Subzero: Fix labels for block profiling.

src/IceClFlags.cpp

Index: src/IceClFlags.cpp
diff --git a/src/IceClFlags.cpp b/src/IceClFlags.cpp
index 60117fd0665bed5c42f77ef224cf2c1d29ad80e0..653d7f9bc28bf953d83f50375ed2bdbb50c0c1e0 100644
--- a/src/IceClFlags.cpp
+++ b/src/IceClFlags.cpp
@@ -76,6 +76,12 @@ cl::opt<bool>
     DumpStats("szstats",
               cl::desc("Print statistics after translating each function"));
 
+// TODO(stichnot): The implementation of block profiling introduces some
+// oddities to be aware of.  First, empty basic blocks that don't normally
+// appear in the asm output, may be profiled anyway, so one might see profile
+// counts for blocks not in the original asm output.  Second, edge-split nodes
+// for advanced phi lowering are added too late, at which point it is not
+// practical to add profiling.
 cl::opt<bool> EnableBlockProfile(
     "enable-block-profile",
     cl::desc("If true, instrument basic blocks, and output profiling "