Add --js-call-indirect option.

Author: juj

src/asm_v_wasm.h

@@ -42,7 +42,7 @@ std::string getSigFromStructs(Type result, const ListType& operands) {
   std::string ret;
   ret += getSig(result);
   for (auto operand : operands) {
-    ret += getSig(operand.type);
+    ret += getSig(operand->type);
   }
   return ret;
 }

src/passes/CMakeLists.txt

@@ -50,6 +50,7 @@ set(passes_SOURCES
   InstrumentLocals.cpp
   InstrumentMemory.cpp
   Intrinsics.cpp
+  JSCallIndirect.cpp
   JSPI.cpp
   LegalizeJSInterface.cpp
   LimitSegments.cpp

src/passes/JsCallIndirect.cpp

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2017 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.
+ */
+
+//
+// This pass replaces all call_indirect instructions with a call to JS side
+// js_call_indirect_xxxx functions that can perform debug analysis of the
+// call in question. Must run after FuncCastEmulation pass, if that is
+// desired.
+//
+
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+
+#include <ir/element-utils.h>
+#include <ir/literal-utils.h>
+#include <pass.h>
+#include <wasm-builder.h>
+#include <wasm.h>
+#include <asm_v_wasm.h>
+
+namespace wasm {
+
+void setFunctionAsImported(std::unique_ptr<Function>& import, Module* m);
+
+typedef std::unordered_map<std::string, std::unique_ptr<Function>>
+  JsCallIndirectMap;
+
+struct ParallelJsCallIndirect
+  : public WalkerPass<PostWalker<ParallelJsCallIndirect>> {
+  bool isFunctionParallel() override { return true; }
+
+  std::unique_ptr<Pass> create() override {
+    return std::make_unique<ParallelJsCallIndirect>();
+  }
+
+  void visitCallIndirect(CallIndirect* curr) {
+    Module* module = getModule();
+    Builder builder(*module);
+    std::vector<Expression*> callArgs;
+    callArgs.push_back(curr->target);
+    callArgs.insert(
+      callArgs.end(), curr->operands.begin(), curr->operands.end());
+    std::string jsCallIndirect =
+      "js_call_indirect_" + getSigFromStructs(curr->type, curr->operands);
+    if (module->getFunctionOrNull(jsCallIndirect)) {
+      replaceCurrent(builder.makeCall(jsCallIndirect, callArgs, curr->type));
+    } else {
+      // The code is attempting a call_indirect via a signature that there does not exist
+      // any function in the whole program. We can abort here since that will not work at runtime.
+      // TODO: Maybe just create on the fly a "js_call_indirect_" function for this nonexisting
+      // signature?
+      replaceCurrent(builder.makeCall("abort", {}, Type::none));
+    }
+  }
+};
+
+struct JsCallIndirect : public Pass {
+  void run(Module* module) override {
+    std::unordered_set<Signature> seen_sigs;
+    for (std::unique_ptr<Function>& func : module->functions) {
+      Signature sig = func->getSig();
+      std::string type_str = getSig(sig.results, sig.params);
+      if (seen_sigs.find(sig) != seen_sigs.end())
+        continue;
+      seen_sigs.insert(sig);
+
+      std::vector<Type> params;
+      params.push_back(Type::i32);
+      for (auto t : sig.params)
+        params.push_back(t);
+      auto& import =
+        Builder::makeFunction(std::string("js_call_indirect_") + type_str,
+                               Signature(Type(params), sig.results.getBasic()),
+                               {});
+      setFunctionAsImported(import, module);
+      import->base = type_str;
+      module->addFunction(std::move(import));
+    }
+
+    // route all call_indirects to js_call_indirect_*() variants
+    ParallelJsCallIndirect().run(getPassRunner(), module);
+  }
+};
+
+Pass* createJsCallIndirectPass() { return new JsCallIndirect(); }
+
+} // namespace wasm

src/passes/LogExecution.cpp

@@ -38,6 +38,28 @@ namespace wasm {
 
 Name LOGGER("log_execution");
 
+void setFunctionAsImported(std::unique_ptr<Function>& import, Module* m)
+{
+  // Import the log function from import "env" if the module
+  // imports other functions from that name.
+  for (auto& func : m->functions) {
+    if (func->imported() && func->module == ENV) {
+      import->module = func->module;
+      return;
+    }
+  }
+
+  // If not, then pick the import name of the first function we find.
+  if (!import->module) {
+    for (auto& func : m->functions) {
+      if (func->imported()) {
+        import->module = func->module;
+        return;
+      }
+    }
+  }
+}
+
 struct LogExecution : public WalkerPass<PostWalker<LogExecution>> {
   void visitLoop(Loop* curr) { curr->body = makeLogCall(curr->body); }
 
@@ -59,25 +81,7 @@ struct LogExecution : public WalkerPass<PostWalker<LogExecution>> {
     // Add the import
     auto import =
       Builder::makeFunction(LOGGER, Signature(Type::i32, Type::none), {});
-
-    // Import the log function from import "env" if the module
-    // imports other functions from that name.
-    for (auto& func : curr->functions) {
-      if (func->imported() && func->module == ENV) {
-        import->module = func->module;
-        break;
-      }
-    }
-
-    // If not, then pick the import name of the first function we find.
-    if (!import->module) {
-      for (auto& func : curr->functions) {
-        if (func->imported()) {
-          import->module = func->module;
-          break;
-        }
-      }
-    }
+    setFunctionAsImported(import, curr);
 
     import->base = LOGGER;
     curr->addFunction(std::move(import));

src/passes/pass.cpp

@@ -160,6 +160,10 @@ void PassRegistry::registerPasses() {
                "emulates function pointer casts, allowing incorrect indirect "
                "calls to (sometimes) work",
                createFuncCastEmulationPass);
+  registerPass("js-call-indirect",
+               "Redirects all call_indirects to occur from JS side, allowing "
+               "these to be audited e.g. for debugging purposes",
+               createJsCallIndirectPass);
   registerPass(
     "func-metrics", "reports function metrics", createFunctionMetricsPass);
   registerPass("generate-dyncalls",

src/passes/passes.h

@@ -48,6 +48,7 @@ Pass* createExtractFunctionPass();
 Pass* createExtractFunctionIndexPass();
 Pass* createFlattenPass();
 Pass* createFuncCastEmulationPass();
+Pass* createJsCallIndirectPass();
 Pass* createFullPrinterPass();
 Pass* createFunctionMetricsPass();
 Pass* createGenerateDynCallsPass();