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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi, This is a fix for #9165. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><a href="http://llvm.org/bugs/show_bug.cgi?id=9165">http://llvm.org/bugs/show_bug.cgi?id=9165</a><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The problem appeared between 2.7 and 2.8 and is still in the LLVM trunk.<o:p></o:p></p><p class=MsoNormal>After the 2.7 release some code was added in X86ISelLowering:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>// For SSE 4.1, use insertps to put the high elements into the low element. <o:p></o:p></p><p class=MsoNormal>if (getSubtarget()->hasSSE41()) {<o:p></o:p></p><p class=MsoNormal>...<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>This optimization created a new pattern, which was previously unexpected.<o:p></o:p></p><p class=MsoNormal>The pattern was a lowering of the BUILD_VECTOR operation to a sequence of<o:p></o:p></p><p class=MsoNormal>simple BUILD_VECTOR (all zero or undef) and a sequence of insert-elements. The<o:p></o:p></p><p class=MsoNormal>next stage, the DAGCombining, is the last stage before the instruction<o:p></o:p></p><p class=MsoNormal>selection. This phase found the new pattern and created a complex BUILD_VECTOR,<o:p></o:p></p><p class=MsoNormal>which was illegal. The last-phase dag-combining is only allowed to create legal<o:p></o:p></p><p class=MsoNormal>instructions. In my patch I added a check that the new pattern is only<o:p></o:p></p><p class=MsoNormal>optimized if we are in the LegalOperations mode, which is allowed to crate<o:p></o:p></p><p class=MsoNormal>illegal instructions such as the one we encountered. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Patch:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Index: DAGCombiner.cpp<o:p></o:p></p><p class=MsoNormal>===================================================================<o:p></o:p></p><p class=MsoNormal>--- DAGCombiner.cpp (revision 124985)<o:p></o:p></p><p class=MsoNormal>+++ DAGCombiner.cpp (working copy)<o:p></o:p></p><p class=MsoNormal>@@ -6377,7 +6377,8 @@<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal> // If the invec is a BUILD_VECTOR and if EltNo is a constant, build a new<o:p></o:p></p><p class=MsoNormal> // vector with the inserted element.<o:p></o:p></p><p class=MsoNormal>- if (InVec.getOpcode() == ISD::BUILD_VECTOR && isa<ConstantSDNode>(EltNo)) {<o:p></o:p></p><p class=MsoNormal>+ if (!LegalOperations && InVec.getOpcode() == ISD::BUILD_VECTOR &&<o:p></o:p></p><p class=MsoNormal>+ isa<ConstantSDNode>(EltNo)) {<o:p></o:p></p><p class=MsoNormal> unsigned Elt = cast<ConstantSDNode>(EltNo)->getZExtValue();<o:p></o:p></p><p class=MsoNormal> SmallVector<SDValue, 8> Ops(InVec.getNode()->op_begin(),<o:p></o:p></p><p class=MsoNormal> InVec.getNode()->op_end());<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div><font face="monospace">---------------------------------------------------------------------<br>
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