From: DJ Delorie <dj@redhat.com>
To: David Malcolm <dmalcolm@redhat.com>
Cc: gcc-patches@gcc.gnu.org, binutils@sourceware.org
Subject: Re: [PATCH 08/16] libiberty.h: Provide a CLEAR_VAR macro
Date: Mon, 01 Jun 2015 21:47:00 -0000 [thread overview]
Message-ID: <201506012147.t51Ll08P015579@greed.delorie.com> (raw)
In-Reply-To: <1433192664-50156-9-git-send-email-dmalcolm@redhat.com> (message from David Malcolm on Mon, 1 Jun 2015 17:04:16 -0400)
> +/* Fill an lvalue with zero bits. */
> +#define CLEAR_VAR(S) \
> + do { memset (&(S), 0, sizeof (S)); } while (0)
Hmmm... I don't see the point in this. The macro is almost as long as
a bare memset() would be, and replaces a well-known function with
something unknown outside this project. It neither hides a bug in an
OS nor provides a common way to handle a difficult task across
platforms.
You also do NOT want to use memset to zero out a C++ structure that
contains more than just "plain old data" - you could easily corrupt
the structure's hidden data.
Also, pedantically speaking, "all bits zero" is not guaranteed to be
the same as float 0.0, double 0.0, or pointer (void *)0.
next prev parent reply other threads:[~2015-06-01 21:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-01 20:50 [PATCH 00/16] RFC: Embedding as and ld inside gcc driver and into libgccjit David Malcolm
2015-06-01 20:50 ` [PATCH 01/16] gcc: Generalization of timevar API; add gcc_jit_timer interface David Malcolm
2015-06-01 20:50 ` [PATCH 05/16] gcc: driver: add g_driver singleton David Malcolm
2015-06-01 20:51 ` [PATCH 15/16] gcc: Use libgas and libld within the driver David Malcolm
2015-06-02 8:32 ` Richard Biener
2015-06-02 11:07 ` Trevor Saunders
2015-06-02 12:12 ` Richard Biener
2015-06-01 20:51 ` [PATCH 10/16] binutils: Introduce "gas_main", and state-purging with "gas" subdir David Malcolm
2015-06-01 20:55 ` [PATCH 09/16] libiberty.h: Provide CTIMER_PUSH/POP David Malcolm
2015-06-01 21:30 ` DJ Delorie
2015-06-02 21:52 ` Jeff Law
2015-06-01 20:55 ` [PATCH 06/16] gcc: driver: add timevars for as, collect2, ld David Malcolm
2015-06-01 20:55 ` [PATCH 08/16] libiberty.h: Provide a CLEAR_VAR macro David Malcolm
2015-06-01 21:47 ` DJ Delorie [this message]
2015-06-02 1:23 ` David Malcolm
2015-06-02 1:39 ` DJ Delorie
2015-06-01 20:55 ` [PATCH 07/16] binutils: bfd: Implement bfd_uninit David Malcolm
2015-06-01 20:56 ` [PATCH 04/16] gcc: Don't keep reinitializing RTL David Malcolm
2015-06-01 20:58 ` [PATCH 14/16] gcc: Add CTIMER_PUSH/POP to gcc's copy of libiberty David Malcolm
2015-06-01 21:33 ` DJ Delorie
2015-06-01 20:58 ` [PATCH 11/16] binutils: gas/Makefile.am: Add libgas.la David Malcolm
2015-06-01 20:58 ` [PATCH 02/16] gcc: Embed the driver in-process within libgccjit David Malcolm
2015-06-03 6:00 ` Bert Wesarg
2015-06-01 20:59 ` [PATCH 12/16] binutils: Introduce "ld_main" and state-purging within "ld" subdir David Malcolm
2015-06-01 20:59 ` [PATCH 03/16] gcc: Use timevars within driver David Malcolm
2015-06-01 21:00 ` [PATCH 13/16] ld/Makefile.am: Introduce a libld.la David Malcolm
2015-06-01 21:00 ` [PATCH 16/16] gcc: Hack up the arguments to the linker David Malcolm
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