I wrote: >> What I conclude is that Red Hat hot-wired gcc to assume -msse4.2, >> but they didn't hot-wire clang the same way.
> In confirmation of that: everything goes through fine if I manually > add -msse4.2 to configure's choice of BITCODE_CFLAGS. Also, possibly useful for testing purposes: I can reproduce the build failure on RHEL8, and probably elsewhere, with ./configure CFLAGS="-O2 -msse4.2" --with-llvm In this form it's clearly pilot error, because I didn't do anything to put -msse4.2 into CXXFLAGS. But this is another way of confirming that the underlying problem is different default -m switches between gcc and clang. I'm kind of surprised we have not gotten bitten by that before. regards, tom lane