similar to: [LLVMdev] LLVM Value Tracking Analysis

On Sat, Mar 3, 2012 at 5:26 PM, Duncan Sands <baldrick at free.fr> wrote: > Hi Xin, > >> It seems to me that LLVM does not do too much on value range analysis. >>   i.e. what are the value constraints on a variable at a given point in >> the program. The closest thing i can find is the ValueTracking API, >> which can do some simple analysis on the value of a

Hi Xin, > It seems to me that LLVM does not do too much on value range analysis. > i.e. what are the value constraints on a variable at a given point in > the program. The closest thing i can find is the ValueTracking API, > which can do some simple analysis on the value of a variables. Am I > missing something/Is there a plan on the implementation of a more > powerful value

Hi, I've been thinking about a (potentially lazy) value tracking analysis that could be reused by several optimization passes. I don't know if it exists in llvm or not, but to my better knowledge it does not. ok there exists the ValueTracking class, but it does not provide a function like e.g. MayHaveTheValue(Value* v, APSInt x) to check if a given var v may ever have the value x My

----- Original Message ----- > From: "Mehdi Amini via cfe-dev" <cfe-dev at lists.llvm.org> > To: "Rafael Espíndola" <rafael.espindola at gmail.com> > Cc: "llvm-dev" <llvm-dev at lists.llvm.org>, "cfe-dev" <cfe-dev at lists.llvm.org> > Sent: Tuesday, March 8, 2016 11:40:47 AM > Subject: Re: [cfe-dev] [llvm-dev] llvm and

Does LLVM have loop multiversioning ? it seems it does not with clang++ -O3 -mllvm -debug-pass=Arguments program.c -c bash-4.1$ clang++ -O3 -mllvm -debug-pass=Arguments fast_algorithms.c -c clang-3.6: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated Pass Arguments: -datalayout -notti -basictti -x86tti -targetlibinfo -no-aa -tbaa -scoped-noalias

Hello, I wonder if llvm has pure range propagation pass. Is correlated value propagation that one? It seems that it is not directly deals with ranges. Maybe there any passes that simply contain some information about value ranges? Will symbolic value range propagation be done in some time? -------------- next part -------------- An HTML attachment was scrubbed... URL:

Thanks for the pointers. Looks like LazyValueInfo has the sort of infrastructure I had in mind. LVILatticeVal could be extended to floating point. (The comment "this can be made a lot more rich in the future" is an invitation :-). I'm thinking a simple lattice would address most cases of interest for floating-point checks. The lattice points for floating-point could be all

Hi, The range metadata can only be attached to LoadInst for now. I am considering extending its usage to IntrinsicInst so that the frontend can annotate the range of the return value of an intrinsic call. e.g., %a = call i32 @llvm.xxx(), !range !0 !0 = metadata !{ i32 0, i23 1024 } The motivation behind this extension is some optimizations we are working on for CUDA programs. Some special

Hello, As I can see, recently LLVM switched to using assume bundles to encode alignment information: https://reviews.llvm.org/rG78de7297abe2e8fa782682168989c70e3cb34a5c However, it seems that the ValueTracking cannot understand the new format. As an example, consider compilation of the following reproducer with clang-11 (old assume format) and clang-trunk (assume bundles): #include

Eh? How do you envision this? -eric On Tue, Jun 17, 2014 at 2:09 PM, Jingyue Wu <jingyue at google.com> wrote: > Hi Nick, > > That makes sense. I think a main issue here is that the ranges of these PTX > special registers (e.g., threadIdx.x) depend on -target-cpu which is only > visible to clang and llc. Would you mind we specify "target cpu" in the IR > similar

Some optimizations depend on whether alloca instruction always has non-zero value. Currently, this checking is done by isKnownNonZero() in ValueTracking, and it assumes alloca in address space 0 always has non-zero value but alloca in non-zero address spaces does not always have non-zero value. However, this assumption is incorrect for certain targets. For example, amdgcn---amdgiz target has

On 17 June 2014 06:41, Eli Bendersky <eliben at google.com> wrote: > On Tue, Jun 17, 2014 at 1:38 AM, Nick Lewycky <nicholas at mxc.ca> wrote: > >> Chandler Carruth wrote: >> >>> This seems fine to me, but I'd like to make sure it looks OK to Nick as >>> well. >>> >> >> I strongly prefer baking in knowledge about the

Chandler Carruth wrote: > This seems fine to me, but I'd like to make sure it looks OK to Nick as > well. I strongly prefer baking in knowledge about the intrinsics themselves into the passes if possible. Metadata will always be secondary. Separately, should value tracking look use range metadata when it's available? Absolutely. I think it should apply to all CallInst not just

Is there any particular reason that CaptureTracking.h isn't folded into ValueTracking.h? I was looking for the method to check whether a pointer would be captured and looked in ValueTracking.h, unaware that a new header had been created for that one method. Would anyone mind if I folded CaptureTracking into ValueTracking? Nick -------------- next part -------------- An HTML attachment was

Hal, Thanks for your suggestion. I think that makes sense. Currently, non-zero alloca address space is already represented by data layout, e.g., the last component of the data layout of amdgcn---amdgiz target is -A5, which means alloca is in address space 5. How about adding a letter z to -A5 to indicate alloca may have zero value? i.e. -A5 means alloca is in address space 5 and always has

> Checks against 1.0 are also common. Why not just add a FP range class, like our constant range, and go from there? That's certainly another way to go. My worry is that a more complicated lattice gets us deeper into rounding-mode issues and considerably more work for smaller gain. I like the idea of creating an FPRange class. We could start with a simple one and extend it as experience

On Tue, Jun 17, 2014 at 2:33 PM, Jingyue Wu <jingyue at google.com> wrote: > Hi Eric, > > In the IR, besides "target datalayout" and "target triple", we have a > special "target cpu" string which is set by the Clang front-end according to > its -target-cpu flag. We also write a Module::getTargetCPU() method to > retrieve this string from the

Hello, This simple patch fixes PR9112: Index: lib/Analysis/ValueTracking.cpp =================================================================== --- lib/Analysis/ValueTracking.cpp (revision 125281) +++ lib/Analysis/ValueTracking.cpp (working copy) @@ -593,6 +593,8 @@ // Otherwise take the unions of the known bit sets of the operands, // taking conservative care to avoid

Hi everyone, I posted some questions related to implementing inference of nsw/nuw flags based on known icmp results to Bug 30428 ( https://llvm.org/bugs/show_bug.cgi?id=30428 ) and it was recommended that I engage a wider audience by coming here. The minimal context is the following, please see the bug report for more detail: > 1. If (X s< Y), then both X + 1 and Y - 1 are nsw. > 2.

>> I realise that the DataTypes.h.in part might be controversial. Also, >> there's probably a better place to put it, but I'm not sure where. > > I didn't apply this part. What problems does it cause to not have > this? Can we fix uses of max and min? I get these errors in lib: .../lib/Analysis/ValueTracking.cpp:162: error: no matching function for call to