<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"><base href="x-msg://13397/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Oct 17, 2012, at 3:33 PM, "Gurd, Preston" <<a href="mailto:preston.gurd@intel.com">preston.gurd@intel.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div lang="EN-US" link="blue" vlink="purple" style="font-family: Helvetica; font-size: medium; 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; "><div class="WordSection1" style="page: WordSection1; "><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">When you compile the attached file using<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "> <span class="Apple-converted-space"> </span><span style="font-family: 'Courier New'; ">llc -march=x86 -mcpu=atom sched-bug.ll -o –<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">The Post-RA scheduler changes the sequence<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span style="font-family: 'Courier New'; ">movl %ecx, (%esp)<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-family: 'Courier New'; "> bsfl (%esp),%eax # this came from inline assembly code</span><o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">to read<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "> <span class="Apple-converted-space"> </span><span style="font-family: 'Courier New'; ">bsfl (%esp),%eax # this came from inline assembly code<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><span style="font-family: 'Courier New'; ">movl %ecx, (%esp)<o:p></o:p></span></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: 0.5in; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">This is an incorrect schedule, because it seems the scheduler is not aware that the memory load by the<span class="Apple-converted-space"> </span><span style="font-family: 'Courier New'; ">bsfl</span><span class="Apple-converted-space"> </span>depends on the memory store by the<span class="Apple-converted-space"> </span><span style="font-family: 'Courier New'; ">movl</span>.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; ">If you are familiar with the Post-RA scheduler works, then I would appreciate any suggestions you might have as to how I could fix this problem, such as by treating inline assembly code as a barrier or by including memory references in scheduling decisions.<o:p></o:p></div><div style="margin: 0in 0in 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div></div></div></blockquote><br></div><div>Hi Preston,</div><div><br></div><div>Someone pointed me to a bug filed for this: <a href="http://llvm.org/PR13504">http://llvm.org/PR13504</a>.</div><div><br></div><div>Maybe you can add a memory clobber as a workaround.</div><div><br></div><div>-Andy</div><div><br></div></body></html>