[BOLT] Add pass to normalize CFG

Summary:
Some optimizations may remove all instructions in a basic block.

The pass will cleanup the CFG afterwards by removing empty basic
blocks and merging duplicate CFG edges.

The normalized CFG is printed under '-print-normalized' option.

(cherry picked from FBD32774360)

1 files changed, 9 insertions, 0 deletions

diff --git a/bolt/lib/Rewrite/BinaryPassManager.cpp b/bolt/lib/Rewrite/BinaryPassManager.cpp
index ab8a8d2..8a5d70d 100644
--- a/bolt/lib/Rewrite/BinaryPassManager.cpp
+++ b/bolt/lib/Rewrite/BinaryPassManager.cpp
@@ -148,6 +148,13 @@ PrintICP("print-icp",
   cl::cat(BoltOptCategory));
 
 static cl::opt<bool>
+PrintNormalized("print-normalized",
+  cl::desc("print functions after CFG is normalized"),
+  cl::ZeroOrMore,
+  cl::Hidden,
+  cl::cat(BoltCategory));
+
+static cl::opt<bool>
 PrintRegReAssign("print-regreassign",
   cl::desc("print functions after regreassign pass"),
   cl::ZeroOrMore,
@@ -409,6 +416,8 @@ void BinaryFunctionPassManager::runAllPasses(BinaryContext &BC) {
 
   Manager.registerPass(std::make_unique<ValidateInternalCalls>(NeverPrint));
 
+  Manager.registerPass(std::make_unique<NormalizeCFG>(PrintNormalized));
+
   Manager.registerPass(std::make_unique<StripRepRet>(NeverPrint),
                        opts::StripRepRet);