Setting -march=native and -mtune=native flags on a Via Nano U2250 produces Core2 optimized code that works very poorly on this CPU (programs fail or don't compile). I wonder if it was a conscious decision of GCC developers to set -march=native options for Via Nano to these values? This issue has been present since I've bought this CPU in June and it persists in GCC 4.3.4 and 4.4.2. gcc -fverbose-asm -mtune=native -march=native -S test.c returns: # GNU C (Gentoo 4.4.2 p1.0) version 4.4.2 (x86_64-pc-linux-gnu) # compiled by GNU C version 4.4.2, GMP version 4.3.1, MPFR version 2.4.1-p5. # GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 # options passed: test2.c -D_FORTIFY_SOURCE=2 -march=core2 -mcx16 -msahf # -mtune=core2 -fverbose-asm # options enabled: -falign-loops -fargument-alias # -fasynchronous-unwind-tables -fauto-inc-dec -fbranch-count-reg -fcommon # -fdwarf2-cfi-asm -fearly-inlining -feliminate-unused-debug-types # -ffunction-cse -fgcse-lm -fident -finline-functions-called-once # -fira-share-save-slots -fira-share-spill-slots -fivopts # -fkeep-static-consts -fleading-underscore -fmath-errno # -fmerge-debug-strings -fmove-loop-invariants -fpeephole # -freg-struct-return -fsched-interblock -fsched-spec # -fsched-stalled-insns-dep -fsigned-zeros -fsplit-ivs-in-unroller # -ftrapping-math -ftree-cselim -ftree-loop-im -ftree-loop-ivcanon # -ftree-loop-optimize -ftree-parallelize-loops= -ftree-reassoc # -ftree-scev-cprop -ftree-switch-conversion -ftree-vect-loop-version # -funit-at-a-time -funwind-tables -fvect-cost-model -fverbose-asm # -fzero-initialized-in-bss -m128bit-long-double -m64 -m80387 # -maccumulate-outgoing-args -malign-stringops -mcx16 -mfancy-math-387 # -mfp-ret-in-387 -mfused-madd -mglibc -mieee-fp -mmmx -mno-sse4 # -mpush-args -mred-zone -msahf -msse -msse2 -msse3 -mssse3 # -mtls-direct-seg-refs On the other hand, I've been using a x86_64 Linux system compiled with: -mtune=generic -mmmx -msse -msse2 -msse3 -mcx16 -msahf -O2 -pipe on this CPUand it's been working with no problems for a few months. I'd like to know if this issue is a bug (I can't find a corresponding bug report) and what steps should I take to report it if that's necessary. cat /proc/cpuinfo looks like this: processor : 0 vendor_id : CentaurHauls cpu family : 6 model : 15 model name : VIA Nano processor U2250@1300+MHz stepping : 2 cpu MHz : 1596.000 fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush acpi mmx fxsr sse sse2 ss tm pbe syscall fxsr_opt rdtscp lm constant_tsc up rep_good pni monitor est tm2 ssse3 cx16 xtpr lahf_lm bogomips : 3195.21 clflush size : 64 cache_alignment : 128 address sizes : 36 bits physical, 48 bits virtual power management:
