Group reference types in binary format. (#4774)

Grouping all references together makes it easier for baseline compilers to
zero out memory (as the zeroing out may be different for MVP types vs.
references).

This puts all references together, either at the start or the end. As a
heuristic for that we see if the first local is a reference. As the optimizer
will sort locals by frequency, this ensures that the most-frequent local
stays in index 0.

Fixes #4773. See more details there

1 files changed, 41 insertions, 0 deletions

diff --git a/test/typed-function-references.wast b/test/typed-function-references.wast
index 1057d4487..40eae6ebd 100644
--- a/test/typed-function-references.wast
+++ b/test/typed-function-references.wast
@@ -41,4 +41,45 @@
       )
     )
   )
+  (func $ref-types-first
+    ;; 6 reference types and 3 MVP types. The binary format should emit all the
+    ;; reference types first since a reference type appears first. In addition,
+    ;; types should be emitted in blocks there, that is, locals of identical
+    ;; types should be adjacent.
+    (local $r1 (ref null $mixed_results))
+    (local $r2 (ref null $mixed_results))
+    (local $i1 i32)
+    (local $r3 anyref)
+    (local $i2 i64)
+    (local $r4 anyref)
+    (local $i3 i64)
+    (local $r5 anyref)
+    (local $r6 funcref)
+  )
+  (func $mvp-types-first
+    ;; Reversed from before, now an MVP type appears first, so they should all
+    ;; be before reference types in the binary format.
+    (local $i1 i32) ;; only this local was moved up.
+    (local $r1 (ref null $mixed_results))
+    (local $r2 (ref null $mixed_results))
+    (local $r3 anyref)
+    (local $i2 i64)
+    (local $r4 anyref)
+    (local $i3 i64)
+    (local $r5 anyref)
+    (local $r6 funcref)
+  )
+  (func $mvp-types-first-param (param $r0 (ref null $mixed_results))
+    ;; As before, but now there is a reference type *parameter*. We should
+    ;; ignore that and sort as in the last function.
+    (local $i1 i32) ;; only this local was moved up.
+    (local $r1 (ref null $mixed_results))
+    (local $r2 (ref null $mixed_results))
+    (local $r3 anyref)
+    (local $i2 i64)
+    (local $r4 anyref)
+    (local $i3 i64)
+    (local $r5 anyref)
+    (local $r6 funcref)
+  )
 )