Strip old implicit operands after foldMemoryOperand.

The TII.foldMemoryOperand hook preserves implicit operands from the
original instruction.  This is not what we want when those implicit
operands refer to the register being spilled.

Implicit operands referring to other registers are preserved.

This fixes PR11347.

llvm-svn: 144247

1 files changed, 19 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/InlineSpiller.cpp b/llvm/lib/CodeGen/InlineSpiller.cpp
index 726af469657..d1e3f1afbfa 100644
--- a/llvm/lib/CodeGen/InlineSpiller.cpp
+++ b/llvm/lib/CodeGen/InlineSpiller.cpp
@@ -1017,14 +1017,18 @@ bool InlineSpiller::foldMemoryOperand(MachineBasicBlock::iterator MI,
                                       const SmallVectorImpl<unsigned> &Ops,
                                       MachineInstr *LoadMI) {
   bool WasCopy = MI->isCopy();
+  unsigned ImpReg = 0;
+
   // TargetInstrInfo::foldMemoryOperand only expects explicit, non-tied
   // operands.
   SmallVector<unsigned, 8> FoldOps;
   for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
     unsigned Idx = Ops[i];
     MachineOperand &MO = MI->getOperand(Idx);
-    if (MO.isImplicit())
+    if (MO.isImplicit()) {
+      ImpReg = MO.getReg();
       continue;
+    }
     // FIXME: Teach targets to deal with subregs.
     if (MO.getSubReg())
       return false;
@@ -1045,7 +1049,20 @@ bool InlineSpiller::foldMemoryOperand(MachineBasicBlock::iterator MI,
   if (!LoadMI)
     VRM.addSpillSlotUse(StackSlot, FoldMI);
   MI->eraseFromParent();
-  DEBUG(dbgs() << "\tfolded: " << *FoldMI);
+
+  // TII.foldMemoryOperand may have left some implicit operands on the
+  // instruction.  Strip them.
+  if (ImpReg)
+    for (unsigned i = FoldMI->getNumOperands(); i; --i) {
+      MachineOperand &MO = FoldMI->getOperand(i - 1);
+      if (!MO.isReg() || !MO.isImplicit())
+        break;
+      if (MO.getReg() == ImpReg)
+        FoldMI->RemoveOperand(i - 1);
+    }
+
+  DEBUG(dbgs() << "\tfolded:  " << LIS.getInstructionIndex(FoldMI) << '\t'
+               << *FoldMI);
   if (!WasCopy)
     ++NumFolded;
   else if (Ops.front() == 0)