[cfe-dev] march=native on Broadwell yields non-Broadwell ISA?
Craig Topper
craig.topper at gmail.com
Sun Mar 22 17:18:41 PDT 2015
Hopefully fixed in r232927.
On Thu, Mar 19, 2015 at 7:53 AM, Steven Noonan <steven at uplinklabs.net>
wrote:
> Seems that -march=native doesn't want to detect I'm on a Broadwell host.
>
> $ clang -v
> clang version 3.6.0 (tags/RELEASE_360/final)
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
>
> $ cat rsqrt.c
> #include <math.h>
>
> float rsqrtf(float f)
> {
> return 1.0f / sqrtf(f);
> }
>
>
> march=native, note non-VEX encoded SSE instructions:
>
> $ clang -O3 -march=native -S -o - rsqrt.c | showasm
> .LCPI0_0:
> rsqrtf: # @rsqrtf
> pushq %rax
> .Ltmp0:
> movaps %xmm0, %xmm1
> xorps %xmm0, %xmm0
> sqrtss %xmm1, %xmm0
> ucomiss %xmm0, %xmm0
> jnp .LBB0_2
> movaps %xmm1, %xmm0
> callq sqrtf
> .LBB0_2: # %.split
> movss .LCPI0_0(%rip), %xmm1
> divss %xmm0, %xmm1
> movaps %xmm1, %xmm0
> popq %rax
> retq
> .Ltmp1:
>
>
> march=broadwell, note use of VEX encoded instructions:
>
> $ clang -O3 -march=broadwell -S -o - rsqrt.c | showasm
> .LCPI0_0:
> rsqrtf: # @rsqrtf
> pushq %rax
> .Ltmp0:
> vmovaps %xmm0, %xmm1
> vxorps %xmm0, %xmm0, %xmm0
> vsqrtss %xmm1, %xmm0, %xmm0
> vucomiss %xmm0, %xmm0
> jnp .LBB0_2
> vmovaps %xmm1, %xmm0
> callq sqrtf
> .LBB0_2: # %.split
> vmovss .LCPI0_0(%rip), %xmm1
> vdivss %xmm0, %xmm1, %xmm0
> popq %rax
> retq
> .Ltmp1:
>
>
> Host CPU details:
>
> $ cat /proc/cpuinfo
> processor : 0
> vendor_id : GenuineIntel
> cpu family : 6
> model : 61
> model name : Intel(R) Core(TM) i7-5600U CPU @ 2.60GHz
> stepping : 4
> microcode : 0x1a
> cpu MHz : 2600.000
> cache size : 4096 KB
> physical id : 0
> siblings : 4
> core id : 0
> cpu cores : 2
> apicid : 0
> initial apicid : 0
> fpu : yes
> fpu_exception : yes
> cpuid level : 20
> 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 c
> onstant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc
> aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est
> tm2 ssse3 fma cx16 xtpr pdcm p
> cid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx
> f16c rdrand lahf_lm abm 3dnowprefetch ida arat epb pln pts dtherm
> tpr_shadow vnmi flexpriority ep
> t vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm
> rdseed adx smap xsaveopt
> bugs :
> bogomips : 5187.73
> clflush size : 64
> cache_alignment : 64
> address sizes : 39 bits physical, 48 bits virtual
> power management:
> [...]
>
> $ ./cpuid -c 0 -d
> CPU 0:
> CPUID 00000000:00 = 00000014 756e6547 6c65746e 49656e69 | ....GenuntelineI
> CPUID 00000001:00 = 000306d4 00100800 7ffafbff bfebfbff | ................
> CPUID 00000002:00 = 76036301 00f0b5ff 00000000 00c30000 | .c.v............
> CPUID 00000003:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000004:00 = 1c004121 01c0003f 0000003f 00000000 | !A..?...?.......
> CPUID 00000004:01 = 1c004122 01c0003f 0000003f 00000000 | "A..?...?.......
> CPUID 00000004:02 = 1c004143 01c0003f 000001ff 00000000 | CA..?...........
> CPUID 00000004:03 = 1c03c163 03c0003f 00000fff 00000006 | c...?...........
> CPUID 00000004:04 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000005:00 = 00000040 00000040 00000003 11142120 | @... at ....... !..
> CPUID 00000006:00 = 00000077 00000002 00000009 00000000 | w...............
> CPUID 00000007:00 = 00000000 021c2fbb 00000000 00000000 | ...../..........
> CPUID 00000008:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000009:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 0000000a:00 = 07300403 00000000 00000000 00000603 | ..0.............
> CPUID 0000000b:00 = 00000001 00000002 00000100 00000000 | ................
> CPUID 0000000b:01 = 00000004 00000004 00000201 00000000 | ................
> CPUID 0000000b:02 = 00000000 00000000 00000002 00000000 | ................
> CPUID 0000000c:00 = 00000000 00000001 00000001 00000000 | ................
> CPUID 0000000d:00 = 00000007 00000340 00000340 00000000 | .... at ...@.......
> CPUID 0000000d:01 = 00000001 00000000 00000000 00000000 | ................
> CPUID 0000000d:02 = 00000100 00000240 00000000 00000000 | .... at ...........
> CPUID 0000000e:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 0000000f:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000010:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000011:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000012:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000013:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 00000014:00 = 00000000 00000001 00000001 00000000 | ................
> CPUID 80000000:00 = 80000008 00000000 00000000 00000000 | ................
> CPUID 80000001:00 = 00000000 00000000 00000121 2c100800 | ........!......,
> CPUID 80000002:00 = 65746e49 2952286c 726f4320 4d542865 | Intel(R) Core(TM
> CPUID 80000003:00 = 37692029 3036352d 43205530 40205550 | ) i7-5600U CPU @
> CPUID 80000004:00 = 362e3220 7a484730 00000000 00000000 | 2.60GHz........
> CPUID 80000005:00 = 00000000 00000000 00000000 00000000 | ................
> CPUID 80000006:00 = 00000000 00000000 01006040 00000000 | ........@`......
> CPUID 80000007:00 = 00000000 00000000 00000000 00000100 | ................
> CPUID 80000008:00 = 00003027 00000000 00000000 00000000 | '0..............
>
> Ideas?
>
> - Steven
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>
--
~Craig
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