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Elide duplicate OP_source_loc opcodes #916

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bnoordhuis opened this issue Feb 14, 2025 · 1 comment
Closed

Elide duplicate OP_source_loc opcodes #916

bnoordhuis opened this issue Feb 14, 2025 · 1 comment
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enhancement New feature or request

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@bnoordhuis
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Example phase 1 bytecode:

;;     print("done")

        source_loc      6:5
        scope_get_var   print,1
        source_loc      6:5       ;; duplicate
        push_atom_value done
        call            1
        drop

Not really a bug, just mildly inefficient. All what emitting the same location twice accomplishes is bloating the bytecode.

Probably easy to fix by remembering the last emitted source location.
@bnoordhuis bnoordhuis added the enhancement New feature or request label Feb 14, 2025
bnoordhuis added a commit to bnoordhuis/quickjs that referenced this issue Feb 14, 2025
@bnoordhuis
Don't emit duplicate source locations
0b468c7 
Requires a little extra bookkeeping but there are two good reasons to
accept that overhead:

1. OP_source_loc is pretty big at 9 bytes so duplicates bloat the
   bytecode considerably

2. An OP_source_loc opcode can throw off the peephole optimizer if it's
   between two opcodes the optimizer is trying to match; removing
   duplicates reduces the chance of that happening

Fixes: quickjs-ng#916
@bnoordhuis bnoordhuis mentioned this issue Feb 14, 2025
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@bnoordhuis
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Closing, in the end not merged because of #917 (comment).

@bnoordhuis bnoordhuis closed this as not planned Won't fix, can't repro, duplicate, stale Feb 17, 2025
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Don't emit duplicate source locations bnoordhuis/quickjs
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