Add initial integrated assembler w/ some Xmm ops.

src/llvm2ice.cpp

Index: src/llvm2ice.cpp
diff --git a/src/llvm2ice.cpp b/src/llvm2ice.cpp
index f14787705780e13e886531f7eb993a089700a349..31faf42b22fa28c79dbf60987e9f1a6f67a635f2 100644
--- a/src/llvm2ice.cpp
+++ b/src/llvm2ice.cpp
@@ -129,6 +129,10 @@ static cl::opt<bool>
 BuildOnRead("build-on-read",
             cl::desc("Build ICE instructions when reading bitcode"),
             cl::init(false));
+static cl::opt<bool>
+    UseIntegratedAssembler("integrated-as",
+                           cl::desc("Use integrated assembler (default yes)"),
+                           cl::init(true));
 
 int main(int argc, char **argv) {
 
@@ -158,6 +162,7 @@ int main(int argc, char **argv) {
   Flags.DisableTranslation = DisableTranslation;
   Flags.DisableGlobals = DisableGlobals;
   Flags.FunctionSections = FunctionSections;
+  Flags.UseIntegratedAssembler = UseIntegratedAssembler;
   Flags.UseSandboxing = UseSandboxing;
   Flags.DumpStats = DumpStats;
   Flags.DefaultGlobalPrefix = DefaultGlobalPrefix;