Add GlobalSubtyping pass (#4306)

This specializes the fields of structs based on the types written to them. That is,
if a field is of type A but in practice we always write some subtype B to it
then we can change the type of the field to that.

On j2wasm this manages to improve at least one field in 2% of types. Not a
large amount, but this does lead to further benefits in later opts (e.g. about a third
of the improvements are to turn a field non-nullable).

1 files changed, 2 insertions, 1 deletions

diff --git a/src/passes/passes.h b/src/passes/passes.h
index a08e42f62..b9ba566d0 100644
--- a/src/passes/passes.h
+++ b/src/passes/passes.h
@@ -51,6 +51,8 @@ Pass* createFunctionMetricsPass();
 Pass* createGenerateDynCallsPass();
 Pass* createGenerateI64DynCallsPass();
 Pass* createGenerateStackIRPass();
+Pass* createGlobalSubtypingPass();
+Pass* createGlobalTypeOptimizationPass();
 Pass* createHeap2LocalPass();
 Pass* createI64ToI32LoweringPass();
 Pass* createInlineMainPass();
@@ -131,7 +133,6 @@ Pass* createTrapModeClamp();
 Pass* createTrapModeJS();
 Pass* createUnteePass();
 Pass* createVacuumPass();
-Pass* createGlobalTypeOptimizationPass();
 
 } // namespace wasm