Back when I was getting NIR up and running, I created a bunch of functions that dealt with modifying control flow; they allowed you to remove control flow nodes (if's, loops, and basic blocks) as well as insert newly-created control flow nodes at certain points. The insertion API's worked well enough for the usecase we had, which was building up NIR while translating from something else, and the removal API found some use in e.g. the select peephole. But there are various things we want to do, some of which are becoming more and more urgent, which involve doing more invasive modifications to the IR. To be able to do these things, this series adds an API which is a little lower-level than the existing one, but a lot less dangerous than manipulating things directly. It uses most of the same internal machinery as the existing functions, but I needed to rework it extensively to fix issues that were usually obscure edges in the old code that become more important in the new code. For more detail on the API itself and how to use it, see patch 20. In addition, there are a few peripheral things that I did which are related to the core objective of the series:
- The control flow code was entangled with the rest of the code in nir.c, and it was about to get larger, so I pulled it out into its own file (nir_control_flow.c) and gave it its own header (nir_control_flow.h). - The new API includes an extract function (for details see patch 20) which needs to take begin and end points. There were going to be many variants necessary for completeness, and even more for convenience, so I decided to do something about it by creating a "cursor" structure. A cursor is a small structure (8 bytes on a 32-bit system, 16 bytes on a 64-bit system) that represents some point where something can be inserted (before or after an instruction or before or after a block). There are helpers for constructing cursors in all the relevant places, and convenience helpers for creating cursors before/after a control flow node and before/after a control flow list. That way, the need for trivial nir_insert_thing_before/after_other_thing wrappers is gone, and it's easy to add new convenience helpers for cursors which will work with every API that uses a cursor. We probably want to use cursors to simplify instruction insertion/deletion and the builder, but I deferred that till later. The series was tested with an updated version of my dead control flow elimination series, which I'm going to post shortly. The structure of the series is as follows: patch 01: adds a lot more checking of block predecessors and successors in the validator, which is useful for checking the results of control flow modification. patch 02-03: prepares for splitting off the control flow code by getting rid of as many dependencies as possible. patch 04: moves the control flow code off to its own file. patch 05-15: fix many different problems with the current control flow code which will become more important when the new API is added. patch 16-19: introduce the cursor helper, and make the old control flow insertion API use it. patch 20: actually adds the new API. patch 21: removes the old, buggy implementation of nir_cf_node_remove() and makes it a small wrapper around the new API instead. The series can also be found at: git://people.freedesktop.org/~cwabbott0/mesa nir-control-flow-mod Connor Connor Abbott (21): nir/validate: check successors/predecessors more carefully nir: inline block_add_pred() a few places nir: make cleanup_cf_node() not use remove_defs_uses() nir: move control flow modification to its own file nir/cf: add insert_phi_undef() helper nir: add nir_foreach_phi_src_safe() nir/cf: add remove_phi_src() helper nir/cf: split up and improve nir_handle_remove_jumps() nir/cf: handle phi nodes better in split_block_beginning() nir/cf: add block_ends_in_jump() nir/cf: handle jumps in split_block_end() nir/cf: handle jumps better in stitch_blocks() nir/cf: remove uses of SSA definitions that are being deleted nir/cf: clean up jumps when cleaning up CF nodes nir/cf: fix link_blocks() when there are no successors nir/cf: add a cursor structure nir/cf: add split_block_before_instr() nir/cf: add split_block_cursor() nir/cf: use a cursor for inserting control flow nir/cf: add new control modification API's nir/cf: reimplement nir_cf_node_remove() using the new API src/gallium/auxiliary/nir/tgsi_to_nir.c | 1 + src/glsl/Makefile.sources | 3 + src/glsl/nir/glsl_to_nir.cpp | 1 + src/glsl/nir/nir.c | 680 +--------------------------- src/glsl/nir/nir.h | 17 +- src/glsl/nir/nir_control_flow.c | 773 ++++++++++++++++++++++++++++++++ src/glsl/nir/nir_control_flow.h | 252 +++++++++++ src/glsl/nir/nir_control_flow_private.h | 38 ++ src/glsl/nir/nir_opt_peephole_select.c | 1 + src/glsl/nir/nir_validate.c | 95 +++- 10 files changed, 1162 insertions(+), 699 deletions(-) create mode 100644 src/glsl/nir/nir_control_flow.c create mode 100644 src/glsl/nir/nir_control_flow.h create mode 100644 src/glsl/nir/nir_control_flow_private.h -- 2.4.3 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
