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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-printing.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;
AllocatingModule 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
printWasm(&module, std::cout);
// Search it for divisions by zero: Walk the module, looking for
// that operation.
struct DivZeroSeeker : public WasmWalker<DivZeroSeeker> {
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);
}
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