Changed my mind. We now allow remat of instructions whose defs have subreg indices.

llvm-svn: 76100

2 files changed, 8 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 873e58e5c7b..d8f2089f31a 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1157,11 +1157,6 @@ bool LiveIntervals::isReMaterializable(const LiveInterval &li,
   if (DisableReMat)
     return false;
 
-  // FIXME: For now, avoid remating instructions whose definition has a subreg
-  // index. It's just incredibly difficult to get right.
-  if (MI->findRegisterDefOperand(li.reg)->getSubReg())
-    return false;
-
   if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF)
     return true;
 
diff --git a/llvm/lib/CodeGen/VirtRegRewriter.cpp b/llvm/lib/CodeGen/VirtRegRewriter.cpp
index 800cdd625f9..a859d80e1b7 100644
--- a/llvm/lib/CodeGen/VirtRegRewriter.cpp
+++ b/llvm/lib/CodeGen/VirtRegRewriter.cpp
@@ -490,7 +490,14 @@ static void ReMaterialize(MachineBasicBlock &MBB,
                           const TargetInstrInfo *TII,
                           const TargetRegisterInfo *TRI,
                           VirtRegMap &VRM) {
-  TII->reMaterialize(MBB, MII, DestReg, 0, VRM.getReMaterializedMI(Reg));
+  MachineInstr *ReMatDefMI = VRM.getReMaterializedMI(Reg);
+#ifdef NDEBUG
+  const TargetInstrDesc &TID = ReMatDefMI->getDesc();
+  assert(TID.getNumDefs() != 1 &&
+         "Don't know how to remat instructions that define > 1 values!");
+#endif
+  TII->reMaterialize(MBB, MII, DestReg,
+                     ReMatDefMI->getOperand(0).getSubReg(), ReMatDefMI);
   MachineInstr *NewMI = prior(MII);
   for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
     MachineOperand &MO = NewMI->getOperand(i);