RFR (S): 7174532: jdk/test/java/lang/Math/WorstCaseTests.java failing on x86 (original) (raw)

Vladimir Kozlov vladimir.kozlov at oracle.com
Thu Jun 7 10:45:12 PDT 2012

Roland Westrelin wrote:

Could you rename verifyctw() to verifyfpuctw() since there are other control words. Could you explain why it is only problem in VM 32-bit and add comment?

It's 32bit only because on 64 bit the fpu cw it set to extended precision (it seems to be the default for the process?). Do we want to extend verifyfpuctw() so it checks the control world on 64 bit as well? It's not checked anywhere else even though I think, in other places than exp and pow, we make assumptions about the control word on 64 bit (that uses the fpu won't trigger exceptions for instance). It's not that simple. We had the failure on windows-x64 (but not solaris-x64 or linux-x64). So something needs to be done on 64 bit as well.

Yes, windows may set different fpu_ctw. May be instead of verification we should save/restore current control word. I surprise that we don't have problems with Log and Trigonometric instructions.

An other thing to test is to run 32bit VM with UseSSE=0.

Thanks, Vladimir

Roland.

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