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Re: Question about default optimizations
- From: Sebastian Huber <sebastian dot huber at embedded-brains dot de>
- To: gcc-help at gcc dot gnu dot org
- Date: Mon, 23 Nov 2015 14:08:15 +0100
- Subject: Re: Question about default optimizations
- Authentication-results: sourceware.org; auth=none
- References: <1448141520901-1208211 dot post at n5 dot nabble dot com>
Hello,
I am pretty sure that a better method exists to figure out the
optimizations enabled by -O.*, but you can use the -fverbose-asm option
and inspect the output. Look for "options enabled", e.g.
.file "x.c"
# rs6000/powerpc options: -msdata=data -G 8
.machine ppc
# GNU C11 (GCC) version 6.0.0 20151102 (experimental) [master revision
678bd42:02cf2eb:2980dcfbdeb643a1cfcf57020186a35bb8740820]
(powerpc-rtems4.12)
# compiled by GNU C version 4.8.1 20130909 [gcc-4_8-branch
revision 202388], GMP version 5.1.2, MPFR version 3.1.2, MPC version 1.0
# GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
# options passed: -Dmpc750 x.c -O2 -fverbose-asm
# options enabled: -faggressive-loop-optimizations -falign-functions
# -falign-jumps -falign-labels -falign-loops -fauto-inc-dec
# -fbranch-count-reg -fcaller-saves -fchkp-check-incomplete-type
# -fchkp-check-read -fchkp-check-write -fchkp-instrument-calls
# -fchkp-narrow-bounds -fchkp-optimize -fchkp-store-bounds
# -fchkp-use-static-bounds -fchkp-use-static-const-bounds
[...]
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.huber@embedded-brains.de
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