Flow analysis on garbage collector and more #615
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gabrielsferre
commented
Jul 21, 2024
gabrielsferre
commented
- Using flow analysis for checking liveness of variables at the garbage collector.
- Using work-list for checking flow analysis convergence (both in gc.lua and uninitialized.lua). See Using a work list when doing flow analysis #609.
- Not using commands as keys for tables anymore. See Stop using commands as keys for tables on the garbage collector #610.
hugomg
requested changes
Jul 22, 2024
| -- appears live at, instead of approximating with first definition and last use. | ||
| -- | ||
| -- 4) Use SSA form or some form of reaching definitions analysis so that we we only need to mirror | ||
| -- 3) Use SSA form or some form of reaching definitions analysis so that we we only need to mirror |
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Perhaps investigating the items on this list could be an interesting experiment for the project... We could do a subsequent PR for that and then compare how the benchmarks fare, before and after.
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Yes! We could start with them.
| kill = {}, -- {var_id -> bool?} variables that are killed inside block | ||
| gen = {}, -- {var_id -> bool?} variables that become live inside block | ||
| } | ||
| end |
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Another question for a future PR:
- How similar is our analysis code to the uninitialized analysis
- Is it worth abstracting some of it to a separate flow analysis file?
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The code is very similar. I was thinking of having a separate flow analysis file at some point, but wanted to do a couple more cases to help me abstract away the pattern.
hugomg
approved these changes
Jul 23, 2024
src/pallene/coder.lua
Outdated
| if gc.cmd_uses_gc(cmd._tag) then | ||
| gen_state.gc_info = { | ||
| live_gc_vars = self.gc[func].live_gc_vars[block_i][cmd_i], | ||
| slot_of_variable = self.gc[func].slot_of_variable, |
| cmd = cmd, | ||
| func = func, | ||
| gc_info = false, | ||
| } |
src/pallene/gc.lua
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| function gc.compute_stack_slots(func) | ||
| local function FlowState() | ||
| return { | ||
| input = {}, -- {var_id -> bool?} live variables at block start |
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