[PATCH] D19522: Read discriminators correctly from object file.

[Dehao Chen via llvm-commits]

>From your comment in previous patch http://reviews.llvm.org/D14464:

Even with column info, its insufficient if both calls came from the same
macro use:

#define X f(); f()
int main() {

X;
}

Both calls to 'f' will have the same line and column, the location of the X
use.


On Wed, Apr 27, 2016 at 11:34 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
> On Tue, Apr 26, 2016 at 1:58 PM, Dehao Chen via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Unfortunately, we can't because I need to have two consecutive
>> instructions that are both from discriminator 1, but different lines
>> to trigger this bug. With your proposed change, the code sequence will
>> be:
>>
>> line 4 discriminator 0
>> line 4 discriminator 1
>> line 5 discriminator 0
>> line 5 discriminator 1
>>
>> But with my test case, the code sequence will be:
>>
>> line 4 discriminator 0
>> line 5 discriminator 0
>> line 4 discriminator 1
>> line 5 discriminator 1
>
>
> Ah, OK - thanks for the description (might be worth including that in the
> test case, but I'm not sure - up to you)
>
> Side note: Are we not including the column info when determining when to add
> discriminators? Is there a reason for that (I vaguely recall asking this
> before, so I assume we are intentionally disregarding column info for some
> good reason I've forgotten). Because these locations are all unique once you
> include column info (which we are including by default now).
>
> - Dave
>
>>
>>
>> On Tue, Apr 26, 2016 at 12:46 PM, David Blaikie <dblaikie at gmail.com>
>> wrote:
>> > dblaikie added inline comments.
>> >
>> > ================
>> > Comment at: test/DebugInfo/X86/discriminator2.ll:9
>> > @@ +8,3 @@
>> > +; #3 void baz() {
>> > +; #4   foo/*discriminator 1*/(bar(),
>> > +; #5       bar());bar()/*discriminator 1*/;
>> > ----------------
>> > Would it be simpler/sufficient to do this:
>> >
>> >   void f1();
>> >   void f2() {
>> >     f1(); f1();
>> >     f1(); f1();
>> >   }
>> >
>> > (with column info off? Or, to keep column info on, #define CALLS f1();
>> > f1() and have the body of the function be:
>> >   CALLS;
>> >   CALLS;
>> > )
>> >
>> >
>> > http://reviews.llvm.org/D19522
>> >
>> >
>> >
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>
>