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clonker
commented
Apr 18, 2026
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| auto const& targetArg = _state.targetArg(offset); | ||
| // if the target arg is junk, we can simply push0 and it's fine | ||
| if (targetArg.isJunk()) |
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this condition should in the future, i think, be extended to "is it junk or a lit that is cheap to push or we don't care about bytecode size and simply want fast execution"
blishko
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Apr 18, 2026
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| initial: [lit1, lit1, v0, v0, lit0, v0, lit0, v0, v0, v0, lit0, v0, v0, v0, lit0, v0, lit0, lit0, v0] | ||
| targetStackTop: [JUNK, lit0, v0, lit0, v0, JUNK, v0, lit0, JUNK, v0, v0, lit0, v0, JUNK, lit0, v0, lit1] | ||
| targetStackTailSet: {v0} | ||
| targetStackSize: 20 |
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I am a bit confused.
Why is it trying to reach for lit1 instead of just doing PUSH lit1?
This should be just one instruction, similar to the JUNK case.
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Oh, now I understand your comment.
PUSH lit1 is potentially expensive, if lit1 is large.
As you say, at some point it would be good to come up with some heuristic to re-create the literal instead of trying to dup/swap existing one.
blishko
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Apr 18, 2026
clonker
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ssa-shuffler-all-necessary-slots-reachable-should-ignore-junk
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Added three tests, where the stack top is either a variable, a lit, or junk and the stack has to grow by one to populate it. For the first two, the shuffler pulls the var/lit out of the tail by shrinking and then growing back; for junk it should simply push0 (when it was previously oscillating).