Very simple module linking in wasm-shell (#3792)

This is a rewrite of the wasm-shell tool, with the goal of improved
compatibility with the reference interpreter and the spec test suite.
To facilitate that, module instances are provided with a list of linked
instances, and imported objects are looked up in the correct instance.

The new shell can:

- register and link modules using the (register ...) command.
- parse binary modules with the syntax (module binary ...).
- provide the "spectest" module defined in the reference interpreter
- assert instantiation traps with assert_trap
- better check linkability by looking up the linked instances in
- assert_unlinkable

It cannot call external function references that are not direct imports.
That would require bigger changes.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 9f7a2af12..e6584972e 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -339,8 +339,19 @@ SExpressionWasmBuilder::SExpressionWasmBuilder(Module& wasm,
   Index i = 1;
   if (module[i]->dollared()) {
     wasm.name = module[i]->str();
+    if (module.size() == 2) {
+      return;
+    }
+    i++;
+  }
+
+  // spec tests have a `binary` keyword after the optional module name. Skip it
+  Name BINARY("binary");
+  if (module[i]->isStr() && module[i]->str() == BINARY &&
+      !module[i]->quoted()) {
     i++;
   }
+
   if (i < module.size() && module[i]->isStr()) {
     // these s-expressions contain a binary module, actually
     std::vector<char> data;
@@ -3290,6 +3301,10 @@ void SExpressionWasmBuilder::parseElem(Element& s, Table* table) {
     // Offset expression (offset (<expr>)) | (<expr>)
     auto& inner = *s[i++];
     if (elementStartsWith(inner, OFFSET)) {
+      if (inner.size() > 2) {
+        throw ParseException(
+          "Invalid offset for an element segment.", s.line, s.col);
+      }
       segment->offset = parseExpression(inner[1]);
     } else {
       segment->offset = parseExpression(inner);