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(set_nonvarying_address_components): Rework and also handle an AND

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used for non-aligned accesses.

From-SVN: r7503
This commit is contained in:
Richard Kenner 1994-06-16 06:47:10 -04:00
parent 88d0b2b865
commit c85663b1a8
1 changed files with 51 additions and 13 deletions
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64
gcc/cse.c
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@ -2240,7 +2240,7 @@ set_nonvarying_address_components (addr, size, pbase, pstart, pend)
HOST_WIDE_INT *pstart, *pend;
{
rtx base;
int start, end;
HOST_WIDE_INT start, end;
base = addr;
start = 0;
@ -2267,20 +2267,58 @@ set_nonvarying_address_components (addr, size, pbase, pstart, pend)
base = qty_const[reg_qty[REGNO (XEXP (base, 0))]];
}
/* By definition, operand1 of a LO_SUM is the associated constant
address. Use the associated constant address as the base instead. */
if (GET_CODE (base) == LO_SUM)
base = XEXP (base, 1);
/* Handle everything that we can find inside an address that has been
viewed as constant. */
/* Strip off CONST. */
if (GET_CODE (base) == CONST)
base = XEXP (base, 0);
if (GET_CODE (base) == PLUS
&& GET_CODE (XEXP (base, 1)) == CONST_INT)
while (1)
{
start += INTVAL (XEXP (base, 1));
base = XEXP (base, 0);
/* If no part of this switch does a "continue", the code outside
will exit this loop. */
switch (GET_CODE (base))
{
case LO_SUM:
/* By definition, operand1 of a LO_SUM is the associated constant
address. Use the associated constant address as the base
instead. */
base = XEXP (base, 1);
continue;
case CONST:
/* Strip off CONST. */
base = XEXP (base, 0);
continue;
case PLUS:
if (GET_CODE (XEXP (base, 1)) == CONST_INT)
{
start += INTVAL (XEXP (base, 1));
base = XEXP (base, 0);
continue;
}
break;
case AND:
/* Handle the case of an AND which is the negative of a power of
two. This is used to represent unaligned memory operations. */
if (GET_CODE (XEXP (base, 1)) == CONST_INT
&& exact_log2 (- INTVAL (XEXP (base, 1))) > 0)
{
set_nonvarying_address_components (XEXP (base, 0), size,
pbase, pstart, pend);
/* Assume the worst misalignment. START is affected, but not
END, so compensate but adjusting SIZE. Don't lose any
constant we already had. */
size = *pend - *pstart - INTVAL (XEXP (base, 1)) - 1;
start += *pstart - INTVAL (XEXP (base, 1)) - 1;
base = *pbase;
}
break;
}
break;
}
end = start + size;