Thorkil Naur wrote:
As I have already mentioned, I think my patch is a mistake. Depending on what anyone can tell me about the barton-mangler-bug, additional work would seem to go in one of two directions: If the floating point numbers are involved incidentally and the mangler bug still threatens, work should attempt to remove the floating point numbers from the output and produce a test case that exposes the bug more succinctly. I would certainly need some additional help to do this. On the other hand, if the floating point difference between, e.g., opt and normal is the real issue, it would still seem advantageous and quite possible to reduce the size of the test case, to make it easier to figure out the cause of the difference.
Sounds like we should modify the test to output floating point values to lesser precision, smoothing over the differences between implementations. Still, sometimes I really like to see these tiny differences: in one case I remember it pointed me to a fairly obscure problem in the x86_64 native code generator that resulted in floating point answers that were bogusly different from the via-C version. Cheers, Simon