[PATCH] D16947: [PGO] assignment operator does not get profile data

[David Blaikie via llvm-commits]

ah, right, sorry about that - gmail didn't render cfe-commits on the to
line in the first email... weird.

Anyway, no need to include llvm-commits on clang-only changes.

On Mon, Feb 8, 2016 at 11:30 AM, Xinliang David Li <davidxl at google.com>
wrote:

> Both cfe-commits and llvm-commits are cc'ed.
>
> David
>
> On Mon, Feb 8, 2016 at 11:29 AM, David Blaikie <dblaikie at gmail.com> wrote:
> > This looks like a change to clang - could you test it in clang (& review
> it
> > on cfe-commits instead of llvm-commits)?
> >
> > On Sat, Feb 6, 2016 at 11:57 AM, David Li via cfe-commits
> > <cfe-commits at lists.llvm.org> wrote:
> >>
> >> davidxl created this revision.
> >> davidxl added a reviewer: vsk.
> >> davidxl added subscribers: llvm-commits, cfe-commits.
> >>
> >> For compiler generated assignment operator that is not trivial (calling
> >> base class operator=()), Clang FE assign region counters to the function
> >> body but does not emit profile counter increment for the function entry.
> >> This leads to many problems:
> >>
> >> 1) the operator body does not have profile data generated leading to
> >> warning in profile-use
> >> 2) the size of the function body may be large and lack of profile data
> may
> >> lead to wrong inlining decisions
> >> 3) when FE assign region counters to the function, it also emit coverage
> >> mapping data for the function -- but it has no coverage data which is
> >> confusing (currently the llvm-cov tool will report malformed format (as
> the
> >> name of the operator is not put into the right name section).
> >>
> >> http://reviews.llvm.org/D16947
> >>
> >> Files:
> >>   lib/CodeGen/CGClass.cpp
> >>   test/Profile/def-assignop.cpp
> >>
> >> Index: test/Profile/def-assignop.cpp
> >> ===================================================================
> >> --- test/Profile/def-assignop.cpp
> >> +++ test/Profile/def-assignop.cpp
> >> @@ -0,0 +1,34 @@
> >> +// RUN: %clang_cc1 -x c++ %s -triple x86_64-unknown-linux-gnu
> >> -main-file-name def-assignop.cpp -o - -emit-llvm
> -fprofile-instrument=clang
> >> | FileCheck --check-prefix=PGOGEN %s
> >> +
> >> +
> >> +struct B {
> >> +  int B;
> >> +  void *operator=(const struct B &b2) {
> >> +    if (b2.B == 0) {
> >> +      B = b2.B + 1;
> >> +    } else
> >> +      B = b2.B;
> >> +    return this;
> >> +  }
> >> +};
> >> +
> >> +struct A : public B {
> >> +  A &operator=(const A &) = default;
> >> +// PGOGEN: define {{.*}}@_ZN1AaSERKS_(
> >> +// PGOGEN: %pgocount = load {{.*}} @__profc__ZN1AaSERKS_
> >> +// PGOGEN: {{.*}}add{{.*}}%pgocount, 1
> >> +// PGOGEN: store{{.*}}@__profc__ZN1AaSERKS_
> >> +  int I;
> >> +  int J;
> >> +  int getI() { return I; }
> >> +};
> >> +
> >> +A aa;
> >> +int g;
> >> +int main() {
> >> +  A aa2;
> >> +  aa2 = aa;
> >> +
> >> +  g = aa2.getI();
> >> +  return 0;
> >> +}
> >> Index: lib/CodeGen/CGClass.cpp
> >> ===================================================================
> >> --- lib/CodeGen/CGClass.cpp
> >> +++ lib/CodeGen/CGClass.cpp
> >> @@ -1608,6 +1608,7 @@
> >>
> >>    LexicalScope Scope(*this, RootCS->getSourceRange());
> >>
> >> +  incrementProfileCounter(RootCS);
> >>    AssignmentMemcpyizer AM(*this, AssignOp, Args);
> >>    for (auto *I : RootCS->body())
> >>      AM.emitAssignment(I);
> >>
> >>
> >>
> >> _______________________________________________
> >> cfe-commits mailing list
> >> cfe-commits at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
> >>
> >
>
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