1 files changed, 140 insertions, 0 deletions
diff --git a/src/passes/InstrumentLocals.cpp b/src/passes/InstrumentLocals.cpp
new file mode 100644
index 000000000..22b8ebf70
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+++ b/src/passes/InstrumentLocals.cpp
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+/*
+ * 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.
+ */
+
+//
+// Instruments the build with code to intercept all local reads and writes.
+//
+// gets:
+//
+//  Before:
+//   (get_local $x)
+//
+//  After:
+//    (call $get_TYPE
+//     (i32.const n) // call id
+//     (i32.const n) // local id
+//     (get_local $x)
+//    )
+//
+// sets:
+//
+//  Before:
+//   (set_local $x (i32.const 1))
+//
+//  After:
+//   (set_local $x
+//    (call $set_TYPE
+//     (i32.const n) // call id
+//     (i32.const n) // local id
+//     (i32.const 1) // value
+//    )
+//   )
+
+#include <wasm.h>
+#include <wasm-builder.h>
+#include <pass.h>
+#include "shared-constants.h"
+#include "asmjs/shared-constants.h"
+#include "asm_v_wasm.h"
+
+namespace wasm {
+
+Name get_i32("get_i32");
+Name get_i64("get_i64");
+Name get_f32("get_f32");
+Name get_f64("get_f64");
+
+Name set_i32("set_i32");
+Name set_i64("set_i64");
+Name set_f32("set_f32");
+Name set_f64("set_f64");
+
+struct InstrumentLocals : public WalkerPass<PostWalker<InstrumentLocals>> {
+  void visitGetLocal(GetLocal* curr) {
+    Builder builder(*getModule());
+    Name import;
+    switch (curr->type) {
+      case i32: import = get_i32; break;
+      case i64: return; // TODO
+      case f32: import = get_f32; break;
+      case f64: import = get_f64; break;
+      default: WASM_UNREACHABLE();
+    }
+    replaceCurrent(
+      builder.makeCallImport(
+        import,
+        {
+          builder.makeConst(Literal(int32_t(id++))),
+          builder.makeConst(Literal(int32_t(curr->index))),
+          curr
+        },
+        curr->type
+      )
+    );
+  }
+
+  void visitSetLocal(SetLocal* curr) {
+    Builder builder(*getModule());
+    Name import;
+    switch (curr->value->type) {
+      case i32: import = set_i32; break;
+      case i64: return; // TODO
+      case f32: import = set_f32; break;
+      case f64: import = set_f64; break;
+      case unreachable: return; // nothing to do here
+      default: WASM_UNREACHABLE();
+    }
+    curr->value = builder.makeCallImport(
+      import,
+      {
+        builder.makeConst(Literal(int32_t(id++))),
+        builder.makeConst(Literal(int32_t(curr->index))),
+        curr->value
+      },
+      curr->value->type
+    );
+  }
+
+  void visitModule(Module* curr) {
+    addImport(curr, get_i32,  "iiii");
+    addImport(curr, get_i64,  "jiij");
+    addImport(curr, get_f32,  "fiif");
+    addImport(curr, get_f64,  "diid");
+    addImport(curr, set_i32,  "iiii");
+    addImport(curr, set_i64,  "jiij");
+    addImport(curr, set_f32,  "fiif");
+    addImport(curr, set_f64,  "diid");
+  }
+
+private:
+  Index id = 0;
+
+  void addImport(Module* wasm, Name name, std::string sig) {
+    auto import = new Import;
+    import->name = name;
+    import->module = INSTRUMENT;
+    import->base = name;
+    import->functionType = ensureFunctionType(sig, wasm)->name;
+    import->kind = ExternalKind::Function;
+    wasm->addImport(import);
+  }
+};
+
+Pass* createInstrumentLocalsPass() {
+  return new InstrumentLocals();
+}
+
+} // namespace wasm