Tweak to ignoring reserved regs. The allocator was occasionally still looking
at them since they'd end up in the register weights list. Tell it to stop
doing that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112756 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index 32dda27..5c62354 100644
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -1147,9 +1147,11 @@
            e = RC->allocation_order_end(*mf_); i != e; ++i) {
       unsigned reg = *i;
       float regWeight = SpillWeights[reg];
+      // Don't even consider reserved regs.
+      if (reservedRegs_.test(reg))
+        continue;
       // Skip recently allocated registers and reserved registers.
-      if (minWeight > regWeight && !isRecentlyUsed(reg) &&
-          !reservedRegs_.test(reg))
+      if (minWeight > regWeight && !isRecentlyUsed(reg))
         Found = true;
       RegsWeights.push_back(std::make_pair(reg, regWeight));
     }