[cfgoptutils] Add a new overload of addNewEdgeValueToBranch that takes an InstModCallback.

I reimplemented the original addNewEdgeValueToBranch to just call the new
overload with a default InstModCallbacks, so nothing changed and now we can plug
in callbacks to this utility!

Author: gottesmm

include/swift/SILOptimizer/Utils/CFGOptUtils.h

@@ -25,6 +25,7 @@
 
 #include "swift/SIL/SILBuilder.h"
 #include "swift/SIL/SILInstruction.h"
+#include "swift/SILOptimizer/Utils/InstOptUtils.h"
 
 namespace llvm {
 template <typename T> class TinyPtrVector;
@@ -35,17 +36,32 @@ namespace swift {
 class DominanceInfo;
 class SILLoop;
 class SILLoopInfo;
+struct InstModCallbacks;
 
 /// Adds a new argument to an edge between a branch and a destination
-/// block.
+/// block. Allows for user injected callbacks via \p callbacks.
 ///
 /// \param branch The terminator to add the argument to.
 /// \param dest The destination block of the edge.
 /// \param val The value to the arguments of the branch.
 /// \return The created branch. The old branch is deleted.
 /// The argument is appended at the end of the argument tuple.
 TermInst *addNewEdgeValueToBranch(TermInst *branch, SILBasicBlock *dest,
-                                  SILValue val);
+                                  SILValue val,
+                                  const InstModCallbacks &callbacks);
+
+/// Adds a new argument to an edge between a branch and a destination
+/// block.
+///
+/// \param branch The terminator to add the argument to.
+/// \param dest The destination block of the edge.
+/// \param val The value to the arguments of the branch.
+/// \return The created branch. The old branch is deleted.
+/// The argument is appended at the end of the argument tuple.
+inline TermInst *addNewEdgeValueToBranch(TermInst *branch, SILBasicBlock *dest,
+                                         SILValue val) {
+  return addNewEdgeValueToBranch(branch, dest, val, InstModCallbacks());
+}
 
 /// Changes the edge value between a branch and destination basic block
 /// at the specified index. Changes all edges from \p Branch to \p Dest to carry

lib/SILOptimizer/Utils/CFGOptUtils.cpp

@@ -23,16 +23,9 @@
 
 using namespace swift;
 
-/// Adds a new argument to an edge between a branch and a destination
-/// block.
-///
-/// \param branch The terminator to add the argument to.
-/// \param dest The destination block of the edge.
-/// \param val The value to the arguments of the branch.
-/// \return The created branch. The old branch is deleted.
-/// The argument is appended at the end of the argument tuple.
 TermInst *swift::addNewEdgeValueToBranch(TermInst *branch, SILBasicBlock *dest,
-                                         SILValue val) {
+                                         SILValue val,
+                                         const InstModCallbacks &callbacks) {
   SILBuilderWithScope builder(branch);
   TermInst *newBr = nullptr;
 
@@ -59,6 +52,7 @@ TermInst *swift::addNewEdgeValueToBranch(TermInst *branch, SILBasicBlock *dest,
         cbi->getLoc(), cbi->getCondition(), cbi->getTrueBB(), trueArgs,
         cbi->getFalseBB(), falseArgs, cbi->getTrueBBCount(),
         cbi->getFalseBBCount());
+    callbacks.createdNewInst(newBr);
   } else if (auto *bi = dyn_cast<BranchInst>(branch)) {
     SmallVector<SILValue, 8> args;
 
@@ -68,13 +62,13 @@ TermInst *swift::addNewEdgeValueToBranch(TermInst *branch, SILBasicBlock *dest,
     args.push_back(val);
     assert(args.size() == dest->getNumArguments());
     newBr = builder.createBranch(bi->getLoc(), bi->getDestBB(), args);
+    callbacks.createdNewInst(newBr);
   } else {
     // At the moment we can only add arguments to br and cond_br.
     llvm_unreachable("Can't add argument to terminator");
   }
 
-  branch->dropAllReferences();
-  branch->eraseFromParent();
+  callbacks.deleteInst(branch);
 
   return newBr;
 }