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Re: [Patch] MIPS: Fix unwinding through signal frames for n32 and n64 ABIs.
David Daney wrote:
+/* The DWARF 2 CFA column which tracks the return address from a
+ signal handler context. This means that to maintain backwards
+ compatibility, no hard register can be assigned this column if it
+ would need to be handled by the DWARF unwinder. */
+#define DWARF_ALT_FRAME_RETURN_COLUMN 66
Thinking about it a bit more, I think the comment is incorrect.
In the future we could put a hard register in column 66, we would just have to move DWARF_ALT_FRAME_RETURN_COLUMN somewhere else. There is no promise that code compiled by future versions of GCC will work with older versions of libgcc_s.so. In fact there are symbol versions in libgcc_s.so that are there to explicitly prevent it from happening.
If the patch is approved, I will remove the second sentence.