reliabilit​y of registers contents within each frame

reliabilit​y of registers contents within each frame

[Ivan Di Prima]

Hi,

How reliable are the registers values within each frame?

Basically if move "up" and "down" between frames and then display the register contents with "info reg" do I see ALL the register captured in that frame or just the registers which are "push" on the stack within the source code?

Also, will optimization affect register values such that even if they are not marked "<value optimized out>" by gdb their values will still be readable but unreliable?

Thanks
Ivan

ps. I am reading a core file with its binary with the command: arm-gdb ProcessBin coreFile

Re: reliabilit​y of registers contents within each frame

[Jan Kratochvil]

On Thu, 12 Apr 2012 20:49:44 +0200, Ivan Di Prima wrote:
> Basically if move "up" and "down" between frames and then display the
> register contents with "info reg" do I see ALL the register captured in that
> frame or just the registers which are "push" on the stack within the source
> code?

"ALL".  Which registers are saved by which frame you see in "info frame".


> Also, will optimization affect register values such that even if they are
> not marked "<value optimized out>" by gdb their values will still be
> readable but unreliable?

I was told it applies to gcc-4.0+.  While the mail below is not a direct
countercase I trust more just gcc-4.5+:
	[patch] Fix regression by me for gcc-4.0...gcc-4.4 i386 -O2 -g parameters (PR 13777)
	http://sourceware.org/ml/gdb-patches/2012-02/msg00673.html


Regards,
Jan