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reload1.c (reload): Ignore equivalences between pseudos and read only memory.

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* reload1.c (reload): Ignore equivalences between pseudos and
	read only memory.

From-SVN: r98466
This commit is contained in:
Jeff Law 2005-04-20 12:02:40 -06:00 committed by Jeff Law
parent 187230a795
commit ad1032fd92
2 changed files with 19 additions and 2 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2005-04-20 Jeff Law <law@redhat.com>
* reload1.c (reload): Ignore equivalences between pseudos and
read only memory.
2005-04-20 Joseph S. Myers <joseph@codesourcery.com>
PR c/12913

16
gcc/reload1.c
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@ -740,8 +740,20 @@ reload (rtx first, int global)
that is not a legitimate memory operand. As later
stages of reload assume that all addresses found
in the reg_equiv_* arrays were originally legitimate,
we ignore such REG_EQUIV notes. */
if (memory_operand (x, VOIDmode))
It can also happen that a REG_EQUIV note contains a
readonly memory location. If the destination pseudo
is set from some other value (typically a different
pseudo), and the destination pseudo does not get a
hard reg, then reload will replace the destination
pseudo with its equivalent memory location. This
is horribly bad as it creates a store to a readonly
memory location and a runtime segfault. To avoid
this problem we reject readonly memory locations
for equivalences. This is overly conservative as
we could find all sets of the destination pseudo
and remove them as they should be redundant. */
if (memory_operand (x, VOIDmode) && ! MEM_READONLY_P (x))
{
/* Always unshare the equivalence, so we can
substitute into this insn without touching the