zig

commit 912fed338019487ec025ecbe3cd27134d75fe6e4 (tree)
parent 6de2d61a0cbcf535b455770b4d7397d580eac6c6
Author: Alex Rønne Petersen <alex@alexrp.com>
Date:   Tue, 14 Oct 2025 09:52:10 +0200

std.debug: use the SP as the initial FP on SPARC

The FP would point to the register save area for the previous frame, while the
SP points to the register save area for the current frame. So use the latter.

Diffstat:
M
lib/std/debug.zig
 | 
15
+++++++++++++--

1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/lib/std/debug.zig b/lib/std/debug.zig
@@ -825,8 +825,19 @@ const StackIterator = union(enum) {
             // in our caller's frame and above.
             return .{ .di = .init(&.current()) };
         }
-        flushSparcWindows();
-        return .{ .fp = @frameAddress() };
+        return .{
+            // On SPARC, the frame pointer will point to the previous frame's save area,
+            // meaning we will read the previous return address and thus miss a frame.
+            // Instead, start at the stack pointer so we get the return address from the
+            // current frame's save area. The addition of the stack bias cannot fail here
+            // since we know we have a valid stack pointer.
+            .fp = if (native_arch.isSPARC()) sp: {
+                flushSparcWindows();
+                break :sp asm (""
+                    : [_] "={o6}" (-> usize),
+                ) + stack_bias;
+            } else @frameAddress(),
+        };
     }
     fn deinit(si: *StackIterator) void {
         switch (si.*) {