From 7ebed91fddbcd259d03c4b438719ac1ce2a4fc87 Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Sat, 19 May 2012 23:34:59 +0000 Subject: Fix 12892. Dead code elimination during coalescing could cause a virtual register to be split into connected components. The following rewriting would be confused about the already joined copies present in the code, but without a corresponding value number in the live range. Erase all joined copies instantly when joining intervals such that the MI and LiveInterval representations are always in sync. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157135 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/LiveRangeEdit.cpp | 4 + lib/CodeGen/RegisterCoalescer.cpp | 24 ++++- test/CodeGen/X86/2012-05-19-CoalescerCrash.ll | 122 ++++++++++++++++++++++++++ 3 files changed, 146 insertions(+), 4 deletions(-) create mode 100644 test/CodeGen/X86/2012-05-19-CoalescerCrash.ll diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp index 8bdad5a..4c2b0bf 100644 --- a/lib/CodeGen/LiveRangeEdit.cpp +++ b/lib/CodeGen/LiveRangeEdit.cpp @@ -308,6 +308,10 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, TheDelegate->LRE_DidCloneVirtReg(Dups.back()->reg, LI->reg); } ConEQ.Distribute(&Dups[0], MRI); + DEBUG({ + for (unsigned i = 0; i != NumComp; ++i) + dbgs() << '\t' << *Dups[i] << '\n'; + }); } } diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp index 74d0454..ca5d280 100644 --- a/lib/CodeGen/RegisterCoalescer.cpp +++ b/lib/CodeGen/RegisterCoalescer.cpp @@ -1081,9 +1081,10 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) { if (!CP.isPhys() && RegClassInfo.isProperSubClass(CP.getNewRC())) InflateRegs.push_back(CP.getDstReg()); - // Remember to delete the copy instruction. - LIS->RemoveMachineInstrFromMaps(CopyMI); - CopyMI->eraseFromParent(); + // CopyMI has been erased by joinIntervals at this point. Remove it from + // ErasedInstrs since copyCoalesceWorkList() won't add a successful join back + // to the work list. This keeps ErasedInstrs from growing needlessly. + ErasedInstrs.erase(CopyMI); // Rewrite all SrcReg operands to DstReg. // Also update DstReg operands to include DstIdx if it is set. @@ -1285,6 +1286,7 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) { SmallVector NewVNInfo; SmallVector DupCopies; + SmallVector DeadCopies; LiveInterval &LHS = LIS->getOrCreateInterval(CP.getDstReg()); DEBUG({ dbgs() << "\t\tLHS = "; LHS.print(dbgs(), TRI); dbgs() << "\n"; }); @@ -1313,6 +1315,7 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) { continue; LHSValsDefinedFromRHS[VNI] = lr->valno; + DeadCopies.push_back(MI); } // Loop over the value numbers of the RHS, seeing if any are defined from @@ -1339,6 +1342,7 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) { continue; RHSValsDefinedFromLHS[VNI] = lr->valno; + DeadCopies.push_back(MI); } LHSValNoAssignments.resize(LHS.getNumValNums(), -1); @@ -1438,6 +1442,17 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) { if (RHSValNoAssignments.empty()) RHSValNoAssignments.push_back(-1); + // Now erase all the redundant copies. + for (unsigned i = 0, e = DeadCopies.size(); i != e; ++i) { + MachineInstr *MI = DeadCopies[i]; + DEBUG(dbgs() << "\t\terased:\t" << LIS->getInstructionIndex(MI) + << '\t' << *MI); + if (!ErasedInstrs.insert(MI)) + continue; + LIS->RemoveMachineInstrFromMaps(MI); + MI->eraseFromParent(); + } + SmallVector SourceRegisters; for (SmallVector::iterator I = DupCopies.begin(), E = DupCopies.end(); I != E; ++I) { @@ -1451,7 +1466,8 @@ bool RegisterCoalescer::joinIntervals(CoalescerPair &CP) { // A = X unsigned Src = MI->getOperand(1).getReg(); SourceRegisters.push_back(Src); - ErasedInstrs.insert(MI); + if (!ErasedInstrs.insert(MI)) + continue; LIS->RemoveMachineInstrFromMaps(MI); MI->eraseFromParent(); } diff --git a/test/CodeGen/X86/2012-05-19-CoalescerCrash.ll b/test/CodeGen/X86/2012-05-19-CoalescerCrash.ll new file mode 100644 index 0000000..837fbc0 --- /dev/null +++ b/test/CodeGen/X86/2012-05-19-CoalescerCrash.ll @@ -0,0 +1,122 @@ +; RUN: llc < %s -verify-coalescing +; PR12892 +; +; Dead code elimination during coalesing causes a live range to split into two +; virtual registers. Stale identity copies that had already been joined were +; interfering with the liveness computations. + +target triple = "i386-pc-linux-gnu" + +define void @_ZN4llvm17AsmMatcherEmitter3runERNS_11raw_ostreamE() align 2 { + invoke void @_ZNK4llvm13CodeGenTarget12getAsmParserEv() + to label %1 unwind label %5 + +;