[PATCH] Warray-bounds: Warn only for generic address spaces

2021-10-12 Thread Siddhesh Poyarekar 
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 
---
 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 000..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

Re: [PATCH] Warray-bounds: Warn only for generic address spaces

2021-10-12 Thread Martin Sebor via Gcc-patches 

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 
---
  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 000..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"

Re: [PATCH] Warray-bounds: Warn only for generic address spaces

2021-10-12 Thread Siddhesh Poyarekar 

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

Re: [PATCH] Warray-bounds: Warn only for generic address spaces

2021-10-13 Thread Richard Biener via Gcc-patches 
On Tue, Oct 12, 2021 at 8:34 PM Siddhesh Poyarekar  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 
> ---
>  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 000..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
>

Re: [PATCH] Warray-bounds: Warn only for generic address spaces

2021-10-13 Thread Siddhesh Poyarekar 

On 10/13/21 13:50, Richard Biener wrote:

On Tue, Oct 12, 2021 at 8:34 PM Siddhesh Poyarekar  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-68bab2cd3...@gmail.com/

Thanks,
Siddhesh