<html><head><base href="x-msg://371/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Wrong link. I'm talking C not C++.<div><br></div><div>Here's the C link:</div><div><br></div><div><a href="http://www.open-std.org/JTC1/SC22/wg14/www/docs/n1425.pdf">http://www.open-std.org/JTC1/SC22/wg14/www/docs/n1425.pdf</a></div><div><br></div><div>PS I am shortly about to change the specs on compare exchange in M3CG_Ops.i3. Stay tuned.</div><div><br></div><div><br><div>
<span class="Apple-style-span" style="font-size: 12px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div><font class="Apple-style-span" color="#0000FF"><font class="Apple-style-span" face="Gill Sans"><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; "><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; ">Antony Hosking</span></span></font></font><font class="Apple-style-span" face="Gill Sans"><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-converted-space"> </span>|<span class="Apple-converted-space"> </span></span></span><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; ">Associate Professor</span></span><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; "> | Computer Science | Purdue University</span></span></font></div><div><font class="Apple-style-span" face="GillSans-Light"><span class="Apple-style-span" style="font-family: GillSans-Light; ">305 N. University Street | West Lafayette | IN 47907 | USA</span></font></div><div><font class="Apple-style-span" color="#0000FF" face="Gill Sans"><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; "><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; ">Office</span></span></font><font class="Apple-style-span" face="GillSans-Light"><span class="Apple-style-span" style="font-family: GillSans-Light; "><span class="Apple-style-span" style="font-family: GillSans-Light; "> +1 765 494 6001 |<span class="Apple-converted-space"> </span></span></span></font><font class="Apple-style-span" color="#0000FF" face="Gill Sans"><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; "><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; ">Mobile</span></span></font><font class="Apple-style-span" face="GillSans-Light"><span class="Apple-style-span" style="font-family: GillSans-Light; "><span class="Apple-style-span" style="font-family: GillSans-Light; "><span class="Apple-converted-space"> </span>+1 765 427 5484</span></span></font></div><div><font class="Apple-style-span" face="GillSans-Light"><br class="khtml-block-placeholder"></font></div></span></span></span></span></span></span></span><br class="Apple-interchange-newline"></span></div></span><br class="Apple-interchange-newline">
</div>
<br><div><div>On 21 Jan 2010, at 17:30, Jay K wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">ok.<br> <br>But notice that they offer both forms really since they also have "modifying asignment operators".<br>Is that useful/possible to expose?<br> <br><br><a href="http://www.open-std.org/jtc1/sc22/WG21/docs/papers/2007/n2145.html">http://www.open-std.org/jtc1/sc22/WG21/docs/papers/2007/n2145.html</a><br> <br><br>"The fetch-and-operation functions return the original stored value. This approach is required for fetch-and-inclusive-or and fetch-and-and because there is no means to compute to the original stored value. In contrast to the core functions, the modifying assignment operators return the new value. We do this for consistency with normal assignment operators. Unlike normal assignment operators, though, the atomic assignments return values rather than references. The reason is that another thread might intervene between an assignment and a subsequent read. Rather than introduce this classic parallel programming bug, we return a value. "<br> <br><br>For now I'll probably just expose add, sub, xor, but not or and and.<br>We can do them later via a compareexchange loop (see winbase.h which<br>does something similar for different reasons: lack of intrinsics).<br> <br><br>Still a ways away from calling this done, because modifying<br>m3x86.m3 so far requires a lot of guessing/patternmatching.<br>I don't understand e.g. what "locked" means (not the<br>one I introduced, what was there).<br> <br><br> - Jay<br><br> <br><hr id="stopSpelling">From:<span class="Apple-converted-space"> </span><a href="mailto:hosking@cs.purdue.edu">hosking@cs.purdue.edu</a><br>Date: Thu, 21 Jan 2010 09:23:59 -0500<br>To:<span class="Apple-converted-space"> </span><a href="mailto:jay.krell@cornell.edu">jay.krell@cornell.edu</a><br>CC:<span class="Apple-converted-space"> </span><a href="mailto:m3devel@elegosoft.com">m3devel@elegosoft.com</a><br>Subject: Re: [M3devel] fetch_and_op?<br><br>I want to implement the <cstdatomic.h> soon-to-be standard. That is defined as fetch_and_op.