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List: openjdk-2d-dev
Subject: Re: [OpenJDK 2D-Dev] [9] RFR of 5100935: No way to access the 64-bit integer multiplication of 64-bi
From: Brian Burkhalter <brian.burkhalter () oracle ! com>
Date: 2015-09-21 18:15:03
Message-ID: AFAC1F0A-D393-4191-ABDD-C42862A24CED () oracle ! com
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Hello, Sergey,
On Sep 19, 2015, at 12:51 PM, Sergey Bylokhov <Sergey.Bylokhov@oracle.com> wrote:
> Hello, I have a related question about the adding of methods to the Math class. \
> Some methods **Exact methods were added to the Math class in jdk8, which throws an \
> exceptions in case of overflow. Is it possible to add the similar saturation \
> arithmetic? It would be quite good to realize a full range of these methods, and \
> give the chance to hotspot to use an intrinsic.
If there are particular methods of interest and there are no corresponding issues on \
file, then one or more issues should be filed in the Java Bug System so that we may \
consider and track them according to the usual process. As there is currently an \
attempt to address some of the omissions in the Math area, now would be a good time \
to get these issues on record. So I suggest that the interested parties do just that. \
I think that one issue containing several method requests would be sufficient if it \
concerns the same area of code.
As to the compiler intrinsics, we are looking into adding a few math-related things \
here as well. This would be tracked by a separate issue which we would file \
ourselves.
Regards,
Brian
> This is mostly request from the java2d team:
>
> http://mail.openjdk.java.net/pipermail/core-libs-dev/2008-December/000954.html
> "I currently use an utility-class heavily for the XRender Java2D
> backend, which performs saturated casts:
>
> 1.) return (short) (x > Short.MAX_VALUE ? Short.MAX_VALUE : (x <
> Short.MIN_VALUE ? Short.MIN_VALUE : x));
> 2.) return (short) (x > 65535 ? 65535 : (x < 0) ? 0 : x);
>
> I spent quite some time benchmarking/tuning the
> protocol-generation-methods, and a lot of cycles are spent in those
> saturated casts, even if the utility methods are static.
> E.g. XRenderFillRectangle takes 40 cycles without clamping, but
> already 70 cycles with on my core2duo with hotspot-server/jdk 14.0.
> Hotspot seems to solve the problem always with conditional jumps,
> although well predictable ones.
>
> Modern processors seem to have support for this kind of operation, in
> x86 there's packssdw in MMX/SSE2.
> I think something like a saturated cast could be quite useful, there
> are already cast-methods in Long/Integer/Short - what do you think
> about adding saturated casts to that API?
> Those could be instrified to use MMX/SSE2 if available.
>
> If that would be too specific how hard would it be to add this kind of
> optimization to hotspot?
> How far does SIMD support in hotspot go (I read some time ago there've
> been some optimizations), if SIMD would be supported 4 casts could be
> done in a single cycle :)
[Attachment #3 (unknown)]
<html><head><meta http-equiv="Content-Type" content="text/html \
charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: \
space; -webkit-line-break: after-white-space;">Hello, Sergey,<div><br><div><div>On \
Sep 19, 2015, at 12:51 PM, Sergey Bylokhov <<a \
href="mailto:Sergey.Bylokhov@oracle.com">Sergey.Bylokhov@oracle.com</a>> \
wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; \
display: inline !important;">Hello, I have a related question about the adding of \
methods to the Math class. Some methods **Exact methods were added to the Math class \
in jdk8, which throws an exceptions in case of overflow. Is it possible to add the \
similar saturation arithmetic? It would be quite good to realize a full range of \
these methods, and give the chance to hotspot to use an intrinsic.</span><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;"></blockquote><div><br></div><div>If there are particular methods of interest \
and there are no corresponding issues on file, then one or more issues should be \
filed in the Java Bug System so that we may consider and track them according to the \
usual process. As there is currently an attempt to address some of the omissions in \
the Math area, now would be a good time to get these issues on record. So I suggest \
that the interested parties do just that. I think that one issue containing several \
method requests would be sufficient if it concerns the same area of \
code.</div><div><br></div><div>As to the compiler intrinsics, we are looking into \
adding a few math-related things here as well. This would be tracked by a separate \
issue which we would file \
ourselves.</div><div><br></div><div>Regards,</div><div><br></div><div>Brian</div><br><blockquote \
type="cite"><span style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
float: none; display: inline !important;">This is mostly request from the java2d \
team:</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;"><br style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;"><a href="http://mail.openjdk.java.net/pipermail/core-libs-dev/2008-December/000954.html" \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;">http://mail.openjdk.java.net/pipermail/core-libs-dev/2008-December/000954.html</a><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; \
display: inline !important;">"I currently use an utility-class heavily for the \
XRender Java2D</span><br style="font-family: Helvetica; font-size: 12px; font-style: \
normal; font-variant: normal; font-weight: normal; letter-spacing: normal; \
line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px;"><span style="font-family: Helvetica; font-size: \
12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px; float: none; display: inline !important;">backend, \
which performs saturated casts:</span><br style="font-family: Helvetica; font-size: \
12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px;"><br style="font-family: Helvetica; font-size: 12px; \
font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px;"><span style="font-family: Helvetica; font-size: \
12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px; float: none; display: inline !important;">1.) return \
(short) (x > Short.MAX_VALUE ? Short.MAX_VALUE : (x <</span><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; \
display: inline !important;">Short.MIN_VALUE ? Short.MIN_VALUE : x));</span><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; \
display: inline !important;">2.) return (short) (x > 65535 ? 65535 : (x < 0) ? \
0 : x);</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;"><br style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;"><span style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
float: none; display: inline !important;">I spent quite some time benchmarking/tuning \
the</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;"><span style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
float: none; display: inline !important;">protocol-generation-methods, and a lot of \
cycles are spent in those</span><br style="font-family: Helvetica; font-size: 12px; \
font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px;"><span style="font-family: Helvetica; font-size: \
12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px; float: none; display: inline !important;">saturated \
casts, even if the utility methods are static.</span><br style="font-family: \
Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: \
normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: \
start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; \
word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span style="font-family: \
Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: \
normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: \
start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; \
word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline \
!important;">E.g. XRenderFillRectangle takes 40 cycles without clamping, \
but</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: \
0px;"><span style="font-family: Helvetica; font-size: 12px; font-style: normal; \
font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: \
normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
float: none; display: inline !important;">already 70 cycles with on my core2duo with \
hotspot-server/jdk 14.0.</span><br style="font-family: Helvetica; font-size: 12px; \
font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px;"><span style="font-family: Helvetica; font-size: \
12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px; float: none; display: inline !important;">Hotspot \
seems to solve the problem always with conditional jumps,</span><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; \
display: inline !important;">although well predictable ones.</span><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; \
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; \
display: inline !important;">Modern processors seem to have support for this kind of \
operation, in</span><br style="font-family: Helvetica; font-size: 12px; font-style: \
normal; font-variant: normal; font-weight: normal; letter-spacing: normal; \
line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px;"><span style="font-family: Helvetica; font-size: \
12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px; float: none; display: inline !important;">x86 there's \
packssdw in MMX/SSE2.</span><br style="font-family: Helvetica; font-size: 12px; \
font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px;"><span style="font-family: Helvetica; font-size: \
12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: \
normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; \
text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; \
-webkit-text-stroke-width: 0px; float: none; display: inline !important;">I think \
something like a saturated cast could be quite useful, there</span><br \
style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: \
normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: \
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