This patch fixes PR ipa/103061 which is P1 regression that shows up as
an ICE in ipa-modref-tree.c's insert_kill when compiling the CSiBE
benchmark. I believe the underlying cause is that the new kill tracking
functionality wasn't anticipating memory accesses that are zero bits
wide!?. The failing source code (test case) contains the unusual lines:
typedef struct { } spinlock_t;
and
q->lock = (spinlock_t) { };
Making spinlock_t larger, or removing the assignment work around the issue.
The one line patch below to useful_for_kill_p teaches IPA that a memory
write is only useful as a "kill" if it is more than zero bits wide.
In theory, the existing known_size_p (size) test is now redundant, as
poly_int64 currently uses the value -1 for unknown size values,
but the proposed change makes the semantics clear, and defends against
possible future changes in representation [but I'm happy to change this].
This patch has been tested on x86_64-pc-linux-gnu with a make bootstrap
and make -k check with no new failures. Ok for mainline?
2021-12-10 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
PR ipa/103601
* ipa-modref-tree.h (useful_for_kill_p): Zero width accesses aren't
useful for kill tracking.
gcc/testsuite/ChangeLog
PR ipa/103601
* gcc.dg/ipa/pr103601.c: New test case.
Thanks in advance,
Roger
--
diff --git a/gcc/ipa-modref-tree.h b/gcc/ipa-modref-tree.h
index 35190c2..4ad556f 100644
--- a/gcc/ipa-modref-tree.h
+++ b/gcc/ipa-modref-tree.h
@@ -87,7 +87,8 @@ struct GTY(()) modref_access_node
{
return parm_offset_known && parm_index != MODREF_UNKNOWN_PARM
&& parm_index != MODREF_RETSLOT_PARM && known_size_p (size)
- && known_eq (max_size, size);
+ && known_eq (max_size, size)
+ && known_gt (size, 0);
}
/* Dump range to debug OUT. */
void dump (FILE *out);
diff --git a/gcc/testsuite/gcc.dg/ipa/pr103601.c
b/gcc/testsuite/gcc.dg/ipa/pr103601.c
new file mode 100644
index 0000000..7bdb5e5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/pr103601.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fgnu89-inline" } */
+
+typedef struct { } spinlock_t;
+struct list_head {
+ struct list_head *next, *prev;
+};
+struct __wait_queue_head {
+ spinlock_t lock;
+ struct list_head task_list;
+};
+typedef struct __wait_queue_head wait_queue_head_t;
+static inline void init_waitqueue_head(wait_queue_head_t *q)
+{
+ q->lock = (spinlock_t) { };
+ do { (&q->task_list)->next = (&q->task_list); (&q->task_list)->prev =
(&q->task_list); } while (0);
+}
+struct timer_list {
+ void (*function)(unsigned long);
+};
+struct rpc_task {
+ struct timer_list tk_timer;
+ wait_queue_head_t tk_wait;
+};
+static void
+rpc_run_timer(struct rpc_task *task)
+{
+}
+inline void
+rpc_init_task(struct rpc_task *task)
+{
+ task->tk_timer.function = (void (*)(unsigned long)) rpc_run_timer;
+ init_waitqueue_head(&task->tk_wait);
+}
+
