4 files changed, 55 insertions, 0 deletions
diff --git a/src/passes/CMakeLists.txt b/src/passes/CMakeLists.txt
index b61b895ef..a49ae8980 100644
--- a/src/passes/CMakeLists.txt
+++ b/src/passes/CMakeLists.txt
@@ -35,6 +35,7 @@ set(passes_SOURCES
   Inlining.cpp
   InstrumentLocals.cpp
   InstrumentMemory.cpp
+  Intrinsics.cpp
   LegalizeJSInterface.cpp
   LimitSegments.cpp
   LocalCSE.cpp
diff --git a/src/passes/Intrinsics.cpp b/src/passes/Intrinsics.cpp
new file mode 100644
index 000000000..1b5a50bbb
--- /dev/null
+++ b/src/passes/Intrinsics.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2021 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ir/intrinsics.h"
+#include "pass.h"
+#include "wasm-builder.h"
+#include "wasm.h"
+
+namespace wasm {
+
+struct IntrinsicLowering : public WalkerPass<PostWalker<IntrinsicLowering>> {
+  bool isFunctionParallel() override { return true; }
+
+  Pass* create() override { return new IntrinsicLowering; }
+
+  void visitCall(Call* curr) {
+    if (Intrinsics(*getModule()).isCallWithoutEffects(curr)) {
+      // Turn into a call, by using the final operand as the function to call.
+      auto& operands = curr->operands;
+      auto* target = operands.back();
+      operands.pop_back();
+      // We could rely on later optimizations here, but at least ensure we emit
+      // a direct call when we can, to avoid a performance cliff if the user
+      // forgets to optimize.
+      Builder builder(*getModule());
+      if (auto* refFunc = target->dynCast<RefFunc>()) {
+        replaceCurrent(builder.makeCall(refFunc->func, operands, curr->type));
+      } else {
+        replaceCurrent(builder.makeCallRef(target, operands, curr->type));
+      }
+    }
+  }
+};
+
+Pass* createIntrinsicLoweringPass() { return new IntrinsicLowering(); }
+
+} // namespace wasm
diff --git a/src/passes/pass.cpp b/src/passes/pass.cpp
index 878ecb3cb..5f53a1d78 100644
--- a/src/passes/pass.cpp
+++ b/src/passes/pass.cpp
@@ -164,6 +164,9 @@ void PassRegistry::registerPasses() {
   registerPass("inlining-optimizing",
                "inline functions and optimizes where we inlined",
                createInliningOptimizingPass);
+  registerPass("intrinsic-lowering",
+               "lower away binaryen intrinsics",
+               createIntrinsicLoweringPass);
   registerPass("legalize-js-interface",
                "legalizes i64 types on the import/export boundary",
                createLegalizeJSInterfacePass);
diff --git a/src/passes/passes.h b/src/passes/passes.h
index 715e5c443..47b246bd4 100644
--- a/src/passes/passes.h
+++ b/src/passes/passes.h
@@ -62,6 +62,7 @@ Pass* createLimitSegmentsPass();
 Pass* createLocalCSEPass();
 Pass* createLocalSubtypingPass();
 Pass* createLogExecutionPass();
+Pass* createIntrinsicLoweringPass();
 Pass* createInstrumentLocalsPass();
 Pass* createInstrumentMemoryPass();
 Pass* createLoopInvariantCodeMotionPass();