similar to: [LLVMdev] New automated decision procedure for path-sensitive analysis

On 4/9/07, Domagoj Babic <babic.domagoj at gmail.com> wrote: > > > Traditionally, such analyses have been considered too expensive to be > practical, and were mostly an academic curiosity. The core of the > problem is the lack of adequate automated decision procedures which > could quickly determine whether a set of constraints is satisfiable or > not, and if it is

Hi Zhongxing, On 4/8/07, Zhongxing Xu <xuzhongxing at gmail.com> wrote: > I think the real difficult thing in path sensitive program analysis (or > symbolic execution) is not the lack of decision procedures, but the > translation of arbitrary pointer operations and library function calls in > C/C++ program into the mathematics supported by the automated theorem > prover. >

> > Spear takes a different approach - it is bit-precise, handles all > operators, but > currently doesn't handle arrays directly. However, the other mentioned > thm provers > handle arrays by encoding them as UIFs + several axioms. As UIFs can be > encoded > to SAT, I think that the theory of arrays could be as well. So, with a > bit of effort, > you should be

IMO super optimizer would yield less benefits on LLVM compared to other compilers. If you check the patch of the instcombine pass, you'll find out people keep dragging "correct" optimization out, not because the optimization violates the semantic of LLVM IR, but it will generate wrong code sequences when lowering to machine code. An example: %3 = fcmp %1, %2 %6 = fcmp %4, %5 %7 =

Seung, On 8/25/07, Chris Lattner <sabre at nondot.org> wrote: > Ok. Note that LLVM can represent irreducible loops. You can handle > this through code duplication. > -Chris If you are willing to invest more effort into a more complicated analysis, in many cases you can even avoid code duplication. See this paper for details: @inproceedings{erosa94taming, author = {Ana M.

Hello all, thanks for the feedback! It sounds like you are planning to follow the approach of Joshi, Nelson and > Randall ("Denali: A Goal-directed Superoptimizer") in that you don't intend > to exhaustively enumerate all possible code sequences, and see if they are > the same as the original only better; but instead start from the original > code > sequence and

On 8/29/07, Domagoj Babic <babic.domagoj at gmail.com> wrote: > Seung, > > On 8/25/07, Chris Lattner <sabre at nondot.org> wrote: > > Ok. Note that LLVM can represent irreducible loops. You can handle > > this through code duplication. > > -Chris > > > If you are willing to invest more effort into a more complicated analysis, > in many cases you

Hi all, I spent several hours today trying to compile llvm-gcc4 from svn and llvm from cvs on amd64 linux. In the case anyone else decides to try the same, this could ease your pain: 1) check out llvm, llvm-gcc 2) create llvm-obj llvm-gcc-obj export LLVM_INSTAL=<install_dir> cd llvm-obj export LLVM_OBJ=`pwd` ../llvm/configure --prefix=$LLVM_INSTALL --enable-debug-runtime 4) At one point,

Daniel, On 8/30/07, Daniel Berlin <dberlin at dberlin.org> wrote: > On 8/29/07, Domagoj Babic <babic.domagoj at gmail.com> wrote: > > Seung, > > > > On 8/25/07, Chris Lattner <sabre at nondot.org> wrote: > > > Ok. Note that LLVM can represent irreducible loops. You can handle > > > this through code duplication. > > > -Chris >

On Sep 29, 2006, at 2:05 PM, Domagoj Babic wrote: > > Check out scc_* iterators. Also note that the call graph > is not aware of the indirect calls, so you will need to write your > own CG implementation if you need to handle function pointers > soundly. > Chris, is this true? If so, it seems like a bad property for the CallGraphSCCPass framework. --Vikram

Hi all, On 11/28/06, Reid Spencer <rspencer at reidspencer.com> wrote: > * Venue: West Coast, USA. Probably either San Francisco Bay Area or > Seattle > * Time Frame: Post 2.0 release, summer 2007 > * Topics: Anything related to use or development of LLVM I'd vote for Seattle. The costs of organization should be lower than in the Bay Area. > * An indication of how

On Oct 2, 2007, at 1:03 AM, Domagoj Babic wrote: > Hi all, > > I have the same problem. My guess is that when a structure > is passed as a parameter, you cast it into an array for optimization > reasons (less parameters, less stack space). This is not an optimization. This behavior is to be ABI complaint when emitting code for your OS. That said, this is not a very good way to

Hi, I'm trying to compile some apps with the new llvm-gcc4 on amd64 linux to .bc files, rather than to the native code. The same process I used to build those apps before with llvm-gcc3 doesn't work: 1) export CC=llvm-gcc CXX=llvm-g++ CFLAGS="-g -fno-inline" CXXFLAGS="-g -fno-inline" 2) cd <whatever-app>; ./configure 3) make CFLAGS+=-emit-llvm

Hi, Here's something I don't understand... How come that UNDEF can appear as a branch condition at all? I just can't think of any ways. If you write something like fun() { int x; if (x > 100) { ... } else { ... } } LLVM generates a boolean temporary that compares (uninitialized) value of x with 100. Second, if it already can appear, isn't that a bug that

Daniel Berlin wrote: > Nick Lewycky wrote: > >>I found that "undef" was disappearing early into the optimization chain. >>SCCP was the culprit, transforming: >> >> br bool undef, label %T, label %F >> >>into >> >> br bool true, label %T, label %F >> >>While that sounds like a great optimization, it shouldn't be

Unless I'm missing something, the problem lies directly with the fact that you are trying to do a link-stage operation with the GCC frontend. GCC, by default, probably runs "ld" or another system linker, which grabs the executable from binutils. This linker hasn't been modified (yet) to include support for .bc files, but you're compiler is emitting byte code to the *.o files.

Hi everybody! I recently started using llvm in a project on inferring additional information about pointers based on their types, casts, etc. The following simple example is giving me a headache :): typedef struct { int a; short b, c; int d, e, f; } foo; void bar(foo f) { short s; s = f.b; } int main(void) { foo p; bar(p); } Because llvm doesn't allow structures and arrays

LLVMers, The LLVM Oversight group is trying to assess whether there is sufficient interest in the LLVM development community for holding an LLVM Conference next summer. If getting together with your fellow LLVM Developers sounds interesting to you, please respond to me (off list) and I'll summarize the results. Here's our current thinking: * Venue: West Coast, USA. Probably either San

I have a FunctionPass F that needs a list of all the SCCs for use in its doFinalization() method. Let's say I write a CallGraphSCCPass C that creates an array of all SCCs. Let C be required by F, and let F call getAnalysis<C>() from its doFinalization() method. Am I guaranteed that C's runOnSCC() method will have executed on all SCCs before F's doFinalization() method?

Hi, I am brand new to LLVM, or more precisely, trying to be. I'm getting stuck on compiling LLVM. - I tried installing on a Mint 18.1 VM with 6GB RAM, and the builds of some large executables were killed by the OOM killer. I finally realized that I needed to build using shared libraries, and succeeded. This was in November. - I put aside my LLVM project, and just got back to it. I got stuck