RFR (S): Failure after windows compiler upgrade

[Vladimir Kozlov]

Looks good.

Thanks,
Vladimir

On 4/27/15 7:10 AM, Nils Eliasson wrote:
> Hi,
>
> Please review this patch.
>
> The bug is caused by the instruction sequence generated by the visual studio compiler when casting a long to a float.
>
> Visual Studio 2013 has a new behavior where it defaults to generating code targeting SSE2 (and avoids x87). Compiling
> for a 64-bit target gives the same result as before. Compiling for 32bit VS2013 generates a call to _ltod3 (long2double)
> and then uses a sse2 instruction to cast it to a float. Casting the long to a double and then to a float gives a
> different result than casting directly to a float. This is true on all tested configurations. It is unclear why they
> just didn't use a MOVQ to load the long to an XMM register and then use the same cvtsi2ss as in the other configurations.
>
> To fix this we need to add the /arch:IA32 flag to all i586 windows builds. It looks like the IA32 option is ignored on
> 64-bit builds but we shouldn't count on that. A drawback is that this option also prevents any usage of SSE on the i586
> platform.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8077590
> Webrev: http://cr.openjdk.java.net/~neliasso/8077590/webrev.03/
>
> Regards
> Nils
>
>
>
>