perf: ShrU 31 befor If can be Clz

dfinity · Dec 10, 2024 · c2403e4 · c2403e4
1 parent ac26d8c
commit c2403e4
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Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/src/codegen/instrList.ml b/src/codegen/instrList.ml
@@ -125,6 +125,10 @@ let optimize : instr list -> instr list = fun is ->
       ({it = Const cr; _} as const) :: ({it = Binary opr; _} as op) :: r'
         when Option.is_some (combine_shifts const op (opl, cl, opr, cr.it)) ->
       go l' (Option.get (combine_shifts const op (opl, cl, opr, cr.it)) @ r')
+    (* Examining topmost bit *)
+    | {it = Binary (I32 I32Op.ShrU); _} as shift :: {it = Const {it = I32 31l; _}; _} :: l',
+      ({it = If (res,then_,else_); _} as if_) :: r' ->
+      go l' ({ shift with it = Unary (I32 I32Op.Clz) } :: { if_ with it = If (res,else_,then_) } :: r')
     (* Null shifts can be eliminated *)
     | l', {it = Const {it = I32 0l; _}; _} :: {it = Binary (I32 I32Op.(Shl|ShrS|ShrU)); _} :: r' ->
       go l' r'

diff --git a/test/bench/ok/heap-32.drun-run.ok b/test/bench/ok/heap-32.drun-run.ok
@@ -1,5 +1,5 @@
 ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
 ingress Completed: Reply: 0x4449444c0000
-debug.print: (50_227, +29_863_068, 723_684_961)
+debug.print: (50_227, +29_863_068, 723_584_961)
 debug.print: (50_070, +32_992_212, 785_200_313)
 ingress Completed: Reply: 0x4449444c0000