Add ref.cast_nop_static (#4656)

This unsafe experimental instruction is semantically equivalent to
ref.cast_static, but V8 will unsafely turn it into a nop. This is meant to help
us measure cast overhead more precisely than we can by globally turning all
casts into nops.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 9a4235cbf..ce70f50fd 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -1984,7 +1984,11 @@ struct PrintExpressionContents
     if (curr->rtt) {
       printMedium(o, "ref.cast");
     } else {
-      printMedium(o, "ref.cast_static ");
+      if (curr->safety == RefCast::Unsafe) {
+        printMedium(o, "ref.cast_nop_static ");
+      } else {
+        printMedium(o, "ref.cast_static ");
+      }
       printHeapType(o, curr->intendedType, wasm);
     }
   }