[Wasm GC] Implement static (rtt-free) StructNew, ArrayNew, ArrayInit (#4172)

See #4149

This modifies the test added in #4163 which used static casts on
dynamically-created structs and arrays. That was technically not
valid (as we won't want users to "mix" the two forms). This makes that
test 100% static, which both fixes the test and gives test coverage
to the new instructions added here.

2 files changed, 44 insertions, 1 deletions

diff --git a/test/lit/passes/heap2local.wast b/test/lit/passes/heap2local.wast
index d49836b99..90ac8a418 100644
--- a/test/lit/passes/heap2local.wast
+++ b/test/lit/passes/heap2local.wast
@@ -254,7 +254,7 @@
   ;; CHECK-NEXT:  (drop
   ;; CHECK-NEXT:   (block ;; (replaces something unreachable we can't emit)
   ;; CHECK-NEXT:    (drop
-  ;; CHECK-NEXT:     (struct.new_with_rtt $struct.A
+  ;; CHECK-NEXT:     (block
   ;; CHECK-NEXT:      (i32.const 2)
   ;; CHECK-NEXT:      (unreachable)
   ;; CHECK-NEXT:      (rtt.canon $struct.A)
@@ -1937,4 +1937,27 @@
       )
     )
   )
+
+  ;; CHECK:      (func $simple-no-rtt
+  ;; CHECK-NEXT:  (local $0 i32)
+  ;; CHECK-NEXT:  (local $1 f64)
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (block (result (ref null $struct.A))
+  ;; CHECK-NEXT:    (local.set $0
+  ;; CHECK-NEXT:     (i32.const 0)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:    (local.set $1
+  ;; CHECK-NEXT:     (f64.const 0)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:    (ref.null $struct.A)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $simple-no-rtt
+    (drop
+      ;; This allocation has no rtt, so we have nothing to drop from it when
+      ;; we optimize.
+      (struct.new_default $struct.A)
+    )
+  )
 )
diff --git a/test/lit/passes/precompute-gc.wast b/test/lit/passes/precompute-gc.wast
index 0a08c02c0..44eff1c5f 100644
--- a/test/lit/passes/precompute-gc.wast
+++ b/test/lit/passes/precompute-gc.wast
@@ -510,4 +510,24 @@
    )
   )
  )
+
+ ;; CHECK:      (func $new_block_unreachable (result anyref)
+ ;; CHECK-NEXT:  (block
+ ;; CHECK-NEXT:   (block
+ ;; CHECK-NEXT:    (unreachable)
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:   (rtt.canon $struct)
+ ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT: )
+ (func $new_block_unreachable (result anyref)
+  (struct.new_with_rtt $struct
+   ;; The value is a block with an unreachable. precompute will get rid of the
+   ;; block, after which fuzz-exec should not crash - this is a regression test
+   ;; for us being careful in how we execute an unreachable struct.new
+   (block $label$1 (result i32)
+    (unreachable)
+   )
+   (rtt.canon $struct)
+  )
+ )
 )