DBL_DENORM_MIN should never be 0

Joseph S. Myers joseph@codesourcery.com
Wed Sep 10 16:42:00 GMT 2014


On Wed, 10 Sep 2014, Marc Glisse wrote:

> Hello,
> 
> according to the C++ standard, numeric_limits::denorm_min should return min
> (not 0) when there are no denormals.
> 
> Tested with bootstrap+testsuite on x86_64-linux-gnu. I also tested a basic
> make all-gcc for vax (only target without denormals apparently) and the macro
> did change as expected.
> 
> The next step might be to define has_denorm as false in more cases (-mno-ieee
> on alpha, -ffast-math on x86, etc) but that's a different issue.
> 
> (this is C++ but I believe Joseph is the floating-point expert, hence the cc)

This is a C issue as well (for C11 *_TRUE_MIN).

> gcc/c-family/
> 
> 2014-09-10  Marc Glisse  <marc.glisse@inria.fr>
> 

	PR target/58757

> 	* c-cppbuiltin.c (builtin_define_float_constants): Correct
> 	__*_DENORM_MIN__ without denormals.

I think there should be some sort of testcase that these values aren't 0.

-- 
Joseph S. Myers
joseph@codesourcery.com



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