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, 7 insertions, 1 deletions

diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 02da4f909..8680ff8cc 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2702,7 +2702,13 @@ Expression* SExpressionWasmBuilder::makeRefCast(Element& s) {
 Expression* SExpressionWasmBuilder::makeRefCastStatic(Element& s) {
   auto heapType = parseHeapType(*s[1]);
   auto* ref = parseExpression(*s[2]);
-  return Builder(wasm).makeRefCast(ref, heapType);
+  return Builder(wasm).makeRefCast(ref, heapType, RefCast::Safe);
+}
+
+Expression* SExpressionWasmBuilder::makeRefCastNopStatic(Element& s) {
+  auto heapType = parseHeapType(*s[1]);
+  auto* ref = parseExpression(*s[2]);
+  return Builder(wasm).makeRefCast(ref, heapType, RefCast::Unsafe);
 }
 
 Expression* SExpressionWasmBuilder::makeBrOn(Element& s, BrOnOp op) {