* [PATCH] Check NULL loop->latch in verify_loop_structure
@ 2015-11-22 23:29 Tom de Vries
2015-11-23 10:29 ` Richard Biener
0 siblings, 1 reply; 8+ messages in thread
From: Tom de Vries @ 2015-11-22 23:29 UTC (permalink / raw)
To: gcc-patches; +Cc: Jakub Jelinek, Richard Biener
[-- Attachment #1: Type: text/plain, Size: 485 bytes --]
Hi,
In verify_loop_structure, we stop checking the latch once we find that
it's NULL.
This patch tries a bit harder:
- if !LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we don't allow a NULL latch
- if LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we check that indeed there's no
single loop latch.
As a consequence of adding this check, I needed to fix
expand_omp_for_generic, which missed an initialization of a loop latch.
Bootstrapped and reg-tested on x86_64.
OK for stage3 trunk?
Thanks,
- Tom
[-- Attachment #2: 0001-Check-NULL-loop-latch-in-verify_loop_structure.patch --]
[-- Type: text/x-patch, Size: 3666 bytes --]
Check NULL loop->latch in verify_loop_structure
2015-11-22 Tom de Vries <tom@codesourcery.com>
* cfgloop.c (find_single_latch): New function, factored out of ...
(flow_loops_find): ... here.
(verify_loop_structure): Verify validity of a NULL loop->latch.
* cfgloop.h (find_single_latch): Declare.
* omp-low.c (expand_omp_for_generic): Initialize latch of orig_loop.
---
gcc/cfgloop.c | 65 +++++++++++++++++++++++++++++++++++++++++------------------
gcc/cfgloop.h | 1 +
gcc/omp-low.c | 1 +
3 files changed, 47 insertions(+), 20 deletions(-)
diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c
index bf00e0e..b610860 100644
--- a/gcc/cfgloop.c
+++ b/gcc/cfgloop.c
@@ -388,6 +388,33 @@ bb_loop_header_p (basic_block header)
return false;
}
+/* Return the latch block for this header block, if it has just a single one.
+ Otherwise, return NULL. */
+
+basic_block
+find_single_latch (struct loop* loop)
+{
+ basic_block header = loop->header;
+ edge_iterator ei;
+ edge e;
+ basic_block latch = NULL;
+
+ FOR_EACH_EDGE (e, ei, header->preds)
+ {
+ basic_block cand = e->src;
+ if (!flow_bb_inside_loop_p (loop, cand))
+ continue;
+
+ if (latch != NULL)
+ /* More than one latch edge. */
+ return NULL;
+
+ latch = cand;
+ }
+
+ return latch;
+}
+
/* Find all the natural loops in the function and save in LOOPS structure and
recalculate loop_father information in basic block structures.
