[1/3] tree-ssa-sink: do not sink to in front of setjmp
Commit Message
gcc/ChangeLog:
* tree-ssa-sink.c (select_best_block): Punt if selected block
has incoming abnormal edges.
gcc/testsuite/ChangeLog:
* gcc.dg/setjmp-7.c: New test.
---
gcc/testsuite/gcc.dg/setjmp-7.c | 13 +++++++++++++
gcc/tree-ssa-sink.c | 6 ++++++
2 files changed, 19 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/setjmp-7.c
Comments
On Fri, Jan 14, 2022 at 7:21 PM Alexander Monakov <amonakov@ispras.ru> wrote:
>
> gcc/ChangeLog:
>
> * tree-ssa-sink.c (select_best_block): Punt if selected block
> has incoming abnormal edges.
OK.
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/setjmp-7.c: New test.
> ---
> gcc/testsuite/gcc.dg/setjmp-7.c | 13 +++++++++++++
> gcc/tree-ssa-sink.c | 6 ++++++
> 2 files changed, 19 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/setjmp-7.c
>
> diff --git a/gcc/testsuite/gcc.dg/setjmp-7.c b/gcc/testsuite/gcc.dg/setjmp-7.c
> new file mode 100644
> index 000000000..44b5bcbfa
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
> +/* { dg-require-effective-target indirect_jumps } */
> +
> +struct __jmp_buf_tag { };
> +typedef struct __jmp_buf_tag jmp_buf[1];
> +struct globals { jmp_buf listingbuf; };
> +extern struct globals *const ptr_to_globals;
> +void foo()
> +{
> + if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
> + ;
> +}
> diff --git a/gcc/tree-ssa-sink.c b/gcc/tree-ssa-sink.c
> index 66d7ae89e..016ecbaec 100644
> --- a/gcc/tree-ssa-sink.c
> +++ b/gcc/tree-ssa-sink.c
> @@ -208,6 +208,12 @@ select_best_block (basic_block early_bb,
> temp_bb = get_immediate_dominator (CDI_DOMINATORS, temp_bb);
> }
>
> + /* Placing a statement before a setjmp-like function would be invalid
> + (it cannot be reevaluated when execution follows an abnormal edge).
> + If we selected a block with abnormal predecessors, just punt. */
> + if (bb_has_abnormal_pred (best_bb))
> + return early_bb;
> +
> /* If we found a shallower loop nest, then we always consider that
> a win. This will always give us the most control dependent block
> within that loop nest. */
> --
> 2.33.1
>
* Alexander Monakov via Gcc-patches:
> diff --git a/gcc/testsuite/gcc.dg/setjmp-7.c b/gcc/testsuite/gcc.dg/setjmp-7.c
> new file mode 100644
> index 000000000..44b5bcbfa
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
> +/* { dg-require-effective-target indirect_jumps } */
> +
> +struct __jmp_buf_tag { };
> +typedef struct __jmp_buf_tag jmp_buf[1];
> +struct globals { jmp_buf listingbuf; };
> +extern struct globals *const ptr_to_globals;
> +void foo()
> +{
> + if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
> + ;
> +}
Is the implicit declaration of _setjmp important to this test?
Could we declare it explicitly instead?
Thanks,
Florian
> Am 08.11.2023 um 10:04 schrieb Florian Weimer <fweimer@redhat.com>:
>
> * Alexander Monakov via Gcc-patches:
>
>> diff --git a/gcc/testsuite/gcc.dg/setjmp-7.c b/gcc/testsuite/gcc.dg/setjmp-7.c
>> new file mode 100644
>> index 000000000..44b5bcbfa
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
>> @@ -0,0 +1,13 @@
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
>> +/* { dg-require-effective-target indirect_jumps } */
>> +
>> +struct __jmp_buf_tag { };
>> +typedef struct __jmp_buf_tag jmp_buf[1];
>> +struct globals { jmp_buf listingbuf; };
>> +extern struct globals *const ptr_to_globals;
>> +void foo()
>> +{
>> + if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
>> + ;
>> +}
>
> Is the implicit declaration of _setjmp important to this test?
> Could we declare it explicitly instead?
It shouldn’t be important.
> Thanks,
> Florian
>
On Wed, 8 Nov 2023, Richard Biener wrote:
> >> --- /dev/null
> >> +++ b/gcc/testsuite/gcc.dg/setjmp-7.c
> >> @@ -0,0 +1,13 @@
> >> +/* { dg-do compile } */
> >> +/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
> >> +/* { dg-require-effective-target indirect_jumps } */
> >> +
> >> +struct __jmp_buf_tag { };
> >> +typedef struct __jmp_buf_tag jmp_buf[1];
> >> +struct globals { jmp_buf listingbuf; };
> >> +extern struct globals *const ptr_to_globals;
> >> +void foo()
> >> +{
> >> + if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
> >> + ;
> >> +}
> >
> > Is the implicit declaration of _setjmp important to this test?
> > Could we declare it explicitly instead?
>
> It shouldn’t be important.
Yes, it's an artifact from testcase minimization, sorry about that.
Florian, I see you've sent a patch to fix this up — thank you!
Alexander
new file mode 100644
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-guess-branch-probability -w" } */
+/* { dg-require-effective-target indirect_jumps } */
+
+struct __jmp_buf_tag { };
+typedef struct __jmp_buf_tag jmp_buf[1];
+struct globals { jmp_buf listingbuf; };
+extern struct globals *const ptr_to_globals;
+void foo()
+{
+ if ( _setjmp ( ((*ptr_to_globals).listingbuf )))
+ ;
+}
@@ -208,6 +208,12 @@ select_best_block (basic_block early_bb,
temp_bb = get_immediate_dominator (CDI_DOMINATORS, temp_bb);
}
+ /* Placing a statement before a setjmp-like function would be invalid
+ (it cannot be reevaluated when execution follows an abnormal edge).
+ If we selected a block with abnormal predecessors, just punt. */
+ if (bb_has_abnormal_pred (best_bb))
+ return early_bb;
+
/* If we found a shallower loop nest, then we always consider that
a win. This will always give us the most control dependent block
within that loop nest. */