[WebAssembly] Print a debug message at the start of each pass

Summary:
Looks like many passes print its pass description as a debug message at
the start of each pass, so added that to (mostly newly added) other
passes as well.

Reviewers: dschuff

Subscribers: jgravelle-google, sbc100, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D56142

llvm-svn: 350771
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
index 8755198..0491f71 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -623,6 +623,8 @@
 }
 
 bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
+  LLVM_DEBUG(dbgs() << "********** Lower Emscripten EH & SjLj **********\n");
+
   LLVMContext &C = M.getContext();
   IRBuilder<> IRB(C);