* [PATCH] Warray-bounds: Warn only for generic address spaces
@ 2021-10-12 18:33 Siddhesh Poyarekar
2021-10-12 19:06 ` Martin Sebor
2021-10-13 8:20 ` Richard Biener
0 siblings, 2 replies; 5+ messages in thread
From: Siddhesh Poyarekar @ 2021-10-12 18:33 UTC (permalink / raw)
To: gcc-patches; +Cc: msebor
The warning is falsely triggered for THREAD_SELF in glibc when
accessing TCB through the segment register.
gcc/ChangeLog:
* gimple-array-bounds.cc
(array_bounds_checker::check_mem_ref): Bail out for
non-generic address spaces.
gcc/testsuite/ChangeLog:
* gcc.target/i386/addr-space-3.c: New test case.
Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
---
gcc/gimple-array-bounds.cc | 3 +++
gcc/testsuite/gcc.target/i386/addr-space-3.c | 5 +++++
2 files changed, 8 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/i386/addr-space-3.c
diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc
index 0517e5ddd8e..36fc1dbe3f8 100644
--- a/gcc/gimple-array-bounds.cc
+++ b/gcc/gimple-array-bounds.cc
@@ -432,6 +432,9 @@ array_bounds_checker::check_mem_ref (location_t location, tree ref,
if (aref.offset_in_range (axssize))
return false;
+ if (!ADDR_SPACE_GENERIC_P (TYPE_ADDR_SPACE (axstype)))
+ return false;
+
if (TREE_CODE (aref.ref) == SSA_NAME)
{
gimple *def = SSA_NAME_DEF_STMT (aref.ref);
diff --git a/gcc/testsuite/gcc.target/i386/addr-space-3.c b/gcc/testsuite/gcc.target/i386/addr-space-3.c
new file mode 100644
index 00000000000..4bd940e696a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/addr-space-3.c
@@ -0,0 +1,5 @@
+/* Verify that __seg_fs/gs marked variables do not trigger an array bounds
+ warning. */
+/* { dg-do compile */
+/* { dg-options "-O2 -Warray-bounds" } */
+#include "addr-space-2.c"
--
2.31.1
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Warray-bounds: Warn only for generic address spaces
2021-10-12 18:33 [PATCH] Warray-bounds: Warn only for generic address spaces Siddhesh Poyarekar
@ 2021-10-12 19:06 ` Martin Sebor
2021-10-13 0:14 ` Siddhesh Poyarekar
2021-10-13 8:20 ` Richard Biener
1 sibling, 1 reply; 5+ messages in thread
From: Martin Sebor @ 2021-10-12 19:06 UTC (permalink / raw)
To: Siddhesh Poyarekar, gcc-patches; +Cc: msebor
On 10/12/21 12:33 PM, Siddhesh Poyarekar wrote:
> The warning is falsely triggered for THREAD_SELF in glibc when
> accessing TCB through the segment register.
Thanks for looking into it! The Glibc warning is being tracked
in PR 102630. The root cause behind it is in compute_objsize_r
in pointer-query.cc (which is used by -Warray-bounds as well as
other warnings). I just posted a patch for it the other day;
it's waiting for approval (though as Joseph noted, I need to
adjust the test and either make it target-independent or move
it under i386).
Martin
PS Noticing gcc.target/i386/addr-space-2.c makes me wish
-Warray-bounds were enabled by default, like other out-of-bounds
warnings, and reminds me that it should be able to run even at
-O1 (and -O0).
>
> gcc/ChangeLog:
>
> * gimple-array-bounds.cc
> (array_bounds_checker::check_mem_ref): Bail out for
> non-generic address spaces.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/addr-space-3.c: New test case.
>
> Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
> ---
> gcc/gimple-array-bounds.cc | 3 +++
> gcc/testsuite/gcc.target/i386/addr-space-3.c | 5 +++++
> 2 files changed, 8 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/i386/addr-space-3.c
>
> diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc
> index 0517e5ddd8e..36fc1dbe3f8 100644
> --- a/gcc/gimple-array-bounds.cc
> +++ b/gcc/gimple-array-bounds.cc
> @@ -432,6 +432,9 @@ array_bounds_checker::check_mem_ref (location_t location, tree ref,
> if (aref.offset_in_range (axssize))
> return false;
>
> + if (!ADDR_SPACE_GENERIC_P (TYPE_ADDR_SPACE (axstype)))
> + return false;
> +
> if (TREE_CODE (aref.ref) == SSA_NAME)
> {
> gimple *def = SSA_NAME_DEF_STMT (aref.ref);
> diff --git a/gcc/testsuite/gcc.target/i386/addr-space-3.c b/gcc/testsuite/gcc.target/i386/addr-space-3.c
> new file mode 100644
> index 00000000000..4bd940e696a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/addr-space-3.c
> @@ -0,0 +1,5 @@
> +/* Verify that __seg_fs/gs marked variables do not trigger an array bounds
> + warning. */
> +/* { dg-do compile */
> +/* { dg-options "-O2 -Warray-bounds" } */
> +#include "addr-space-2.c"
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Warray-bounds: Warn only for generic address spaces
2021-10-12 19:06 ` Martin Sebor
@ 2021-10-13 0:14 ` Siddhesh Poyarekar
0 siblings, 0 replies; 5+ messages in thread
From: Siddhesh Poyarekar @ 2021-10-13 0:14 UTC (permalink / raw)
To: Martin Sebor, gcc-patches; +Cc: msebor
On 10/13/21 00:36, Martin Sebor wrote:
> On 10/12/21 12:33 PM, Siddhesh Poyarekar wrote:
>> The warning is falsely triggered for THREAD_SELF in glibc when
>> accessing TCB through the segment register.
