similar to: [LLVMdev] Missed optimization opportunity

On Dec 28, 2010, at 9:39 AM, Lup Gratian wrote: > I recently downloaded LLVM 2.8 and started playing with the optimizations a bit. > I saw something curious while trying the following function: > > int g(unsigned int a) { > unsigned int c[100]; > c[10] = a; > c[11] = a; > unsigned int b = c[10] + c[11]; > > if(b > a*2) a = 4; > else a = 8; >

On Dec 28, 2010, at 12:48 PM, Chris Lattner wrote: > On Dec 28, 2010, at 9:39 AM, Lup Gratian wrote: >> I find it strange that it hasn't found that %add and %mul have the same value, %cmp would be then false, selecting and returning 15. If 'a' is replaced by a constant it works. > > You're right, that is a missed optimization. I added it to the missed optimization

Hi! I'm a student who would like to participate on Google SOC for LLVM, and was thinking about what project to pick. I saw on the "Open projects" page that Value Range Propagation is not implemented and thought about doing it, based on a paper by Patterson (it's also used by GCC). But then I saw that last year someone did a Range Analysis pass that seems to do pretty much the

Hi, Gratian, I did that Summer of Code. I used a different algorithm than Patterson's. It is a constraint system by Su and Wagner, which is more modern, and has some advantages over older works. In particular, it is non-iterative. I found it very hard to compare it with Patterson's analysis, because there is not much description in that paper. However, there is another paper, by

Does someone know the rules by which 'coxph' returns 'frail', the predicted frailty terms? In my test function: ----------------------------------------------- fr <- function(){ #testing(frailty terms in 'survival' require(survival) dat <- data.frame(exit = 1:6, event = rep(1, 6), x = rep(c(0, 1), 3),

While looking at what llvm writes for this testcase, I noticed that there is one redundant operation in resulting assembly. The second 'cmp' operation there is essentially identical to the first one, with reversed order of arguments. Therefore, it is not needed. This testcase is a simple integer comparison routine, similar to what qsort would take to sort an integer array. I think

Hi, I have a server and ten clients in a Gigabit network. The server has 125mbps network bandwidth. I want that the server has 40Mbps bandwidth reserved for client 1 (IP 192.168.5.141), and the rest bandwidth is for all other clients. My script looks like this (I use IFB for incoming traffic): #!/bin/bash export TC="/sbin/tc" $TC qdisc add dev ifb0 root handle 1: htb default 30

Hi David/Renato, By AST I mean Abstract Syntax Tree. We are writing an optimization pass for some FORTRAN95 + MPI code that requires us to analyze the AST. We thought of 2 ways of doing this: 1. Compile the code using Clang/llvm-gfortran, get the textual AST dump (somehow), analyze the AST dump using Ruby, modify it and then feed back the modified AST to LLVM. 2. Do the analysis as an LLVM

2009/11/3 David Greene <dag at cray.com>: > Your best bet is to use llvm-gfortran.  I don't know what you mean by > "AST."  Do you really want an AST or something else (LLVM IR, something > higher-level, etc.)?  LLVM doesn't understand ASTs directly. Probably for high-level optimisations, or just to see if the parser is good, as I do in my compiler. But AST is

I have taken over some old Rails code and am trying to get the tests to run. In the functional test every time the assertion ''assert_redirected_to'' is called I get the following error: test_should_update_venue(VenuesControllerTest): NoMethodError: undefined method `[]'' for #<Enumerable::Enumerator:0x102f747e0>

Hello, After commit r114523, I start to get crash when compiling with clang (Release+Asserts) for i386: (I know I should fill a bug report instead of posting here, but I don't get much time right now). Trying to compile the following simple code, clang asserts. ---------- round.c -------- #include <math.h> float test() { return llround(1); } -------------------- [MacPro:~/Desktop]

llvm-generated code that runs fine on linux/i386 causes EXC_BAD_ACCESS with misaligned_stack_error_ on MacOS/i386. I read online that each function should have stack aligned by 16 on MacOS/i386 and such code should be used: Fn->addAttribute(~0U, llvm::Attribute::constructStackAlignmentFromInt(16)); But when I run clang on some C++ code I don't see alignstack instructions generated at

Hello > What is the right way for fix this misaligned_stack_error? Codegen stuff for darwin, there are many other differences in Linux/Darwin ABIs. -- With best regards, Anton Korobeynikov Faculty of Mathematics and Mechanics, Saint Petersburg State University

Thanks! I also found test/CodeGen/ARM/ghc-tcreturn-lowered.ll, which tests only for thumbv7-eabi, so, i tried a few more variations: [x] arm64-apple-ios [x] arm64-apple-ios7.0.0 [x] arm64-apple-darwin [x] armv7-apple [x] thumbv7-apple [x] thumbv7-apple-darwin [x] i386-apple-ios [x] i386-apple-darwin [f] thumbv7-apple-ios [f] thumbv7-apple-ios7.0.0 [f] armv7-apple-ios I’ve also just build a

I will take a look in the next couple hours. Feel free to revert it in the meantime, thanks! -Chris On Sep 22, 2010, at 1:53 AM, Jean-Daniel Dupas <devlists at shadowlab.org> wrote: > Hello, > > After commit r114523, I start to get crash when compiling with clang (Release+Asserts) for i386: > (I know I should fill a bug report instead of posting here, but I don't get

Hey Scott, On Wed, Apr 24, 2013 at 1:40 PM, Scott Pakin <pakin at lanl.gov> wrote: ... > > Is there some semantic reason that the increments aren't allowed to be > combined, or is this a missed optimization opportunity in LLVM? > > I believe that the wildcard is the extern keyword. Since the external symbol isn't resolved until link time, I suspect that it would be

On 4/24/2013 1:35 PM, Cameron McInally wrote: > > I believe that the wildcard is the extern keyword. > > Since the external symbol isn't resolved until link time, I suspect that > it would be a legal C program to do something like (maybe the language > lawyers know better though): > > XXX> cat test.c > extern int x; > > int kung( ) { > return x; > }

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] > On Behalf Of Scott Pakin > Subject: [LLVMdev] Another missed optimization opportunity? > I'm doing the equivalent of "myarray[5]++" (on an > "extern int *myarray"), repeated three times: > I had expected the three increments by 1 to > be collapsed into a single increment

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] > On Behalf Of Scott Pakin > Subject: Re: [LLVMdev] Another missed optimization opportunity? > > Is this a potential aliasing effect? Since myarray is defined as a > > pointer, not an array, it's theoretically possible that the address > > therein refers to the same memory location as

On 04/24/2013 01:29 PM, Caldarale, Charles R wrote: > Is this a potential aliasing effect? Since myarray is defined as a pointer, not an array, it's theoretically possible that the address therein refers to the same memory location as the pointer itself. I was thinking along those lines, but I haven't been able to come up with a specific instance of what could possibly be aliased.