Syntax and validation for ref.get_desc

document/core/syntax/instructions.rst

@@ -231,6 +231,7 @@ The ${:DATA.DROP} instruction prevents further use of a passive data segment. Th
 .. _syntax-ref.is_null:
 .. _syntax-ref.as_non_null:
 .. _syntax-ref.eq:
+.. _syntax-ref.get_desc:
 .. _syntax-ref.test:
 .. _syntax-ref.cast:
 .. _syntax-instr-ref:
@@ -247,7 +248,9 @@ The ${:REF.NULL} and ${:REF.FUNC} instructions produce a :ref:`null <syntax-null
 The instruction ${:REF.IS_NULL} checks for null,
 while ${:REF.AS_NON_NULL} converts a :ref:`nullable <syntax-reftype>` to a non-null one, and :ref:`traps <trap>` if it encounters null.
 
-The ${:REF.EQ} compares two references.
+The instruction ${:REF.EQ} compares two references.
+
+The instruction ${:REF.GET_DESC} gets the :ref:`descriptor <syntax-desctype>` of an allocated value.
 
 The instructions ${:REF.TEST} and ${:REF.CAST} test the :ref:`dynamic type <type-inst>` of a reference operand.
 The former merely returns the result of the test,

document/core/util/macros.def

@@ -551,6 +551,7 @@
 .. |REFISNULL| mathdef:: \xref{syntax/instructions}{syntax-instr-ref}{\K{ref{.}is\_null}}
 .. |REFASNONNULL| mathdef:: \xref{syntax/instructions}{syntax-instr-ref}{\K{ref{.}as\_non\_null}}
 .. |REFEQ| mathdef:: \xref{syntax/instructions}{syntax-instr-ref}{\K{ref{.}eq}}
+.. |REFGETDESC| mathdef:: \xref{syntax/instructions}{syntax-instr-ref}{\K{ref.get\_desc}}
 .. |REFTEST| mathdef:: \xref{syntax/instructions}{syntax-instr-ref}{\K{ref{.}test}}
 .. |REFCAST| mathdef:: \xref{syntax/instructions}{syntax-instr-ref}{\K{ref{.}cast}}
 

document/core/valid/instructions.rst

@@ -803,6 +803,16 @@ $${rule-prose: Instr_ok/ref.eq}
 $${rule: Instr_ok/ref.eq}
 
 
+.. _valid-ref.get_desc:
+
+:math:`\REFGETDESC~x`
+.....................
+
+$${rule-prose: Instr_ok/ref.get_desc}
+
+$${rule: Instr_ok/ref.get_desc Instr_ok/ref.get_desc-exact}
+
+
 .. _valid-ref.test:
 
 :math:`\REFTEST~\X{rt}`

specification/wasm-latest/1.3-syntax.instructions.spectec

@@ -306,6 +306,7 @@ syntax instr/ref hint(desc "reference instruction") = ...
   | REF.IS_NULL
   | REF.AS_NON_NULL
   | REF.EQ
+  | REF.GET_DESC typeidx
   | REF.TEST reftype
   | REF.CAST reftype
   | ...

specification/wasm-latest/2.3-validation.instructions.spectec

@@ -231,6 +231,14 @@ rule Instr_ok/ref.as_non_null:
 rule Instr_ok/ref.eq:
   C |- REF.EQ : (REF NULL EQ) (REF NULL EQ) -> I32
 
+rule Instr_ok/ref.get_desc:
+  C |- REF.GET_DESC x : (REF NULL (_IDX x)) -> (REF (_IDX y))
+  -- ExpandDesc: C.TYPES[x] ~~ describestype? (DESCRIPTOR (_IDX y)) ct
+
+rule Instr_ok/ref.get_desc-exact:
+  C |- REF.GET_DESC x : (REF NULL (EXACT (_IDX x))) -> (REF (EXACT (_IDX y)))
+  -- ExpandDesc: C.TYPES[x] ~~ describestype? (DESCRIPTOR (_IDX y)) ct
+
 rule Instr_ok/ref.test:
   C |- REF.TEST rt : rt' -> I32
   -- Reftype_ok: C |- rt : OK