GlobalISel: remove G_SEQUENCE instruction.

It was trying to do too many things. The basic lumping together of values for
legalization purposes is now handled by G_MERGE_VALUES. More complex things
involving gaps and odd sizes are handled by G_INSERT sequences.

llvm-svn: 306120

2 files changed, 1 insertions, 72 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp b/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp
index bfb02bd1d3c..b699156c568 100644
--- a/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp
@@ -50,70 +50,6 @@ void Legalizer::getAnalysisUsage(AnalysisUsage &AU) const {
 void Legalizer::init(MachineFunction &MF) {
 }
 
-bool Legalizer::combineExtracts(MachineInstr &MI, MachineRegisterInfo &MRI,
-                                const TargetInstrInfo &TII) {
-  bool Changed = false;
-  if (MI.getOpcode() != TargetOpcode::G_EXTRACT)
-    return Changed;
-
-  unsigned NumDefs = (MI.getNumOperands() - 1) / 2;
-  unsigned SrcReg = MI.getOperand(NumDefs).getReg();
-  MachineInstr &SeqI = *MRI.def_instr_begin(SrcReg);
-  if (SeqI.getOpcode() != TargetOpcode::G_SEQUENCE)
-    return Changed;
-
-  unsigned NumSeqSrcs = (SeqI.getNumOperands() - 1) / 2;
-  bool AllDefsReplaced = true;
-
-  // Try to match each register extracted with a corresponding insertion formed
-  // by the G_SEQUENCE.
-  for (unsigned Idx = 0, SeqIdx = 0; Idx < NumDefs; ++Idx) {
-    MachineOperand &ExtractMO = MI.getOperand(Idx);
-    assert(ExtractMO.isReg() && ExtractMO.isDef() &&
-           "unexpected extract operand");
-
-    unsigned ExtractReg = ExtractMO.getReg();
-    unsigned ExtractPos = MI.getOperand(NumDefs + Idx + 1).getImm();
-
-    while (SeqIdx < NumSeqSrcs &&
-           SeqI.getOperand(2 * SeqIdx + 2).getImm() < ExtractPos)
-      ++SeqIdx;
-
-    if (SeqIdx == NumSeqSrcs) {
-      AllDefsReplaced = false;
-      continue;
-    }
-
-    unsigned OrigReg = SeqI.getOperand(2 * SeqIdx + 1).getReg();
-    if (SeqI.getOperand(2 * SeqIdx + 2).getImm() != ExtractPos ||
-        MRI.getType(OrigReg) != MRI.getType(ExtractReg)) {
-      AllDefsReplaced = false;
-      continue;
-    }
-
-    assert(!TargetRegisterInfo::isPhysicalRegister(OrigReg) &&
-           "unexpected physical register in G_SEQUENCE");
-
-    // Finally we can replace the uses.
-    MRI.replaceRegWith(ExtractReg, OrigReg);
-  }
-
-  if (AllDefsReplaced) {
-    // If SeqI was the next instruction in the BB and we removed it, we'd break
-    // the outer iteration.
-    assert(std::next(MachineBasicBlock::iterator(MI)) != SeqI &&
-           "G_SEQUENCE does not dominate G_EXTRACT");
-
-    MI.eraseFromParent();
-
-    if (MRI.use_empty(SrcReg))
-      SeqI.eraseFromParent();
-    Changed = true;
-  }
-
-  return Changed;
-}
-
 bool Legalizer::combineMerges(MachineInstr &MI, MachineRegisterInfo &MRI,
                               const TargetInstrInfo &TII,
                               MachineIRBuilder &MIRBuilder) {
@@ -271,12 +207,6 @@ bool Legalizer::runOnMachineFunction(MachineFunction &MF) {
       // Get the next Instruction before we try to legalize, because there's a
       // good chance MI will be deleted.
       NextMI = std::next(MI);
-
-      // combineExtracts erases MI.
-      if (combineExtracts(*MI, MRI, TII)) {
-        Changed = true;
-        continue;
-      }
       Changed |= combineMerges(*MI, MRI, TII, Helper.MIRBuilder);
     }
   }
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerInfo.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerInfo.cpp
index 4d459104229..595802f2228 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerInfo.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerInfo.cpp
@@ -75,8 +75,7 @@ LegalizerInfo::getAction(const InstrAspect &Aspect) const {
 
   // FIXME: the long-term plan calls for expansion in terms of load/store (if
   // they're not legal).
-  if (Aspect.Opcode == TargetOpcode::G_SEQUENCE ||
-      Aspect.Opcode == TargetOpcode::G_EXTRACT ||
+  if (Aspect.Opcode == TargetOpcode::G_EXTRACT ||
       Aspect.Opcode == TargetOpcode::G_MERGE_VALUES ||
       Aspect.Opcode == TargetOpcode::G_UNMERGE_VALUES)
     return std::make_pair(Legal, Aspect.Type);