Subject: Re: The ELF ABI issue
To: None <>
From: Jason R Thorpe <>
List: port-arm
Date: 03/26/2002 10:33:13
On Tue, Mar 26, 2002 at 10:01:45AM +0000, Richard Earnshaw wrote:

 > No, disastrous.

We can skip the TLS register if we're going to call this ABI temporary...

 > The ABI doesn't mandate any particular register for the PIC register -- it 
 > can be any register you like; it can even be different in each function 
 > you have.  GCC only uses a fixed register because there are "bugs" in the 
 > compiler which mean that it can allocate a different register in each 
 > function properly for this purpose (it would be better if this could be 
 > fixed, but I'm not sure precisely where the problems are).

Ah, I see.

 > The TLS register, on the other hand must be fixed (since the value is 
 > persistent across the whole thread).  If you pick r8 then you will 
 > fragment the register ranges, particularly when not inside a shared 
 > library.  There are different reasons why r9 or r10 might be the best 
 > choice, but r8 certainly would be a bad choice.

Ah, okay.  Chris Gilbert suggested r11 to me after I posted my message.

        -- Jason R. Thorpe <>