Hi,
after fixing few issues I gotto stage where 1.4M icf mismatches are due to
comparing two gimple clobber. The problem is that operand_equal_p match
clobber
case CONSTRUCTOR:
/* In GIMPLE empty constructors are allowed in initializers of
aggregates. */
return !CONSTRUCTOR_NELTS (arg0) && !CONSTRUCTOR_NELTS (arg1);
But this happens too late after comparing semantics of its type (that
are not very relevant for memory store and fails way too often).
In the context of ipa-icf we do not really need to match RHS of gimple clobbers:
it is enough to know that the LHS stores can be considered equivalent.
I this added logic to hash them all the same way and compare using
TREE_CLOBBER_P flag. I see other option in extending operand_equal_p
in fold-const to handle them more generously or making stmt hash and compare
to skip comparing/hashing RHS of gimple_clobber_p.
I am now down to 1453 opernad_equal_p mismatches so it seems we are getting
into shape.
Bootstrapped/regtested x86_64, looks reasonable?
Honza
* ipa-icf-gimple.c (func_checker::hash_operand): Hash gimple clobber.
(func_checker::operand_equal_p): Special case gimple clobber.
diff --git a/gcc/ipa-icf-gimple.c b/gcc/ipa-icf-gimple.c
index ffb1baddbdb..69bc9ab5b34 100644
--- a/gcc/ipa-icf-gimple.c
+++ b/gcc/ipa-icf-gimple.c
@@ -245,6 +245,14 @@ func_checker::hash_operand (const_tree arg, inchash::hash
&hstate,
break;
}
+ /* In gimple all clobbers can be considered equal: while comparaing two
+ gimple clobbers we match the left hand memory accesses. */
+ if (TREE_CLOBBER_P (arg))
+ {
+ hstate.add_int (0xc10bbe5);
+ return;
+ }
+
return operand_compare::hash_operand (arg, hstate, flags);
}
@@ -306,6 +314,10 @@ func_checker::operand_equal_p (const_tree t1, const_tree
t2,
default:
break;
}
+ /* In gimple all clobbers can be considered equal. We match the right hand
+ memory accesses. */
+ if (TREE_CLOBBER_P (t1) || TREE_CLOBBER_P (t2))
+ return TREE_CLOBBER_P (t1) == TREE_CLOBBER_P (t2);
return operand_compare::operand_equal_p (t1, t2, flags);
}
