Hi!
ipa_polymorphic_call_context offset field is in bits (for whatever reason),
and the following computations can overflow and invoke UB.
This patch computes it in offset_int instead and punts if there is overflow.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2017-07-31 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/81603
* ipa-polymorphic-call.c
(ipa_polymorphic_call_context::ipa_polymorphic_call_context): Perform
offset arithmetic in offset_int, bail out if the resulting bit offset
doesn't fit into shwi.
--- gcc/ipa-polymorphic-call.c.jj 2017-06-12 12:41:55.000000000 +0200
+++ gcc/ipa-polymorphic-call.c 2017-07-28 15:02:43.747354910 +0200
@@ -921,9 +921,13 @@ ipa_polymorphic_call_context::ipa_polymo
and MEM_REF is meaningless, but we can look futher. */
if (TREE_CODE (base) == MEM_REF)
{
+ offset_int o = mem_ref_offset (base) * BITS_PER_UNIT;
+ o += offset;
+ o += offset2;
+ if (!wi::fits_shwi_p (o))
+ break;
base_pointer = TREE_OPERAND (base, 0);
- offset
- += offset2 + mem_ref_offset (base).to_short_addr () *
BITS_PER_UNIT;
+ offset = o.to_shwi ();
outer_type = NULL;
}
/* We found base object. In this case the outer_type
@@ -961,10 +965,15 @@ ipa_polymorphic_call_context::ipa_polymo
break;
}
else if (TREE_CODE (base_pointer) == POINTER_PLUS_EXPR
- && tree_fits_uhwi_p (TREE_OPERAND (base_pointer, 1)))
+ && TREE_CODE (TREE_OPERAND (base_pointer, 1)) == INTEGER_CST)
{
- offset += tree_to_shwi (TREE_OPERAND (base_pointer, 1))
- * BITS_PER_UNIT;
+ offset_int o = offset_int::from (TREE_OPERAND (base_pointer, 1),
+ SIGNED);
+ o *= BITS_PER_UNIT;
+ o += offset;
+ if (!wi::fits_shwi_p (o))
+ break;
+ offset = o.to_shwi ();
base_pointer = TREE_OPERAND (base_pointer, 0);
}
else
Jakub
