[lldb] Prefer triple from module in precise invocations

[kastiglione]

When using precise compiler invocations, prefer the triple of the dylib/framework (aka image/module), and not the target binary. This is particularly vital for explicitly built modules, where the pcms for the dylib target can differ from the main target. The difference in pcms can cause expression evaluation to fail.

rdar://130284825

[kastiglione]

@swift-ci test

[adrian-prantl]

I think it would be less confusing if we called this module_arch or maybe image_arch (even though module is a very overloaded term).

[kastiglione]

This is a variable that holds either the module/image arch, and if that's not available, holds the target arch. "Active" meaning, the one we found, in order of preference (module first, target second).

So it's not module_arch, but maybe active_arch is also not right.

[kastiglione]

I'm going to rename it to preferred_… hopefully you'll agree that's ok.

[kastiglione]

@swift-ci test

[fredriss]

Should playgrounds just turn off precise compiler invocations rather than threading this as a different dimension in the API?

[kastiglione]

@fredriss here's the new commit, which disables precise compiler invocation for playgrounds 9ec444b

The tests in TestSwiftPlaygrounds.py expect the semantics that the target's triple is used to evaluate Swift code, not the current module.

[kastiglione]

Should playgrounds just turn off precise compiler invocations rather than threading this as a different dimension in the API?

@fredriss let me look into that.

[kastiglione]

@fredriss it turns out that the existing SymbolContext parameter itself controls whether a precise compiler invocation is used. I've changed the code to pass nullptr for the symbol context, whenever the expression is run from a playground (or repl). This avoids risks that could come with unprotected temporary mutation of a global (the swift-precise-compiler-invocation setting).

Thoughts?

[kastiglione]

@swift-ci test

[fredriss]

LGTM

[kastiglione]

@swift-ci test linux

[kastiglione]

The linux test failures need investigation.

[kastiglione]

@swift-ci test linux

[kastiglione]

@swift-ci test linux

[kastiglione]

@swift-ci test linux

[kastiglione]

@swift-ci test linux

[kastiglione]

@swift-ci test linux

[kastiglione]

@swift-ci test linux

[kastiglione]

@swift-ci test

[kastiglione]

@swift-ci test linux

[kastiglione]

@swift-ci test

[kastiglione]

@swift-ci test windows

[kastiglione]

@fredriss the issues with playgrounds and linux have been resolved, this is ready to be squashed & merged.