[Bug testsuite/109147] New: Missing IPA-VRP for return values

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109147

            Bug ID: 109147
           Summary: Missing IPA-VRP for return values
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: testsuite
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
                CC: david.spickett at linaro dot org, unassigned at gcc dot 
gnu.org
        Depends on: 109146
  Target Milestone: ---

+++ This bug was initially created as a clone of Bug #109146 +++

I guess we should turn this primarily into an enhancement request to optimize
this.
I believe that is a request for return value ranges in IPA-VRP.

So a testcase could be:
__attribute__((noinline)) static int
foo (int a, int b)
{
  return a == b;
}

int
bar (int a, int b)
{
  return foo (a, b) != 0;
}

__attribute__((noinline)) static int
baz (int a)
{
  if (a > 10 || a < -10)
    return 0;
  return a;
}

int
qux (int a)
{
  return baz (a) == 42;
}

where if we determine that foo always returns [0, 1] and baz [-10, 10], then we
can
optimize that return ret != 0; into return ret; and ret == 42 into 0.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109146
[Bug 109146] Tail call prevention in frame-address.c is not correct