> > Did you audit all callers of mem_attrs_eq_p to see if they really > only care about that? After all MEM_EXPR, via access paths, encode > type-based alias info and thus replacing one with the other (cse.c use > or ifcvt.c use) is only valid if that doesn't break dependences.
Hmm, expr is used by ao_ref_from_mem and nonoverlapping_memrefs_p. The alias set of the access is not taken from expr, but from alias set info stored in the memory attribute itself (and it is checked by those to match) I still think it is an address of the expression that matters, not the value. I think operand_equal_p may, for example, consider two different VAR_DECL equivalent if their constructors are, because the value is (it doesn't do that), but their addresses differ. I will look more into nonoverlapping_memrefs_p and ao_ref_from_mem. The first one may need some update to tree-alias infrastructure.... Honza > > So I don't believe this is safe. > > Thanks, > Richard. > > > Honza > > > > * emit-rtl.c (mem_attrs_eq_p, mem_expr_equal_p): Pass OEP_ADDRESS_OF > > to operand_equal_p. > > > > Index: emit-rtl.c > > =================================================================== > > --- emit-rtl.c (revision 228131) > > +++ emit-rtl.c (working copy) > > @@ -334,7 +334,7 @@ mem_attrs_eq_p (const struct mem_attrs * > > && p->addrspace == q->addrspace > > && (p->expr == q->expr > > || (p->expr != NULL_TREE && q->expr != NULL_TREE > > - && operand_equal_p (p->expr, q->expr, 0)))); > > + && operand_equal_p (p->expr, q->expr, OEP_ADDRESS_OF)))); > > } > > > > /* Set MEM's memory attributes so that they are the same as ATTRS. */ > > @@ -1657,7 +1657,7 @@ mem_expr_equal_p (const_tree expr1, cons > > if (TREE_CODE (expr1) != TREE_CODE (expr2)) > > return 0; > > > > - return operand_equal_p (expr1, expr2, 0); > > + return operand_equal_p (expr1, expr2, OEP_ADDRESS_OF); > > } > > > > /* Return OFFSET if XEXP (MEM, 0) - OFFSET is known to be ALIGN > > > > > > -- > Richard Biener <rguent...@suse.de> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB > 21284 (AG Nuernberg)
