Re: [dpdk-stable] [dpdk-dev] [PATCH] eal/ppc: ignore gcc 10 stringop-overflow warnings

Re: [dpdk-stable] [dpdk-dev] [PATCH] eal/ppc: ignore gcc 10 stringop-overflow warnings

[David Christensen]

On 7/5/21 2:28 AM, David Marchand wrote:
> On Wed, Jun 23, 2021 at 6:13 PM David Christensen
> <drc@linux.vnet.ibm.com> wrote:
>>
>> Suppress gcc warning "warning: writing 16 bytes into a region of
>> size 0" for users of the POWER rte_memcpy() function.  Existing
>> rte_memcpy() code takes different code paths based on the actual
>> size of the move so the warning is already addressed. See also
>> commit b5b3ea803e47 ("eal/x86: ignore gcc 10 stringop-overflow warnings")
> 
> Bugzilla ID: 739 ?

Different compiler warning, though same gcc version involved.

> What about a Cc: stable@dpdk.org?
> We did backport such change for x86.

Yes, should apply to stable as well.  Do I need to resubmit patch or is 
the CC: enough?

Dave

Re: [dpdk-stable] [dpdk-dev] [PATCH] eal/ppc: ignore gcc 10 stringop-overflow warnings

[David Christensen]

On 7/12/21 12:35 PM, David Christensen wrote:
> 
> 
> On 7/5/21 2:28 AM, David Marchand wrote:
>> On Wed, Jun 23, 2021 at 6:13 PM David Christensen
>> <drc@linux.vnet.ibm.com> wrote:
>>>
>>> Suppress gcc warning "warning: writing 16 bytes into a region of
>>> size 0" for users of the POWER rte_memcpy() function.  Existing
>>> rte_memcpy() code takes different code paths based on the actual
>>> size of the move so the warning is already addressed. See also
>>> commit b5b3ea803e47 ("eal/x86: ignore gcc 10 stringop-overflow 
>>> warnings")
>>
>> Bugzilla ID: 739 ?
> 
> Different compiler warning, though same gcc version involved.
> 
>> What about a Cc: stable@dpdk.org?
>> We did backport such change for x86.
> 
> Yes, should apply to stable as well.  Do I need to resubmit patch or is 
> the CC: enough?

Any reservations about including this in 21.08-rc3?

Dave

[dpdk-stable] [PATCH] eal/ppc: ignore gcc 10 stringop-overflow warnings

[David Christensen]

Suppress gcc warning "warning: writing 16 bytes into a region of
size 0" for users of the POWER rte_memcpy() function.  Existing
rte_memcpy() code takes different code paths based on the actual
size of the move so the warning is already addressed. See also
commit b5b3ea803e47 ("eal/x86: ignore gcc 10 stringop-overflow warnings")

Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
---
v2:
- update copyright year
- rebase for 21.11-rc0
---
 lib/eal/ppc/include/rte_memcpy.h | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/eal/ppc/include/rte_memcpy.h b/lib/eal/ppc/include/rte_memcpy.h
index c2a1f356d5..6f388c0234 100644
--- a/lib/eal/ppc/include/rte_memcpy.h
+++ b/lib/eal/ppc/include/rte_memcpy.h
@@ -1,6 +1,6 @@
 /*
  * SPDX-License-Identifier: BSD-3-Clause
- * Copyright (C) IBM Corporation 2014.
+ * Copyright (C) IBM Corporation 2014,2021
  */

 #ifndef _RTE_MEMCPY_PPC_64_H_
@@ -18,11 +18,16 @@ extern "C" {

 #include "generic/rte_memcpy.h"

-#if (GCC_VERSION >= 90000 && GCC_VERSION < 90400)
+#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 90000)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warray-bounds"
 #endif

+#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 100000)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+#endif
+
 static inline void
 rte_mov16(uint8_t *dst, const uint8_t *src)
 {
@@ -198,7 +203,11 @@ rte_memcpy_func(void *dst, const void *src, size_t n)
 	return ret;
 }

-#if (GCC_VERSION >= 90000 && GCC_VERSION < 90400)
+#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 100000)
+#pragma GCC diagnostic pop
+#endif
+
+#if defined(RTE_TOOLCHAIN_GCC) && (GCC_VERSION >= 90000)
 #pragma GCC diagnostic pop
 #endif

--
2.27.0

Re: [dpdk-stable] [PATCH] eal/ppc: ignore gcc 10 stringop-overflow warnings

[David Christensen]

> Suppress gcc warning "warning: writing 16 bytes into a region of
> size 0" for users of the POWER rte_memcpy() function.  Existing
> rte_memcpy() code takes different code paths based on the actual
> size of the move so the warning is already addressed. See also
> commit b5b3ea803e47 ("eal/x86: ignore gcc 10 stringop-overflow warnings")
> 
> Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>
> ---
> v2:
> - update copyright year
> - rebase for 21.11-rc0

David M,

Any chance of getting this approved in the 21.11 cycle?  Patch was 
originally submitted on 6/23, is only applicable to PPC architecture, 
and has no functional impact because it only disables warnings. 
Patchwork reports a performance test regression on x86 systems:

http://patches.dpdk.org/project/dpdk/patch/20210902221514.3215704-1-drc@linux.vnet.ibm.com/

But I don't see how that is possible.  Applying the patch on a local x86 
system results in identical x86 binaries with and without the patch 
applied.  It would appear that the test-to-test performance variations 
exceed the failure threshold on the CI setup.

Dave

Re: [dpdk-stable] [PATCH] eal/ppc: ignore gcc 10 stringop-overflow warnings

[David Marchand]

On Fri, Sep 3, 2021 at 12:15 AM David Christensen
<drc@linux.vnet.ibm.com> wrote:
>
> Suppress gcc warning "warning: writing 16 bytes into a region of
> size 0" for users of the POWER rte_memcpy() function.  Existing
> rte_memcpy() code takes different code paths based on the actual
> size of the move so the warning is already addressed. See also
> commit b5b3ea803e47 ("eal/x86: ignore gcc 10 stringop-overflow warnings")
>

Cc: stable@dpdk.org

> Signed-off-by: David Christensen <drc@linux.vnet.ibm.com>

Applied, thanks.


-- 
David Marchand