Date: Sun, 12 May 2002 08:45:29 -0700 (PDT) From: Bruce Evans <bde@FreeBSD.org> To: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/boot/i386/boot2 Makefile Message-ID: <200205121545.g4CFjTT12885@freefall.freebsd.org>
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bde 2002/05/12 08:45:28 PDT
Modified files:
sys/boot/i386/boot2 Makefile
Log:
Saved 176 bytes by compiling with -fno-guess-branch-probability. The
default of -fguess-branch-probablility causes time optimizations (?)
like rewriting `if (foo) x++;' as
`if (!foo) goto forth; back: ; ...; forth: x++; goto back;". This is
pessimizes space especially well on i386's because one short branch
gets converted to 2 long ones.
Removed -fno-align-foo since it is implied by -Os. Previous commit
messages seem to have overstated the new alignment bugs in gcc. The
only case that affects boot2 is that -fno-align-functions (or
equivalently -falign-functions=1) actually gives -falign-functions=2.
This is caused by FUNCTION_BOUNDARY being 2 (bytes) instead of 1.
The default case where the optimization level is 1 and no alignment
options are given is more broken. All alignments are minimal, modulo
the bug in FUNCTION_BOUNDARY. This is caused by toplev.c setting
defaults too early.
Some hacks in previous commits ar not needed now, but may as well be
kept until gcc is fixed. The previous on in the Makefile saved 96
bytes of text due to the wrong FUNCTION_BOUNDARY and 32 bytes of data
due to unrelated bloat in the alignment of large objects. There aren't
even any options to control alignment of data.
Revision Changes Path
1.26 +1 -1 src/sys/boot/i386/boot2/Makefile
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