[Bug target/96373] SVE miscompilation on vectorized division loop, leading to FP exception

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96373

--- Comment #19 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Richard Sandiford
<rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:e11513c7688f583d1f4d0961d79d8aa775add03d

commit r12-9384-ge11513c7688f583d1f4d0961d79d8aa775add03d
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Mon Apr 3 09:57:09 2023 +0100

    vect: Make partial trapping ops use predication [PR96373]

    PR96373 points out that a predicated SVE loop currently converts
    trapping unconditional ops into unpredicated vector ops.  Doing
    the operation on inactive lanes can then raise an exception.

    As discussed in the PR trail, we aren't 100% consistent about
    whether we preserve traps or not.  But the direction of travel
    is clearly to improve that rather than live with it.  This patch
    tries to do that for the SVE case.

    Doing this regresses gcc.target/aarch64/sve/fabd_1.c.  I've added
    -fno-trapping-math for now and filed PR108571 to track it.
    A similar problem applies to fsubr_1.c.

    I think this is likely to regress Power 10, since conditional
    operations are only available for masked loops.  I think we'll
    need to add -fno-trapping-math to any affected testcases,
    but I don't have a Power 10 system to test on.

    gcc/
            PR tree-optimization/96373
            PR tree-optimization/108979
            * tree-vect-stmts.cc (vectorizable_operation): Predicate trapping
            operations on the loop mask.  Reject partial vectors if this isn't
            possible.  Don't mask operations on invariants.

    gcc/testsuite/
            PR tree-optimization/96373
            PR tree-optimization/108571
            PR tree-optimization/108979
            * gcc.target/aarch64/sve/fabd_1.c: Add -fno-trapping-math.
            * gcc.target/aarch64/sve/fsubr_1.c: Likewise.
            * gcc.target/aarch64/sve/fmul_1.c: Expect predicate ops.
            * gcc.target/aarch64/sve/fp_arith_1.c: Likewise.
            * gfortran.dg/vect/pr108979.f90: New test.