[SR-7616] 'code will never execute' for compound conditions && other simple cases

[AnthonyLatsis]

Previous ID	SR-7616
Radar	None
Original Reporter	@AnthonyLatsis
Type	Improvement

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Improvement, DiagnosticsQoI, SILDiagnostics
Assignee	@devincoughlin
Priority	Medium

md5: a72fd643f6cd244d0b74c73ad93da4eb

Issue Description:

There are relatively simple cases when we can show this warning, e.g.

func test(pred: Bool) {
  if false && pred {} // Doesn't warn
}

let i = 0
if i > 10 {} // Doesn't warn

let bool1 = true
if !bool1 {} // Warns

let bool2 = true || false
if !bool2 {} // Doesn't warn

[belkadan]

@AnnaZaks, @devincoughlin, are we collecting these sorts of CFG analysis improvements anywhere?

[devincoughlin]

@belkadan What do you think about creating a SILDiagnostics label?

[belkadan]

Works for me. (Contributors to Swift should feel free to add labels as they need them.)