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

3 files changed, 39 insertions, 5 deletions

diff --git a/test/lit/merge/global-ordering.wat b/test/lit/merge/global-ordering.wat
new file mode 100644
index 000000000..2cc3b504b
--- /dev/null
+++ b/test/lit/merge/global-ordering.wat
@@ -0,0 +1,30 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+
+;; RUN: wasm-merge %s first %s.second second -all -S -o - | filecheck %s
+
+;; After the merge this module's global will read a value from a global that is
+;; appended after it, from the second module. Those must be reordered so that
+;; we validate, as a global can only read from previous ones.
+
+(module
+  (import "second" "second.global.export" (global i32))
+
+  ;; CHECK:      (type $0 (func (result i32)))
+
+  ;; CHECK:      (global $second.global i32 (i32.const 42))
+
+  ;; CHECK:      (global $first.global (mut i32) (global.get $second.global))
+  (global $first.global (mut i32) (global.get 0))
+
+  ;; CHECK:      (export "run" (func $run))
+
+  ;; CHECK:      (export "second.global.export" (global $second.global))
+
+  ;; CHECK:      (func $run (type $0) (result i32)
+  ;; CHECK-NEXT:  (global.get $first.global)
+  ;; CHECK-NEXT: )
+  (func $run (export "run") (result i32)
+    ;; Use the global to avoid it being removed.
+    (global.get $first.global)
+  )
+)
diff --git a/test/lit/merge/global-ordering.wat.second b/test/lit/merge/global-ordering.wat.second
new file mode 100644
index 000000000..7676599e4
--- /dev/null
+++ b/test/lit/merge/global-ordering.wat.second
@@ -0,0 +1,3 @@
+(module
+  (global $second.global (export "second.global.export") i32 (i32.const 42))
+)
diff --git a/test/lit/merge/renamings.wat b/test/lit/merge/renamings.wat
index 6d4de5c65..98aac63be 100644
--- a/test/lit/merge/renamings.wat
+++ b/test/lit/merge/renamings.wat
@@ -23,20 +23,21 @@
 
   ;; CHECK:      (import "elsewhere" "some.tag" (tag $imported (param f64)))
 
+  ;; CHECK:      (global $bar_2 i32 (i32.const 4))
+
+  ;; CHECK:      (global $other i32 (i32.const 3))
+
+  ;; CHECK:      (global $bar i32 (i32.const 2))
+
   ;; CHECK:      (global $foo i32 (i32.const 1))
   (global $foo i32 (i32.const 1))
 
   ;; This global has a conflict in second.wat, and so second.wat's $bar
   ;; will be renamed.
-  ;; CHECK:      (global $bar i32 (i32.const 2))
   (global $bar i32 (i32.const 2))
 
   ;; This memory has a conflict in second.wat, and so second.wat's $foo
   ;; will be renamed.
-  ;; CHECK:      (global $other i32 (i32.const 3))
-
-  ;; CHECK:      (global $bar_2 i32 (i32.const 4))
-
   ;; CHECK:      (memory $foo 10 20)
   (memory $foo 10 20)