[Bug target/93453] New: PPC: rldimi not taken into account to avoid shift+or

[jens.seifert at de dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93453

            Bug ID: 93453
           Summary: PPC: rldimi not taken into account to avoid shift+or
           Product: gcc
           Version: 8.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jens.seifert at de dot ibm.com
  Target Milestone: ---

2 samples:

unsigned long long load8r(unsigned long long *in)
{
   return __builtin_bswap64(*in);
}

unsigned long long rldimi(unsigned int hi, unsigned int lo)
{
   return (((unsigned long long)hi) << 32) | ((unsigned long long)lo);
}

Command line:
gcc -maix64 -mcpu=power6 -save-temps -O2 rldimi.C 

Even if number range is known to not cause conflicts shift+or does not get
replaces by rldimi.

Output:
._Z6load8rPy:
LFB..0:
        addi 9,3,4
        lwbrx 3,0,3
        lwbrx 10,0,9
        sldi 10,10,32
        or 3,3,10
        blr

._Z6rldimijj:
LFB..1:
        sldi 3,3,32
        or 3,3,4
        blr