Add a few Subzero intrinsics (not the atomic ones yet).

src/llvm2ice.cpp

Index: src/llvm2ice.cpp
diff --git a/src/llvm2ice.cpp b/src/llvm2ice.cpp
index 374d753769eff6b00403fb787bd52ce49430a428..6f8fed0cd60d2b3f2cccd42d07a6bdac3880f4de 100644
--- a/src/llvm2ice.cpp
+++ b/src/llvm2ice.cpp
@@ -526,8 +526,30 @@ private:
     unsigned NumArgs = Inst->getNumArgOperands();
     // Note: Subzero doesn't (yet) do anything special with the Tail
     // flag in the bitcode, i.e. CallInst::isTailCall().
-    Ice::InstCall *NewInst =
-        Ice::InstCall::create(Func, NumArgs, Dest, CallTarget);
+    Ice::InstCall *NewInst = NULL;
+
+    if (Ice::ConstantRelocatable *Target =
+        llvm::dyn_cast<Ice::ConstantRelocatable>(CallTarget)) {
+      // Check if this direct call is to an Intrinsic (starts with "llvm.")
+      static const char LLVMPrefix[] = "llvm.";
+      const size_t LLVMPrefixLen = strlen(LLVMPrefix);
+      Ice::IceString Name = Target->getName();
+      if (Name.substr(0, LLVMPrefixLen) == LLVMPrefix) {
+        Ice::IceString NameSuffix = Name.substr(LLVMPrefixLen);
+        Ice::IntrinsicInfo Info = Ctx->getIntrinsicInfo(NameSuffix);
+        if (Info == Ice::UnknownIntrinsicInfo) {
+          report_fatal_error(std::string("Invalid PNaCl intrinsic call: ") +
+                             LLVMObjectAsString(Inst));
+        }
+        NewInst = Ice::InstIntrinsicCall::create(Func, NumArgs, Dest,
+                                                 CallTarget, Info);
+      }
+    }
+
+    // Not an intrinsic call.
+    if (NewInst == NULL) {
+      NewInst = Ice::InstCall::create(Func, NumArgs, Dest, CallTarget);
+    }
     for (unsigned i = 0; i < NumArgs; ++i) {
       NewInst->addArg(convertOperand(Inst, i));
     }