Hi,
I am autotuning for x86 using this tutorial, and I am trying to choose the correct llvm target string (option for -mcpu).
According to How to choose the correct the target for CPU?, I should just use the CPU architecture codename, such as broadwell. But in the tutorial, they add -avx2 or -avx512 at the end of the name.
So here are my questions:
-mcpu?llvm as target)?Example:
Which target string should I use?
Output of /proc/cpuinfo:
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 142
model name : Intel(R) Core(TM) i5-7300U CPU @ 2.60GHz
stepping : 9
microcode : 0xb4
cpu MHz : 500.018
cache size : 3072 KB
physical id : 0
siblings : 4
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 22
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf tsc_known_freq pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx rdseed adx smap clflushopt intel_pt xsaveopt xsavec xgetbv1 xsaves dtherm ida arat pln pts hwp hwp_notify hwp_act_window hwp_epp md_clear flush_l1d
bugs : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds
bogomips : 5424.00
clflush size : 64
cache_alignment : 64
address sizes : 39 bits physical, 48 bits virtual
power management:
Link to specifications:
Both llvm -mcpu=kabylake and llvm -mcpu=kabylake-avx2 show this error:
'kabylake' is not a recognized processor for this target (ignoring processor)
LLVM ERROR: 64-bit code requested on a subtarget that doesn't support it!
llvm -mcpu=core-avx2 should work.