nir: Add algebraic opt for int comparisons with identical operands.

No change on shader-db on i965.

v2: Reword the comment due to feedback from Erik Faye-Lund

Reviewed-by: Connor Abbott <cwabbott0@gmail.com> (v1)
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com> (v1)

diff --git a/src/glsl/nir/nir_opt_algebraic.py b/src/glsl/nir/nir_opt_algebraic.py
index a5fe19a..2b4259e 100644 (file)
--- a/src/glsl/nir/nir_opt_algebraic.py
+++ b/src/glsl/nir/nir_opt_algebraic.py
@@ -83,6 +83,15 @@ optimizations = [
    (('fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
    (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
    (('fmin', ('fmax', a, 0.0), 1.0), ('fsat', a)),
+   # Comparison with the same args.  Note that these are not done for
+   # the float versions because NaN always returns false on float
+   # inequalities.
+   (('ilt', a, a), False),
+   (('ige', a, a), True),
+   (('ieq', a, a), True),
+   (('ine', a, a), False),
+   (('ult', a, a), False),
+   (('uge', a, a), True),
    # Logical and bit operations
    (('fand', a, 0.0), 0.0),
    (('iand', a, a), a),