[Bug target/15106] New: vector varargs failure passing from altivec to non-altivec code for -m32

janis187 at us dot ibm dot com gcc-bugzilla@gcc.gnu.org
Fri Apr 23 20:09:00 GMT 2004

It should be possible to write a library function that accepts vector
arguments in a variable-length argument list, with that function
compiled with -mno-altivec, the caller compiled with -maltivec, and
both using the same Altivec ABI.  With mainline this works for -m64 but
not with -m32.  The hammer-3.3 branch has the same problem; I haven't
tried it for other branches but assume that 3.4 has does the same thing.
The tarball includes two source files plus a Makefile that will build
them in different combinations.  The specific problem described here
is demonstrated by the following, using a biarch powerpc64-linux
compiler from mainline sources.  Results for this test are not affected
by patches from Alan Modra on April 23 or from Fariborz Jahanian on
April 21.
dufur% $GCC -m32 -maltivec -mabi=altivec -c -o bug_passer.o bug_passer.c
dufur% $GCC -m32 -mno-altivec -mabi=altivec -c -o bug_passee.o bug_passee.c
dufur% $GCC -m32 bug_passer.o bug_passee.o
dufur% a.out
If other failing combinations generated by the Makefile are not supported
then they should be documented as not expected to work.

           Summary: vector varargs failure passing from altivec to non-
                    altivec code for -m32
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: janis187 at us dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: powerpc64-linux powerpc-linux


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