[Mesa-dev] [PATCH 0/6] nir: Add an integer divide by constant optimization

[Jason Ekstrand]

It's reasonably well-known that you can replace an unsigned integer
division by a constant with a sequence of multiply (by constant), adds, and
shifts.  This little series implements such an optimization for NIR.  As
can be seen from the last patch, there really aren't that many shaders
affected by this and most of them are because we are finally optimizing
signed integer division by powers of two.  However, it seems like a good
thing to have in our pockets none-the-less, especially for 64-bit where
divisions turn into manually implementing the division algorithm.

Jason Ekstrand (6):
  util: Add a simple big math library
  util: Add a uint inverse helper
  nir: Allow [iu]mul_high on non-32-bit types
  nir/lower_int64: Add support for [iu]mul_high
  nir: Add a pass for lowering integer division by constants
  i965: Enable nir_opt_idiv_const for all bit sizes

 configure.ac                                  |   1 +
 src/compiler/Makefile.sources                 |   1 +
 src/compiler/nir/meson.build                  |   1 +
 src/compiler/nir/nir.h                        |   3 +
 src/compiler/nir/nir_constant_expressions.py  |   1 +
 src/compiler/nir/nir_lower_int64.c            |  54 +++++
 src/compiler/nir/nir_opcodes.py               |  43 +++-
 src/compiler/nir/nir_opt_idiv_const.c         | 192 ++++++++++++++++
 src/intel/compiler/brw_nir.c                  |   4 +-
 src/util/Makefile.am                          |   3 +-
 src/util/Makefile.sources                     |   1 +
 src/util/bigmath.h                            |  95 ++++++++
 src/util/meson.build                          |   2 +
 src/util/tests/uint_inverse/Makefile.am       |  43 ++++
 src/util/tests/uint_inverse/meson.build       |  30 +++
 .../tests/uint_inverse/uint_inverse_test.cpp  |  83 +++++++
 src/util/uint_inverse.h                       | 206 ++++++++++++++++++
 17 files changed, 757 insertions(+), 6 deletions(-)
 create mode 100644 src/compiler/nir/nir_opt_idiv_const.c
 create mode 100644 src/util/bigmath.h
 create mode 100644 src/util/tests/uint_inverse/Makefile.am
 create mode 100644 src/util/tests/uint_inverse/meson.build
 create mode 100644 src/util/tests/uint_inverse/uint_inverse_test.cpp
 create mode 100644 src/util/uint_inverse.h

-- 
2.17.1