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...>0)) a contruct like that that use __builtin_unreachable: int foo(int x, int y){ if(x>0 && y>0){ ...function codeblock... } { __builtin_unreachable (); } } I can get the optimization without really having a branch jump in the machine code?Thank you again, Niko Zarzani > Date: Mon, 22 Oct 2012 23:41:43 -0400 > From: xi.wang at gmail.com > To: koni10 at hotmail.it > CC: llvmdev at cs.uiuc.edu > Subject: Re: [LLVMdev] precondition suggestion to LLVM > > You may want to check this out: > > http://lists.cs.uiuc.edu/pipermail/llvmdev/2012...

On Mon, Oct 22, 2012 at 9:33 PM, Niko Zarzani <koni10 at hotmail.it> wrote: > Thank you, it was what I really was searching for :) > > However, I don't know if I well understood. I've find this link in the > second link which seemed what i was looking for: > http://nondot.org/sabre/LLVMNotes/BuiltinUnreachable.txt...

...(such as x>0) then it will be possible to better optimize the code given that information (which the compiler does not know).I am new in this field and I don't know if there are ways to tell the compiler preconditions (such as by using some preprocessing directives).Thank you in advance,Niko Zarzani -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20121023/257a2358/attachment.html>

You may want to check this out: http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-October/053924.html and also http://llvm.org/PR810 - xi On 10/22/12 6:05 PM, Niko Zarzani wrote: > Hi all, > Is there any way to tell LLVM some additional information about the > variables in the code in order to make better optimization? > For example, if my function has a certain precondition (such as x>0) > then it will be possible to better optimize the code give...

Hi Niko, Do you mean branch prediction, i.e. __builtin_expect [1]? Many compilers support it, I think clang (LLVM's C/C++ frontend) is among them. - D. [1] http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html 2012/10/23 Niko Zarzani <koni10 at hotmail.it>: > Hi all, > Is there any way to tell LLVM some additional information about the > variables in the code in order to make better optimization? > For example, if my function has a certain precondition (such as x>0) then it > will be possible to better o...

...passes -O3 test.c -o /dev/null > > Note that I believe you need asserts enabled or some other build > configuration for this to work, > the timing code is disabled in fully release builds IIRC. > > Hope this helps! > > ~Will> > On Thu, Sep 12, 2013 at 11:50 AM, Niko Zarzani <koni10 at hotmail.it> wrote: > > Hi all, > > > > I was interested in knowing which of the passes spends the most of the time > > compiling the dns server BIND. > > With the -CC option I selected clang as my compiler and, as I was expecting, > > the compila...

Hi all, I wrote 2 passes and I want to make run llvm run the passes in this order: -mem2reg -load=…/mypass1.dylib -mypass1 -load=…/mypass2.dylib -mypass2 -O1 -O2 -O3 I know I can do this by manually passing them as an argument to opt. Is there any way to force this sequence directly from clang? I am asking this because I am trying to compile a program and I can specify in the ./configure

On Oct 5, 2013, at 9:17 PM, Niko Zarzani <koni10 at hotmail.it> wrote: > Hi all, > > I wrote 2 passes and I want to make run llvm run the passes in this order: > -mem2reg -load=…/mypass1.dylib -mypass1 -load=…/mypass2.dylib -mypass2 -O1 -O2 -O3 > > I know I can do this by manually passing them as an argument to...

This compiler does not have mem-SSA, as far as I know, only few pass can propagate value along memory. You need to promote those local variable into register first before sccp is invoked. e.g1. opt a.ll -basicaa -gvn -sccp -S eg.2. opt a.ll -sroa -sccp -S On 4/16/13 12:37 PM, Niko Zarzani wrote: > Hi all, > > I am trying to see how single llvm optimizations work by running them > one by one with opt and looking how the IR changes. > Since I was interested in seeing how constant propagation was working > I tried to run opt on the Sparse Conditional Constant Propag...

