<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Jan 31, 2012, at 11:42 PM, Andrew Trick <<a href="mailto:atrick@apple.com">atrick@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><base href="x-msg://684/"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>On Jan 31, 2012, at 7:18 AM, Sergei Larin <<a href="mailto:slarin@codeaurora.org">slarin@codeaurora.org</a>> wrote:</div><blockquote type="cite"><div bgcolor="white" lang="EN-US" link="blue" vlink="purple" style="color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div class="WordSection1" style="page: WordSection1; "><br><div><div style="border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; border-image: initial; border-top-style: solid; border-top-color: rgb(181, 196, 223); border-top-width: 1pt; padding-top: 3pt; padding-right: 0in; padding-bottom: 0in; padding-left: 0in; position: static; z-index: auto; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; color: windowtext; ">From:</span></b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; color: windowtext; "><span class="Apple-converted-space"> </span><a href="mailto:llvm-commits-bounces@cs.uiuc.edu" style="color: purple; text-decoration: underline; ">llvm-commits-bounces@cs.uiuc.edu</a><span class="Apple-converted-space"> </span>[mailto:llvm-commits-bounces@cs.uiuc.edu]<span class="Apple-converted-space"> </span><b>On Behalf Of<span class="Apple-converted-space"> </span></b>Sergei Larin<br><b>Sent:</b><span class="Apple-converted-space"> </span>Friday, January 27, 2012 10:47 AM<br><b>To:</b><span class="Apple-converted-space"> </span><a href="mailto:llvm-commits@cs.uiuc.edu" style="color: purple; text-decoration: underline; ">llvm-commits@cs.uiuc.edu</a><br><b>Subject:</b><span class="Apple-converted-space"> </span>[llvm-commits] Hexagon VLIW instruction scheduler framework patch for review<o:p></o:p></span></div></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><o:p> </o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "> Hello everybody,<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><o:p> </o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "> Attached is initial patch for a VLIW specific scheduler framework that utilizes deterministic finite automaton (DFA) .<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><o:p> </o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">Several key points:<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 20.25pt; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; text-indent: -0.25in; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><span>-<span style="font-family: 'Times New Roman'; font-size: 7pt; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; "> <span class="Apple-converted-space"> </span></span></span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">The scheduler is largely based on the existing framework, but introduces several VLIW specific concepts. It could be classified as a top down list scheduler, critical path first, with DFA used for parallel resources modeling. It also models and tracks register pressure in the way similar to the current RegPressure scheduler. It employs a slightly different way to compute “cost” function for all SUs in AQ which allows for somewhat easier balancing of multiple heuristic inputs. Current version does _<i>not</i>_ generates bundles/packets (but models them internally). It could be easily modified to do so, and it is our plan to make it a part of bundle generation in the near future.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 20.25pt; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; text-indent: -0.25in; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><span>-<span style="font-family: 'Times New Roman'; font-size: 7pt; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; "> <span class="Apple-converted-space"> </span></span></span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">The scheduler is enabled for the Hexagon backend. Comparing to any existing scheduler, for this VLIW target this code produces between 1.9% slowdown and 11% speedup on our internal test suite. This test set comprised from a variety of real world applications ranging from DSP specific applications to SPEC. Some DSP kernels (when taken out of context) enjoy up to 20% speedup when compared to the “default” scheduling mechanism (RegPressure pre-RA + post RA). Main reason for this kind of corner case behavior is long chains of independent memory accesses that are conservatively serialized by the default scheduler (and there is no HW scheduler to sort it out at the run time).<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 20.25pt; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; text-indent: -0.25in; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><span>-<span style="font-family: 'Times New Roman'; font-size: 7pt; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; "> <span class="Apple-converted-space"> </span></span></span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">This patch is an initial submission with a bare minimum of features, and more heuristics will be added to it later. We prefer to submit it in stages to simplify review process and improve SW management.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 20.25pt; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; text-indent: -0.25in; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><span>-<span style="font-family: 'Times New Roman'; font-size: 7pt; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; "> <span class="Apple-converted-space"> </span></span></span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">Patch also contains minor updates to two Hexagon specific tests in order to compensate for new order of instructions generated by the Hexagon backend __with scheduler disabled__.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 20.25pt; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; text-indent: -0.25in; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><span>-<span style="font-family: 'Times New Roman'; font-size: 7pt; font-style: normal; font-variant: normal; font-weight: normal; line-height: normal; "> <span class="Apple-converted-space"> </span></span></span></span><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">SVN revision 149130. LLVM verification test run for x86 platform detects no additional failures.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><o:p> </o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; color: black; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "> Comments and reviews are eagerly anticipated<span class="Apple-converted-space"> </span></span><span style="font-size: 11pt; font-family: Wingdings; color: rgb(31, 73, 125); ">J</span></div></div></div></blockquote></div></div></blockquote><div><br></div>Sergei,</div><div><br></div><div>Let me know if these superficial changes are ok with you, and I'll commit (or if you can commit, go ahead):<br><br></div><div></div></body></html>