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Date: Sat, 14 Sep 1996 00:41:07 -0700 (PDT)
From: Bruce Evans <bde>
Message-Id: <199609140741.AAA15326@freefall.freebsd.org>
To: CVS-committers, cvs-all, cvs-sys
Subject: cvs commit:  src/sys/i386/boot/biosboot disk.c sys.c
Sender: owner-cvs-sys@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

bde         96/09/14 00:41:07

  Modified:    sys/i386/boot/biosboot  disk.c sys.c
  Log:
  Moved instantiation of `poff' to sys.c.  It is no longer used in disk.c.
  
  Saved a few bytes by copying `dosdev' and/or `name' to local variables.
  This optimization (for dosdev) was done in one place before but this
  was lost in the devread() cleanup.   This optimization (for dosdev)
  can almost be done by bogusly declaring dosdev as const, but gcc still
  often space-pessimizes code like the following:
  
  	extern const int dosdev; ... foo(dosdev); bar(dosdev);
  
  gcc often doesn't bother to copy dosdev to a temporary local because
  the local would have to be preserved in memory across the call to
  foo().  OTOH, for
  
  	extern int dosdev; ... auto int dosdev_copy = dosdev; ...
  		foo(dosdev_copy); bar(dosdev_copy);
  
  the copy must be made because foo() might alter dosdev.
  
  Revision  Changes    Path
  1.20      +12 -9     src/sys/i386/boot/biosboot/disk.c
  1.15      +18 -15    src/sys/i386/boot/biosboot/sys.c