[Bug tree-optimization/49773] New: use of class data members prevent vectorization

[Bug tree-optimization/49773] New: use of class data members prevent vectorization

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49773

           Summary: use of class data members prevent vectorization
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: vincenzo.innocente@cern.ch


in this example below the loop in the first method does not vectorize, the
second does.


struct Foo {
  float a;
  float b;

  void compute1(float * __restrict__ x, float const * __restrict__ y, int N)
const;
  void compute2(float * __restrict__ x, float const * __restrict__ y, int N)
const;

};

void Foo::compute1(float * __restrict__ x, float const * __restrict__ y, int N)
const {
  for (int i=0; i!=N; ++i)
    x[i] = a + b*y[i];
}

void Foo::compute2(float * __restrict__ x, float const * __restrict__ y, int N)
const {
  float la=a, lb=b;
  for (int i=0; i!=N; ++i)
    x[i] = la + lb*y[i];
}


test/vectClass.cpp:11: note: not vectorized: loop contains function calls or
data references that cannot be analyzed
test/vectClass.cpp:10: note: vectorized 0 loops in function.
vs

test/vectClass.cpp:17: note: Profitability threshold is 5 loop iterations.
test/vectClass.cpp:17: note: LOOP VECTORIZED.
test/vectClass.cpp:15: note: vectorized 1 loops in function.

[Bug tree-optimization/49773] use of class data members prevent vectorization

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49773

--- Comment #1 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2011-07-18 14:11:11 UTC ---
I just upgraded to

c++ -v
Using built-in specs.
COLLECT_GCC=c++
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-apple-darwin10.8.0/4.7.0/lto-wrapper
Target: x86_64-apple-darwin10.8.0
Configured with: ./configure --enable-languages=c,c++,fortran --enable-lto
--with-build-config=bootstrap-lto CFLAGS='-O2 -ftree-vectorize -fPIC'
CXXFLAGS='-O2 -fPIC -ftree-vectorize -fvisibility-inlines-hidden'
Thread model: posix
gcc version 4.7.0 20110716 (experimental) (GCC) 

and it seem to vectorize fine…
was stil not ok in gcc version 4.7.0 20110702 (experimental) (GCC) 


it still pretends to check for
test/vectClass.cpp:11: note: Detected interleaving this_9(D)->a and
this_9(D)->b
test/vectClass.cpp:11: note: versioning for alias required: can't determine
dependence between this_9(D)->a and *D.1537_8
test/vectClass.cpp:11: note: mark for run-time aliasing test between
this_9(D)->a and *D.1537_8
test/vectClass.cpp:11: note: versioning for alias required: can't determine
dependence between this_9(D)->b and *D.1537_8
test/vectClass.cpp:11: note: mark for run-time aliasing test between
this_9(D)->b and *D.1537_8

I hope it will be addressed in PR49774

[Bug tree-optimization/49773] use of class data members prevent vectorization

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49773

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
             Blocks|                            |53947
           Keywords|                            |missed-optimization


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations

[Bug tree-optimization/49773] use of class data members prevent vectorization

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49773

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |6.0
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
starting in GCC 6 can do it without aliasing checks.
Starting in GCC 8, the prologue code has improved.

So we can close this as fixed in GCC 6 really.