[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Libunwind-devel] Explicitly exporting CFA

From: Andrew Cagney
Subject: Re: [Libunwind-devel] Explicitly exporting CFA
Date: Tue, 08 Jan 2008 15:30:08 -0500
User-agent: Thunderbird (X11/20071115)

Arun Sharma wrote:
On Jan 8, 2008 6:59 AM, Andrew Cagney <address@hidden <mailto:address@hidden>> wrote:

    1.98c worth:

    - the "CFA" value is from the frame inner to cursor
    can I suggest a name like UNW_REG_INNER_CFA?

Is there an ambiguity that the longer name helps resolve?

  foo() -- inner
  main() - outer


  bar_cursor = foo_cursor

so that bar's inner is foo; then foo's CFA can only be obtained by:


and not:


This is because foo's CFA is only computed when stepping the cursor to bar (and the computed value is saved in bar).


    - can it be assigned a negative constant value so that it can't polute
    the ISA register number space
    when extending the x86 register numbers I had to leave a gap in the
    middle to ensure "binary" number compatibility, giving these libunwind
"registers" constant -ve values would help avoid that in the future

This sounds like a good thing to do.

But because we have other libunwind registers (eg: UNW_TDEP_IP) whose values change when new ISA registers are added, this should be a separate patch.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]