Merge branch 'binaryen'

1 files changed, 56 insertions, 0 deletions

diff --git a/test/example/find_div0s.cpp b/test/example/find_div0s.cpp
new file mode 100644
index 000000000..60eed5f62
--- /dev/null
+++ b/test/example/find_div0s.cpp
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+
+//
+// Tiny example, using Binaryen to walk a WebAssembly module in search
+// for direct integer divisions by zero. To do so, we inherit from
+// WasmWalker, and implement visitBinary, which is called on every
+// Binary node in the module's functions.
+//
+
+#include <ostream>
+#include <wasm.h>
+#include <wasm-s-parser.h>
+
+using namespace wasm;
+
+int main() {
+  // A simple WebAssembly module in S-Expression format.
+  char input[] =
+    "(module"
+    "  (func $has_div_zero"
+    "    (i32.div_s"
+    "      (i32.const 5)"
+    "      (i32.const 0)"
+    "    )"
+    "  )"
+    ")";
+
+  // Parse the S-Expression text, and prepare to build a WebAssembly module.
+  SExpressionParser parser(input);
+  Element& root = *parser.root;
+  Module module;
+
+  // The parsed code has just one element, the module. Build the module
+  // from that (and abort on any errors, but there won't be one here).
+  SExpressionWasmBuilder builder(module, *root[0], [&]() { abort(); });
+
+  // Print it out
+  std::cout << module;
+
+  // Search it for divisions by zero: Walk the module, looking for
+  // that operation.
+  struct DivZeroSeeker : public WasmWalker {
+    void visitBinary(Binary* curr) {
+      // In every Binary, look for integer divisions
+      if (curr->op == BinaryOp::DivS || curr->op == BinaryOp::DivU) {
+        // Check if the right operand is a constant, and if it is 0
+        auto right = curr->right->dyn_cast<Const>();
+        if (right && right->value.getInteger() == 0) {
+          std::cout << "We found that " << curr->left << " is divided by zero\n";
+        }
+      }
+    }
+  };
+  DivZeroSeeker seeker;
+  seeker.startWalk(&module);
+}
+