[Mesa-dev] [PATCH 0/9] Global dead write vars removal pass

[Caio Marcelo de Oliveira Filho]

Our code currently only remove dead writes to vars for each block, but
doesn't tackle cases that involve multiple blocks.  This series will
add a pass that use an iterative data-flow analysis to cover those
cases.  Commit message for patch 6 has a detailed example.

I'm working on a subsequent series for adding global capabilities to
copy propagation.  While those optimizations can be done locally
together (as we currently do), the way we iterate the blocks for
data-flow analysis is different (dead write uses backward, copy
propagation uses forward), so it helps keeping them separate.

The motivation for this series (and the upcoming copy propagation)
work is to improve our generated code when we move other memory
accesses (e.g. SSBOs) to use derefs.

Patches 1-4 are small and are worth regardless the series -- I have
other series locally that use some of those.  So I intend to land them
earlier as they get reviewed.

Caio Marcelo de Oliveira Filho (9):
  util/dynarray: add a clone function
  nir: Export deref comparison functions
  nir: Skip common instructions when comparing deref paths
  nir: Give end_block its own index
  nir: Add a local dead write vars removal pass
  nir: Make dead_write_vars pass global
  intel/nir: Use the new dead write vars pass
  freedreno/ir3: Use the new dead write vars pass
  nir: Remove handling of dead writes from copy_prop_vars

 src/compiler/Makefile.sources               |   1 +
 src/compiler/nir/meson.build                |   1 +
 src/compiler/nir/nir.c                      |   2 +-
 src/compiler/nir/nir.h                      |   2 +
 src/compiler/nir/nir_deref.c                | 112 +++
 src/compiler/nir/nir_deref.h                |  10 +
 src/compiler/nir/nir_opt_copy_prop_vars.c   | 208 +-----
 src/compiler/nir/nir_opt_dead_write_vars.c  | 761 ++++++++++++++++++++
 src/gallium/drivers/freedreno/ir3/ir3_nir.c |   1 +
 src/intel/compiler/brw_nir.c                |   1 +
 src/util/u_dynarray.h                       |   9 +
 11 files changed, 913 insertions(+), 195 deletions(-)
 create mode 100644 src/compiler/nir/nir_opt_dead_write_vars.c

-- 
2.18.0