From 924279ca0e2f9990e8cd6bc240f8ca5359540868 Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Tue, 22 May 2012 14:52:12 +0000 Subject: Only erase virtregs with no uses left. Also make sure registers aren't erased twice if the dead def mentions the register twice. This fixes PR12911. llvm-svn: 157254 --- llvm/lib/CodeGen/LiveRangeEdit.cpp | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'llvm/lib/CodeGen') diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp index 4c2b0bffa6d..434388b94ef 100644 --- a/llvm/lib/CodeGen/LiveRangeEdit.cpp +++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp @@ -220,6 +220,9 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI); + // Collect virtual registers to be erased after MI is gone. + SmallVector RegsToErase; + // Check for live intervals that may shrink for (MachineInstr::mop_iterator MOI = MI->operands_begin(), MOE = MI->operands_end(); MOI != MOE; ++MOI) { @@ -245,10 +248,8 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, if (TheDelegate) TheDelegate->LRE_WillShrinkVirtReg(LI.reg); LI.removeValNo(VNI); - if (LI.empty()) { - ToShrink.remove(&LI); - eraseVirtReg(Reg); - } + if (LI.empty()) + RegsToErase.push_back(Reg); } } } @@ -258,6 +259,16 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, LIS.RemoveMachineInstrFromMaps(MI); MI->eraseFromParent(); ++NumDCEDeleted; + + // Erase any virtregs that are now empty and unused. There may be + // uses around. Keep the empty live range in that case. + for (unsigned i = 0, e = RegsToErase.size(); i != e; ++i) { + unsigned Reg = RegsToErase[i]; + if (LIS.hasInterval(Reg) && MRI.reg_nodbg_empty(Reg)) { + ToShrink.remove(&LIS.getInterval(Reg)); + eraseVirtReg(Reg); + } + } } if (ToShrink.empty()) -- cgit v1.2.3