SimplifyGlobals: Propagate constant globals into nested gets in other globals (#6285)

Before we propagated to the top level, but not to anything interior.

2 files changed, 31 insertions, 2 deletions

diff --git a/src/passes/SimplifyGlobals.cpp b/src/passes/SimplifyGlobals.cpp
index 3baec4409..323ebd6a7 100644
--- a/src/passes/SimplifyGlobals.cpp
+++ b/src/passes/SimplifyGlobals.cpp
@@ -41,6 +41,7 @@
 #include <atomic>
 
 #include "ir/effects.h"
+#include "ir/find_all.h"
 #include "ir/linear-execution.h"
 #include "ir/properties.h"
 #include "ir/utils.h"
@@ -659,10 +660,11 @@ struct SimplifyGlobals : public Pass {
         // This is the init of a passive segment, which is null.
         return;
       }
-      if (auto* get = init->dynCast<GlobalGet>()) {
+      for (auto** getp : FindAllPointers<GlobalGet>(init).list) {
+        auto* get = (*getp)->cast<GlobalGet>();
         auto iter = constantGlobals.find(get->name);
         if (iter != constantGlobals.end()) {
-          init = builder.makeConstantExpression(iter->second);
+          *getp = builder.makeConstantExpression(iter->second);
         }
       }
     };
diff --git a/test/lit/passes/simplify-globals-nested.wast b/test/lit/passes/simplify-globals-nested.wast
new file mode 100644
index 000000000..925d71161
--- /dev/null
+++ b/test/lit/passes/simplify-globals-nested.wast
@@ -0,0 +1,27 @@
+;; NOTE: Assertions have been generated by update_lit_checks.py --all-items and should not be edited.
+;; NOTE: This test was ported using port_passes_tests_to_lit.py and could be cleaned up.
+
+;; RUN: foreach %s %t wasm-opt --simplify-globals -all -S -o - | filecheck %s
+
+;; Test that we propagate globals into nested children of other globals.
+
+(module
+ ;; CHECK:      (type $struct (struct (field i32) (field i32)))
+ (type $struct (struct i32 i32))
+
+ ;; CHECK:      (global $a i32 (i32.const 42))
+ (global $a i32 (i32.const 42))
+
+ ;; CHECK:      (global $b i32 (i32.const 1337))
+ (global $b i32 (i32.const 1337))
+
+ ;; CHECK:      (global $struct (ref $struct) (struct.new $struct
+ ;; CHECK-NEXT:  (i32.const 42)
+ ;; CHECK-NEXT:  (i32.const 1337)
+ ;; CHECK-NEXT: ))
+ (global $struct (ref $struct) (struct.new $struct
+  (global.get $a)
+  (global.get $b)
+ ))
+)
+