[Bug c/47644] New: [avr] Regression in choosing registers

[Kip.Hicit at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47644

           Summary: [avr] Regression in choosing registers
           Product: gcc
           Version: 4.3.3
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: Kip.Hicit@gmail.com


Created attachment 23275
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23275
Test case in C

Consider the following snippet compiled with -O3:

int lsl_short(int f) {
    return f << 1;
}

gcc 4.3.3 is copying the value from r25:r24 (first parameter) to r19:r18, then
moving back to r25:r24 (return value). Same for longs but with 4 registers.

Expected:
The lsl and rol should happen directly on r25:r24, just as they did in 4.2