[Bug rtl-optimization/51374] [avr] insn combine reorders volatile memory accesses

["andyw at pobox dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51374

--- Comment #4 from andyw at pobox dot com 2011-12-01 13:22:44 UTC ---
Compiler command line & -v output showing configure options (thought I had
pasted this in the initial report - apparently not.) Do not know what happened
to the attachment, the box said text/plain...

$ avr-gcc -mmcu=atmega128 -Wall -O2 -g -c -save-temps -v test.c
Using built-in specs.
COLLECT_GCC=avr-gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/avr/4.6.2/lto-wrapper
Target: avr
Configured with: ../configure --target=avr --enable-languages=c,c++
--disable-nls --disable-libssp --with-dwarf2 : (reconfigured) ../configure
--target=avr --enable-languages=c,c++ --disable-nls --disable-libssp
--with-dwarf2 --with-gmp=/usr/local --with-mpc=/usr/local
--with-mpfr=/usr/local
Thread model: single
gcc version 4.6.2 (GCC) 
COLLECT_GCC_OPTIONS='-mmcu=atmega128' '-Wall' '-O2' '-g' '-c' '-save-temps'
'-v'
 /usr/local/libexec/gcc/avr/4.6.2/cc1 -E -quiet -v -imultilib avr51 test.c
-mmcu=atmega128 -Wall -g -fworking-directory -O2 -fpch-preprocess -o test.i
ignoring nonexistent directory
"/usr/local/lib/gcc/avr/4.6.2/../../../../avr/sys-include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/lib/gcc/avr/4.6.2/include
 /usr/local/lib/gcc/avr/4.6.2/include-fixed
 /usr/local/lib/gcc/avr/4.6.2/../../../../avr/include
End of search list.
COLLECT_GCC_OPTIONS='-mmcu=atmega128' '-Wall' '-O2' '-g' '-c' '-save-temps'
'-v'
 /usr/local/libexec/gcc/avr/4.6.2/cc1 -fpreprocessed test.i -quiet -dumpbase
test.c -mmcu=atmega128 -auxbase test -g -O2 -Wall -version -o test.s
GNU C (GCC) version 4.6.2 (avr)
        compiled by GNU C version 4.1.2 20070925 (Red Hat 4.1.2-33), GMP
version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C (GCC) version 4.6.2 (avr)
        compiled by GNU C version 4.1.2 20070925 (Red Hat 4.1.2-33), GMP
version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 8445704570d64b6b795b8847e7060bc6
test.c: In function '__vector_18':
test.c:10:16: warning: unused variable 'data' [-Wunused-variable]
COLLECT_GCC_OPTIONS='-mmcu=atmega128' '-Wall' '-O2' '-g' '-c' '-save-temps'
'-v'
 /usr/local/lib/gcc/avr/4.6.2/../../../../avr/bin/as -mmcu=atmega128 -o test.o
test.s
COMPILER_PATH=/usr/local/libexec/gcc/avr/4.6.2/:/usr/local/libexec/gcc/avr/4.6.2/:/usr/local/libexec/gcc/avr/:/usr/local/lib/gcc/avr/4.6.2/:/usr/local/lib/gcc/avr/:/usr/local/lib/gcc/avr/4.6.2/../../../../avr/bin/
LIBRARY_PATH=/usr/local/lib/gcc/avr/4.6.2/avr51/:/usr/local/lib/gcc/avr/4.6.2/../../../../avr/lib/avr51/:/usr/local/lib/gcc/avr/4.6.2/:/usr/local/lib/gcc/avr/4.6.2/../../../../avr/lib/
COLLECT_GCC_OPTIONS='-mmcu=atmega128' '-Wall' '-O2' '-g' '-c' '-save-temps'
'-v'
$