[Bug target/72853] gcc/testsuite/gcc.c-torture/execute/20021120-1.c generates incorrect stxssp op with -mcpu=power9

["meissner at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72853

Michael Meissner <meissner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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  Attachment #39090|0                           |1
        is obsolete|                            |

--- Comment #4 from Michael Meissner <meissner at gcc dot gnu.org> ---
Created attachment 39092
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39092&action=edit
Proposed patch to fix the problem #2

I was looking at the wrong line of assembly in the previous patch.

This patches adds a check for the address being offsettable.  In the movdf
patterns, the ISA 3.0 d-form (reg+offset) address alternatives (stxsd, lxsd)
come before the ISA 2.06 x-form (reg+reg) alternatives (stxsdx, lxsdx).  So if
an indexed address using the Altivec regsiters is emitted when -mcpu=power9 is
used, the compiler will emit an illegal instruction.