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pranayr710
78ed76f0d9
TExpr::moveToOutput() and the abs(x - y) -> absdiff(x, y) peephole in
TExpr::emitUnary() retire a value's arg slot (reclassify it to NONE) once
its single consumer has been emitted. That holds for an anonymous
intermediate, but a value the parser bound to a name ("t = ...;") may be
referenced again: the parser's name table still points at the retired slot,
so the later reference resolved to the reserved empty operand and
cv::texpr() silently returned a wrong result - for
t = {0} - {1}; abs(t) + t
t = {0} - {1}; (abs(t), t)
t = {0} + {1}; (t, t)
the reused name yielded input {0} instead of its own value, with no
assertion.
Mark a slot as pinned when the parser binds it to a name and skip both
retire manoeuvres for a pinned slot; each then takes the non-destructive
path it already has - moveToOutput() copies into the output via OP_CAST,
and the abs peephole falls through to the plain absdiff(a, 0) form, keeping
the OP_SUB that the name still needs. Anonymous intermediates are
unaffected, so the zero-temp fast path for single-op programs still fires.