Re: CURRENT: build failure with clang 3.7.0

On Wednesday, October 07, 2015 09:09:50 PM O. Hartmann wrote:
> Am Wed, 07 Oct 2015 11:03 -0700
> John Baldwin <jhb_at_freebsd.org> schrieb:
> 
> > On Wednesday, October 07, 2015 01:33:23 PM O. Hartmann wrote:
> > > On Wed, 7 Oct 2015 13:23:48 +0200
> > > Dimitry Andric <dim_at_FreeBSD.org> wrote:
> > > 
> > > > On 07 Oct 2015, at 09:37, O. Hartmann <ohartman_at_zedat.fu-berlin.de> wrote:
> > > > > 
> > > > > I hit on a box this nasty/sticky error when performing buildworld.
> > > > > 
> > > > > /usr/src is on r288980
> > > > ...
> > > > > --- ieee802_11_common.o ---
> > > > ...
> > > > > -c /usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/common/ieee802_11_common.c
> > > > > -o ieee802_11_common.o Cannot emit physreg copy instruction UNREACHABLE
> > > > > executed
> > > > > at /usr/src/lib/clang/libllvmx86codegen/../../../contrib/llvm/lib/Target/X86/X86InstrInfo.cpp:3935!
> > > > 
> > > > Somebody else reported the same to me yesterday.  This is an upstream
> > > > bug with AVX (which is still present in llvm trunk), so for now you need
> > > > to set your CPUTYPE to something that doesn't have AVX, or simply unset
> > > > your CPUTYPE.
> > > > 
> > > > The bug has been reported upstream, and once there is a fix, I will
> > > > import it ASAP.
> > > > 
> > > > -Dimitry
> > > > 
> > > 
> > > Funny, I have several other boxes, definitely having AVX aboard:
> > > 
> > > [... from dmesg]
> > > Jul 29 07:05:52 freyja kernel: CPU: Intel(R) Xeon(R) CPU E5-1650 v3 _at_ 3.50GHz
> > > (3491.98-MHz K8-class CPU)
> > > Jul 29 07:05:52 freyja kernel: Origin="GenuineIntel"  Id=0x306f2  Family=0x6
> > > Model=0x3f  Stepping=2
> > > Jul 29 07:05:52 freyja kernel:
> > > Features=0xbfebfbff<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,HTT,TM,PBE>
> > > Jul 29 07:05:52 freyja kernel:
> > > Features2=0x7dfefbff<SSE3,PCLMULQDQ,DTES64,MON,DS_CPL,VMX,SMX,EST,TM2,SSSE3,SDBG,FMA,CX16,xTPR,PDCM,PCID,DCA,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,TSCDLT,XSAVE,OSXSAVE,AVX,F16C,RDRAND>
> > > Jul 29 07:05:52 freyja kernel: AMD
> > > Features=0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM>
> > > Jul 29 07:05:52 freyja kernel: AMD Features2=0x21<LAHF,ABM>
> > > Jul 29 07:05:52 freyja kernel: Structured Extended
> > > Features=0x37ab<FSGSBASE,TSCADJ,BMI1,AVX2,SMEP,BMI2,ERMS,INVPCID,PQM,NFPUSG>
> > > 
> > > [...]
> > > 
> > > which is a most recent Haswell XEON and builds world fine. My personal failing
> > > box is a i3-32XX, IvyBridge, but the IvyBridge E3-124XX XEON builds well.
> > 
> > It's not about whether your CPU supports it, it is about whether or not you have
> > asked the compiler to use it.  Normally by setting 'CPUTYPE' in /etc/make.conf
> > or the like.  (I also was bitten by this yesterday on my sandbridge laptop
> > where I have 'CPUTYPE=corei7-avx' in /etc/src.conf.)  The workaround is to not
> > set CPUTYPE (or set it to something without AVX like just 'corei7').
> > 
> 
> Hello.
> 
> Well, I guess I understood the usage of CPUTYPE. Maybe I did not express myself in the
> clear, but I wanted to emphasize the fact that I'm using two CPUs supposedly of the same
> architectural design and if the AVX feature is indeed the culprit, then the question is
> why the one CPU compiles and the other not. I use on all machines the very same src.conf
> and make.conf except for the kernel name. So this would imply that on all boxes the very
> same feature set, identified by the CPU type, would be used. So far the theory.
> 
> I did not check the expansion of CPUTYPE on both systems failing the buildworld, so maybe
> there is a slight difference there ...

Are you using CPUTYPE=native?  If so, the Haswell box might very well follow a
different chain of optimizations that avoids this edge case.

-- 
John Baldwin