[WebAssembly] Add some comments. NFC.

llvm-svn: 254096

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 2933294..c98bea9 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -187,7 +187,12 @@ void WebAssemblyPassConfig::addPostRegAlloc() {
 void WebAssemblyPassConfig::addPreSched2() {}
 
 void WebAssemblyPassConfig::addPreEmitPass() {
+  // Put the CFG in structured form; insert BLOCK and LOOP markers.
   addPass(createWebAssemblyCFGStackify());
+
+  // Create a mapping from LLVM CodeGen virtual registers to wasm registers.
   addPass(createWebAssemblyRegNumbering());
+
+  // Perform the very last peephole optimizations on the code.
   addPass(createWebAssemblyPeephole());
 }