RFR: 8255368: Math.exp() gives wrong result for large values on x86 32-bit platforms [v5]

[Joe Darcy]

On Wed, 11 Nov 2020 20:39:14 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 refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR.

Marked as reviewed by darcy (Reviewer).

test/jdk/java/lang/Math/ExpCornerCaseTests.java line 2:

> 1: /*
> 2:  * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.

Before pushing, [lease update the copyright year to "2011, 2020" (since this file was based on one from 2020).

test/jdk/java/lang/Math/ExpCornerCaseTests.java line 28:

> 26:  * @bug 8255368
> 27:  * @summary Tests corner cases of Math.exp
> 28:  * @author Xubo Zhang

We don't use @author tags on new tests, but haven't removed from old tests.

src/hotspot/cpu/x86/macroAssembler_x86_exp.cpp line 593:

> 591:   jmp(L_2TAG_PACKET_2_0_2);
> 592:   cmpl(ecx, INT_MIN);
> 593:   jcc(Assembler::below, L_2TAG_PACKET_3_0_2);

If all the changed instructions are not covered by the two test arguments, please add additional values to the test covering the other instructions.

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