From 1edc3cf65d54130542fc91bac67ecf616ef88d48 Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Mon, 11 Apr 2011 15:00:39 +0000 Subject: [PATCH] Don't shrink live ranges after dead code elimination unless it is going to help. In particular, don't repeatedly recompute the PIC base live range after rematerialization. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129275 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/LiveRangeEdit.cpp | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp index b96575eea0c..88ee457f4fb 100644 --- a/lib/CodeGen/LiveRangeEdit.cpp +++ b/lib/CodeGen/LiveRangeEdit.cpp @@ -203,6 +203,7 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, SetVector, SmallPtrSet > ToShrink; + MachineRegisterInfo &MRI = VRM.getRegInfo(); for (;;) { // Erase all dead defs. @@ -236,8 +237,13 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, continue; LiveInterval &LI = LIS.getInterval(Reg); - // Shrink read registers. - if (MI->readsVirtualRegister(Reg)) + // Shrink read registers, unless it is likely to be expensive and + // unlikely to change anything. We typically don't want to shrink the + // PIC base register that has lots of uses everywhere. + // Always shrink COPY uses that probably come from live range splitting. + if (MI->readsVirtualRegister(Reg) && + (MI->isCopy() || MOI->isDef() || MRI.hasOneNonDBGUse(Reg) || + LI.killedAt(Idx))) ToShrink.insert(&LI); // Remove defined value. @@ -266,7 +272,7 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, // Shrink just one live interval. Then delete new dead defs. LiveInterval *LI = ToShrink.back(); ToShrink.pop_back(); - if (foldAsLoad(LI, Dead, VRM.getRegInfo(), LIS, TII)) + if (foldAsLoad(LI, Dead, MRI, LIS, TII)) continue; if (delegate_) delegate_->LRE_WillShrinkVirtReg(LI->reg); @@ -286,7 +292,7 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, if (delegate_) delegate_->LRE_DidCloneVirtReg(Dups.back()->reg, LI->reg); } - ConEQ.Distribute(&Dups[0], VRM.getRegInfo()); + ConEQ.Distribute(&Dups[0], MRI); } } -- 2.11.0