[Bug rtl-optimization/15927] THUMB -O2: strength-reduced iteration variable ends up off by 1

danfuzz at milk dot com gcc-bugzilla@gcc.gnu.org
Sat Jun 19 00:49:00 GMT 2004


------- Additional Comments From danfuzz at milk dot com  2004-06-19 00:49 -------
With the new file (m2.c) I tried turning off every single fine-grained "-f" option documented as being 
enabled by "-Os" and still the problem persists. That is, the following compile line still causes the 
compiler to spit out bad code:

    $ arm-elf-gcc -W -Wall -save-temps -c m2.c -mthumb -fno-builtin -Os -fno-strength-reduce 
    -fno-strict-aliasing -fno-force-mem -fno-optimize-sibling-calls -fno-cse-follow-jumps
    -fno-cse-skip-blocks -fno-rerun-cse-after-loop -fno-rerun-loop-opt -fno-gcse  -fno-gcse-lm  
    -fno-gcse-sm  -fno-gcse-las -fno-delete-null-pointer-checks -fno-expensive-optimizations
    -fno-regmove -fno-schedule-insns  -fno-schedule-insns2 -fno-sched-interblock
    -fno-sched-spec -fno-caller-saves -fno-peephole2 -fno-reorder-blocks  -fno-reorder-functions 
    -fno-strict-aliasing -fno-unit-at-a-time -fno-crossjumping 

This leads me to believe the documentation (at <http://gcc.gnu.org/onlinedocs/gcc-3.4.0/gcc/
Optimize-Options.html#Optimize%20Options>) is out-of-date with respect to what options -O2 and 
-Os enable.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15927



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