>
> Thanks for looking into it! The Glibc warning is being tracked
> in PR 102630. The root cause behind it is in compute_objsize_r
> in pointer-query.cc (which is used by -Warray-bounds as well as
> other warnings). I just posted a patch for it the other day;
> it's waiting for approval (though as Joseph noted, I need to
> adjust the test and either make it target-independent or move
> it under i386).
Ahh, targetm.addr_space.zero_address_valid was what I was looking for
and didn't find. Your fix looks good to me module moving the test out
into gcc.target/i386.
Thanks,
Siddhesh
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Warray-bounds: Warn only for generic address spaces
2021-10-12 18:33 [PATCH] Warray-bounds: Warn only for generic address spaces Siddhesh Poyarekar
2021-10-12 19:06 ` Martin Sebor
@ 2021-10-13 8:20 ` Richard Biener
2021-10-13 8:27 ` Siddhesh Poyarekar
1 sibling, 1 reply; 5+ messages in thread
From: Richard Biener @ 2021-10-13 8:20 UTC (permalink / raw)
To: Siddhesh Poyarekar; +Cc: GCC Patches, Martin Sebor
On Tue, Oct 12, 2021 at 8:34 PM Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
>
> The warning is falsely triggered for THREAD_SELF in glibc when
> accessing TCB through the segment register.
I think this is a more generic bug - the warning is also bogus if the
general address space is involved.
Martin?
> gcc/ChangeLog:
>
> * gimple-array-bounds.cc
> (array_bounds_checker::check_mem_ref): Bail out for
> non-generic address spaces.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/addr-space-3.c: New test case.
>
> Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
> ---
> gcc/gimple-array-bounds.cc | 3 +++
> gcc/testsuite/gcc.target/i386/addr-space-3.c | 5 +++++
> 2 files changed, 8 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/i386/addr-space-3.c
>
> diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc
> index 0517e5ddd8e..36fc1dbe3f8 100644
> --- a/gcc/gimple-array-bounds.cc
> +++ b/gcc/gimple-array-bounds.cc
> @@ -432,6 +432,9 @@ array_bounds_checker::check_mem_ref (location_t location, tree ref,
> if (aref.offset_in_range (axssize))
> return false;
>
> + if (!ADDR_SPACE_GENERIC_P (TYPE_ADDR_SPACE (axstype)))
> + return false;
> +
> if (TREE_CODE (aref.ref) == SSA_NAME)
> {
> gimple *def = SSA_NAME_DEF_STMT (aref.ref);
> diff --git a/gcc/testsuite/gcc.target/i386/addr-space-3.c b/gcc/testsuite/gcc.target/i386/addr-space-3.c
> new file mode 100644
> index 00000000000..4bd940e696a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/addr-space-3.c
> @@ -0,0 +1,5 @@
> +/* Verify that __seg_fs/gs marked variables do not trigger an array bounds
> + warning. */
> +/* { dg-do compile */
> +/* { dg-options "-O2 -Warray-bounds" } */
> +#include "addr-space-2.c"
> --
> 2.31.1
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Warray-bounds: Warn only for generic address spaces
2021-10-13 8:20 ` Richard Biener
@ 2021-10-13 8:27 ` Siddhesh Poyarekar
0 siblings, 0 replies; 5+ messages in thread
From: Siddhesh Poyarekar @ 2021-10-13 8:27 UTC (permalink / raw)
To: Richard Biener; +Cc: GCC Patches, Martin Sebor
On 10/13/21 13:50, Richard Biener wrote:
> On Tue, Oct 12, 2021 at 8:34 PM Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
>>
>> The warning is falsely triggered for THREAD_SELF in glibc when
>> accessing TCB through the segment register.
>
> I think this is a more generic bug - the warning is also bogus if the
> general address space is involved.
I agree, Martin pointed me to a different fix that he posted earlier:
https://patchwork.sourceware.org/project/gcc/patch/806cc630-86ef-2e3f-f72b-68bab2cd3e86@gmail.com/
Thanks,
Siddhesh
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-10-12 18:33 [PATCH] Warray-bounds: Warn only for generic address spaces Siddhesh Poyarekar
2021-10-12 19:06 ` Martin Sebor
2021-10-13 0:14 ` Siddhesh Poyarekar
2021-10-13 8:20 ` Richard Biener
2021-10-13 8:27 ` Siddhesh Poyarekar
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