[Bug target/87033] New: The compiler does not generate the LWAX instruction

[meissner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87033

            Bug ID: 87033
           Summary: The compiler does not generate the LWAX instruction
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

Created attachment 44566
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44566&action=edit
Simple test case to show the bug

The compiler does not generate LWAX instruction to load up a 32-bit integer
value and sign extend it to 64-bits.  This is due to the constraint for
extendsi<mode>2 for the LWA being just 'Y' (offset addressing using DS mode
instruction format) and it should be 'YZ'.