[Bug c/15434] -mcpu=601 -O2 optimization problems

["stefaan dot simoens at tiscali dot be" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From stefaan dot simoens at tiscali dot be  2004-05-24 19:41 -------
Further investigation showed that optimization errors also occur in other 
files.

/bin/ps compiled with -mcpu=601 -O2 gave me a broken executable. I tried to 
pin-point the problem and I found some very strange things:
* /bin/ps compiled with -mcpu=601 -O1 was broken, too
* /bin/ps compiled with -mcpu=601 works fine
* /bin/ps compiled with -mcpu=601 -fdefer-pop -fmerge-constants -fthread-
jumps -floop-optimize -fif-conversion -fif-conversion2 -fguess-branch-
probability -fcprop-registers -fomit-frame-pointer works fine, too
* (adding -fdelayed-branch to the latter gives a warning and a working 
executable)

According to the man-page, all those f-options should give the same 
functionality as -O1 does. Compiling whith -fverbose-asm confirms this (equal 
options enabled), but the assembler code differs a lot.

I'm going to look if I can find ONE (1) file where 'wrong-code' gets 
generated. I'm curious, however, why there is different assembler code beween -
O1 and the -f-options ... Has this anything to do with PR7257 ?

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15434