Switch some getAliasSet clients to MCRegAliasIterator.

[oota-llvm.git] / lib / CodeGen / SpillPlacement.cpp

diff --git a/lib/CodeGen/SpillPlacement.cpp b/lib/CodeGen/SpillPlacement.cpp
index ce7b37bfce5eed4195b38130e8a3301818cd7ba5..320128a999ea8cf170a002bec46498273f503947 100644 (file)
--- a/lib/CodeGen/SpillPlacement.cpp
+++ b/lib/CodeGen/SpillPlacement.cpp
@@ -207,6 +207,17 @@ void SpillPlacement::activate(unsigned n) {
     return;
   ActiveNodes->set(n);
   nodes[n].clear();
+
+  // Very large bundles usually come from big switches, indirect branches,
+  // landing pads, or loops with many 'continue' statements. It is difficult to
+  // allocate registers when so many different blocks are involved.
+  //
+  // Give a small negative bias to large bundles such that 1/32 of the
+  // connected blocks need to be interested before we consider expanding the
+  // region through the bundle. This helps compile time by limiting the number
+  // of blocks visited and the number of links in the Hopfield network.
+  if (bundles->getBlocks(n).size() > 100)
+    nodes[n].Bias = -0.0625f;
 }
 
 
@@ -220,6 +231,7 @@ void SpillPlacement::addConstraints(ArrayRef<BlockConstraint> LiveBlocks) {
       0,           // DontCare,
       1,           // PrefReg,
       -1,          // PrefSpill
+      0,           // PrefBoth
       -HUGE_VALF   // MustSpill
     };
 
@@ -240,10 +252,12 @@ void SpillPlacement::addConstraints(ArrayRef<BlockConstraint> LiveBlocks) {
 }
 
 /// addPrefSpill - Same as addConstraints(PrefSpill)
-void SpillPlacement::addPrefSpill(ArrayRef<unsigned> Blocks) {
+void SpillPlacement::addPrefSpill(ArrayRef<unsigned> Blocks, bool Strong) {
   for (ArrayRef<unsigned>::iterator I = Blocks.begin(), E = Blocks.end();
        I != E; ++I) {
     float Freq = getBlockFrequency(*I);
+    if (Strong)
+      Freq += Freq;
     unsigned ib = bundles->getBundle(*I, 0);
     unsigned ob = bundles->getBundle(*I, 1);
     activate(ib);