If LOOPS is non-NULL then the loop structures for already recorded loops
@@ -482,29 +509,10 @@ flow_loops_find (struct loops *loops)
{
struct loop *loop = larray[i];
basic_block header = loop->header;
- edge_iterator ei;
- edge e;
flow_loop_tree_node_add (header->loop_father, loop);
loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
-
- /* Look for the latch for this header block, if it has just a
- single one. */
- FOR_EACH_EDGE (e, ei, header->preds)
- {
- basic_block latch = e->src;
-
- if (flow_bb_inside_loop_p (loop, latch))
- {
- if (loop->latch != NULL)
- {
- /* More than one latch edge. */
- loop->latch = NULL;
- break;
- }
- loop->latch = latch;
- }
- }
+ loop->latch = find_single_latch (loop);
}
return loops;
@@ -1440,6 +1448,23 @@ verify_loop_structure (void)
err = 1;
}
}
+ else
+ {
+ if (loops_state_satisfies_p (LOOPS_MAY_HAVE_MULTIPLE_LATCHES))
+ {
+ if (find_single_latch (loop) != NULL)
+ {
+ error ("loop %d%'s latch is missing", i);
+ err = 1;
+ }
+ }
+ else
+ {
+ error ("loop %d%'s latch is missing, and loops may not have"
+ " multiple latches", i);
+ err = 1;
+ }
+ }
if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
{
if (!single_succ_p (loop->latch))
diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index ee73bf9..7faf591 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -270,6 +270,7 @@ bool mark_irreducible_loops (void);
void release_recorded_exits (function *);
void record_loop_exits (void);
void rescan_loop_exit (edge, bool, bool);
+basic_block find_single_latch (struct loop*);
/* Loop data structure manipulation/querying. */
extern void flow_loop_tree_node_add (struct loop *, struct loop *);
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index b47864e..00e314d6 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -8900,6 +8900,7 @@ expand_omp_for_generic (struct omp_region *region,
orig_loop->header = l1_bb;
/* The loop may have multiple latches. */
add_loop (orig_loop, new_loop);
+ orig_loop->latch = find_single_latch (orig_loop);
}
}
}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Check NULL loop->latch in verify_loop_structure
2015-11-22 23:29 [PATCH] Check NULL loop->latch in verify_loop_structure Tom de Vries
@ 2015-11-23 10:29 ` Richard Biener
2015-11-24 15:19 ` [PATCH] Improve verification of " Tom de Vries
0 siblings, 1 reply; 8+ messages in thread
From: Richard Biener @ 2015-11-23 10:29 UTC (permalink / raw)
To: Tom de Vries; +Cc: gcc-patches, Jakub Jelinek
On Mon, 23 Nov 2015, Tom de Vries wrote:
> Hi,
>
> In verify_loop_structure, we stop checking the latch once we find that it's
> NULL.
>
> This patch tries a bit harder:
> - if !LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we don't allow a NULL latch
> - if LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we check that indeed there's no
> single loop latch.
>
> As a consequence of adding this check, I needed to fix expand_omp_for_generic,
> which missed an initialization of a loop latch.
>
> Bootstrapped and reg-tested on x86_64.
>
> OK for stage3 trunk?
You miss to catch the case where loop->latch is non-NULL but there
are multiple latches, so I think the patch can be improved.
That case is more important for correctness (passes
seeing ->latch non-NULL assume a single latch).
Thanks,
Richard.
> Thanks,
> - Tom
>
--
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] Improve verification of loop->latch in verify_loop_structure
2015-11-23 10:29 ` Richard Biener
@ 2015-11-24 15:19 ` Tom de Vries
2015-11-25 10:44 ` Richard Biener
0 siblings, 1 reply; 8+ messages in thread
From: Tom de Vries @ 2015-11-24 15:19 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches, Jakub Jelinek
[-- Attachment #1: Type: text/plain, Size: 1016 bytes --]
[ was: Re: [PATCH] Check NULL loop->latch in verify_loop_structure ]
On 23/11/15 11:28, Richard Biener wrote:
> On Mon, 23 Nov 2015, Tom de Vries wrote:
>
>> Hi,
>>
>> In verify_loop_structure, we stop checking the latch once we find that it's
>> NULL.
>>
>> This patch tries a bit harder:
>> - if !LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we don't allow a NULL latch
>> - if LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we check that indeed there's no
>> single loop latch.
>>
>> As a consequence of adding this check, I needed to fix expand_omp_for_generic,
>> which missed an initialization of a loop latch.
>>
>> Bootstrapped and reg-tested on x86_64.
>>
>> OK for stage3 trunk?
>
> You miss to catch the case where loop->latch is non-NULL but there
> are multiple latches, so I think the patch can be improved.
> That case is more important for correctness (passes
> seeing ->latch non-NULL assume a single latch).
>
Updated according to comment.
Bootstrapped and reg-tested on x86_64.
OK for stage3 trunk?
