From 7fc4d9cbc54c2e5393440a40b566c1f0527d8037 Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Fri, 4 May 2012 22:53:28 +0000 Subject: [PATCH] Make sure findRepresentativeClass picks the widest super-register. We want the representative register class to contain the largest super-registers available. This makes the function less sensitive to the register class numbering. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156220 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/TargetLowering.cpp | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp index 77aa0073e70..5132f01e866 100644 --- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -719,18 +719,22 @@ TargetLowering::findRepresentativeClass(EVT VT) const { return std::make_pair(RC, 0); // Compute the set of all super-register classes. - // Include direct sub-classes of RC in case there are no super-registers. BitVector SuperRegRC(TRI->getNumRegClasses()); - for (SuperRegClassIterator RCI(RC, TRI, true); RCI.isValid(); ++RCI) + for (SuperRegClassIterator RCI(RC, TRI); RCI.isValid(); ++RCI) SuperRegRC.setBitsInMask(RCI.getMask()); - // Find the first legal register class in the set. + // Find the first legal register class with the largest spill size. + const TargetRegisterClass *BestRC = RC; for (int i = SuperRegRC.find_first(); i >= 0; i = SuperRegRC.find_next(i)) { const TargetRegisterClass *SuperRC = TRI->getRegClass(i); - if (isLegalRC(SuperRC)) - return std::make_pair(SuperRC, 1); + // We want the largest possible spill size. + if (SuperRC->getSize() <= BestRC->getSize()) + continue; + if (!isLegalRC(SuperRC)) + continue; + BestRC = SuperRC; } - llvm_unreachable("Inconsistent register class tables."); + return std::make_pair(BestRC, 1); } /// computeRegisterProperties - Once all of the register classes are added,