[4.0] [sil-combine] Make sure that (apply (partial_apply)) -> (apply') bail…

[gottesmm]

…s if we have an argument with a dependent type.

What is going on here is that currently this optimization if itneeds to perform
lfietime extension always creates an alloc_stack at the beginning/end of a
function. If the object whose lifetime is being extended has a dependent type,
then the alloc_stack will be created before the dependent type exists resulting
in the compiler crashing.

rdar://33595317

[gottesmm]

@swiftix Can I get a review?

[gottesmm]

@swift-ci test

[swift-ci]

Build failed
Jenkins build - Swift Test Linux Platform
Git Commit - ae2dae6
Test requested by - @gottesmm

[swift-ci]

Build failed
Jenkins build - Swift Test OS X Platform
Git Commit - ae2dae6
Test requested by - @gottesmm

[gottesmm]

I don't think that this is from my change.

[gottesmm]

It is a typechecker error. Just out of paranoia I am going to try compiling again, this time clean maybe?

[gottesmm]

@swift-ci clean test

[gottesmm]

@swift-ci clean test

[swift-ci]

Build failed
Jenkins build - Swift Test Linux Platform
Git Commit - ae2dae6
Test requested by - @gottesmm

[swift-ci]

Build failed
Jenkins build - Swift Test OS X Platform
Git Commit - ae2dae6
Test requested by - @gottesmm

[gottesmm]

@swiftix I took a look at the bots. It looks like swift-4.0-branch is broken:

https://ci.swift.org/view/swift-4.0-branch/job/oss-swift-4.0-incremental-RA-osx/

Since here:

https://ci.swift.org/view/swift-4.0-branch/job/oss-swift-4.0-incremental-RA-osx/863/

[swiftix]

LGTM!

[gottesmm]

@swift-ci test

[gottesmm]

Mishal said that the problem here is fixed.

[gottesmm]

Explanation: This small patch stops the optimizer from transforming (apply (partial-apply)) -> (apply') when the partial apply: 1. has an address argument that needs to be lifetime extended. 2. Uses a dependent type. In such a situation, the currently the implemented algorithm would create stack locations at the beginning and end of the function to lifetime extend the address arguments. Since the type parameter does not exist at that point, and the compiler needs the type parameter to create the stack location, the compiler crashes.
Scope: This eliminates a compiler crash.
Radar (and possibly SR Issue): rdar://33595317
Risk: None. It just turns off an optimization and if the optimization was still enabled, we would crash.
Testing: I added a test to the compiler test suite that would cause the crash and verify no transformation occurs.

[gottesmm]

Approved by Ted via email.