<div><br><div><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><div style="word-wrap: break-word; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><div><font class="ecxApple-style-span" color="#0000ff"><font class="ecxApple-style-span" face="Gill Sans"><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); ">Antony Hosking</span></span></font></font><font class="ecxApple-style-span" face="Gill Sans"><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-converted-space"> </span>|<span class="ecxApple-converted-space"> </span></span></span><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; ">Associate Professor</span></span><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "> | Computer Science | Purdue University</span></span></font></div><div><font class="ecxApple-style-span" face="GillSans-Light"><span class="ecxApple-style-span" style="font-family: GillSans-Light; ">305 N. University Street | West Lafayette | IN 47907 | USA</span></font></div><div><font class="ecxApple-style-span" color="#0000ff" face="Gill Sans"><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); ">Office</span></span></font><font class="ecxApple-style-span" face="GillSans-Light"><span class="ecxApple-style-span" style="font-family: GillSans-Light; "><span class="ecxApple-style-span" style="font-family: GillSans-Light; "> <skype:span id="softomate_v3_highlight_0" class="skype_v3_tb_injection" title="Call this phone number in United States of America with Skype: +17654946001" skypeid="0" skypeaction="call" nof="" isfax="" freecall="" fwidth=".w16" type=".flex" mode=".compat" path="file://C:/Users/jay/Temp/__SkypeIEToolbar_Cache/e70d95847a8f5723cfca6b3fd9946506/static/" durex2="%DADDYHEIGHT%" durex="%DADDYWIDTH%" context="+1 765 494 6001"><skype:span id="skype_v3_tb_droppart_0" class="skype_v3_tb_imgA" title="Skype actions" skypeid="0" skypeaction="drop" skypesms="0" style="background-image: url(file://C:/Users/jay/Temp/__SkypeIEToolbar_Cache/e70d95847a8f5723cfca6b3fd9946506/static/inactive_a.compat.flex.w16.gif); "><skype:span id="skype_v3_tb_img_f0" class="skype_v3_tb_imgFlag" style="background-image: url(file://C:/Users/jay/Temp/__SkypeIEToolbar_Cache/e70d95847a8f5723cfca6b3fd9946506/static/famfamfam/US.gif); "></skype:span></skype:span><skype:span id="skype_v3_tb_img_s0" class="skype_v3_tb_imgS"></skype:span><skype:span id="skype_v3_tb_text0" class="skype_v3_tb_injectionIn"><skype:span id="skype_v3_tb_innerText0" class="skype_v3_tb_innerText"> +1 765 494 6001 </skype:span></skype:span><skype:span id="skype_v3_tb_img_r0" class="skype_v3_tb_imgR"></skype:span></skype:span><span class="Apple-converted-space"> </span><skype:span id="softomate_v3_print_0" class="skype_v3_tb_injection_print" context="">+1 765 494 6001</skype:span><span class="Apple-converted-space"> </span>|<span class="ecxApple-converted-space"> </span></span></span></font><font class="ecxApple-style-span" color="#0000ff" face="Gill Sans"><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); ">Mobile</span></span></font><font class="ecxApple-style-span" face="GillSans-Light"><span class="ecxApple-style-span" style="font-family: GillSans-Light; "><span class="ecxApple-style-span" style="font-family: GillSans-Light; "><span class="ecxApple-converted-space"> </span><skype:span id="softomate_v3_highlight_1" class="skype_v3_tb_injection" title="Call this phone number in United States of America with Skype: +17654275484" skypeid="1" skypeaction="call" nof="" isfax="" freecall="" fwidth=".w16" type=".flex" mode=".compat" path="file://C:/Users/jay/Temp/__SkypeIEToolbar_Cache/e70d95847a8f5723cfca6b3fd9946506/static/" durex2="%DADDYHEIGHT%" durex="%DADDYWIDTH%" context="+1 765 427 5484"><skype:span id="skype_v3_tb_droppart_1" class="skype_v3_tb_imgA" title="Skype actions" skypeid="1" skypeaction="drop" skypesms="1" style="background-image: url(file://C:/Users/jay/Temp/__SkypeIEToolbar_Cache/e70d95847a8f5723cfca6b3fd9946506/static/inactive_a.compat.flex.w16.gif); "><skype:span id="skype_v3_tb_img_f1" class="skype_v3_tb_imgFlag" style="background-image: url(file://C:/Users/jay/Temp/__SkypeIEToolbar_Cache/e70d95847a8f5723cfca6b3fd9946506/static/famfamfam/US.gif); "></skype:span></skype:span><skype:span id="skype_v3_tb_img_s1" class="skype_v3_tb_imgS"></skype:span><skype:span id="skype_v3_tb_text1" class="skype_v3_tb_injectionIn"><skype:span id="skype_v3_tb_innerText1" class="skype_v3_tb_innerText"> +1 765 427 5484 </skype:span></skype:span><skype:span id="skype_v3_tb_img_r1" class="skype_v3_tb_imgR"></skype:span></skype:span><span class="Apple-converted-space"> </span><skype:span id="softomate_v3_print_1" class="skype_v3_tb_injection_print" context="">+1 765 427 5484</skype:span></span></span></font></div><div><font class="ecxApple-style-span" face="GillSans-Light"><br class="ecxkhtml-block-placeholder"></font></div></span></span></span></span></span></span></span><br class="ecxApple-interchange-newline"></span></div></span></span><br class="ecxApple-interchange-newline"></div><br><div><div>On 21 Jan 2010, at 08:29, Jay K wrote:</div><br class="ecxApple-interchange-newline"><blockquote><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal medium/normal Helvetica; white-space: normal; letter-spacing: normal; word-spacing: 0px; "><div class="ecxhmmessage" style="font-family: Verdana; font-size: 10pt; ">(* tmp := Mem [s1.A].t;<br> Mem [s1.A].t := tmp op s0.u;<br> s1.u := tmp; pop *)<br><br><br>Tony, are you sure you want to return the old value, not the new value?<br>That's not great on x86.<br>I believe for "or" and "and", you end up having to do a compare exchange loops.<br> <br> <br>For xor, add, sub, you can compute the old value, ok.<br>But if caller wanted the old value, he can do that himself also.<br>Caller can also write a compare_exchange loop.<br> <br> <br>Therefore, I think it should be:<br> <br>(* tmp := Mem [s1.A].t;<br> Mem [s1.A].t := tmp op s0.u;<br> s1.u := tmp op s0.u; pop *)<br><br>There is of course value in storing the value in mem and stack, since mem<br>can change right away.<br> <br> <br> - Jay<br><br></div></span></blockquote></div><br></div></div></span><br class="Apple-interchange-newline"></blockquote></div><br></div></body></html>