From 710182ad26ce0155b71f20cbb8dc6ade45919802 Mon Sep 17 00:00:00 2001
From: Ryan Hunt <rhunt@eqrion.net>
Date: Mon, 6 Jan 2020 15:36:46 -0600
Subject: [PATCH] Wasm: Add support for nullref type

Reference types now supports proper a nullref type. This commit changes
the Wasm translator to support this.
---
 cranelift/wasm/src/func_translator.rs   |  1 +
 cranelift/wasm/src/translation_utils.rs |  7 +++++--
 cranelift/wasmtests/nullref.wat         | 11 +++++++++++
 3 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 cranelift/wasmtests/nullref.wat

diff --git a/cranelift/wasm/src/func_translator.rs b/cranelift/wasm/src/func_translator.rs
index a7dbf0820a..cc61b28c9b 100644
--- a/cranelift/wasm/src/func_translator.rs
+++ b/cranelift/wasm/src/func_translator.rs
@@ -196,6 +196,7 @@ fn declare_locals<FE: FuncEnvironment + ?Sized>(
             let constant_handle = builder.func.dfg.constants.insert([0; 16].to_vec().into());
             builder.ins().vconst(ir::types::I8X16, constant_handle)
         }
+        NullRef => builder.ins().null(environ.reference_type()),
         AnyRef => builder.ins().null(environ.reference_type()),
         AnyFunc => builder.ins().null(environ.reference_type()),
         ty => return Err(wasm_unsupported!("unsupported local type {:?}", ty)),
diff --git a/cranelift/wasm/src/translation_utils.rs b/cranelift/wasm/src/translation_utils.rs
index 9d38d9dbb6..d431c13f29 100644
--- a/cranelift/wasm/src/translation_utils.rs
+++ b/cranelift/wasm/src/translation_utils.rs
@@ -131,7 +131,9 @@ pub fn type_to_type<PE: TargetEnvironment + ?Sized>(
         wasmparser::Type::F32 => Ok(ir::types::F32),
         wasmparser::Type::F64 => Ok(ir::types::F64),
         wasmparser::Type::V128 => Ok(ir::types::I8X16),
-        wasmparser::Type::AnyRef | wasmparser::Type::AnyFunc => Ok(environ.reference_type()),
+        wasmparser::Type::AnyRef | wasmparser::Type::AnyFunc | wasmparser::Type::NullRef => {
+            Ok(environ.reference_type())
+        }
         ty => Err(wasm_unsupported!("type_to_type: wasm type {:?}", ty)),
     }
 }
@@ -171,6 +173,7 @@ pub fn blocktype_params_results(
             wasmparser::Type::V128 => (&[], &[wasmparser::Type::V128]),
             wasmparser::Type::AnyRef => (&[], &[wasmparser::Type::AnyRef]),
             wasmparser::Type::AnyFunc => (&[], &[wasmparser::Type::AnyFunc]),
+            wasmparser::Type::NullRef => (&[], &[wasmparser::Type::NullRef]),
             wasmparser::Type::EmptyBlockType => (&[], &[]),
             ty => return Err(wasm_unsupported!("blocktype_params_results: type {:?}", ty)),
         },
@@ -203,7 +206,7 @@ pub fn ebb_with_params<PE: TargetEnvironment + ?Sized>(
             wasmparser::Type::F64 => {
                 builder.append_ebb_param(ebb, ir::types::F64);
             }
-            wasmparser::Type::AnyRef | wasmparser::Type::AnyFunc => {
+            wasmparser::Type::AnyRef | wasmparser::Type::AnyFunc | wasmparser::Type::NullRef => {
                 builder.append_ebb_param(ebb, environ.reference_type());
             }
             wasmparser::Type::V128 => {
diff --git a/cranelift/wasmtests/nullref.wat b/cranelift/wasmtests/nullref.wat
new file mode 100644
index 0000000000..86714a2b6e
--- /dev/null
+++ b/cranelift/wasmtests/nullref.wat
@@ -0,0 +1,11 @@
+(module
+	(func (result nullref)
+		ref.null
+	)
+
+	(func (result nullref)
+		(block (result nullref)
+			ref.null
+		)
+	)
+)