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From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
To: Stanislaw Kardach <kda@semihalf.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	Frank Zhao <Frank.Zhao@starfivetech.com>,
	Sam Grove <sam.grove@sifive.com>,
	"mw@semihalf.com" <mw@semihalf.com>,
	"upstream@semihalf.com" <upstream@semihalf.com>, nd <nd@arm.com>,
	nd <nd@arm.com>
Subject: RE: [PATCH v2 1/1] test/ring: remove excessive inlining
Date: Wed, 11 May 2022 16:51:03 +0000	[thread overview]
Message-ID: <DBAPR08MB581458919EA1024892721E8398C89@DBAPR08MB5814.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <20220511150725.744021-1-kda@semihalf.com>

<snip>
> 
> Forcing inlining in test_ring_enqueue and test_ring_dequeue can cause the
> compiled code to grow extensively when compiled with no optimization
> (-O0 or -Og). This is default in the meson's debug configuration. This can collide
> with compiler bugs and cause issues during linking of unit tests where the
> api_type or esize are non-const variables causing inlining cascade. In perf tests
> this is not the case in perf-tests as esize and api_type are const values.
> 
> One such case was discovered when porting DPDK to RISC-V. GCC 11.2 (and no
> fix still in 12.1) is generating a short relative jump instruction (J <offset>) for
> goto and for loops. When loop body grows extensively in ring test, the target
> offset goes beyond supported offfset of +/- 1MB from PC. This is an obvious
> bug in the GCC as RISC-V has a two-instruction construct to jump to any
> absolute address (AUIPC+JALR).
> 
> However there is no reason to force inlining as the test code works perfectly
> fine without it.
> 
> GCC has a bug report for a similar case (with conditionals):
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93062
> 
> Fixes: a9fe152363 test/ring: add custom element size functional tests
> 
> Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

  parent reply	other threads:[~2022-05-11 16:51 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-10 11:57 [PATCH 1/1] test/ring: remove excessive inlining Stanislaw Kardach
2022-05-10 23:23 ` Honnappa Nagarahalli
2022-05-11  9:14   ` Bruce Richardson
2022-05-11 14:39   ` Stanisław Kardach
2022-05-11 15:07 ` [PATCH v2 " Stanislaw Kardach
2022-05-11 15:48   ` Bruce Richardson
2022-05-23 13:31     ` David Marchand
2022-05-11 16:51   ` Honnappa Nagarahalli [this message]
2022-05-19 22:50   ` Konstantin Ananyev

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