...em with "-mllvm": clang -mllvm -time-passes -O3 test.c -o /dev/null Note that I believe you need asserts enabled or some other build configuration for this to work, the timing code is disabled in fully release builds IIRC. Hope this helps! ~Will On Thu, Sep 12, 2013 at 11:50 AM, Niko Zarzani <koni10 at hotmail.it> wrote: > Hi all, > > I was interested in knowing which of the passes spends the most of the time > compiling the dns server BIND. > With the -CC option I selected clang as my compiler and, as I was expecting, > the compilation gave me no problems. >...

Hi all, I was interested in knowing which of the passes spends the most of the time compiling the dns server BIND.With the -CC option I selected clang as my compiler and, as I was expecting, the compilation gave me no problems.Now I have a question, is there any way to set an option similiar to "-time-passes" to clang in order to get those information I was interested in?Or do you think

Hi all, I am trying to see how single llvm optimizations work by running them one by one with opt and looking how the IR changes.Since I was interested in seeing how constant propagation was working I tried to run opt on the Sparse Conditional Constant Propagation, however by passing as argument -S -sccp -die it does not change anything in the output IR code. I attached the file with the source

On Mon, Feb 11, 2013 at 1:32 PM, Niko Zarzani <koni10 at hotmail.it> wrote: > Hi, I am trying to write a Pass that reads metadata passed as a argument to > a function. > > I have written them by hand in the .s file in the same way of the IR > reference (http://llvm.org/docs/LangRef.html#named-metadata) : > > define i...

That's metadata for arguments to calling a function, you tried to attach metadata to the arguments of a declaration of a function. On 11 February 2013 22:58, Niko Zarzani <koni10 at hotmail.it> wrote: > > > I have written them by hand in the .s file in the same way of the IR > > > reference (http://llvm.org/docs/LangRef.html#named-metadata) : > > > > > > define i32 @function(i32 %argInt, metadata !3) nounwind { > > &...

Hi, I am new with the llvm infrastructure and I am trying to write a Pass that prints the mapping between IR variable names and the names of the variables in the source code.As I can see from the generated IR .s files of simple programs variables preserve the same name. If it is not always the case that names are preserved, there is a way during the execution of a Pass to access a table with the

Why in the webpage http://llvm.org/docs/Passes.html some of the passes such as "correlated value propagation" or "early cse" are not described? Am I missing some other webpage with these informations? Thank you in advance, Niko -------------- next part -------------- An HTML attachment was scrubbed... URL:

Hi, I am interested in developing some passes using the Xcode IDE. I create a pass directory with a simple pass in it, add it to the lib/Trasform/ directory, changed and added some CMakeList.txt files and compiled using cmake (cmake -G Xcode). The compilation gives me no errors but then I've found that I have not a Debug+Asserts folder and opt has no option related to my pass...what can I do

Hi, I am trying to write a Pass that reads metadata passed as a argument to a function. I have written them by hand in the .s file in the same way of the IR reference (http://llvm.org/docs/LangRef.html#named-metadata) : define i32 @function(i32 %argInt, metadata !3) nounwind {entry: %argInt.addr = alloca i32, align 4 store i32 %argInt, i32* %argInt.addr, align 4 %1 = load i32* %argInt.addr,

> > I have written them by hand in the .s file in the same way of the IR > > reference (http://llvm.org/docs/LangRef.html#named-metadata) : > > > > define i32 @function(i32 %argInt, metadata !3) nounwind { > > This seems wrong. "metadata" is a type (like i32), and the exclamation > mark is only used to refer to metadata nodes, not to declare functions

Since variables in the source code are renamed in the IR, I wanted to ask you how and where this mapping is done in Clang.I am interested in converting the variable names in some C strings to the one in the IR.For example if at a certain point of the program I have a string like "x>0" I want to change it in "%x>0" (I already implemented a parser to recognize the