This patch resolves PR target/102785 where my recent patch to constant
fold saturating addition/subtraction exposed a latent bug in the bfin
backend.  The patterns used for blackfin's V2HI ssaddsub and sssubadd
instructions had the indices/operations swapped.  This was harmless
until we started evaluating these expressions at compile-time, when
the mismatch was caught by the testsuite.

Many thanks to Jeff Law for confirming that this patch fixes these
regressions on bfin-elf.  Ok for mainline?


2021-10-18  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
        PR target/102785
        * config/bfin/bfin.md (addsubv2hi3, subaddv2hi3, ssaddsubv2hi3,
        sssubaddv2hi3):  Swap the order of operators in vec_concat.

Thanks again,
Roger
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