From 640c11171bf8d13776629941f3305cf11c62c1f3 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Thu, 28 Aug 2025 18:32:51 -0700
Subject: [PATCH] LLVM backend:fix align 1 sret parameter load returned

closes #25067
---
 src/codegen/llvm.zig     |  1 +
 test/behavior/struct.zig | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index 9cbe1f8c56..e4abfcca43 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -9773,6 +9773,7 @@ pub const FuncGen = struct {
         const ptr = try fg.resolveInst(ty_op.operand);
 
         elide: {
+            if (ptr_info.flags.alignment != .none) break :elide;
             if (!isByRef(Type.fromInterned(ptr_info.child), zcu)) break :elide;
             if (!canElideLoad(fg, body_tail)) break :elide;
             return ptr;
diff --git a/test/behavior/struct.zig b/test/behavior/struct.zig
index 29e9986e5e..f1c10a1461 100644
--- a/test/behavior/struct.zig
+++ b/test/behavior/struct.zig
@@ -2136,3 +2136,21 @@ test "field access through mem ptr arg" {
         &.{ .field = 0x0ced271f },
     ) == 0x0ced271f);
 }
+
+test "align 1 struct parameter dereferenced and returned" {
+    if (builtin.zig_backend == .stage2_spirv) return error.SkipZigTest;
+
+    const S = extern struct {
+        a: u32,
+
+        fn gimme(p: *align(1) @This()) @This() {
+            return p.*;
+        }
+    };
+    var buffer: [5]u8 align(4) = .{ 1, 2, 3, 4, 5 };
+    const s = S.gimme(@ptrCast(buffer[1..]));
+    switch (native_endian) {
+        .big => try expect(s.a == 0x02030405),
+        .little => try expect(s.a == 0x05040302),
+    }
+}