This is the mail archive of the mailing list for the binutils project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [Gold] how to do relax in Gold ?

On 2013å01æ16æ 14:09, Ian Lance Taylor wrote:
On Tue, Jan 15, 2013 at 10:02 PM, Shawn <> wrote:
Hi All:
     I'am porting Gold to our processor right now ,everything is fine except
the label whose value is big.  For Example, the following instruction assign
a LABEL value to register R0:
     R0 = LABEL_0;

1. Our Objects
   Our instruction is encoded in 32bit,   if the value of "LABLE_0" is too
big, for example 0x40000, there is not enough space to encode the
instruction into a 32bit instruction, we have to expand "R0 = LABEL_0" into
a 64bit instruction automatically.
   Because the value of "LABEL_0" is not known until link-time, we hope
"Gold" can handle this .

2. My plan  & Question:
   I found the function related to our object is  the "Target::do_relax"
function, but only & has overwritten it. The "do_relax" in & is too complicate to analyze. I hope to get a clean
implementation of Our Objects.
    a)  Scan  relocation info in all input objects, find the relocations that
may  need relaxation ( read & compare the symbol value )
          How can I read the relocation info ?
          How can I reany advice ad the symbol  value ? Is the value read
from the Symbol_table represent the value after layout ?
    b)  for each relocation that  need relaxation, insert a 32bit stub in the
VIEW, and update the value of the symbol which is located after the
relocation site.

     And is there any other example related to relaxation except & ? or any document ?
No, sorry.

I think one approach would be to record the possible relaxation points
in your scan_relocs routine.  You will have all the relocation
information available there.  That will let you detect out of range
relocations where you can insert stubs.


Thanks Ian. Did your mean Target::scan_relocs ? I will try that.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]