similar to: [LLVMdev] Proposal for ""llvm.mem.vectorize.safelen"

----- Original Message ----- > From: "Roel Jordans" <r.jordans at tue.nl> > To: llvmdev at cs.uiuc.edu > Sent: Wednesday, August 13, 2014 5:57:15 AM > Subject: Re: [LLVMdev] Proposal for ""llvm.mem.vectorize.safelen" > > > > > WHY CURRENT METADATA DOES NOT SUFFICE > > ------------------------------------- > > > > There

> Sorry for coming to the discussion so late. I have a couple of questions/comments: Actually, you're note is timely, because I'm planning to send out a patch (as soon as I update LangRef and rerun tests) that supports safelen but *not* lexical dependences. I don't need the safelen for Julia, but having done the work and seeing that OpenMP needs it, feel that I should finish the

It's a problem in the OpenMP specification. The authors (including some from Intel) intended that the OpenMP simd construct assert no lexically backward dependences exist, but as you say, it's not obvious from the spec. One of our OpenMP community members is going to bring up the ambiguity with the OpenMP committee. - Arch -----Original Message----- From: Humphreys, Jonathan

> I recommend that you send patches for an implementation > (including the Loop::GetAnnotatedVectorSafelen function > and associated updates to the vectorizer) for review. I expect to send the patches for review later this week. > Make sure to remember LangRef updates! Thanks for the reminder. > Also, looking at the original proposal again, I see no reason > to restrict

More precisely, for a simd loop, if the safelen(VL) clause is specified, there should have no loop-carried lexical backward data dependency within the specified safe vector length VL. We will make this clear in the OpenMP 4.1 spec. Xinmin Tian (Intel) -----Original Message----- From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Hal Finkel Sent:

Here's an attempt to nail down the annotation semantics with support for respecting forward lexical dependences. Each load, store, call, or invoke instruction can be labeled with !llvm.mem.vector_loop_access, which has two operands: * The first operand is an integer denoting lexical position. The positions need not be consecutive, and may contain duplicates. * The second operand is the

----- Original Message ----- > From: "Renato Golin" <renato.golin at linaro.org> > To: "Hal Finkel" <hfinkel at anl.gov> > Cc: "Arnold Schwaighofer" <aschwaighofer at apple.com>, "Arch Robison" <arch.robison at intel.com>, "LLVM Dev" > <llvmdev at cs.uiuc.edu> > Sent: Wednesday, August 20, 2014 2:21:08

On 12 August 2014 18:49, Johannes Doerfert <doerfert at cs.uni-saarland.de> wrote: > I recently submitted a patch to the list [1] which would allow Polly to > extract the dependency distance for each analyzable loop. While the > distance is often not constant but parametric we would also need to > version the vectorized loop based on the actual runtime values. Since this is a

On 08/20, Arnold Schwaighofer wrote: > > > On Aug 20, 2014, at 8:08 AM, Robison, Arch <arch.robison at intel.com> wrote: > > > >> I recommend that you send patches for an implementation > >> (including the Loop::GetAnnotatedVectorSafelen function > >> and associated updates to the vectorizer) for review. > > > > I expect to send the

Yes, I think the 2 outcomes are: - the current spec is unclear and will be clarified - in order to support safelen() and even the simd construct itself, LLVM will require infrastructure work to know when a lexically backwards dependence may have been introduced. Jon -----Original Message----- From: Tian, Xinmin [mailto:xinmin.tian at intel.com] Sent: Monday, September 29, 2014 10:43 AM To:

On 28 September 2014 22:09, Hal Finkel <hfinkel at anl.gov> wrote: > Thanks Xinmin! > > So we'll need a method to ensure the correct (partial) ordering. I thought that the idea was to avoid computing loop dependencies when safelen is specified, at least at that level. We might do it to a greater length, but we should assume it to be safe for distances < VL. We still need

----- Original Message ----- > From: "Arnold Schwaighofer" <aschwaighofer at apple.com> > To: "Johannes Doerfert" <doerfert at cs.uni-saarland.de> > Cc: llvmdev at cs.uiuc.edu, "Arch Robison" <arch.robison at intel.com> > Sent: Wednesday, August 20, 2014 11:29:16 AM > Subject: Re: [LLVMdev] Proposal for

Hi all, Running LLVM 3.4 to create a custom pass for OpenCL transformations. I am attempting to GEP into a struct using IRBuilder's CreateStructGEP, but I keep getting this assert: aoc: ../../../../../../compiler/llvm/include/llvm/Instructions.h:703: llvm::Type* llvm::checkGEPType(llvm::Type*): Assertion `Ty && "Invalid GetElementPtrInst indices for type!"' failed.

cB->getType()->getPointerElementType()->dump(); gives: %struct.RB = type opaque2189 x_idx = builder.CreateStructGEP(cB, 0); cB->dump() gives: %struct.RB addrspace(1)* %cB $1 = void //To undo confusion, the last cB is the function arg name. For this example I unfortunately chose the same name for my argument Value* as the argument name. //Also one correction. I am running

If I do M.dump(), at the top of the output I have: %struct.RB = type opaque Further down I have: @.str18 = internal addrspace(2) constant [13 x i8] c"RB_t*\00" However nowhere does it dump the full struct type when I call "M.dump()". I have it explicitly defined above the kernel in the kernel file, but LLVM doesn't seem to pick it up. Opaque is a placeholder until it

Sure, it is the Rodinia 2.4 Hotspot benchmark OpenCL kernel (not my kernel), with the addition of my struct as the last argument in the kernel function. //------- kernel file start ------------------------------- #define BLOCK_SIZE 16 //dlowell's type #define BUFFER_LEN 0x100000 typedef struct RB{ unsigned int x; unsigned int y; int z[BUFFER_LEN]; unsigned int xx[BUFFER_LEN];

----- Original Message ----- > From: "Renato Golin" <renato.golin at linaro.org> > To: "Hal Finkel" <hfinkel at anl.gov> > Cc: "Arnold Schwaighofer" <aschwaighofer at apple.com>, "Arch Robison" <arch.robison at intel.com>, "LLVM Dev" > <llvmdev at cs.uiuc.edu> > Sent: Wednesday, August 20, 2014 2:16:56

Hi Johannes, Perfect, thanks! The CFG now looks very similar to what I got on LLVM 3.9.0 ([1] vs [2]). Any idea why setting -simplifycfg-sink-common=false is necessary? Similar to LLVM 5.0.1, the default for 3.9.0 is true [3], and setting it to false wasn't necessary in the latter version. [1] https://nautilus.bjornweb.nl/files/polly501-cfg-simplifycfg-sink-common.pdf [2]

Hi Tobi, Thanks for reviewing the proposal. I imagine that it may also affects your parallelization work in Polly. > > I am not sure if I am able to follow your reasoning. How could the -loop-vectorizer detect parallelism violations? I had the feeling that we introduce the llvm.loop meta-data for the case where we want to inform the loop vectorizer that it can assume the absence of

The ivdep pragma is designed to do exactly what the name states - ignore vector dependencies.  Cray Research first implemented this in 1978 in their CFT compiler, and has supported it since. This pragma is typically used by application developers who want vectorized code when the compiler cannot automatically determine safety; it is not equivalent to the OpenMP SIMD pragma in that the compiler is