[SR-6880] synthesized ObjC constructors with struct parameters are not lowered properly on ARM VFP CC

[compnerd]

Previous ID	SR-6880
Radar	None
Original Reporter	@compnerd
Type	Bug

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, Swift4, Windows, arm, armhf, linux
Assignee	None
Priority	Medium

md5: 61a8547c2722f009225e364a21a95711

Issue Description:

When materializing the implicit constructor containing a HFA, the VFP CC will result in an incorrect attempt to coerce parameters to the structure type. This causes an assertion in LLVM as we attempt to store a structure value into the alloca when trafficking through memory.

[compnerd]

There is a test case for this in PR14304

[belkadan]

Aside: why the "Swift4" label?

[compnerd]

Oh, that is because it shows up in Swift 4 and newer I believe. Is that keyword meant for something else?

[belkadan]

I don't think anyone uses it at all (though it is on a few other bugs). It's interesting to know when something was a regression (4.0Regression, 4.1Regression, etc), but not usually when it's a new feature that just never worked under certain conditions.