[polly] Add diagnostic remark for ReportVariantBasePtr

[Hal Finkel]

[adding some debug-info folks...]

 -Hal

----- Original Message -----
> From: "Tobias Grosser" <tobias at grosser.es>
> To: "Andreas Simbuerger" <simbuerg at googlemail.com>
> Cc: llvm-commits at cs.uiuc.edu, "Andreas Simbuerger" <simbuerg at fim.uni-passau.de>
> Sent: Thursday, June 26, 2014 3:41:32 PM
> Subject: Re: [polly] Add diagnostic remark for ReportVariantBasePtr
> 
> On 26/06/2014 22:12, Andreas Simbuerger wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> >
> >
> > On 06/26/2014 09:25 PM, Tobias Grosser wrote:
> >> On 26/06/2014 21:16, Andreas Simbürger wrote:
> >>> What was the exact output?
> >>
> >> polly-clang /tmp/test.c  -c -mllvm -polly -O3  -Rpass-missed=polly
> >> -mllvm -polly-detect-track-failures -mllvm
> >> -polly-detect-keep-going -gcolumn-info /tmp/test.c:6:9: remark:
> >> The
> >> following errors keep this region from being a Scop.
> >> [-Rpass-missed=polly-detect] for (int i=0; i<32; i++) ^
> >> /tmp/test.c:7:6: remark: The base address of this array is not
> >> invariant inside the loop [-Rpass-missed=polly-detect] A->b[i] =
> >> A->b[i+p]; ^ /tmp/test.c:7:6: remark: The base address of this
> >> array is not invariant inside the loop
> >> [-Rpass-missed=polly-detect]
> >>
> >>
> >>> I would expect the source location reported for the write and
> >>> then just the message with the line/column info but without
> >>> source code.
> >>
> >> Both remarks give the very same location. I would have expected
> >> the first one referring to the first memory address, the second
> >> one
> >> to the second memory address. (I would also expect to see the
> >> source line twice. Once with the caret at the first read, once at
> >> the second).
> >>
> >
> > That would be nice. However, if you have a look at the attached
> > *.ll
> > file (your example translated with the command-line you posted),
> > you
> > will see that the dbg metadata that is attached to all instructions
> > inside the loop body is:
> >
> > !26 = metadata !{i32 7, i32 5, metadata !18, null}.
> >
> > So no matter what instruction I use inside the body, I will only be
> > able to report line 7 column 5 :o(.
> > The fact that both errors have the same DebugLoc leads to to effect
> > that you don't get the same source location printed twice in a row
> > (I
> > guess).
> >
> > How can we increase the precision of the column info?
> 
> This clang hack helps:
> 
> diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
> index 62ecc73..53c63f4 100644
> --- a/lib/CodeGen/CGExpr.cpp
> +++ b/lib/CodeGen/CGExpr.cpp
> @@ -771,6 +771,9 @@ LValue CodeGenFunction::EmitCheckedLValue(const
> Expr
> *E, TypeCheckKi
>   /// length type, this is not possible.
>   ///
>   LValue CodeGenFunction::EmitLValue(const Expr *E) {
> +  if (CGDebugInfo *DI = getDebugInfo()) {
> +  DI->EmitLocation(Builder, E->getLocEnd(), true);
> +  }
>     switch (E->getStmtClass()) {
>     default: return EmitUnsupportedLValue(E, "l-value expression");
> 
> 
> /tmp/test.c:7:16: remark: The base address of this array is not
> invariant inside the loop [-Rpass-missed=polly-detect]
>       A->b[i] = A->b[i+p];
>                 ^
> /tmp/test.c:7:6: remark: The base address of this array is not
> invariant
> inside the loop [-Rpass-missed=polly-detect]
>       A->b[i] = A->b[i+p];
>       ^
> The patch is probably to aggressive, but it may be a start. Could we
> possibly emit column info for all load instructions? That would be
> good
> enough for Polly at least, no? We probably need to understand the
> overhead and if other people could also use this information.
> 
> Tobias
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory