On Tue, Jul 04, 2017 at 02:00:13PM +0200, Richard Biener wrote:
> > That was intentional. If a->e != NULL, then we know that b->e != NULL,
> > because we have
> > else if (a->e != NULL && b->e == NULL)
> > return -1;
> > earlier. Similarly, if a->e == NULL, then we know that b-> == NULL, because
> > we have:
> > if (a->e == NULL && b->e != NULL)
> > return 1;
> > earlier.
>
> Ah, ok. Twisty ;) I suppose jump threading will have eliminated
> the extra test.
In the first case maybe, I doubt it would do that after the
iterative_hash_expr calls which are likely not pure.
> > > Otherwise looks ok to me. I wonder if we should merge the two
> > > sorting functions and change behavior with a global var or a
> > > template parameter instead (to reduce source duplication). Does
> > >
> > > vec.qsort (function_template<true>);
> > >
> > > work?
> >
> > Let me try that.
Seems to work, so like this if it passes bootstrap/regtest?
2017-07-04 Jakub Jelinek <ja...@redhat.com>
PR debug/81278
* tree-vrp.c (compare_assert_loc): Turn into a function template
with stable template parameter. Only test if a->e is NULL,
!a->e == !b->e has been verified already. Use e == NULL or
e != NULL instead of e or ! e tests. If stable is true, don't use
iterative_hash_expr, on the other side allow a or b or both NULL
and sort the NULLs last.
(process_assert_insertions): Sort using compare_assert_loc<false>
instead of compare_assert_loc, later sort using
compare_assert_loc<true> before calling process_assert_insertions_for
in a loop. Use break instead of continue once seen NULL pointer.
--- gcc/tree-vrp.c.jj 2017-07-04 10:43:48.627706528 +0200
+++ gcc/tree-vrp.c 2017-07-04 14:37:06.823101453 +0200
@@ -6393,20 +6393,37 @@ process_assert_insertions_for (tree name
gcc_unreachable ();
}
-/* Qsort helper for sorting assert locations. */
+/* Qsort helper for sorting assert locations. If stable is true, don't
+ use iterative_hash_expr because it can be unstable for -fcompare-debug,
+ on the other side some pointers might be NULL. */
+template <bool stable>
static int
compare_assert_loc (const void *pa, const void *pb)
{
assert_locus * const a = *(assert_locus * const *)pa;
assert_locus * const b = *(assert_locus * const *)pb;
- if (! a->e && b->e)
+
+ /* If stable, some asserts might be optimized away already, sort
+ them last. */
+ if (stable)
+ {
+ if (a == NULL)
+ return b != NULL;
+ else if (b == NULL)
+ return -1;
+ }
+
+ if (a->e == NULL && b->e != NULL)
return 1;
- else if (a->e && ! b->e)
+ else if (a->e != NULL && b->e == NULL)
return -1;
+ /* After the above checks, we know that (a->e == NULL) == (b->e == NULL),
+ no need to test both a->e and b->e. */
+
/* Sort after destination index. */
- if (! a->e && ! b->e)
+ if (a->e == NULL)
;
else if (a->e->dest->index > b->e->dest->index)
return 1;
@@ -6419,11 +6436,27 @@ compare_assert_loc (const void *pa, cons
else if (a->comp_code < b->comp_code)
return -1;
+ hashval_t ha, hb;
+
+ /* E.g. if a->val is ADDR_EXPR of a VAR_DECL, iterative_hash_expr
+ uses DECL_UID of the VAR_DECL, so sorting might differ between
+ -g and -g0. When doing the removal of redundant assert exprs
+ and commonization to successors, this does not matter, but for
+ the final sort needs to be stable. */
+ if (stable)
+ {
+ ha = 0;
+ hb = 0;
+ }
+ else
+ {
+ ha = iterative_hash_expr (a->expr, iterative_hash_expr (a->val, 0));
+ hb = iterative_hash_expr (b->expr, iterative_hash_expr (b->val, 0));
+ }
+
/* Break the tie using hashing and source/bb index. */
- hashval_t ha = iterative_hash_expr (a->expr, iterative_hash_expr (a->val,
0));
- hashval_t hb = iterative_hash_expr (b->expr, iterative_hash_expr (b->val,
0));
if (ha == hb)
- return (a->e && b->e
+ return (a->e != NULL
? a->e->src->index - b->e->src->index
: a->bb->index - b->bb->index);
return ha - hb;
@@ -6452,7 +6485,7 @@ process_assert_insertions (void)
auto_vec<assert_locus *, 16> asserts;
for (; loc; loc = loc->next)
asserts.safe_push (loc);
- asserts.qsort (compare_assert_loc);
+ asserts.qsort (compare_assert_loc<false>);
/* Push down common asserts to successors and remove redundant ones. */
unsigned ecnt = 0;
@@ -6506,11 +6539,14 @@ process_assert_insertions (void)
}
}
+ /* The asserts vector sorting above might be unstable for
+ -fcompare-debug, sort again to ensure a stable sort. */
+ asserts.qsort (compare_assert_loc<true>);
for (unsigned j = 0; j < asserts.length (); ++j)
{
loc = asserts[j];
if (! loc)
- continue;
+ break;
update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
num_asserts++;
free (loc);
Jakub
