Always normalize spill weights, also for intervals created by spilling.

Moderate the weight given to very small intervals.

The spill weight given to new intervals created when spilling was not
normalized in the same way as the original spill weights calculated by
CalcSpillWeights. That meant that restored registers would tend to hang around
because they had a much higher spill weight that unspilled registers.

This improves the runtime of a few tests by up to 10%, and there are no
significant regressions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96613 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CalcSpillWeights.cpp

@@ -131,10 +131,7 @@ bool CalculateSpillWeights::runOnMachineFunction(MachineFunction &fn) {
       if (Hint.first || Hint.second)
         li.weight *= 1.01F;
 
-      // Divide the weight of the interval by its size.  This encourages
-      // spilling of intervals that are large and have few uses, and
-      // discourages spilling of small intervals with many uses.
-      li.weight /= lis->getApproximateInstructionCount(li) * SlotIndex::NUM;
+      lis->normalizeSpillWeight(li);
     }
   }