[llvm-commits] [llvm] r126353 - /llvm/trunk/lib/CodeGen/InlineSpiller.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Wed Feb 23 19:07:55 2011
New Revision: 126353

URL: http://llvm.org/viewvc/llvm-project?rev=126353&view=rev
Log:
Use the same spill slot for all live ranges that descend form the same original
register.

This avoids some silly stack slot shuffling when both sides of a copy get
spilled.

Modified:
    llvm/trunk/lib/CodeGen/InlineSpiller.cpp

Modified: llvm/trunk/lib/CodeGen/InlineSpiller.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/InlineSpiller.cpp?rev=126353&r1=126352&r2=126353&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/InlineSpiller.cpp (original)
+++ llvm/trunk/lib/CodeGen/InlineSpiller.cpp Wed Feb 23 19:07:55 2011
@@ -345,7 +345,8 @@
          && "Trying to spill a stack slot.");
   DEBUG(dbgs() << "Inline spilling "
                << mri_.getRegClass(edit.getReg())->getName()
-               << ':' << edit.getParent() << "\n");
+               << ':' << edit.getParent() << "\nFrom original "
+               << PrintReg(vrm_.getOriginal(edit.getReg())) << '\n');
   assert(edit.getParent().isSpillable() &&
          "Attempting to spill already spilled value.");
 
@@ -356,12 +357,20 @@
     return;
 
   rc_ = mri_.getRegClass(edit.getReg());
-  stackSlot_ = vrm_.assignVirt2StackSlot(edit_->getReg());
+
+  // Share a stack slot among all descendants of Orig.
+  unsigned Orig = vrm_.getOriginal(edit.getReg());
+  stackSlot_ = vrm_.getStackSlot(Orig);
+  if (stackSlot_ == VirtRegMap::NO_STACK_SLOT)
+    stackSlot_ = vrm_.assignVirt2StackSlot(Orig);
+
+  if (Orig != edit.getReg())
+    vrm_.assignVirt2StackSlot(edit.getReg(), stackSlot_);
 
   // Update LiveStacks now that we are committed to spilling.
   LiveInterval &stacklvr = lss_.getOrCreateInterval(stackSlot_, rc_);
-  assert(stacklvr.empty() && "Just created stack slot not empty");
-  stacklvr.getNextValue(SlotIndex(), 0, lss_.getVNInfoAllocator());
+  if (!stacklvr.hasAtLeastOneValue())
+    stacklvr.getNextValue(SlotIndex(), 0, lss_.getVNInfoAllocator());
   stacklvr.MergeRangesInAsValue(edit_->getParent(), stacklvr.getValNumInfo(0));
 
   // Iterate over instructions using register.