Move stack slot assignments into LiveRangeEdit.

All registers created during splitting or spilling are assigned to the same
stack slot as the parent register.

When splitting or rematting, we may not spill at all. In that case the stack
slot is still assigned, but it will be dead.

llvm-svn: 116546

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index 8a123fbe701..463ebcb4ae5 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -18,12 +18,21 @@
 
 using namespace llvm;
 
+int LiveRangeEdit::assignStackSlot(VirtRegMap &vrm) {
+  int ss = vrm.getStackSlot(getReg());
+  if (ss != VirtRegMap::NO_STACK_SLOT)
+    return ss;
+  return vrm.assignVirt2StackSlot(getReg());
+}
+
 LiveInterval &LiveRangeEdit::create(MachineRegisterInfo &mri,
                                     LiveIntervals &lis,
                                     VirtRegMap &vrm) {
   const TargetRegisterClass *RC = mri.getRegClass(parent_.reg);
   unsigned VReg = mri.createVirtualRegister(RC);
   vrm.grow();
+  // Immediately assign to the same stack slot as parent.
+  vrm.assignVirt2StackSlot(VReg, assignStackSlot(vrm));
   LiveInterval &li = lis.getOrCreateInterval(VReg);
   newRegs_.push_back(&li);
   return li;