Optimizer: eliminate struct_extracts of an owned struct where the struct_extracts are inside a borrow scope
#84766
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…have changed This makes sure that instruction simplification doesn't terminate too early, missing some optimization opportunities.
… `struct_extract`s are inside a borrow scope This is done by splitting the `begin_borrow` of the whole struct into individual borrows of the fields (for trivial fields no borrow is needed). And then sinking the `struct` to it's consuming use(s). ``` %3 = struct $S(%nonTrivialField, %trivialField) // owned ... %4 = begin_borrow %3 %5 = struct_extract %4, #S.nonTrivialField %6 = struct_extract %4, #S.trivialField use %5, %6 end_borrow %4 ... end_of_lifetime %3 ``` -> ``` ... %5 = begin_borrow %nonTrivialField use %5, %trivialField end_borrow %5 ... %3 = struct $S(%nonTrivialField, %trivialField) end_of_lifetime %3 ``` This optimization is important for Array code where the Array buffer is constantly wrapped into structs and then extracted again to access the buffer.
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eeckstein
requested review from
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This is done by splitting the
begin_borrowof the whole struct into individual borrows of the fields (for trivial fields no borrow is needed).And then sinking the
structto it's consuming use(s).->
This optimization is important for Array code where the Array buffer is constantly wrapped into structs and then extracted again to access the buffer.