5.9: [TempRValueOpt] Fold new destroy_addrs into loads. #65070
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In preparation for "folding" an "inserted destroy" into a load [copy] or copy_addr, rename the variable that indicates whether the copyInst's source must be deinitialized after its last "load".
As a separate commit to make the behavior change more obvious.
To avoid introducing new copies--which is illegal for move-only values-- don't rewrite `load [take]`s and `copy_addr [take]`s as `load [copy]`s and `copy_addr`s respectively and introduce new `destroy_addr`s after them. Instead, get the effect of folding such a newly created `destroy_addr` into the preceding rewritten `load [copy]` or `copy_addr`. Get that effect by neither modifying the `copy_addr [take]` or `load [take]` nor adding a subsequent `destroy_addr`. An example for each kind (`load [take]` and `copy_addr [take]`): ``` // Input 1 (`load [take]`) copy_addr [take] %src to [init] %tmp %val = load [take] %src // Old Output 1 %val = load [copy] %src destroy_addr %src // New Output 2 %val = load [take] %src ``` ``` // Input 2 (`copy_addr [take]`) copy_addr [take] %src to [init] %tmp copy_addr [take] %src to [init] %dst // Old Output 2 copy_addr %src to [init] %dst destroy_addr %src // New Output 2 copy_addr [take] %src to [init] %dst ``` rdar://107839979
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@swift-ci please test |
tbkka
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Apr 11, 2023
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Can't comment on the implementation, but I like that we're eliminating copies!
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Cherry-pick of #65052 .
To avoid introducing new copies--which is illegal for move-only values-- don't rewrite
load [take]s andcopy_addr [take]s asload [copy]s andcopy_addrs respectively and introduce newdestroy_addrs after them. Instead, get the effect of folding such a newly createddestroy_addrinto the preceding rewrittenload [copy]orcopy_addr. Get that effect by neither modifying thecopy_addr [take]orload [take]nor adding a subsequentdestroy_addr.An example for each kind (
load [take]andcopy_addr [take]):rdar://107839979