MLIR DAG rewriter w/ SSA IR, dominance and CFG analysis passes
iterate in reverse postorder for faster fixpoint convergence
author
vm.fail
date
(Jul 23, 2026, 5:51 PM UTC)
commit
4d00d647
4d00d647d00edd59a863226943303f877cd557ad
parent
ee8d504c
ee8d504ca88d5799ebf404057a28e90414ecd178
vm.fail
date
(Jul 23, 2026, 5:51 PM UTC)
commit
4d00d647
4d00d647d00edd59a863226943303f877cd557ad
parent
ee8d504c
ee8d504ca88d5799ebf404057a28e90414ecd178
+28
-9
+28
-9
lib/dominance.ml
+28
-9
lib/dominance.ml
···
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in
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find strict_doms
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let rev_postorder cfg =
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let visited = ref IntSet.empty in
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let order = ref [] in
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let rec dfs id =
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if IntSet.mem id !visited then ()
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else begin
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visited := IntSet.add id !visited;
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let b = IntMap.find id cfg.blocks in
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List.iter dfs b.succs;
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order := id :: !order
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end
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in
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dfs cfg.entry;
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let remaining = IntMap.fold (fun k _ acc ->
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if IntSet.mem k !visited then acc else k :: acc
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) cfg.blocks [] in
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!order @ remaining
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+
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let dominators cfg =
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let all = IntMap.fold (fun k _ s -> IntSet.add k s) cfg.blocks IntSet.empty in
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let init = IntSet.singleton cfg.entry in
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let rpo = rev_postorder cfg in
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let rec fixpoint doms =
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-
let new_doms = IntMap.mapi (fun id _ ->
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if id = cfg.entry then init
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let new_doms = List.fold_left (fun acc id ->
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if id = cfg.entry then IntMap.add id init acc
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else
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let b = IntMap.find id cfg.blocks in
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match b.preds with
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| [] -> IntSet.empty
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| [] -> IntMap.add id IntSet.empty acc
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| p :: ps ->
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let inter = List.fold_left (fun acc pr ->
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try IntSet.inter acc (IntMap.find pr doms)
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with Not_found -> acc
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) (try IntMap.find p doms with Not_found -> IntSet.empty) ps in
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IntSet.add id inter
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) cfg.blocks in
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let inter = List.fold_left (fun a pr ->
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try IntSet.inter a (IntMap.find pr acc)
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with Not_found -> a
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) (try IntMap.find p acc with Not_found -> IntSet.empty) ps in
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IntMap.add id (IntSet.add id inter) acc
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) IntMap.empty rpo in
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if IntMap.equal IntSet.equal doms new_doms then doms
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else fixpoint new_doms
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in