RFR: 8255368: Math.exp() gives wrong result for large values on x86 32-bit platforms [v3]

[Joe Darcy]

On Mon, 9 Nov 2020 21:18:08 GMT, Xubo Zhang <github.com+58006833+xbzhang99 at openjdk.org> wrote:

>> Math.exp(10000) produces 0 instead of positive infinity on x86 32-bit platform. The reason was for some jmp instructions, it used jge instead of jae. Also changed movdqu to movsd as it was supposed to load a 64-bit number
>
> Xubo Zhang has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Merge branch 'JDK-8255368' of github.com:xbzhang99/bugfixes into JDK-8255368
>  - Added test cases for exp at the value of 1024 and 10000

test/jdk/java/lang/Math/WorstCaseTests.java line 117:

> 115:             {+0x1.1D5C2DAEBE367p4,      0x1.A8C02E974C314p25},
> 116:             {+0x1.C44CE0D716A1Ap4,      0x1.B890CA8637AE1p40},
> 117:             {+0x4.0p8,                  Double.POSITIVE_INFINITY}, //bug 8255368 gave 0

This is not an appropriate test to update to cover this bug. This test is specifically probing at difficult cases in double arithmetic for the underlying mathematically function as opposed to flaws in a particular implementation.

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PR: https://git.openjdk.java.net/jdk/pull/894