[prev in list] [next in list] [prev in thread] [next in thread] 

List:       gcc
Subject:    TARGET_FLAGS_REGNUM breaks gcc
From:       "Paulo J. Matos" <pocmatos () gmail ! com>
Date:       2011-07-21 9:39:55
Message-ID: j08s5b$ooe$1 () dough ! gmane ! org
[Download RAW message or body]

Hi,

After the discussion we had on the previous thread 'splitting add 
instructions', I added support for TARGET_FLAGS_RENUM to my port along 
with *_flags rules similar to how it is done in rx backend (gcc 4.6.1).

Then I decided to create a very simple C program:
unsigned long foo(unsigned int a, unsigned int b)
{
   if(a < b)
     return a << b;
   else
     return a >> b;
}

When I compile it (with my backend) it I either gets into an infinite 
loop or segfaults in kill_value_one_regno (unsigned int regno, struct 
value_data *vd), regcprop.c, called from cprop_hardreg pass.

The infinite cycle, or segfault, is in the cycle (regcprop.c:138):
       for (i = vd->e[regno].oldest_regno;
            vd->e[i].next_regno != regno;
            i = vd->e[i].next_regno)
           continue;

That i goes into the loop 0, 7, -1, 0... where regno passed into the 
function is 14, my FIRST_PSEUDO_REGISTER, and CC_REGNUM is 13.
When it segfaults the loop goes 0, 7, 15127832392 (some obscene number).

Then I decided to turn on checking. So I configured gcc with 
--enable-checking=all and with this I get:
internal compiler error: in df_live_verify_transfer_functions, at
df-problems.c:1816

I followed to see what happened to rx. So I compiled the rx backend and 
used the same example, also with checking enabled and I get the same 
assertion. So I assume this is  GCC issue and reported it. Bug 49801 
(http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49801).

In the meantime I am trying to pinpoint the exact problem. If someone 
has any idea and know of a workaround, can you please let me know?

Cheers,

-- 
PMatos

[prev in list] [next in list] [prev in thread] [next in thread]