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<p class="MsoNormal"><span lang="EN-GB">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I find it’s quite strange how condition dependent instructions are processed in PeepholeOptimizer::runOnMachineFunction:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01577 if ((isUncoalescableCopy(*MI) &&<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01578 optimizeUncoalescableCopy(MI, LocalMIs)) ||<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01579 (MI->isCompare() && optimizeCmpInstr(MI, &MBB)) ||<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01580 (MI->isSelect() && optimizeSelect(MI, LocalMIs))) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01581 // MI is deleted.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01582 LocalMIs.erase(MI);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01583 Changed = true;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01584 continue;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01585 }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01586 <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01587 if (MI->isConditionalBranch() && optimizeCondBranch(MI)) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01588 Changed = true;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01589 continue;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">01590 }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">CmpInstr, SelectInstr and CondBranch are processed separately. It’s assumed that CmpInstr and SelectInstr are deleted but CondBranch is not.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">In fact CmpInstr is always connected to SelectInstr or CondBranch or both of them. So if such connection exists it should be processed as a whole.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">For example, there are cases when CMP+BRC can be replaced by BR. The same is true for CMP+SEL.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">The main problem I have is that I have to find corresponding CmpInstr and to repeat analysis of it in optimizeSelect and in optimizeCondBranch.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Any thoughts why it’s implemented in such way.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Evgeny Astigeevich<o:p></o:p></span></p>
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