b)),
(('ffma', a, 1.0, b), ('fadd', a, b)),
(('ffma', 1.0, a, b), ('fadd', a, b)),
(('flrp', a, b, 0.0), a),
(('flrp', a, b, 1.0), b),
(('flrp', a, a, b), a),
(('flrp', 0.0, a, b), ('fmul', a, b)),
(('flrp', a, b, ('b2f', c)), ('bcsel', c, b, a), 'options->lower_flrp'),
(('~flrp', a, b, 0.0), a),
(('~flrp', a, b, 1.0), b),
(('~flrp', a, a, b), a),
(('~flrp', 0.0, a, b), ('fmul', a, b)),
(('~flrp', a, b, ('b2f', c)), ('bcsel', c, b, a), 'options->lower_flrp'),
(('flrp', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp'),
(('ffract', a), ('fsub', a, ('ffloor', a)), 'options->lower_ffract'),
(('fadd', ('fmul', a, ('fadd', 1.0, ('fneg', ('b2f', c)))), ('fmul', b, ('b2f', c))), ('bcsel', c, b, a), 'options->lower_flrp'),
(('fadd', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp'),
(('fadd', a, ('fmul', ('b2f', c), ('fadd', b, ('fneg', a)))), ('bcsel', c, b, a), 'options->lower_flrp'),
(('fadd', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp'),
(('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', ('b2f', c)))), ('fmul', b, ('b2f', c))), ('bcsel', c, b, a), 'options->lower_flrp'),
(('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp'),
(('~fadd', a, ('fmul', ('b2f', c), ('fadd', b, ('fneg', a)))), ('bcsel', c, b, a), 'options->lower_flrp'),
(('~fadd', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp'),
(('ffma', a, b, c), ('fadd', ('fmul', a, b), c), 'options->lower_ffma'),
(('fadd', ('fmul', a, b), c), ('ffma', a, b, c), '!options->lower_ffma'),
(('~fadd', ('fmul', a, b), c), ('ffma', a, b, c), '!options->lower_ffma'),
# Comparison simplifications
(('inot', ('flt', a, b)), ('fge', a, b)),
(('inot', ('fge', a, b)), ('flt', a, b)),
(('inot', ('feq', a, b)), ('fne', a, b)),
(('inot', ('fne', a, b)), ('feq', a, b)),
(('~inot', ('flt', a, b)), ('fge', a, b)),
(('~inot', ('fge', a, b)), ('flt', a, b)),
(('~inot', ('feq', a, b)), ('fne', a, b)),
(('~inot', ('fne', a, b)), ('feq', a, b)),
(('inot', ('ilt', a, b)), ('ige', a, b)),
(('inot', ('ige', a, b)), ('ilt', a, b)),
(('inot', ('ieq', a, b)), ('ine', a, b)),
@ -132,15 +132,15 @@ optimizations = [
(('imax', a, a), a),
(('umin', a, a), a),
(('umax', a, a), a),
(('fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
(('fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
(('~fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
(('~fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
(('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'),
(('fsat', ('fsat', a)), ('fsat', a)),
(('fmin', ('fmax', ('fmin', ('fmax', a, 0.0), 1.0), 0.0), 1.0), ('fmin', ('fmax', a, 0.0), 1.0)),
(('ior', ('flt', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
(('ior', ('flt', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
(('ior', ('fge', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
(('ior', ('fge', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
(('~ior', ('flt', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
(('~ior', ('flt', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
(('~ior', ('fge', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
(('~ior', ('fge', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
(('fabs', ('slt', a, b)), ('slt', a, b)),
(('fabs', ('sge', a, b)), ('sge', a, b)),
(('fabs', ('seq', a, b)), ('seq', a, b)),
@ -191,35 +191,35 @@ optimizations = [
(('iand', 0xff, ('ushr', a, 24)), ('ushr', a, 24)),
(('iand', 0xffff, ('ushr', a, 16)), ('ushr', a, 16)),
# Exponential/logarithmic identities
(('fexp2', ('flog2', a)), a), # 2^lg2(a) = a
(('flog2', ('fexp2', a)), a), # lg2(2^a) = a
(('~fexp2', ('flog2', a)), a), # 2^lg2(a) = a
(('~flog2', ('fexp2', a)), a), # lg2(2^a) = a
(('fpow', a, b), ('fexp2', ('fmul', ('flog2', a), b)), 'options->lower_fpow'), # a^b = 2^(lg2(a)*b)
(('fexp2', ('fmul', ('flog2', a), b)), ('fpow', a, b), '!options->lower_fpow'), # 2^(lg2(a)*b) = a^b
(('fexp2', ('fadd', ('fmul', ('flog2', a), b), ('fmul', ('flog2', c), d))),
('fmul', ('fpow', a, b), ('fpow', c, d)), '!options->lower_fpow'), # 2^(lg2(a) * b + lg2(c) + d) = a^b * c^d
(('fpow', a, 1.0), a),
(('fpow', a, 2.0), ('fmul', a, a)),
(('fpow', a, 4.0), ('fmul', ('fmul', a, a), ('fmul', a, a))),
