------- Comment #3 from hjl dot tools at gmail dot com 2010-08-21 04:10 ------- (In reply to comment #2) > How are they are not commutative with respect of the NaNs? Is it only when > both are operands are NaNs, it causes an issue? > > > If I read your testcase correctly, x87 and SSE both don't do IEEE FP correctly > with respect of NaNs. For multiply and add if either operand is a NaN, the > result is also a NaN IIRC.
The difference is QNaN and SNaN. They are both NaNs, but not the same. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45365
