From 2eca0e42e59fafae839b507148e8a3679d172079 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Thu, 16 Oct 2025 13:50:39 +0200
Subject: [PATCH] std.debug: FP-based unwinding is impossible on avr, csky,
 msp430, and xcore

The ABIs do not define a frame pointer register, nor do they define a guaranteed
and fixed area on the stack where one might find saved registers such as a frame
pointer or return address.
---
 lib/std/debug.zig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index d9eb0cd907..377028236e 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -872,10 +872,14 @@ const StackIterator = union(enum) {
     };
 
     const fp_usability: FpUsability = switch (builtin.target.cpu.arch) {
+        .avr,
+        .csky,
         .mips,
         .mipsel,
         .mips64,
         .mips64el,
+        .msp430,
+        .xcore,
         => .useless,
         .hexagon,
         // The PowerPC ABIs don't actually strictly require a backchain pointer; they allow omitting