Ever since 4246c2869c and 7d85dc4f35 loop unrolling can no
longer depend on inot being eliminated from the loop
terminator condition so we need to be able to handle it.
Here we simply check to see if the inot contains a simple
terminator condition we previously handled. We also update
the previous users of this function to use a newly name
copy of the previous behaviour
nir_is_terminator_condition_with_two_inputs().
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18006>
This pass detects induction variables and calculates the
trip count of loops to be used for loop unrolling.
V2: Rebase, adapt to removal of function overloads
V3: (Timothy Arceri)
- don't try to find trip count if loop terminator conditional is a phi
- fix trip count for do-while loops
- replace conditional type != alu assert with return
- disable unrolling of loops with continues
- multiple fixes to memory allocation, stop leaking and don't destroy
structs we want to use for unrolling.
- fix iteration count bugs when induction var not on RHS of condition
- add FIXME for && conditions
- calculate trip count for unsigned induction/limit vars
V4: (Timothy Arceri)
- count instructions in a loop
- set the limiting_terminator even if we can't find the trip count for
all terminators. This is needed for complex unrolling where we handle
2 terminators and the trip count is unknown for one of them.
- restruct structs so we don't keep information not required after
analysis and remove dead fields.
- force unrolling in some cases as per the rules in the GLSL IR pass
V5: (Timothy Arceri)
- fix metadata mask value 0x10 vs 0x16
V6: (Timothy Arceri)
- merge loop_variable and nir_loop_variable structs and lists suggested by Jason
- remove induction var hash table and store pointer to induction information in
the loop_variable suggested by Jason.
- use lowercase list_addtail() suggested by Jason.
- tidy up init_loop_block() as per Jasons suggestions.
- replace switch with nir_op_infos[alu->op].num_inputs == 2 in
is_var_basic_induction_var() as suggested by Jason.
- use nir_block_last_instr() in and rename foreach_cf_node_ex_loop() as suggested
by Jason.
- fix else check for is_trivial_loop_terminator() as per Connors suggetions.
- simplify offset for induction valiables incremented before the exit conditions is
checked.
- replace nir_op_isub check with assert() as it should have been lowered away.
V7: (Timothy Arceri)
- use rzalloc() on nir_loop struct creation. Worked previously because ralloc()
was broken and always zeroed the struct.
- fix cf_node_find_loop_jumps() to find jumps when loops contain
nested if statements. Code is tidier as a result.
V8: (Timothy Arceri)
- move is_trivial_loop_terminator() to nir.h so we can use it to assert is
the loop unroll pass
- fix analysis to not bail when looking for terminator when the break is in the else
rather then the if
- added new loop terminator fields: break_block, continue_from_block and
continue_from_then so we don't have to gather these when doing unrolling.
- get correct array length when forcing unrolling of variables
indexed arrays that are the same size as the iteration count
- add support for induction variables of type float
- update trival loop terminator check to allow an if containing
instructions as long as both branches contain only a single
block.
V9: (Timothy)
- bunch of tidy ups and simplifications suggested by Jason.
- rewrote trivial terminator detection, now the only restriction is there
must be no nested jumps, anything else goes.
- rewrote the iteration test to use nir_eval_const_opcode().
- count instruction properly even when forcing an unroll.
- bunch of other tidy ups and simplifications.
V10: (Timothy)
- some trivial tidy ups suggested by Jason.
- conditional fix for break inside continue branch by Jason.
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
