https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82286
--- Comment #4 from Herman ten Brugge <hermantenbrugge at home dot nl> --- Created attachment 42238 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42238&action=edit modified test case I modified the testcase a little bit and did some debugging. The code outputs a failure if compiled with: gcc -O3 -Wall -c tst.c -DERROR -fdump-tree-cunrolli-details tst.c: In function 'mtrx_decompose_matrix': tst.c:34:17: warning: array subscript is above array bounds [-Warray-bounds] sum += tmp.data[row][sub]; The code is ok of compiled with: gcc -O3 -Wall -c tst.c -DERROR -fdump-tree-cunrolli-details -fno-aggressive-loop-optimizations or: gcc -O3 -Wall -c tst.c -fdump-tree-cunrolli-details The dumpfile that are created are in case of error containing or if -fno-aggressive-loop-optimizations is given: ... Analyzing # of iterations of loop 3 exit condition [0, + , 1](no_overflow) < row_8 bounds on difference of bases: 0 ... 4294967294 result: # of iterations row_8, bounded by 4294967294 ... The dumpfile looks correct in the case the sqrtf function is not used: ... Analyzing # of iterations of loop 3 exit condition [0, + , 1](no_overflow) < row_5 bounds on difference of bases: 0 ... 5 result: # of iterations row_5, bounded by 5 ... Something must go wrong when aggressive-loop-optimizations is enabled.
