From 0c12363fd3e82b8c1e7b37c9c43fdca66cf8c520 Mon Sep 17 00:00:00 2001
From: kbkpbot <kbkpbot@sina.com>
Date: Fri, 11 Jul 2025 22:13:30 +0800
Subject: [PATCH] arm64: Save func results before struct args

In gfunc_call(), structure members are loaded into registers during
argument handling.
This operation may overwrite previous function call results stored in
registers (e.g., s0). To prevent this, we must save function call
results to the stack before processing structure arguments.
---
 arm64-gen.c                                 |  3 +++
 tests/tests2/137_funcall_struct_args.c      | 23 +++++++++++++++++++++
 tests/tests2/137_funcall_struct_args.expect |  2 ++
 3 files changed, 28 insertions(+)
 create mode 100644 tests/tests2/137_funcall_struct_args.c
 create mode 100644 tests/tests2/137_funcall_struct_args.expect

diff --git a/arm64-gen.c b/arm64-gen.c
index d15446d3..ccb5a5c1 100644
--- a/arm64-gen.c
+++ b/arm64-gen.c
@@ -1101,6 +1101,9 @@ ST_FUNC void gfunc_call(int nb_args)
             // value in floating-point registers
             if ((vtop->type.t & VT_BTYPE) == VT_STRUCT) {
                 uint32_t j, sz, n = arm64_hfa(&vtop->type, &sz);
+                // save regs because struct may overwrite previous func call result
+                save_regs(0);
+
                 vtop->type.t = VT_PTR;
                 gaddrof();
                 gv(RC_R30);
diff --git a/tests/tests2/137_funcall_struct_args.c b/tests/tests2/137_funcall_struct_args.c
new file mode 100644
index 00000000..20768e34
--- /dev/null
+++ b/tests/tests2/137_funcall_struct_args.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+// arm64-gen.c: gfunc_call() Second pass when struct args may overwrite previous func call result
+struct vec {
+        float x;
+        float y;
+};
+
+void bug(float x, float y) {
+    printf("x=%f\ny=%f\n", x, y);
+}
+
+float dot(struct vec v) {
+    return 999.5;
+}
+
+void main(void) {
+        struct vec a;
+        a.x = 33.0f;
+        a.y = 77.0f;
+        bug(dot(a), dot(a));
+}
+
diff --git a/tests/tests2/137_funcall_struct_args.expect b/tests/tests2/137_funcall_struct_args.expect
new file mode 100644
index 00000000..ea381eae
--- /dev/null
+++ b/tests/tests2/137_funcall_struct_args.expect
@@ -0,0 +1,2 @@
+x=999.500000
+y=999.500000