Fix two problems with withoutActuallyEscaping
#78885
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… the throwing case withoutActuallyEscaping checks that the passed closure has not beed escaped by ensuring that its reference count is exactly 1 at the end of the code block. So far this was only done in the regular return case. But if the code block throws, the check was not done. Fixes an undetected undefined behavior.
…escaped_closure` The problem with `is_escaping_closure` was that it didn't consume its operand and therefore reference count checks were unreliable. For example, copy-propagation could break it. As this instruction was always used together with an immediately following `destroy_value` of the closure, it makes sense to combine both into a `destroy_not_escaped_closure`. It 1. checks the reference count and returns true if it is 1 2. consumes and destroys the operand
eeckstein
requested review from
compnerd,
jckarter,
rjmccall and
xymus
as code owners
eeckstein
requested review from
kavon,
atrick,
aschwaighofer,
meg-gupta and
nate-chandler
and removed request for
compnerd,
xymus and
rjmccall
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1. let
withoutActuallyEscapingalso catch an escaping closure in the throwing case.withoutActuallyEscapingchecks that the passed closure has not beed escaped by ensuring that its reference count is exactly 1 at the end of the code block.So far this was only done in the regular return case. But if the code block throws, the check was not done.
Fixes an undetected undefined behavior.
2. replace the
is_escaping_closureinstruction withdestroy_not_escaped_closureThe problem with
is_escaping_closurewas that it didn't consume its operand and therefore reference count checks were unreliable.For example, copy-propagation could break it.
As this instruction was always used together with an immediately following
destroy_valueof the closure, it makes sense to combine both into adestroy_not_escaped_closure.It
This is part of rdar://140229560.