[Bug target/93133] New: __builtin_isgreater emits trapping compare instruction

[kretz at kde dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93133

            Bug ID: 93133
           Summary: __builtin_isgreater emits trapping compare instruction
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kretz at kde dot org
  Target Milestone: ---
            Target: aarch64-*-*

Compile the following test case for aarch64 with -O2:

#include <cfenv>

int f(float x, float y)
{
  std::feclearexcept(FE_ALL_EXCEPT);
  int r = -__builtin_isgreater(x, y);
  if (std::fetestexcept(FE_ALL_EXCEPT) != 0)
    __builtin_abort();
  return r;
}

int main()
{
  float x = 0.f;
  return f(x / x, 1.f);
}

The __builtin_isgreater call is turned into a trapping fcmgt instruction. The
negation is necessary to trigger this issue. The same issue seems to exists for
all non-trapping compare functions.