[Bug middle-end/88575] New: gcc got confused by different comparison operators

[bugzilla@poradnik-webmastera.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88575

            Bug ID: 88575
           Summary: gcc got confused by different comparison operators
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bugzilla@poradnik-webmastera.com
  Target Milestone: ---

In test() gcc is not able to determine that for a==b it does not have to
evaluate 2nd comparison and can use value of a if 1st comparison is true. When
operators are swapped like in test2() or are the same, code is optimized.

[code]
double test(double a, double b)
{
    if (a <= b)
        return a < b ? a : b;
    return 0.0;
}

double test2(double a, double b)
{
    if (a < b)
        return a <= b ? a : b;
    return 0.0;
}
[/code]

[asm]
test(double, double):
  vcomisd xmm1, xmm0
  jnb .L10
  vxorpd xmm0, xmm0, xmm0
  ret
.L10:
  vminsd xmm0, xmm0, xmm1
  ret

test2(double, double):
  vcmpnltsd xmm1, xmm0, xmm1
  vxorpd xmm2, xmm2, xmm2
  vblendvpd xmm0, xmm0, xmm2, xmm1
  ret
[/asm]