Fixes a false "used before being initialized" error when using self-mutating functions inside conditional operators (`&&`, `||`) in initializers.
This is a follow-up on https://github.com/swiftlang/swift/pull/35276.
rdar://168784050
It doesn't make sense to de-virtualize `destroy_value [dead_end]` because such operations are no-ops anyway.
This is especially important for Embedded Swift, because introducing calls to generic deinit functions after the mandatory pipeline can result in IRGen crashes.
rdar://168171608
Because `destructure_struct` acts as lifetime-ending use. Removing this instruction results in an ownership error.
This can happen if a non-copyable struct only has trivial fields.
Fixes a verifier crash
https://github.com/swiftlang/swift/issues/86901
rdar://169285436
Do this even if the function then contains references to other functions with wrong linkage.
MandatoryPerformanceOptimization fixes the linkage afterwards.
This is similar to what we already do with de-virtualizing class and witness methods: https://github.com/swiftlang/swift/pull/76032
rdar://168171608
Wihtout this change an alloc_stack instruction that is defined in a different
basic block than its use could result in instructions that are not dominated by
its operands. In an asserts build this is caught by the SIL verifier, but in a
non-asserts build it can crash the compiler.
Thanks to Erik Eckstein for the actual implementation of the fix!
rdar://168622625
Make sure that debug locations are correct so that instruction which are inserted by DI after a no-return call doesn't cause DiagnoseUnreachable to print a wrong warning.
Also, add `extend_lifetime` to the list of excluded instructions in DiagnoseUnreachable.
The OwnershipRAUW utility is called by CSE, SILCombine, etc. whenever OSSA
values are substituted or combined. It handles ownership corner cases by
creating new copies. Destroys need to be insert for those new copies after all
original uses. It is impossible to do that when phis are involved. The utility
already checks for phis involving owned or guaranteed values, but unowned phis
were not anticipated.
Fixes rdar://168620481 swift-frontend crash: While running pass
SILFunctionTransform "GenericSpecializer"
With this option an MD5 hash of the SIL is printed after each function or module pass - if the pass has changed the SIL.
This is useful for finding non-determinisms in the optimizer.
Even if an indirect argument is unused, pretend that the function reads from it.
If the unused argument is passed to another generic function and that function is specialized,
the argument may be re-abstracted and the specializer inserts a load from the indirect argument.
Therefore we must be prepared that unused indirect argument might get loaded from at some time.
Fixes a compiler crash
rdar://168623362
When computing the region to search for deinit barriers, include _all_ destroys of a canonical liverange - including destroys of all copies.
Before this fix, only destroys of the original def were considered which resulted in moving destroys across deinit barriers.
Fixes a miscompile
rdar://168337959
If the result of the `partial_apply` is lexical we must make sure to make its captured arguments lexical.
Otherwise the argument lifetimes may be shortened after inlining because the (lexical) `partial_apply` is not there anymore to keep the arguments alive.
Fixes a mis-compile
rdar://168337959
If a value is "copied" to the stack location via a `load` and `store` instruction pair and the source location is written or de-allocated between both instructions,
the optimization generated wrong SIL.
The fix is to make sure that writes to the source locations are always checked between the `load` and `store`.
rdar://168595700
This new OSSA invariant simplifies many optimizations because they don't have to take care of the corner case of incomplete lifetimes in dead-end blocks.
The implementation basically consists of these changes:
* add the lifetime completion utility
* add a flag in SILFunction which tells optimization that they need to run the lifetime completion utility
* let all optimizations complete lifetimes if necessary
* enable the ownership verifier to check complete lifetimes
These two new invariants eliminate corner cases which caused bugs if optimization didn't handle them.
Also, it will significantly simplify lifetime completion.
The implementation basically consists of these changes:
* add a flag in SILFunction which tells optimization if they need to take care of infinite loops
* add a utility to break infinite loops
* let all optimizations remove unreachable blocks and break infinite loops if necessary
* add verification to check the new SIL invariants
The new `breakIfniniteLoops` utility breaks infinite loops in the control flow by inserting an "artificial" loop exit to a new dead-end block with an `unreachable`.
It inserts a `cond_br` with a `builtin "infinite_loop_true_condition"`:
```
bb0:
br bb1
bb1:
br bb1 // back-end branch
```
->
```
bb0:
br bb1
bb1:
%1 = builtin "infinite_loop_true_condition"() // always true, but the compiler doesn't know
cond_br %1, bb2, bb3
bb2: // new back-end block
br bb1
bb3: // new dead-end block
unreachable
```
Inserts an unreachable after an unconditional fail:
```
%0 = integer_literal 1
cond_fail %0, "message"
// following instructions
```
->
```
%0 = integer_literal 1
cond_fail %0, "message"
unreachable
deadblock:
// following instructions
```
Remove the old SILCombine implementation because it's not working well with OSSA lifetime completion.
This also required to move the `shouldRemoveCondFail` utility function from SILCombine to InstOptUtils.
Make sure to create `destroy_value` with correct dead_end flags.
Especially, in a dead-end region where the original value's lifetime was ended with a `destroy_value [dead_end]`, the optimization must not re-create a destroy without the dead_end flag.
^ Conflicts:
^ test/SILOptimizer/mandatory-destroy-hoisting.sil
Make sure to create `destroy_value` with correct dead_end flags.
Especially, in a dead-end region where the original value's lifetime was ended with a `destroy_value [dead_end]`, the optimization must not re-create a destroy without the dead_end flag.
^ Conflicts:
^ test/SILOptimizer/destroy-hoisting.sil
