[Bug target/105325] power10: Error: operand out of range

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105325

--- Comment #17 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Michael Meissner <meissner@gcc.gnu.org>:

https://gcc.gnu.org/g:370de1488a9a49956c47e5ec8c8f1489b4314a34

commit r14-2049-g370de1488a9a49956c47e5ec8c8f1489b4314a34
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Fri Jun 23 11:32:39 2023 -0400

    Fix power10 fusion bug with prefixed loads, PR target/105325

    This changes fixes PR target/105325.  PR target/105325 is a bug where an
    invalid lwa instruction is generated due to power10 fusion of a load
    instruction to a GPR and an compare immediate instruction with the
immediate
    being -1, 0, or 1.

    In some cases, when the load instruction is done, the GCC compiler would
    generate a load instruction with an offset that was too large to fit into
the
    normal load instruction.

    In particular, loads from the stack might originally have a small offset,
so
    that the load is not a prefixed load.  However, after the stack is set up,
and
    register allocation has been done, the offset now is large enough that we
would
    have to use a prefixed load instruction.

    The support for prefixed loads did not consider that patterns with a fused
load
    and compare might have a prefixed address.  Without this support, the
proper
    prefixed load won't be generated.

    In the original code, when the split2 pass is run after reload has finished
the
    ds_form_mem_operand predicate that was used for lwa and ld no longer
returns
    true.  When the pattern was created, ds_form_mem_operand recognized the
insn as
    being valid since the offset was small.  But after register allocation,
    ds_form_mem_operand did not return true.  Because it didn't return true,
the
    insn could not be split.  Since the insn was not split and the prefix
support
    did not indicate a prefixed instruction was used, the wrong load is
generated.

    The solution involves:

        1)  Don't use ds_form_mem_operand for ld and lwa, always use
            non_update_memory_operand.

        2)  Delete ds_form_mem_operand since it is no longer used.

        3)  Use the "YZ" constraints for ld/lwa instead of "m".

        4)  If we don't need to sign extend the lwa, convert it to lwz, and use
            cmpwi instead of cmpdi.  Adjust the insn name to reflect the code
            generate.

        5)  Insure that the insn using lwa will be recognized as having a
prefixed
            operand (and hence the insn length will be 16 bytes instead of 8
            bytes).

            5a) Set the prefixed and maybe_prefix attributes to know that
                fused_load_cmpi are also load insns;

            5b) In the case where we are just setting CC and not using the
memory
                afterward, set the clobber to use a DI register, and put an
                explicit sign_extend operation in the split;

            5c) Set the sign_extend attribute to "yes" for lwa.

            5d) 5a-5c are the things that prefixed_load_p in rs6000.cc checks
to
                ensure that lwa is treated as a ds-form instruction and not as
                a d-form instruction (i.e. lwz).

        6)  Add a new test case for this case.

        7)  Adjust the insn counts in fusion-p10-ldcmpi.c.  Because we are no
            longer using ds_form_mem_operand, the ld and lwa instructions will
fuse
            x-form (reg+reg) addresses in addition ds-form (reg+offset or reg).

    2023-06-23   Michael Meissner  <meissner@linux.ibm.com>

    gcc/

            PR target/105325
            * config/rs6000/genfusion.pl (gen_ld_cmpi_p10_one): Fix problems
that
            allowed prefixed lwa to be generated.
            * config/rs6000/fusion.md: Regenerate.
            * config/rs6000/predicates.md (ds_form_mem_operand): Delete.
            * config/rs6000/rs6000.md (prefixed attribute): Add support for
load
            plus compare immediate fused insns.
            (maybe_prefixed): Likewise.

    gcc/testsuite/

            PR target/105325
            * g++.target/powerpc/pr105325.C: New test.
            * gcc.target/powerpc/fusion-p10-ldcmpi.c: Update insn counts.

    Co-Authored-By: Aaron Sawdey  <acsawdey@linux.ibm.com>