From 036be2d1860dae2ddc95fce1d5a73500806e8ed3 Mon Sep 17 00:00:00 2001 From: Stanislav Mekhanoshin Date: Wed, 1 Feb 2017 01:18:36 +0000 Subject: [PATCH] Fix regalloc assignment of overlapping registers SplitEditor::defFromParent() can create a register copy. If register is a tuple of other registers and not all lanes are used a copy will be done on a full tuple regardless. Later register unit for an unused lane will be considered free and another overlapping register tuple can be assigned to a different value even though first register is live at that point. That is because interference only look at liveness info, while full register copy clobbers all lanes, even unused. This patch fixes copy to only cover used lanes. Differential Revision: https://reviews.llvm.org/D29105 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293728 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SplitKit.cpp | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp index 1c6a84e5394..68999240355 100644 --- a/lib/CodeGen/SplitKit.cpp +++ b/lib/CodeGen/SplitKit.cpp @@ -522,6 +522,27 @@ VNInfo *SplitEditor::defFromParent(unsigned RegIdx, Def = LIS.getSlotIndexes() ->insertMachineInstrInMaps(*CopyMI, Late) .getRegSlot(); + if (LI->hasSubRanges()) { + LaneBitmask LM = LaneBitmask::getNone(); + for (LiveInterval::SubRange &S : LI->subranges()) + LM |= S.LaneMask; + + if (MRI.getMaxLaneMaskForVReg(LI->reg) != LM) { + // Find subreg for the lane mask. + unsigned SubIdx = 0; + for (unsigned I = 1, E = TRI.getNumSubRegIndices(); I < E; ++I) { + if (TRI.getSubRegIndexLaneMask(I) == LM) { + SubIdx = I; + break; + } + } + if (SubIdx == 0) + report_fatal_error("Cannot find subreg index to cover all alive lanes"); + CopyMI->getOperand(0).setSubReg(SubIdx); + CopyMI->getOperand(1).setSubReg(SubIdx); + CopyMI->getOperand(0).setIsUndef(true); + } + } ++NumCopies; } -- 2.50.1