llvm: add attributes to the arguments of function pointer calls

Closes #13605

test/c_abi/cfuncs.c

@@ -842,3 +842,32 @@ struct ByRef c_modify_by_ref_param(struct ByRef in) {
     in.val = 42;
     return in;
 }
+
+struct ByVal {
+    struct {
+        unsigned long x;
+        unsigned long y;
+        unsigned long z;
+    } origin;
+    struct {
+        unsigned long width;
+        unsigned long height;
+        unsigned long depth;
+    } size;
+};
+
+void c_func_ptr_byval(void *a, void *b, struct ByVal in, unsigned long c, void *d, unsigned long e) {
+    assert_or_panic((intptr_t)a == 1);
+    assert_or_panic((intptr_t)b == 2);
+
+    assert_or_panic(in.origin.x == 9);
+    assert_or_panic(in.origin.y == 10);
+    assert_or_panic(in.origin.z == 11);
+    assert_or_panic(in.size.width == 12);
+    assert_or_panic(in.size.height == 13);
+    assert_or_panic(in.size.depth == 14);
+
+    assert_or_panic(c == 3);
+    assert_or_panic((intptr_t)d == 4);
+    assert_or_panic(e == 5);
+}

test/c_abi/main.zig

@@ -1001,3 +1001,34 @@ test "C function modifies by ref param" {
     const res = c_modify_by_ref_param(.{ .val = 1, .arr = undefined });
     try expect(res.val == 42);
 }
+
+const ByVal = extern struct {
+    origin: extern struct {
+        x: c_ulong,
+        y: c_ulong,
+        z: c_ulong,
+    },
+    size: extern struct {
+        width: c_ulong,
+        height: c_ulong,
+        depth: c_ulong,
+    },
+};
+
+extern fn c_func_ptr_byval(*anyopaque, *anyopaque, ByVal, c_ulong, *anyopaque, c_ulong) void;
+test "C function that takes byval struct called via function pointer" {
+    if (comptime builtin.cpu.arch.isPPC()) return error.SkipZigTest;
+
+    var fn_ptr = &c_func_ptr_byval;
+    fn_ptr(
+        @intToPtr(*anyopaque, 1),
+        @intToPtr(*anyopaque, 2),
+        ByVal{
+            .origin = .{ .x = 9, .y = 10, .z = 11 },
+            .size = .{ .width = 12, .height = 13, .depth = 14 },
+        },
+        @as(c_ulong, 3),
+        @intToPtr(*anyopaque, 4),
+        @as(c_ulong, 5),
+    );
+}