https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103538
--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> --- gcc-interface/Makefile.in has ifeq ($(strip $(filter-out x86_64, $(target_cpu))),) ifeq ($(strip $(MULTISUBDIR)),/32) target_cpu:=i686 else ifeq ($(strip $(MULTISUBDIR)),/x32) target_cpu:=x32 endif endif endif It doesn't set the right target_cpu when -mx32 is the default with x86_64-linux-gnux32.