similar to: [LLVMdev] X86 rsqrt instruction generated

On Wed, Nov 14, 2012 at 10:43 PM, Chakraborty, Soham <Soham.Chakraborty at amd.com> wrote: > Hi, > > > > We have implemented the rsqrt instruction generation for X86 target > architecture. We have introduced a flag -fp-rsqrt flag which controls the > generatation of X86 rsqrt instruction generation. > > We have observed minor effects on precision due to rsqrt and

Hi, Please find attached the modified patch and description. We have modified and retested the patch taking into consideration the comments and inputs provided earlier. Thanks & Regards, soham -----Original Message----- From: Eli Friedman [mailto:eli.friedman at gmail.com] Sent: Thursday, November 15, 2012 12:59 PM To: Chakraborty, Soham Cc: llvmdev at cs.uiuc.edu Subject: Re: [LLVMdev]

Hi, We have implemented the rcp instruction generation for X86 target architecture. We have introduced a flag -fp-rcp flag which controls the generatation of X86 rcp instruction generation. We have observed minor effects on precision and hence hve put these transformations under the mentioned flag. Note that -fp-rcp is only enabled with -enable-unsafe-fp-math flag presently. Moreover we have

What is the value of undef * 0 in LLVM? According to its definition in the LLVM IR reference; "The string ‘undef‘ can be used anywhere a constant is expected..." Am I correct to say that undef * 0 = 0 following this definition? Best Regards, soham

Hello I am facing a curious problem.I have a time series data with which i want to fit auto-regressive model of order p, where p runs from 1:9.I am using a for loop which will fit an AR(p) model for each value of p using the *ar.ols* function. I am using the following code for ( p in 1:9){ a=ar.ols (x=data.ts, order.max=p, demean=T, intercept=T) } Specifying the *order.max* to be p, it gives me a

Hi, Can anybody please suggest where to add architecture specific code generation flags(e.g. X86) in llvm? Thanks in advance. Best Regards, soham

Hi, > Both A and B are undef: > LHS = (undef & undef) | (undef & undef) = undef // Since ~undef = undef > RHS = undef > Thus transform is correct. LLVM documentation (http://llvm.org/docs/LangRef.html#undefined-values) suggests that it is unsafe to consider (a & undef = undef) and (a | undef = undef). "As such, it is unsafe to optimize or assume

Thanks for your answers. Another example of unsound transformation on Boolean algebra. According to the LLVM documentation (http://llvm.org/docs/LangRef.html#undefined-values) it is unsafe to consider ' a & undef = undef ' and ' a | undef = undef ' but 'undef xor undef = undef' is safe. Now, given an expression ((a & (~b)) | ((~a) & b)) where a and b are

Hi All, I'm tring to use RSQRT instructions on follow case for ARM (now what using is sqrt): 1.0 / sqrt(x) The RSQRT instructions(VRSQRTE/VRSQRTS) are vector type, but above operation is scalar type. So a transformation must be done(transform sqrt pattern to rsqrt). I have completed a patch for this, but I made the transformation in the backend which will leads to additional

I don't know of a way to do it from the command-line, but if you're willing to change the IR, you can add the optsize (for -Os) or minsize (for -Oz) IR attribute to the function you're compiling. On Fri, Sep 2, 2016 at 5:59 AM, Bruce Hoult via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Idle question, if anyone is reading still ... how do you get llc to do -Os > or

I'm getting this on LLVM trunk: SplitVectorResult #0: 0x27e6250: v8f32 = llvm.x86.avx.rsqrt.ps.256 0x2739310, 0x2739420 [ORD=16] [ID=0] LLVM ERROR: Do not know how to split the result of this operator! clang: error: linker command failed with exit code 1 (use -v to see invocation) Oddly, when I build the same code without -flto I don't see this issue. I see a similar bug was reported

All llvm-devs, We're going to introduce the new possible implementation for such optimizations as reciprocal estimation instead of fdiv. In short it's a replacement of fdiv instruction (which is very expensive in most of CPUs) with alternative sequence of instructions which is usually cheaper but has appropriate precision (see genReciprocalDiv in lib/Target/X86/X86InstrInfo.cpp for

In fact to commit the change before dealing with worst-case performance is a good idea because here we have 2 different issues. But the main idea of this RFC is an attempt to show the better approach to to these kinds of transformations and to suggest to use this approach in the future. At the same time, I'm trying to explain that this patch is not the performance one because the

It does, when the function has a body. When it doesn't, it ignores <https://godbolt.org/g/2BCvht>. The body might be provided later on in the toolchain via linking a library. Regards, Soham Sinha PhD Student, Department of Computer Science Boston University On Tue, Jun 26, 2018 at 10:25 AM Hans Wennborg <hans at chromium.org> wrote: > It works for me: > >

For the same reason GCC allowed the attribute. Even if I want to use/inline a function later on in the pipeline. Regards, Soham Sinha PhD Student, Department of Computer Science Boston University On Tue, Jun 26, 2018 at 8:30 AM mayuyu.io <admin at mayuyu.io> wrote: > Out of curiosity, how does an unused declaration affect the emitted object > file > > Zhang > > > 在

Hello, How can I inline a function mentioned in other file? I have an inline function *foo* in C source file (a.c) which is not referenced in this file. I compile this file to a.ll (I notice that the compiled a.ll doesn't have *foo*'s definition, probably because it was inlined but not called anywhere) I have another C source file b.c with function *bar*; I compile this to b.ll I link

clang doesn't seem to respect __attribute__((used)) in C functions. Even if I declare a function like the following: __attribute__((used)) void function(), then also it doesn't declare the function in its IR file if I don't use the function. Is there any other way to force the declaration of "unused" function declarations with clang. I have hacked in clang 6.0.0 in

Hi Soham, “extern inline” keyword will help in this case, with this keyword compiler is forced to keeps the definition of the function and make it available for the external usage. Also it retains the “inlinehint” attribute on the function, with that lto inliner may make it inline. Best, Ashutosh From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Mehdi AMINI via llvm-dev

Hi, How do I access the loop variables in a loop. for(i = 0; i < N; i++) for(j = 0; j < M; j++) A[i][j+k] = i + j; Is there anyway for me to know that in A[i][j+k], i & j are loop variables whereas k is not! Regards, Prasenjit Chakraborty Performance Modeling and Analysis IBM Systems & Technology Lab

How to compute the p-value of a statistic generally? -- View this message in context: http://r.789695.n4.nabble.com/p-value-tp2217867p2217867.html Sent from the R help mailing list archive at Nabble.com.