similar to: [LLVMdev] -mcpu=help doesn't seem to work?

On Feb 15, 2010, at 4:20 PM, Russell Wallace wrote: > llc -mcpu=help doesn't print any output, just tries to silently read > from standard input. Am I doing something wrong? Annoyingly enough, you have to give it a bc file as input as well.

Hi Anitha, Thanks for your answer but -mcpu=cortex-a9 -mattr=+vfp4 doesn' t enable fused mac generation for me. I would like just to understand why -mtriple=armv7-eabi enables it while -mcpu=cortex-a9 seems to disable it ? Seb > -----Original Message----- > From: Anitha Boyapati [mailto:anitha.boyapati at gmail.com] > Sent: Thursday, November 08, 2012 10:22 AM > To: Sebastien

Hi Bastien, Weird gcc is generating fma for my platform STEricsson Novathor with Linaro, code works. It also works when I use LLVM to generate fma (using llc -mtriple=armv7-eabi). Maybe someone from ARM can answer the question ? Seb From: JF Bastien [mailto:jfb at google.com] Sent: Friday, November 09, 2012 5:36 PM To: Sebastien DELDON-GNB Cc: Anitha Boyapati; llvmdev at cs.uiuc.edu Subject:

Hi all, I've a .ll code that use double precision fmul/fadd or fmul/fsub. When I compile it using llc -mcpu=cortex-a9 I couldn't get vmla/vmls generated even using -fp-contract=fast, but when I use option -mtriple=armv7-eabi instead of -mcpu=cortex-a9 fused mac are generated. Can someone explain me why ? Thanks for your answers Seb -------------- next part -------------- An HTML

Hi Renato, It's definitively not A15. Can this be the case that NEON units for cortex-A9 support it but isn't documented/recommended ? And as mentioned before code is working ! Seb > -----Original Message----- > From: rengolin at gmail.com [mailto:rengolin at gmail.com] On Behalf Of > Renato Golin > Sent: Friday, November 09, 2012 6:27 PM > To: Sebastien DELDON-GNB >

Thanks Martin, I'm generating the code using LLVM (writing llvm::Triple myself and llvm::TargetRegistry::lookupTarget is working), and that's how my bitcode is generated then using LLC to cross-compile that. So using armv7-win32-msvc is getting me a bit closer, but what CPU, raspberry pi 3 is running a Cortext-A53, but when I specify that in -mcpu argument I get this error: > llc.exe

AFAIK A9 doesn't have VFPv4 or AdvSIMDv2, so it doesn't have VFMA. I don't know what LLVM does, but it shouldn't emit VFMA when you target A9. VMLA isn't a fused multiply-add, it's a multiply followed by an add and has different latency as well as precision. On Thu, Nov 8, 2012 at 4:57 AM, Sebastien DELDON-GNB < sebastien.deldon at st.com> wrote: > Hi Anitha,

Hi Sebastien, ARMv7-M has VFMA and LLVM's "triple" is far from perfect. Wikipedia tells me NovaThor can also be A15, or STE could have cramped a VFPv4 in it? ;) Or possibly, your code never branches into the VFMA. Many things could be happening, but usually, VFMA shouldn't be generated for A9. A GCC bug, maybe? On 9 November 2012 16:51, Sebastien DELDON-GNB

cat /proc/cpuinfo ? Are you sure it's generating VFMA and not VMLA? On Fri, Nov 9, 2012 at 9:35 AM, Sebastien DELDON-GNB < sebastien.deldon at st.com> wrote: > Hi Renato, > > It's definitively not A15. Can this be the case that NEON units for > cortex-A9 support it but isn't documented/recommended ? > And as mentioned before code is working ! > > Seb >

