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This PR updates the
expandarray
instruction for YJIT.expandarray
is an instruction that appears for array decomposition or multiple assignment.Most commonly,
expandarray
will be encountered when assigning multiple variables at once from array,example -
But it can often appear with non-arrays, when assigning multiple variables to a single value. It is common enough to see
expandarray
on a singlenil
thatgen_expandarray
previously had a special case if the operand wasnil
, but this is potentially incorrect becauseto_ary
can be redefined onNilClass
.This PR updates the non-array case by bailing if
to_ary
is defined on a non-array operand. Otherwise, we pushnil
s to fill the unset values, then push the original operand, which also helps get rid of side exits from a pattern like:This pattern was one of the most commonly seen side-exits for GitHub benchmarks.
Quick benchmark: