From 237d8ad703d1eabe7e990b43dfc4fc4b9808e3a6 Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@vectorware.com>
Date: Mon, 13 Oct 2025 10:17:43 +0300
Subject: [PATCH] abi: use `PassMode::Direct` even for data types that can be
 passed as scalar pairs.

---
 crates/rustc_codegen_spirv/src/abi.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/crates/rustc_codegen_spirv/src/abi.rs b/crates/rustc_codegen_spirv/src/abi.rs
index 3c0c025845..f80bf6092c 100644
--- a/crates/rustc_codegen_spirv/src/abi.rs
+++ b/crates/rustc_codegen_spirv/src/abi.rs
@@ -69,6 +69,15 @@ pub(crate) fn provide(providers: &mut Providers) {
             // <https://github.com/rust-lang/rust/commit/eaaa03faf77b157907894a4207d8378ecaec7b45>
             arg.make_direct_deprecated();
 
+            // FIXME(eddyb) detect `#[rust_gpu::vector::v1]` more specifically,
+            // to avoid affecting anything should actually be passed as a pair.
+            if let PassMode::Pair(..) = arg.mode {
+                // HACK(eddyb) this avoids breaking e.g. `&[T]` pairs.
+                if let TyKind::Adt(..) = arg.layout.ty.kind() {
+                    arg.mode = PassMode::Direct(ArgAttributes::new());
+                }
+            }
+
             // Avoid pointlessly passing ZSTs, just like the official Rust ABI.
             if arg.layout.is_zst() {
                 arg.mode = PassMode::Ignore;