Thanks,
- Tom
[-- Attachment #2: 0001-Improve-verification-of-loop-latch-in-verify_loop_structure.patch --]
[-- Type: text/x-patch, Size: 3847 bytes --]
Improve verification of loop->latch in verify_loop_structure
2015-11-22 Tom de Vries <tom@codesourcery.com>
* cfgloop.c (find_single_latch): New function, factored out of ...
(flow_loops_find): ... here.
(verify_loop_structure): Improve verification of loop->latch.
* cfgloop.h (find_single_latch): Declare.
* omp-low.c (expand_omp_for_generic): Initialize latch of orig_loop.
---
gcc/cfgloop.c | 70 ++++++++++++++++++++++++++++++++++++++++++-----------------
gcc/cfgloop.h | 1 +
gcc/omp-low.c | 1 +
3 files changed, 52 insertions(+), 20 deletions(-)
diff --git a/gcc/cfgloop.c b/gcc/cfgloop.c
index bf00e0e..a6850e3 100644
--- a/gcc/cfgloop.c
+++ b/gcc/cfgloop.c
@@ -388,6 +388,33 @@ bb_loop_header_p (basic_block header)
return false;
}
+/* Return the latch block for this header block, if it has just a single one.
+ Otherwise, return NULL. */
+
+basic_block
+find_single_latch (struct loop* loop)
+{
+ basic_block header = loop->header;
+ edge_iterator ei;
+ edge e;
+ basic_block latch = NULL;
+
+ FOR_EACH_EDGE (e, ei, header->preds)
+ {
+ basic_block cand = e->src;
+ if (!flow_bb_inside_loop_p (loop, cand))
+ continue;
+
+ if (latch != NULL)
+ /* More than one latch edge. */
+ return NULL;
+
+ latch = cand;
+ }
+
+ return latch;
+}
+
/* Find all the natural loops in the function and save in LOOPS structure and
recalculate loop_father information in basic block structures.
If LOOPS is non-NULL then the loop structures for already recorded loops
@@ -482,29 +509,10 @@ flow_loops_find (struct loops *loops)
{
struct loop *loop = larray[i];
basic_block header = loop->header;
- edge_iterator ei;
- edge e;
flow_loop_tree_node_add (header->loop_father, loop);
loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
-
- /* Look for the latch for this header block, if it has just a
- single one. */
- FOR_EACH_EDGE (e, ei, header->preds)
- {
- basic_block latch = e->src;
-
- if (flow_bb_inside_loop_p (loop, latch))
- {
- if (loop->latch != NULL)
- {
- /* More than one latch edge. */
- loop->latch = NULL;
- break;
- }
- loop->latch = latch;
- }
- }
+ loop->latch = find_single_latch (loop);
}
return loops;
@@ -1439,6 +1447,28 @@ verify_loop_structure (void)
error ("loop %d%'s latch is not dominated by its header", i);
err = 1;
}
+ if (find_single_latch (loop) == NULL)
+ {
+ error ("loop %d%'s latch is is not the only latch", i);
+ err = 1;
+ }
+ }
+ else
+ {
+ if (loops_state_satisfies_p (LOOPS_MAY_HAVE_MULTIPLE_LATCHES))
+ {
+ if (find_single_latch (loop) != NULL)
+ {
+ error ("loop %d%'s latch is missing", i);
+ err = 1;
+ }
+ }
+ else
+ {
+ error ("loop %d%'s latch is missing, and loops may not have"
+ " multiple latches", i);
+ err = 1;
+ }
}
if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
{
diff --git a/gcc/cfgloop.h b/gcc/cfgloop.h
index ee73bf9..7faf591 100644
