On 2012.10.12 at 21:43 +0200, Jan Hubicka wrote: > I finally tracked down twolf misoptimization triggered by my loop-unroll.c > changes. It has turned out to be semi-latent wrong code issue in webizer. > What happens is: > > 1) gcse.c drop REG_EQUAL note on the induction variable > 2) loop optimizer unrolls the loop enabling webizer to cleanup > 3) webizer do not track reaching refs into REG_EQUAL note because > the variable is dead and renames it to unused pseudo > Program is stil valid but the REG_EQUAL is bogus. > 4) CSE eventually takes the value and put it back into the code > 5) init-regs initializes it to 0 > > and result is a segfault on the following testcase. > Fixed by making webizer to not prune dead regs. > Will commit it after testing on x86_64-linux.
FYI this also fixes the lto/profiledbootstrap breakage, PR 54885. Thanks. -- Markus
