On Wed, Aug 31, 2022 at 12:50:07PM +0000, Christophe Leroy wrote:
> Le 29/08/2022 à 07:52, Sathvika Vasireddy a écrit :
> > +   opcode = insn >> 26;
> > +
> > +   switch (opcode) {
> > +   case 18: /* bl */
> 
> case 18 is more than 'bl', it includes also 'b'.
> In both cases, the calculation of *immediate is the same.

It also is "ba" and "bla", sometimes written as "b[l][a]".

> It would therefore be more correct to perform the calculation and setup 
> of *immediate outside the 'if ((insn & 3) == 1)', that would avoid 
> unnecessary churn the day we add support for branches without link.
> 
> > +           if ((insn & 3) == 1) {
> > +                   *type = INSN_CALL;
> > +                   *immediate = insn & 0x3fffffc;
> > +                   if (*immediate & 0x2000000)
> > +                           *immediate -= 0x4000000;
> > +           }
> > +           break;
> > +   }

Does this handle AA=1 correctly at all?  That is valid both with and
without relocations, just like AA=0.  Same for AA=1 LK=0 btw.

If you only handle AA=0, the code should explicitly test for that.


Segher

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