From 0253df9a897ce541d56146699cedd79c464bda5e Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Thu, 7 Oct 2010 23:34:34 +0000
Subject: After splitting, the remaining LiveInterval may be fragmented into
 multiple connected components. These components should be allocated different
 virtual registers because there is no reason for them to be allocated
 together.

Add the ConnectedVNInfoEqClasses class to calculate the connected components,
and move values to new LiveIntervals.

Use it from SplitKit::rewrite by creating new virtual registers for the
components.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116006 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SplitKit.cpp | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

(limited to 'lib/CodeGen/SplitKit.cpp')

diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 7f98bc13a3..19733e4e68 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -828,7 +828,29 @@ void SplitEditor::rewrite() {
     }
   }
 
+  // Get rid of unused values and set phi-kill flags.
+  dupli_.getLI()->RenumberValues(lis_);
+
+  // Now check if dupli was separated into multiple connected components.
+  ConnectedVNInfoEqClasses ConEQ(lis_);
+  if (unsigned NumComp = ConEQ.Classify(dupli_.getLI())) {
+    DEBUG(dbgs() << "  Remainder has " << NumComp << " connected components: "
+                 << *dupli_.getLI() << '\n');
+    unsigned firstComp = intervals_.size();
+    intervals_.push_back(dupli_.getLI());
+    // Did the remainder break up? Create intervals for all the components.
+    if (NumComp > 1) {
+      for (unsigned i = 1; i != NumComp; ++i)
+        intervals_.push_back(createInterval());
+      ConEQ.Distribute(&intervals_[firstComp]);
+    }
+  } else {
+    DEBUG(dbgs() << "  dupli became empty?\n");
+    lis_.removeInterval(dupli_.getLI()->reg);
+    dupli_.reset(0);
+  }
 
+  // Rewrite instructions.
   const LiveInterval *curli = sa_.getCurLI();
   for (MachineRegisterInfo::reg_iterator RI = mri_.reg_begin(curli->reg),
        RE = mri_.reg_end(); RI != RE;) {
@@ -843,7 +865,7 @@ void SplitEditor::rewrite() {
     }
     SlotIndex Idx = lis_.getInstructionIndex(MI);
     Idx = MO.isUse() ? Idx.getUseIndex() : Idx.getDefIndex();
-    LiveInterval *LI = dupli_.getLI();
+    LiveInterval *LI = 0;
     for (unsigned i = firstInterval, e = intervals_.size(); i != e; ++i) {
       LiveInterval *testli = intervals_[i];
       if (testli->liveAt(Idx)) {
@@ -851,21 +873,12 @@ void SplitEditor::rewrite() {
         break;
       }
     }
+    assert(LI && "No register was live at use");
     MO.setReg(LI->reg);
     DEBUG(dbgs() << "  rewrite BB#" << MI->getParent()->getNumber() << '\t'
                  << Idx << '\t' << *MI);
   }
 
-  // dupli_ goes in last, after rewriting.
-  if (dupli_.getLI()->empty()) {
-    DEBUG(dbgs() << "  dupli became empty?\n");
-    lis_.removeInterval(dupli_.getLI()->reg);
-    dupli_.reset(0);
-  } else {
-    dupli_.getLI()->RenumberValues(lis_);
-    intervals_.push_back(dupli_.getLI());
-  }
-
   // Calculate spill weight and allocation hints for new intervals.
   VirtRegAuxInfo vrai(vrm_.getMachineFunction(), lis_, sa_.loops_);
   for (unsigned i = firstInterval, e = intervals_.size(); i != e; ++i) {
-- 
cgit v1.2.3-70-g09d2