wasm-merge: Sort globals to ensure proper validation (#6221)

If the first module has a global that reads from a global that appears in a later
module, then we need to reorder the globals, because if we just append the
globals from the later module we'd end up with a global reading from another
that is not before it.

Changes to the existing renamings test are just due to the global sorting
pass that now runs (it not only fixes up validation errors but also tries to sort
in a more optimal order for size).

Fixes #6220

1 files changed, 5 insertions, 1 deletions

diff --git a/src/passes/ReorderGlobals.cpp b/src/passes/ReorderGlobals.cpp
index d1c26b2cc..9b5940a21 100644
--- a/src/passes/ReorderGlobals.cpp
+++ b/src/passes/ReorderGlobals.cpp
@@ -58,7 +58,11 @@ private:
 
 struct ReorderGlobals : public Pass {
   // Whether to always reorder globals, even if there are very few and the
-  // benefit is minor. That is useful for testing.
+  // benefit is minor. That is useful for testing, and also internally in passes
+  // that use us to reorder them so dependencies appear first (that is, if a
+  // pass ends up with an earlier global reading a later one, the sorting in
+  // this pass will reorder them properly; we need to take those dependencies
+  // into account anyhow here).
   bool always;
 
   ReorderGlobals(bool always) : always(always) {}