[Bug regression/63175] New: [4.9/5 regression] FAIL: gcc.dg/vect/costmodel/ppc/costmodel-bb-slp-9a.c scan-tree-dump-times slp2" basic block vectorized using SLP" 1

[macro@linux-mips.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63175

            Bug ID: 63175
           Summary: [4.9/5 regression] FAIL:
                    gcc.dg/vect/costmodel/ppc/costmodel-bb-slp-9a.c
                    scan-tree-dump-times slp2" basic block vectorized
                    using SLP" 1
           Product: gcc
           Version: 4.9.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
          Assignee: unassigned at gcc dot gnu.org
          Reporter: macro@linux-mips.org
              Host: i686-linux-gnu
            Target: powerpc-linux-gnu

I see this failure in Power/Linux testing with 4.9.1 and also trunk
(5.0), so presumably the regression happened sometime between 4.8 and
4.9:

FAIL: gcc.dg/vect/costmodel/ppc/costmodel-bb-slp-9a.c scan-tree-dump-times
slp2" basic block vectorized using SLP" 1

This test passed with 4.8.  This is with powerpc-linux-gnu.

Looking at the generated assembly the quality of code has indeed
regressed, copying between `pin' and `pout' in `main1' is no longer
optimised away.

This happens for AltiVec multilibs only, seen with:

-mcpu=603e
-mcpu=603e -msoft-float
-mcpu=7400 -maltivec -mabi=altivec
-mcpu=e6500 -maltivec -mabi=altivec
-mcpu=e6500 -m64 -maltivec -mabi=altivec

option selections here.

Options used to configure the compiler:

--build=i686-pc-linux-gnu
--target=powerpc-linux-gnu
--with-cpu-32=603e
--with-cpu-64=e5500
--with-long-double-128