--- a/gcc/cfgloop.h
+++ b/gcc/cfgloop.h
@@ -270,6 +270,7 @@ bool mark_irreducible_loops (void);
void release_recorded_exits (function *);
void record_loop_exits (void);
void rescan_loop_exit (edge, bool, bool);
+basic_block find_single_latch (struct loop*);
/* Loop data structure manipulation/querying. */
extern void flow_loop_tree_node_add (struct loop *, struct loop *);
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 0d4c6e5..2d782eb 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -8903,6 +8903,7 @@ expand_omp_for_generic (struct omp_region *region,
orig_loop->header = l1_bb;
/* The loop may have multiple latches. */
add_loop (orig_loop, new_loop);
+ orig_loop->latch = find_single_latch (orig_loop);
}
}
}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Improve verification of loop->latch in verify_loop_structure
2015-11-24 15:19 ` [PATCH] Improve verification of " Tom de Vries
@ 2015-11-25 10:44 ` Richard Biener
2015-11-26 11:46 ` Alan Lawrence
0 siblings, 1 reply; 8+ messages in thread
From: Richard Biener @ 2015-11-25 10:44 UTC (permalink / raw)
To: Tom de Vries; +Cc: gcc-patches, Jakub Jelinek
On Tue, 24 Nov 2015, Tom de Vries wrote:
> [ was: Re: [PATCH] Check NULL loop->latch in verify_loop_structure ]
>
> On 23/11/15 11:28, Richard Biener wrote:
> > On Mon, 23 Nov 2015, Tom de Vries wrote:
> >
> > > Hi,
> > >
> > > In verify_loop_structure, we stop checking the latch once we find that
> > > it's
> > > NULL.
> > >
> > > This patch tries a bit harder:
> > > - if !LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we don't allow a NULL latch
> > > - if LOOPS_MAY_HAVE_MULTIPLE_LATCHES, we check that indeed there's no
> > > single loop latch.
> > >
> > > As a consequence of adding this check, I needed to fix
> > > expand_omp_for_generic,
> > > which missed an initialization of a loop latch.
> > >
> > > Bootstrapped and reg-tested on x86_64.
> > >
> > > OK for stage3 trunk?
> >
> > You miss to catch the case where loop->latch is non-NULL but there
> > are multiple latches, so I think the patch can be improved.
> > That case is more important for correctness (passes
> > seeing ->latch non-NULL assume a single latch).
> >
>
> Updated according to comment.
>
> Bootstrapped and reg-tested on x86_64.
>
> OK for stage3 trunk?
Ok.
Thanks,
Richard.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Improve verification of loop->latch in verify_loop_structure
2015-11-25 10:44 ` Richard Biener
@ 2015-11-26 11:46 ` Alan Lawrence
2015-11-26 11:57 ` Alan Lawrence
2015-11-26 12:16 ` Richard Biener
0 siblings, 2 replies; 8+ messages in thread
From: Alan Lawrence @ 2015-11-26 11:46 UTC (permalink / raw)
To: Richard Biener; +Cc: Tom de Vries, gcc-patches, Jakub Jelinek
This caused an ICE compiling value.c from gdb on
aarch64-none-linux-gnu; the testcase, after preprocessing on aarch64,
ICEs on both aarch64 and x86_64, but is about 1MB - I'm working on
reducing that down to something small enough to post...
