<html><head><base href="x-msg://2/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Feb 2, 2012, at 11:03 PM, Kodakara, Sreekumar V wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Optima; 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-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; font-size: medium; "><div lang="EN-US" link="blue" vlink="purple"><div class="WordSection1" style="page: WordSection1; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">Hi All,<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">I am using llvm-3.0 release version for compiling some files. I have a cpp file on which I did a few custom passes. After that I used llc to convert the *.bc file to *.s file at –O1 optimization level. llc took ~2630 seconds to perform this conversion. I timed llc and these are the top three passes that is taking most of the time.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "> <o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "> ---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name ---<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "> 1816.1735 ( 77.8%) 23.3215 ( 69.7%) 1839.4950 ( 77.6%) 1839.4132 ( 77.6%) Simple Register Coalescing<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "> 493.5948 ( 21.1%) 9.1846 ( 27.4%) 502.7794 ( 21.2%) 502.7681 ( 21.2%) X86 DAG->DAG Instruction Selection<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "> 5.7244 ( 0.2%) 0.0000 ( 0.0%) 5.7244 ( 0.2%) 5.7204 ( 0.2%) Machine Instruction LICM<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">I am running this in a fairly new Xeon server. Furthermore, at –O0, llc takes less than 20 seconds to complete. Is this behavior expected and is there a way to disable Simple Register Coalescing pass without switching to –O0 optimization level to get around this problem?</div></div></div></span></blockquote><div><br></div><div>Without coalescing you will get really bad code, but the llc option to turn it off is -join-intervals=0.</div><div><br></div><div>There is a good chance the performance problem has already been fixed on trunk.</div><div><br></div><div>/jakob</div><div><br></div></div></body></html>