[Bug c/70742] New: Add a builtin for obtaining a quotient and remainder of an integer division

["daniel.gutson at tallertechnologies dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70742

            Bug ID: 70742
           Summary: Add a builtin for obtaining a quotient and remainder
                    of an integer division
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: daniel.gutson at tallertechnologies dot com
  Target Milestone: ---

Created attachment 38318
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38318&action=edit
example with disassembly listing

This idea has been originated here
https://sourceware.org/ml/libc-alpha/2016-04/msg00503.html
and later from here
https://sourceware.org/bugzilla/show_bug.cgi?id=19974

Due to suggestions in both the libc-alpha mailing list and in the glibc issue
tracker, I created this issue here as a compiler enhencement.

Basically the idea is to create the __builtin_div builtins family, so they
finally get translated to a single asm insn (if available) that calculates both
the quotient and the remainder. I attach the same file that is attached in the
glibc's bug tracker.

The goal is that std::div and cstdlib's div can be reimplemented as calling
this builtin.