The lcssa and phis_to_regs passes are used by various NIR optimizations
that modify the CFG. Putting a couple of asserts will help ensure that
we don't accidentally put derefs in phis as part of an optimization
pass.
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
V2: Do a "depth first search" to convert to LCSSA
V3: Small comment fixup
V4: Rebase, adapt to removal of function overloads
V5: Rebase, adapt to relocation of nir to compiler/nir
Still need to adapt to potential if-uses
Work around nir_validate issue
V6 (Timothy):
- tidy lcssa and stop leaking memory
- dont rewrite the src for the lcssa phi node
- validate lcssa phi srcs to avoid postvalidate assert
- don't add new phi if one already exists
- more lcssa phi validation fixes
- Rather than marking ssa defs inside a loop just mark blocks inside
a loop. This is simpler and fixes lcssa for intrinsics which do
not have a destination.
- don't create LCSSA phis for loops we won't unroll
- require loop metadata for lcssa pass
- handle case were the ssa defs use outside the loop is already a phi
V7: (Timothy)
- pass indirect mask to metadata call
v8: (Timothy)
- make convert to lcssa a helper function rather than a nir pass
- replace inside loop bitset with on the fly block index logic.
- remove lcssa phi validation special cases
- inline code from useless helpers, suggested by Jason.
- always do lcssa on loops, suggested by Jason.
- stop making lcssa phis special. Add as many source as the block
has predecessors, suggested by Jason.
V9: (Timothy)
- fix regression with the is_lcssa_phi field not being initialised
to false now that ralloc() doesn't zero out memory.
V10: (Timothy)
- remove extra braces in SSA example, pointed out by Topi
V11: (Timothy)
- add missing support for LCSSA phis in if conditions.
V12: (Timothy)
- small tidy up suggested by Jason.
- always create lcssa phi even if it just points to an lcssa
phi from an inner loop
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
