Re: Abt long long support

[Mike Stump <mrs at apple dot com>]

On Nov 9, 2006, at 6:39 AM, Mohamed Shafi wrote:
> When i diff the rtl dumps for programs passing negative value with and
> without frame pointer i find  changes from file.greg .

And, is that change bad?  We do expect changes in codegen, you didn't  
say if those changes are invalid, or what was invalid about them.  If  
they are valid, which pass is the first pass that contains invalid  
rtl?  If this was the first pass with invalid rtl, which instruction  
was invalid and why?  What assembly do you get in both cases?  Which  
instruction is wrong?  What's wrong about it?

Did you examine:

  long long l, k;
  l = -k;

for correctness by itself?  Was it valid or invalid?

[ read ahead for spoilers, I'd rather you pull this information out  
of the dump and present it to us... ]

A quick glance at the rtl shows that insn 95 tries to use [a4+4] but  
insn 94 clobbered a4 already, also d3 is used by insn 93, but there  
isn't a set for it.

The way the instructions are numbered suggests that the code went  
wrong before this point.  You have to read and understand all the  
dumps, whether they are right or wrong and why, track down the code  
in the compiler that is creating the wrong code and then see if you  
can guess why.  If not, fire up gdb, and watch it add/remove/reorder  
instructions and why it was doing it and the conditions it checked  
before doing the transformation and then reason about why it is wrong  
and what it should be doing instead.  I'd suspect the bug lies in  
your port file and gcc is using information from it and coming up  
with the bad code.

For example, what pass removed the setting of d3?