wasm: Implement `@wasmMemorySize()` builtin

This implements the `wasmMemorySize` builtin, in Sema and the Wasm backend.
The Stage2 implementation differs from stage1 in the way that `index` must be a comptime value.
The stage1 variant is incorrect, as the index is part of the instruction encoding, and therefore,
cannot be a runtime value.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index 252d449fc2..a22d8e01b0 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -2314,6 +2314,8 @@ pub const FuncGen = struct {
                 .wrap_errunion_payload => try self.airWrapErrUnionPayload(inst),
                 .wrap_errunion_err     => try self.airWrapErrUnionErr(inst),
 
+                .wasm_memory_size => try self.airWasmMemorySize(inst),
+
                 .constant => unreachable,
                 .const_ty => unreachable,
                 .unreach  => self.airUnreach(inst),
@@ -3474,6 +3476,11 @@ pub const FuncGen = struct {
         return partial;
     }
 
+    fn airWasmMemorySize(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
+        _ = inst;
+        return self.todo("`@wasmMemorySize()`", .{});
+    }
+
     fn airMin(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {
         if (self.liveness.isUnused(inst)) return null;