$ ./gcc/xgcc -B ./gcc -O2 -g value.c
../../binutils-gdb/gdb/value.c: In function ‘show_convenience’:
../../binutils-gdb/gdb/value.c:2615:1: error: loop 3’s latch is missing
../../binutils-gdb/gdb/value.c:2615:1: internal compiler error: in
verify_loop_structure, at cfgloop.c:1669
0x71e653 verify_loop_structure()
/work/alalaw01/src2/gcc/gcc/cfgloop.c:1669
0x97c6ae checking_verify_loop_structure
/work/alalaw01/src2/gcc/gcc/cfgloop.h:325
0x97c6ae loop_optimizer_init(unsigned int)
/work/alalaw01/src2/gcc/gcc/loop-init.c:106
0x97c78a rtl_loop_init
/work/alalaw01/src2/gcc/gcc/loop-init.c:398
0x97c78a execute
/work/alalaw01/src2/gcc/gcc/loop-init.c:425
--Alan
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Improve verification of loop->latch in verify_loop_structure
2015-11-26 11:46 ` Alan Lawrence
@ 2015-11-26 11:57 ` Alan Lawrence
2015-11-26 12:16 ` Richard Biener
1 sibling, 0 replies; 8+ messages in thread
From: Alan Lawrence @ 2015-11-26 11:57 UTC (permalink / raw)
To: Richard Biener, Tom de Vries, gcc-patches, Jakub Jelinek
Here's a reduced testcase (reduced to the point of generating lots of
warnings, I'm compiling with -O2 -w, on x86_64):
struct __jmp_buf_tag
{
};
typedef struct __jmp_buf_tag sigjmp_buf[1];
extern struct cmd_list_element *showlist;
struct internalvar
{
struct internalvar *next;
};
static struct internalvar *internalvars;
struct internalvar *
create_internalvar (const char *name)
{
struct internalvar *var = ((struct internalvar *) xmalloc (sizeof
(struct internalvar)));
internalvars = var;
}
void
show_convenience (char *ignore, int from_tty)
{
struct gdbarch *gdbarch = get_current_arch ();
int varseen = 0;
for (struct internalvar *var = internalvars; var; var = var->next)
{
if (!varseen)
varseen = 1;
sigjmp_buf *buf = exceptions_state_mc_init ();
__sigsetjmp ();
while (exceptions_state_mc_action_iter ())
while (exceptions_state_mc_action_iter_1 ())
;
}
if (!varseen)
printf_unfiltered ();
}
On 26 November 2015 at 11:33, Alan Lawrence <alan.lawrence@arm.com> wrote:
> This caused an ICE compiling value.c from gdb on
> aarch64-none-linux-gnu; the testcase, after preprocessing on aarch64,
> ICEs on both aarch64 and x86_64, but is about 1MB - I'm working on
> reducing that down to something small enough to post...
>
> $ ./gcc/xgcc -B ./gcc -O2 -g value.c
> ../../binutils-gdb/gdb/value.c: In function ‘show_convenience’:
> ../../binutils-gdb/gdb/value.c:2615:1: error: loop 3’s latch is missing
> ../../binutils-gdb/gdb/value.c:2615:1: internal compiler error: in
> verify_loop_structure, at cfgloop.c:1669
> 0x71e653 verify_loop_structure()
> /work/alalaw01/src2/gcc/gcc/cfgloop.c:1669
> 0x97c6ae checking_verify_loop_structure
> /work/alalaw01/src2/gcc/gcc/cfgloop.h:325
> 0x97c6ae loop_optimizer_init(unsigned int)
> /work/alalaw01/src2/gcc/gcc/loop-init.c:106
> 0x97c78a rtl_loop_init
> /work/alalaw01/src2/gcc/gcc/loop-init.c:398
> 0x97c78a execute
> /work/alalaw01/src2/gcc/gcc/loop-init.c:425
>
> --Alan
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Improve verification of loop->latch in verify_loop_structure
2015-11-26 11:46 ` Alan Lawrence
2015-11-26 11:57 ` Alan Lawrence
@ 2015-11-26 12:16 ` Richard Biener
2015-11-26 14:44 ` Tom de Vries
1 sibling, 1 reply; 8+ messages in thread
From: Richard Biener @ 2015-11-26 12:16 UTC (permalink / raw)
To: Alan Lawrence; +Cc: Tom de Vries, gcc-patches, Jakub Jelinek
[-- Attachment #1: Type: TEXT/PLAIN, Size: 1214 bytes --]
On Thu, 26 Nov 2015, Alan Lawrence wrote:
> This caused an ICE compiling value.c from gdb on
> aarch64-none-linux-gnu; the testcase, after preprocessing on aarch64,
> ICEs on both aarch64 and x86_64, but is about 1MB - I'm working on
> reducing that down to something small enough to post...
