[Bug debug/65997] New: -mregparm=3 causes bad DWARF debug info

["hjl.tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65997

            Bug ID: 65997
           Summary: -mregparm=3 causes bad DWARF debug info
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---
            Target: x86

On Linux/x86, I got

[hjl@gnu-6 gcc]$ cat /tmp/x.c
typedef unsigned int size_t;
void
bzero(void *b , size_t length)
{
  char *ptr = (char *)b;
  while (length--)
    *ptr++ = 0;
}
[hjl@gnu-6 gcc]$ /usr/gcc-5.1.1/bin/gcc  -m32  -O2 -g /tmp/x.i -c -o /tmp/x.o 
-mregparm=3  
[hjl@gnu-6 gcc]$ readelf -w /tmp/x.o >! /dev/null
readelf: Warning: There are 44 unused bytes at the end of section .zdebug_loc
readelf: Error: '/dev/null' is not an ordinary file
[hjl@gnu-6 gcc]$ /usr/gcc-5.1.1/bin/gcc  -m32  -O2 -g /tmp/x.i -c -o /tmp/x.o 
[hjl@gnu-6 gcc]$ readelf -w /tmp/x.o >! /dev/null
readelf: Error: '/dev/null' is not an ordinary file
[hjl@gnu-6 gcc]$