[PATCH] D19567: PR21823: 'nodebug' attribute on global/static variables

[Paul Robinson via cfe-commits]

probinson added a comment.

In http://reviews.llvm.org/D19567#413997, @dblaikie wrote:

> For 3 code paths (that seem fairly independent from one another) I'd only really expect to see 3 variables in the test - one to exercise each codepath. What's the reason for the larger set of test cases?


I'm not interested in testing code-paths, I'm interested in testing a feature, and relying on the fact that (at the moment) only 3 code paths are involved is not really robust.  Granted there is some duplication, and I took that out (r267804), but there are more than 3 relevant cases from an end-user-feature perspective.

> Then it might be simpler just to include 6 variables, one of each kind with the attribute, one of each kind without. & I think you could check this reliably with:

> 

> CHECK: DIGlobalVariable

>  CHECK-NEXT: "name"

> 

> repeated three times with a CHECK-NOT: DIGlobalVariable at the end - that way the CHECK wouldn't skip past an existing variable, and you'd check you got the right ones. I think.


If I cared only about DIGlobalVariable that does sound like it would work.  Sadly, the static const data member comes out as a DIDerivedType, not a DIGlobalVariable.  Also, it's *really* important to us that the DICompositeType for "S1" is not present; that's actually where we get the major benefit.
Once you have more than one kind of thing to look for (or -NOT look for) it gets a lot more tedious to show it's all correct in one pass like you are suggesting.

(Re. getting rid of the types:  We have licensees with major template metaprogramming going on, but if they can mark those variables 'nodebug' and consequently suppress the instantiated types from the debug info, they should see a major size win.  One licensee reported that reducing some name from 19 characters to 1 char got them a 5MB reduction. Imagine if they could get rid of all of those types...)


Repository:
  rL LLVM

http://reviews.llvm.org/D19567