[GC] Add br_on_func/data/i31 (#3525)

This expands the existing BrOnCast into BrOn that can also handle the
func/data/i31 variants. This is not as elegant as RefIs / RefAs in that BrOnCast
has an extra rtt field, but I think it is still the best option. We already have optional
fields on Break (the value and condition), so making rtt optional is not odd. And
it allows us to share all the behavior of br_on_* which aside from the cast or the
check itself, is identical - returning the value if the branch is not taken, etc.

1 files changed, 19 insertions, 3 deletions

diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 197581e33..0ccca0e23 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -1990,9 +1990,25 @@ void BinaryInstWriter::visitRefCast(RefCast* curr) {
   o << int8_t(BinaryConsts::GCPrefix) << U32LEB(BinaryConsts::RefCast);
 }
 
-void BinaryInstWriter::visitBrOnCast(BrOnCast* curr) {
-  o << int8_t(BinaryConsts::GCPrefix) << U32LEB(BinaryConsts::BrOnCast)
-    << U32LEB(getBreakIndex(curr->name));
+void BinaryInstWriter::visitBrOn(BrOn* curr) {
+  o << int8_t(BinaryConsts::GCPrefix);
+  switch (curr->op) {
+    case BrOnCast:
+      o << U32LEB(BinaryConsts::BrOnCast);
+      break;
+    case BrOnFunc:
+      o << U32LEB(BinaryConsts::BrOnFunc);
+      break;
+    case BrOnData:
+      o << U32LEB(BinaryConsts::BrOnData);
+      break;
+    case BrOnI31:
+      o << U32LEB(BinaryConsts::BrOnI31);
+      break;
+    default:
+      WASM_UNREACHABLE("invalid br_on_*");
+  }
+  o << U32LEB(getBreakIndex(curr->name));
 }
 
 void BinaryInstWriter::visitRttCanon(RttCanon* curr) {