[LLVMdev] SIGFPE generation

Dan Gohman gohman at apple.com
Fri Apr 9 15:44:52 PDT 2010

On Apr 9, 2010, at 2:52 PM, Sarah Thompson wrote:

> Just a quick question...
> I've been attempting to trap floating point badness by setting up a  
> SIGFPE handler. However, I'm not seeing it trigger, even for simple  
> test code that forces division by zero. I'm generating bitcode with  
> llvm-gcc and then executing it with a (modified) version of the  
> jitter, for reference.
> Is there any arcane magic necessary to turn on SIGFPE generation?

Most platforms default to "non-stop" mode, where floating-point
exceptions do not trap. The interfaces defined in <fenv.h> can be
used to query floating-point exceptions. Trapping on exceptions
can usually be enabled, though it requires platform-specific code.
See your platform's documentation for details.

Note that enabling traps can cause degraded performance, and it
can cause incompatibilities with library code that doesn't expect


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