On 8 November 2012 13:56, Sebastien DELDON-GNB <sebastien.deldon at st.com> wrote: > Hi all, > > > > > > I’ve a .ll code that use double precision fmul/fadd or fmul/fsub. When I > compile it using llc –mcpu=cortex-a9 I couldn’t get vmla/vmls generated even > using –fp-contract=fast, but when I use option –mtriple=armv7-eabi instead > of –mcpu=cortex-a9 fused mac

Is there a way to use LLC to cross-compile some code to run on Windows IOT on Raspberry Pi ? I was able to convince LLVM to spit out some bitcode for this, but when I try llc it dumps: llc.exe test.bc -o test.obj -filetype=obj -O3 -mtriple=aarch64-win32-msvc -mcpu=cortex-a53 Wrote crash dump file "C:\Users\clovett\AppData\Local\Temp\llc.exe-4990d8.dmp" 0x0000000000000000

Thanks for everyone giving their feedback! I saw pretty unanimous support for making -mcpu=generic the default and making -mcpu=generic schedule for an in-order CPU (Cortex-A8 in this case). I'll be making those changes shortly. I think the comments also make clear that it's less obvious whether we'd want -mcpu=native to become a default. It's probably good for some use cases, but

Motivation At the moment, when targeting armv7a, clang defaults to generate code as if -mcpu=cortex-a8 was specified. When targeting armv8a, it defaults to generate code as if -mcpu=cortex-a53 was specified. This leads to surprising code generation, by the compiler optimizing for a specific micro-architecture, whereas the intent from the user was probably to generate code that is

Hi Renato, You're right it's VMLA/VMLS that are generated. Still don't understand what drives generation for Cortex-A9. I was using fmac for floating point MAC not for fused MAC. Than I realized that we spoke about fma instead of fmac. So back to the original problem why when using -mcpu=cortex-a9 VMLA/VMLS are not generated and when I use -mtriple=armv7-eabi they are ? Best

Hi All, For quite some time there's been a side project for developing an AVR back end for LLVM: http://sourceforge.net/projects/avr-llvm/ What is required from us to be able to add this work to the LLVM repo? And when do you think would be a good time for us to do that? If this is located somewhere in the docs and I've missed it, pointers would certainly be appreciated. Thanks, Eric

That's right. In your example, if the target isn't specified anywhere, an llc invocation would be equivalent to "llc -mtriple=x86_64-unknown-linux-gnu -mcpu=generic". TTI queries (in e.g., CodeGenPrepare) would be based on this. From opt, if the target triple is left unspecified, we will use the "base" TTI implementation (not x86). -- Matt On Wed, Nov 30, 2016 at 2:07

Yeah, this makes a lot of sense, -mcpu=generic (as opposed to -mcpu=native) is the sane default. I guess I was just expecting an x86 host to get a "generic x86 TTI" (whatever that means), not a "generic TTI". On Wed, Nov 30, 2016 at 11:49 AM, Matthew Simpson <mssimpso at codeaurora.org> wrote: > That's right. In your example, if the target isn't specified

On Fri, Mar 18, 2016 at 12:49 PM, Eric Christopher <echristo at gmail.com> wrote: > > > On Wed, Mar 16, 2016 at 2:53 PM Rail Shafigulin via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > >> I'm confused about the clang --target, -mcpu, -march >> >> Can someone give a clear explanation on what is the difference between >> them? >>

I'm confused about the clang --target, -mcpu, -march Can someone give a clear explanation on what is the difference between them? Originally I thought need to specify -mcpu (which I assume means CPU) and -march but then I can't figure out how --target fits into the picture. Sometimes it tells me that -march or -mcpu options is not used. I would really appreciate any help on this. --

Nadav, Please forgive my ignorance, but 'opt -mcpu=corei7 -loop-vectorize -S -debug double.ll' doesn't appear to make a difference. In fact it seems to be ignored as garbage values for -mcpu don't raise an error. Am I overlooking something else also? Many Thanks, Josh On Thu, May 9, 2013 at 6:06 PM, Nadav Rotem <nrotem at apple.com> wrote: > Hi Josh, > > Your