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PR ipa/103601: ICE compiling CSiBE in ipa-modref's insert_kill. 

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.

2021-12-10  Roger Sayle  <roger@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.
This commit is contained in:
Roger Sayle 2021-12-10 12:02:04 +00:00
parent 4a87a8e4b1
commit 2a1c3b69c0
2 changed files with 37 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
gcc/ipa-modref-tree.h
View File

@ -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);

35
gcc/testsuite/gcc.dg/ipa/pr103601.c Normal file
View File

@ -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);
}