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Re: Generating DWARF CIE info
Eric Botcazou wrote:
When I looked at what sparc-gcc was generating for the return
address column, I discovered that it didn't generate anything.
At least it generates the RA column:
The CIE says what the RA column is, but there is no initial value
location expression generated for the return address. That means
that on entry to a function, the CIE cannot be used to tell what
the return address is.
Is there any reason to discard it?
It's supposed to be a constant offset.
-- Macro: RETURN_ADDR_OFFSET
If defined, an integer-valued C expression for which rtl will be
generated to add it to the exception handler address before it is
searched in the exception handling tables, and to subtract it
again from the address before using it to return to the exception
handler.
The macro is INCOMING_RETURN_ADDR_RTX.
INCOMING_RETURN_ADDR_RTX [Macro]
A C expression whose value is RTL representing the location of the incoming return
address at the beginning of any function, before the prologue. This RTL is either a
REG, indicating that the return value is saved in âREGâ, or a MEM representing a
location in the stack.
Other than the code which translates RTL to LocExpr not handling REG+offset,
I don't see a reason why REG+OFFSET is not valid, or why the comment says
that it is unnecessary. On Sparc, it's only unnecessary because Sparc
ignores the CIE.
--
Michael Eager eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306 650-325-8077