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.
