On 01/05/2017 11:03 AM, Jeff Law wrote:
On 12/12/2016 06:36 PM, Martin Sebor wrote:
The attached patch avoids infinite recursion when traversing phi
nodes in maybe_warn_alloc_args_overflow by using a bitmap to keep
track of those already visited and breaking out.
Thanks
Martin
gcc-78775.diff
PR tree-optimization/78775 - ICE in maybe_warn_alloc_args_overflow
gcc/ChangeLog:
PR tree-optimization/78775
* calls.c (operand_signed_p): Add overload and avoid getting into
infinite recursion when traversing phi nodes.
gcc/testsuite/ChangeLog:
PR tree-optimization/78775
* gcc.dg/pr78775.c: New test.
So Richi asked for removal of the VR_ANTI_RANGE handling, which would
imply removal of operand_signed_p.
What are the implications if we do that?
I just got back to this yesterday. The implications of the removal
of the anti-range handling are a number of false negatives in the
test suite:
FAIL: gcc.dg/attr-alloc_size-3.c (test for warnings, line 448)
FAIL: gcc.dg/attr-alloc_size-4.c (test for warnings, line 137)
FAIL: gcc.dg/attr-alloc_size-4.c (test for warnings, line 139)
FAIL: gcc.dg/attr-alloc_size-4.c (test for warnings, line 175)
with the second one, for example, being:
n = ~[-4, MAX]; (I.e., n is either negative or too big.)
p = malloc (n);
Passing signed integers as arguments to allocation functions is
common so I've been looking into how else to avoid the phi recursion
(which I assume is the concern here) without compromising this case.
Removing just the operand_signed_p() handling causes a number of
false positives in the test suite, such as for
m = [-3, 7];
n = [-5, 11];
p = calloc (m, n);
which I suspect are common in the wild as well.
Martin
