stage2: cleanups to wasm memory intrinsics

 * AIR: use pl_op instead of ty_pl for wasm_memory_size. No need to
   store the type because the type is always `u32`.
 * AstGen: use coerced_ty for `@wasmMemorySize` and `@wasmMemoryGrow`
   and do the coercions in Sema.
 * Sema: use more accurate source locations for errors.
 * Provide more information in the compiler error message.
 * Codegen: use liveness data to avoid lowering unused
   `@wasmMemorySize`.
 * LLVM backend: add implementation
   - I wasn't able to test it because we are hitting a linker error for
     `-target wasm32-wasi -fLLVM`.
 * C backend: use `zig_unimplemented()` instead of silently doing wrong
   behavior for these builtins.
 * behavior tests: branch only on stage2_arch for inclusion of the
   wasm.zig file. We would change it to `builtin.cpu.arch` but that is
   causing a compiler crash on some backends.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
index b1c4be9fef..ca571370ad 100644
--- a/src/arch/wasm/CodeGen.zig
+++ b/src/arch/wasm/CodeGen.zig
@@ -3430,10 +3430,12 @@ fn airPrefetch(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
 }
 
 fn airWasmMemorySize(self: *Self, inst: Air.Inst.Index) !WValue {
-    const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
+    if (self.liveness.isUnused(inst)) return WValue{ .none = {} };
+
+    const pl_op = self.air.instructions.items(.data)[inst].pl_op;
 
     const result = try self.allocLocal(self.air.typeOfIndex(inst));
-    try self.addLabel(.memory_size, ty_pl.payload);
+    try self.addLabel(.memory_size, pl_op.payload);
     try self.addLabel(.local_set, result.local);
     return result;
 }