[WebAssembly] Disable register stackification and coloring when not optimizing

These passes are optimizations, and should be disabled when not
optimizing.
Also create an MCCodeGenInfo so the opt level is correctly plumbed to
the backend pass manager.
Also remove the command line flag for disabling register coloring;
running llc with -O0 should now be useful for debugging, so it's not
necessary.

Differential Revision: http://reviews.llvm.org/D17327

llvm-svn: 261176

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 25f009d2fb3b..2e2a1194502e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -185,11 +185,13 @@ void WebAssemblyPassConfig::addPostRegAlloc() {
   // Fails with: should be run after register allocation.
   disablePass(&MachineCopyPropagationID);
 
-  // Mark registers as representing wasm's expression stack.
-  addPass(createWebAssemblyRegStackify());
+  if (getOptLevel() != CodeGenOpt::None) {
+    // Mark registers as representing wasm's expression stack.
+    addPass(createWebAssemblyRegStackify());
 
-  // Run the register coloring pass to reduce the total number of registers.
-  addPass(createWebAssemblyRegColoring());
+    // Run the register coloring pass to reduce the total number of registers.
+    addPass(createWebAssemblyRegColoring());
+  }
 
   TargetPassConfig::addPostRegAlloc();