[GC] Add struct.new and start to test interesting execution (#3433)

With struct.new read/write support, we can start to do interesting
things! This adds a test of creating a struct and seeing that references
behave like references, that is, if we write to the value X refers to, and
if Y refers to the same thing, when reading from Y's value we see the
change as well.

The test is run through all of -O1, which uncovered a minor issue in
Precompute: We can't try to precompute a reference type, as we can't
replace a reference with a value.

Note btw that the test shows the optimizer properly running
CoalesceLocals on reference types, merging two locals.

1 files changed, 13 insertions, 0 deletions

diff --git a/test/heap-types.wast.fromBinary b/test/heap-types.wast.fromBinary
index 537096fe0..315d30d38 100644
--- a/test/heap-types.wast.fromBinary
+++ b/test/heap-types.wast.fromBinary
@@ -88,6 +88,19 @@
    (local.get $x)
    (i32.const 100)
   )
+  (drop
+   (struct.new_default_with_rtt ${i32_f32_f64}
+    (rtt.canon ${i32_f32_f64})
+   )
+  )
+  (drop
+   (struct.new_with_rtt ${i32_f32_f64}
+    (rtt.canon ${i32_f32_f64})
+    (i32.const 1)
+    (f32.const 2.3450000286102295)
+    (f64.const 3.14159)
+   )
+  )
   (unreachable)
  )
  (func $rtt-param-with-depth (param $rtt (rtt 1 ${}))