similar to: IndVarSimplify: getBackedgeTakenCount and Release vs Assert

This might be hard cases making bad law, but the loop: void f (unsigned short *x, int *l) { int c = *l; int i; for (i = 0; i < c; i++) if (x[i]) x[i]++; } is converted to decrement-and-branch form by LoopStrengthReduce while: void f (unsigned short *x, int *l) { int i; for (i = 0; i < *l; i++) if (x[i]) x[i]++; } isn't.

Hi Sanjoy, Thanks for investigating the issue! I am more interested in getting the underlying problem fixed rather than making this particular test case work. I think I have more test cases where this problem crops up. I would any day prefer consistent results over compile time savings which can lead to inconsistencies. These inconsistencies require significant developer time to analyze and fix

On Mar 13, 2011, at 2:01 PM, Arnaud Allard de Grandmaison wrote: > Hi all, > > The IndVarSimplify pass seems to be too aggressive when it enlarge the induction variable type ; this can pessimize the generated code when the new induction variable size is not natively supported by the target. This is probably not an issue for x86_64, which supports natively all types, but it is a real one

Hi, Here is the code in IndVarSimplify.cpp. SmallVector<WeakVH, 16> DeadInsts; while (!DeadInsts.empty()) if (Instruction *Inst = dyn_cast_or_null<Instruction>(&*DeadInsts.pop_back_val())) RecursivelyDeleteTriviallyDeadInstructions(Inst, TLI); Since DeadInsts.pop_back_val() is WeakVH which could hold a NULL pointer, the expression,

On Mar 13, 2011, at 2:01 PM, Arnaud Allard de Grandmaison wrote: > Hi all, > > The IndVarSimplify pass seems to be too aggressive when it enlarge the induction variable type ; this can pessimize the generated code when the new induction variable size is not natively supported by the target. This is probably not an issue for x86_64, which supports natively all types, but it is a real one

Hi all, The IndVarSimplify pass seems to be too aggressive when it enlarge the induction variable type ; this can pessimize the generated code when the new induction variable size is not natively supported by the target. This is probably not an issue for x86_64, which supports natively all types, but it is a real one for several embedded targets, with very few native types. I attached a patch to

> From: Eric Christopher > Subject: Re: [LLVMdev] How to associate extra comments to a > MachineInstruction ? > > Should be spelled like this yes? > > Asm->OutStreamer.AddComment("foo") > Asm->EmitFoo(); > > -eric That should work at the moment that you are emitting the instructions. But what would you do when you are manipulating a

Thanks Eli, After digging thru mail archives & bugzilla, it seems fixing properly this issue would require a major change in the selectionDAG code --- to have it operate on a per function basis instead of per basic-block. This however, does not seem to be the only issue. The following C code does not produce an efficicient assembly sequence either. extern void f(unsigned long long v); void

Ok I think we have some common ground - CSE should choose the aliased pointer over the non-aliased one because we don't want the no-aliasing information to creep outwards from the inlined callsite. I'll put together a patch in the coming days and add y'all as reviewers so you get visibility. Cheers, -Neil. On Wed, Jan 22, 2020 at 4:47 PM Jeroen Dobbelaere < Jeroen.Dobbelaere at

Hi, I am trying to make my tablegen files more flexible and for that I would like to have a name that in the end will be replaced with a type. If tablegen would support c preprocssing, I would do it like this: --- #define myBaseType i32 ... def imm32 : Operand<myBaseType>; def immZExt10 : ImmLeaf<myBaseType, [{return isUInt<10>(Imm);}]>; ... --- Is there a way to achieve

Johannes, Thanks, I have been following along some of the thread(s) and the phab reviews. The scope of this work is more encompassing than our current needs and I've looked at trying to carve a piece out. It's not clear to me what purpose the llvm.noalias intrinsic serves right now. Also, if a mem instruction has !noalias metadata, then it should not be aliased, but I must be missing

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On Sun, Mar 13, 2011 at 5:01 PM, Arnaud Allard de Grandmaison <Arnaud.AllardDeGrandMaison at dibcom.com> wrote: > Hi all, > > The IndVarSimplify pass seems to be too aggressive when it enlarge the induction variable type ; this can pessimize the generated code when the new induction variable size is not natively supported by the target. This is probably not an issue for x86_64,

Thanks, Jeroen, that really helps. A follow-up question, if you don't mind. What if we have code somewhat similar to your example in assign3() but it's in C++ and the pointer derived from x is stored in a class member field: class S { public: S(int *d): data(d) {} int *getData() { return data; } private: int *__restrict__ data; }; void assign4(int *pA, long N) { int

Hi, I noticed a significant performance regression (up to 40%) on some internal CUDA benchmarks (a reduced example presented below). The root cause of this regression seems that IndVarSimpilfy widens induction variables assuming arithmetics on wider integer types are as cheap as those on narrower ones. However, this assumption is wrong at least for the NVPTX64 target. Although the NVPTX64 target

Great, thanks! Are you planning on just talking about these things with slides? Do we have other things to which we can link for people to read? -Hal Hal Finkel Lead, Compiler Technology and Programming Languages Leadership Computing Facility Argonne National Laboratory ________________________________ From: Tarique Islam <tislam at ca.ibm.com> Sent: Thursday, May 21, 2020 8:19:31 AM To:

Hi, is there a convenient way to associate/add a comment to a MachineInstruction, so that in the produced assembly file, the comment is added next to the instruction ? Greetings, Jeroen Dobbelaere

Hi, everyone, We had a great call last month, and progress is definitely being made on several fronts. The notes from our last call are available here: https://docs.google.com/document/d/1ybwEKDVtIbhIhK50qYtwKsL50K-NvB6LfuBsfepBZ9Y/edit#heading=h.vpxs8lkuxy79 and, also, pasted below. DOODLE POLL: As we discussed on our last call, I would like to schedule a regular call to discuss

On Thu, May 30, 2013 at 2:16 PM, Jeroen Dobbelaere <Jeroen.Dobbelaere at synopsys.com> wrote: >> From: Eric Christopher >> Subject: Re: [LLVMdev] How to associate extra comments to a >> MachineInstruction ? >> >> Should be spelled like this yes? >> >> Asm->OutStreamer.AddComment("foo") >> Asm->EmitFoo(); >> >> -eric

Hi, I am trying to get llvm working for an architecture that has 64bit registers, but 32bit addresses. Because of that, I want the pointers to also be 32bit, although they will live in a 64 bit register. On the frontend, I do not encounter any issues, but when I provide a ... "p:32:32:32" ... DataLayout specification to the backend, things get ugly: - SelectionDag is producing a