From: Tom Tromey <tom@tromey.com>
To: Pedro Alves <palves@redhat.com>
Cc: Tom Tromey <tom@tromey.com>, gdb-patches@sourceware.org
Subject: Re: [PATCH 0/9] Add UBSan to the build
Date: Thu, 30 Aug 2018 18:56:00 -0000 [thread overview]
Message-ID: <8736uv3crj.fsf@tromey.com> (raw)
In-Reply-To: <00b73eed-01eb-ff51-e81d-35b0d6ae75d9@redhat.com> (Pedro Alves's message of "Thu, 30 Aug 2018 19:41:41 +0100")
>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:
Pedro> Might be noticeable in "make check" time.
Pedro> If you're doing performance analysis, say, running "make check-perf", or running
Pedro> some use case under "perf", sounds like you'll need to be sure to
Pedro> disable UBSan. I also mildly worry about random people comparing the
Pedro> performance of master GDB or some ftp snapshot against previous GDB versions
Pedro> or against other debuggers and being mislead. If that slowdown is true, I think we
Pedro> should at least document it somewhere more prominently, as I think that so
Pedro> far release vs development mode didn't have much of an impact?
Anyone doing performance analysis really must compile with -O2 and
disable all the checking. It really does matter, IIRC the sleb/uleb
decoders really suffer without optimization.
Pedro> Kind of like how GCC documents --enable-checking, at
Pedro> <https://gcc.gnu.org/install/configure.html>:
Pedro> "When you specify this option, the compiler is built to perform internal consistency
Pedro> checks of the requested complexity. This does not change the generated code, but adds
Pedro> error checking within the compiler. This will slow down the compiler and may only work
Pedro> properly if you are building the compiler with GCC. This is ‘yes,extra’ by default when
Pedro> building from SVN or snapshots, but ‘release’ for releases."
Do we have a similar doc somewhere? I could update it.
Also I think this series should update NEWS for the new configure option.
Tom
next prev parent reply other threads:[~2018-08-30 18:56 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-27 14:57 Tom Tromey
2018-08-27 14:57 ` [PATCH 7/9] Avoid undefined behavior in ada_operator_length Tom Tromey
2018-08-27 14:57 ` [PATCH 6/9] Avoid undefined behavior in read_signed_leb128 Tom Tromey
2018-08-27 14:57 ` [PATCH 3/9] Avoid undefined behavior in extract_integer Tom Tromey
2018-08-28 18:39 ` Pedro Alves
2018-08-29 0:11 ` Tom Tromey
2018-08-27 14:57 ` [PATCH 1/9] Do not pass NULL to memcpy Tom Tromey
2018-08-27 19:12 ` Simon Marchi
2018-08-28 22:40 ` Tom Tromey
2018-08-27 14:57 ` [PATCH 2/9] Use unsigned as base type for some enums Tom Tromey
2018-08-27 19:22 ` Simon Marchi
2018-08-27 20:22 ` Tom Tromey
2018-08-27 21:26 ` Simon Marchi
2018-08-28 18:54 ` Pedro Alves
2018-08-28 22:42 ` Tom Tromey
2018-08-29 0:01 ` Tom Tromey
2018-08-27 14:57 ` [PATCH 5/9] Avoid undefined behavior in parse_number Tom Tromey
2018-08-27 14:59 ` [PATCH 4/9] Avoid undefined behavior in read_subrange_type Tom Tromey
2018-08-27 14:59 ` [PATCH 8/9] Avoid undefined behavior in expression dumping Tom Tromey
2018-08-28 18:49 ` Pedro Alves
2018-08-29 0:27 ` Tom Tromey
2018-08-27 14:59 ` [PATCH 9/9] Add --enable-ubsan Tom Tromey
2018-08-28 19:03 ` [PATCH 0/9] Add UBSan to the build Pedro Alves
2018-08-29 0:45 ` Tom Tromey
2018-08-30 18:41 ` Pedro Alves
2018-08-30 18:56 ` Tom Tromey [this message]
2018-08-30 19:06 ` Pedro Alves
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