(('fpow', 2.0, a), ('fexp2', a)),
(('fpow', ('fpow', a, 2.2), 0.454545), a),
(('fpow', ('fabs', ('fpow', a, 2.2)), 0.454545), ('fabs', a)),
(('fsqrt', ('fexp2', a)), ('fexp2', ('fmul', 0.5, a))),
(('frcp', ('fexp2', a)), ('fexp2', ('fneg', a))),
(('frsq', ('fexp2', a)), ('fexp2', ('fmul', -0.5, a))),
(('flog2', ('fsqrt', a)), ('fmul', 0.5, ('flog2', a))),
(('flog2', ('frcp', a)), ('fneg', ('flog2', a))),
(('flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
(('flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
(('fadd', ('flog2', a), ('flog2', b)), ('flog2', ('fmul', a, b))),
(('fadd', ('flog2', a), ('fneg', ('flog2', b))), ('flog2', ('fdiv', a, b))),
(('fmul', ('fexp2', a), ('fexp2', b)), ('fexp2', ('fadd', a, b))),
(('~fexp2', ('fmul', ('flog2', a), b)), ('fpow', a, b), '!options->lower_fpow'), # 2^(lg2(a)*b) = a^b
(('~fexp2', ('fadd', ('fmul', ('flog2', a), b), ('fmul', ('flog2', c), d))),
('~fmul', ('fpow', a, b), ('fpow', c, d)), '!options->lower_fpow'), # 2^(lg2(a) * b + lg2(c) + d) = a^b * c^d
(('~fpow', a, 1.0), a),
(('~fpow', a, 2.0), ('fmul', a, a)),
(('~fpow', a, 4.0), ('fmul', ('fmul', a, a), ('fmul', a, a))),
(('~fpow', 2.0, a), ('fexp2', a)),
(('~fpow', ('fpow', a, 2.2), 0.454545), a),
(('~fpow', ('fabs', ('fpow', a, 2.2)), 0.454545), ('fabs', a)),
(('~fsqrt', ('fexp2', a)), ('fexp2', ('fmul', 0.5, a))),
(('~frcp', ('fexp2', a)), ('fexp2', ('fneg', a))),
(('~frsq', ('fexp2', a)), ('fexp2', ('fmul', -0.5, a))),
(('~flog2', ('fsqrt', a)), ('fmul', 0.5, ('flog2', a))),
(('~flog2', ('frcp', a)), ('fneg', ('flog2', a))),
(('~flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
(('~flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
(('~fadd', ('flog2', a), ('flog2', b)), ('flog2', ('fmul', a, b))),
(('~fadd', ('flog2', a), ('fneg', ('flog2', b))), ('flog2', ('fdiv', a, b))),
(('~fmul', ('fexp2', a), ('fexp2', b)), ('fexp2', ('fadd', a, b))),
# Division and reciprocal
(('fdiv', 1.0, a), ('frcp', a)),
(('~fdiv', 1.0, a), ('frcp', a)),
(('fdiv', a, b), ('fmul', a, ('frcp', b)), 'options->lower_fdiv'),
(('frcp', ('frcp', a)), a),
(('frcp', ('fsqrt', a)), ('frsq', a)),
(('~frcp', ('frcp', a)), a),
(('~frcp', ('fsqrt', a)), ('frsq', a)),
(('fsqrt', a), ('frcp', ('frsq', a)), 'options->lower_fsqrt'),
(('frcp', ('frsq', a)), ('fsqrt', a), '!options->lower_fsqrt'),
(('~frcp', ('frsq', a)), ('fsqrt', a), '!options->lower_fsqrt'),
# Boolean simplifications
(('ieq', 'a@bool', True), a),
(('ine', 'a@bool', True), ('inot', a)),
@ -256,7 +256,7 @@ optimizations = [
(('iand', 0xffff, a), ('extract_u16', a, 0), '!options->lower_extract_word'),
# Subtracts
(('fsub', a, ('fsub', 0.0, b)), ('fadd', a, b)),
(('~fsub', a, ('fsub', 0.0, b)), ('fadd', a, b)),
(('isub', a, ('isub', 0, b)), ('iadd', a, b)),
(('ussub_4x8', a, 0), a),
(('ussub_4x8', a, ~0), 0),
@ -264,7 +264,7 @@ optimizations = [
(('isub', a, b), ('iadd', a, ('ineg', b)), 'options->lower_sub'),
(('fneg', a), ('fsub', 0.0, a), 'options->lower_negate'),
(('ineg', a), ('isub', 0, a), 'options->lower_negate'),
(('fadd', a, ('fsub', 0.0, b)), ('fsub', a, b)),
(('~fadd', a, ('fsub', 0.0, b)), ('fsub', a, b)),
(('iadd', a, ('isub', 0, b)), ('isub', a, b)),
(('fabs', ('fsub', 0.0, a)), ('fabs', a)),
(('iabs', ('isub', 0, a)), ('iabs', a)),
@ -393,10 +393,13 @@ for op in ['flt', 'fge', 'feq', 'fne',
# they help code generation but do not necessarily produce code that is
# more easily optimizable.
late_optimizations = [
# Most of these optimizations aren't quite safe when you get infinity or
# Nan involved but the first one should be fine.
(('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
(('fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
(('feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
(('fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
(('~fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
(('~feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
(('~fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
(('fdot2', a, b), ('fdot_replicated2', a, b), 'options->fdot_replicates'),
(('fdot3', a, b), ('fdot_replicated3', a, b), 'options->fdot_replicates'),
(('fdot4', a, b), ('fdot_replicated4', a, b), 'options->fdot_replicates'),