>
> $ ./gcc/xgcc -B ./gcc -O2 -g value.c
> ../../binutils-gdb/gdb/value.c: In function ‘show_convenience’:
> ../../binutils-gdb/gdb/value.c:2615:1: error: loop 3’s latch is missing
> ../../binutils-gdb/gdb/value.c:2615:1: internal compiler error: in
> verify_loop_structure, at cfgloop.c:1669
> 0x71e653 verify_loop_structure()
> /work/alalaw01/src2/gcc/gcc/cfgloop.c:1669
> 0x97c6ae checking_verify_loop_structure
> /work/alalaw01/src2/gcc/gcc/cfgloop.h:325
> 0x97c6ae loop_optimizer_init(unsigned int)
> /work/alalaw01/src2/gcc/gcc/loop-init.c:106
> 0x97c78a rtl_loop_init
> /work/alalaw01/src2/gcc/gcc/loop-init.c:398
> 0x97c78a execute
> /work/alalaw01/src2/gcc/gcc/loop-init.c:425
See also PR68549 for why I think this happens "by design". Thus
I think we need to revert the checking when
LOOPS_MAY_HAVE_MULTIPLE_LATCHES for now.
Richard.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Improve verification of loop->latch in verify_loop_structure
2015-11-26 12:16 ` Richard Biener
@ 2015-11-26 14:44 ` Tom de Vries
0 siblings, 0 replies; 8+ messages in thread
From: Tom de Vries @ 2015-11-26 14:44 UTC (permalink / raw)
To: Richard Biener, Alan Lawrence; +Cc: gcc-patches, Jakub Jelinek
On 26/11/15 13:15, Richard Biener wrote:
> On Thu, 26 Nov 2015, Alan Lawrence wrote:
>
>> This caused an ICE compiling value.c from gdb on
>> aarch64-none-linux-gnu; the testcase, after preprocessing on aarch64,
>> ICEs on both aarch64 and x86_64, but is about 1MB - I'm working on
>> reducing that down to something small enough to post...
>>
>> $ ./gcc/xgcc -B ./gcc -O2 -g value.c
>> ../../binutils-gdb/gdb/value.c: In function âshow_convenienceâ:
>> ../../binutils-gdb/gdb/value.c:2615:1: error: loop 3âs latch is missing
>> ../../binutils-gdb/gdb/value.c:2615:1: internal compiler error: in
>> verify_loop_structure, at cfgloop.c:1669
>> 0x71e653 verify_loop_structure()
>> /work/alalaw01/src2/gcc/gcc/cfgloop.c:1669
>> 0x97c6ae checking_verify_loop_structure
>> /work/alalaw01/src2/gcc/gcc/cfgloop.h:325
>> 0x97c6ae loop_optimizer_init(unsigned int)
>> /work/alalaw01/src2/gcc/gcc/loop-init.c:106
>> 0x97c78a rtl_loop_init
>> /work/alalaw01/src2/gcc/gcc/loop-init.c:398
>> 0x97c78a execute
>> /work/alalaw01/src2/gcc/gcc/loop-init.c:425
>
> See also PR68549 for why I think this happens "by design". Thus
> I think we need to revert the checking when
> LOOPS_MAY_HAVE_MULTIPLE_LATCHES for now.
I'll revert the whole patch for now.
Thanks,
- Tom
^ permalink raw reply [flat|nested] 8+ messages in thread
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Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2015-11-22 23:29 [PATCH] Check NULL loop->latch in verify_loop_structure Tom de Vries
2015-11-23 10:29 ` Richard Biener
2015-11-24 15:19 ` [PATCH] Improve verification of " Tom de Vries
2015-11-25 10:44 ` Richard Biener
2015-11-26 11:46 ` Alan Lawrence
2015-11-26 11:57 ` Alan Lawrence
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