https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71626
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
One possibility would be to allow SUBREG of constant for the V1XXmode vectors
like:
--- gcc/varasm.c.jj 2016-06-10 20:24:03.000000000 +0200
+++ gcc/varasm.c 2016-06-27 11:43:25.330955071 +0200
@@ -3834,6 +3834,17 @@ output_constant_pool_2 (machine_mode mod
machine_mode submode = GET_MODE_INNER (mode);
unsigned int subalign = MIN (align, GET_MODE_BITSIZE (submode));
+ /* For V1??mode, allow SUBREGs. */
+ if (GET_CODE (x) == SUBREG
+ && GET_MODE_NUNITS (mode) == 1
+ && GET_MODE_BITSIZE (submode) == GET_MODE_BITSIZE (mode)
+ && SUBREG_BYTE (x) == 0
+ && GET_MODE (SUBREG_REG (x)) == submode)
+ {
+ output_constant_pool_2 (submode, SUBREG_REG (x), align);
+ break;
+ }
+
gcc_assert (GET_CODE (x) == CONST_VECTOR);
units = CONST_VECTOR_NUNITS (x);
Without -fpic the result looks good, but with -fpic it forces something that
needs relocations into .rodata.cst.* constants, which I think is bad. Though,
can't find right now where we normally avoid pushing relocatable stuff through
force_const_mem...
Another option is to do something in the i386 vector move expansion.
