[PATCH] CodeGen: improve ms instrincics support

[Reid Kleckner]

lgtm with some nits

================
Comment at: include/clang/Basic/Builtins.def:690
@@ -688,1 +689,3 @@
 LANGBUILTIN(_InterlockedExchangeAdd, "LiLiD*Li", "n", ALL_MS_LANGUAGES)
+LANGBUILTIN(_InterlockedExchangePointer, "v*v*D*v*", "n", ALL_MS_LANGUAGES)
+LANGBUILTIN(_InterlockedExchange, "LiLiD*Li", "n", ALL_MS_LANGUAGES)
----------------
MSVC doesn't provide this in 32-bit mode, but I think we can go ahead and do that anyway.

================
Comment at: lib/CodeGen/CGBuiltin.cpp:1523
@@ +1522,3 @@
+  }
+  case Builtin::BI_InterlockedCompareExchangePointer: {
+    llvm::Type *RTy;
----------------
I'd like this to be factored better, but I can live with it as is.

================
Comment at: lib/CodeGen/CGBuiltin.cpp:1535
@@ +1534,3 @@
+    RTy = Exchange->getType();
+    Exchange = Builder.CreatePtrToInt(Exchange, CGM.Int32Ty);
+
----------------
CGM.Int32Ty doesn't seem correct for x64, it should be IntType.

================
Comment at: lib/CodeGen/CGBuiltin.cpp:1537
@@ +1536,3 @@
+
+    llvm::Value *Comparend =
+      Builder.CreatePtrToInt(EmitScalarExpr(E->getArg(2)), CGM.Int32Ty);
----------------
MSDN says "Comparand" with an 'a'.

================
Comment at: lib/CodeGen/CGBuiltin.cpp:1540
@@ +1539,3 @@
+
+    Value *Result = Builder.CreateAtomicCmpXchg(Destination, Comparend,
+                                                Exchange,
----------------
MSDN says the 'Dest' is volatile, so I'd call Result->setVolatile(true) here.

http://reviews.llvm.org/D4182