Mohamed Shafi wrote:
On Wed, May 21, 2008 at 1:42 AM, Jeff Law <[EMAIL PROTECTED]> wrote:
Ian Lance Taylor wrote:
"Mohamed Shafi" <[EMAIL PROTECTED]> writes:
For the 16 bit target that i am currently porting can have only
positive offsets less than 0x100. (unsigned 8 bit) for offset
addressing mode.
I would expect reload to be able to handle this kind of thing anyhow,
assuming you define GO_IF_LEGITIMATE_ADDRESS correctly. reload should
automatically try loading an out of range offset into a register.
Agreed.
Typically if there are problems in this area it is because the port hasn't
properly defined secondary reloads, or the valid offsets are not consistent
within a machine mode.
Mohamed, without more details, there's not much we can do to help you.
I am sure that i have written GO_IF_LEGITIMATE_ADDRESS correctly.
What i have in my port is something similar to mcore back-end. These
are the relevant parts:
else if (GET_CODE (X) == PLUS)
{
rtx xop0 = XEXP (X,0);
rtx xop1 = XEXP (X,1);
if (BASE_REGISTER_RTX_P (xop0))
return legitimate_index_p (mode, xop1);
}
static int
legitimate_index_p (enum machine_mode mode, rtx OP)
{
if (GET_CODE (OP) == CONST_INT)
{
if (GET_MODE_SIZE (mode) >= 4
&& (((unsigned)INTVAL (OP)) % 4) == 0
&& ((unsigned)INTVAL (OP)) <= 0x0100)
return 1;
if (GET_MODE_SIZE (mode) == 2
&& (((unsigned)INTVAL (OP)) % 2) == 0
&& ((unsigned)INTVAL (OP)) <= 0x0100)
return 1;
if (GET_MODE_SIZE (mode) == 1
&& ((unsigned)INTVAL (OP)) <= 0x0100)
return 1;
}
return 0;
}
The compiler is crashing in change_address_1, at emit-rtl.c
...
if (validate)
{
if (reload_in_progress || reload_completed)
gcc_assert (memory_address_p (mode, addr));
else
addr = memory_address (mode, addr);
}
....
Everything starts when cleanup_subreg_operands() is called from
reload() for the following pattern.
(set (subreg:HI (mem:SI (plus:HI (reg:HI 12 [SP]) (const_int 256)) 2)
(reg:HI 3))
and then this becomes
(set (mem:HI (plus:HI (reg:HI 12 [SP] ) (const_int 258)))
(reg:HI 3))
This pattern is not legitimate due to out of range offset.
Will i be able to overcome this if i write LEGITIMIZE_RELOAD_ADDRESS
or LEGITIMIZE_ADDRESS
You have a (subreg (mem)) expression. The mem part of that expression
should have been reloaded into a register. You probably want to look
at your reload debugging dumps to see how/why that's not happening properly.
Using LEGITIMIZE_RELOAD_ADDRESS is definitely not the way to solve this
problem. It's intended solely as a means to optimize how reload
generates code for certain cases. LEGITIMIZE_ADDRESS won't have an
affect at this stage in the compiler.
jeff
Thank you for your time.
Regards,
Shafi
