AFAIR GCC bootstrap builds by default with "-g -O2". There are 3 stages: 1) use system compiler to compile GCC's source code, 2) use resulting binary to build s

AFAIR GCC bootstrap builds by default with "-g -O2". There are 3 stages: 1) use system compiler to compile GCC's source code, 2) use resulting binary to build same source, 3) use binary from 2) to build source one more time. After all stages the binaries from stage 2 and 3 are compared byte for byte if they are identical. Bootstrap failures are taken very seriously by the GCC developers. So I really doubt that -g and -O* lead to non-deterministic builds.