similar to: Information Loss of Array Type in Function Interface in IR Generated by Clang

Dear David, Thanks for your prompt reply! Sure, I can implement a AST visitor to go through the AST to get the information but I just wonder whether there is any other way to let Clang do so. What I am considering is how to let the generated IR looks like below, which some tools realize: define dso_local i32 @_Z1fPii([51 x i32]* %A, i32 %x) local_unnamed_addr #0 !dbg !7 { entry: ...

Dear all, I write a new LoopPass which wants to use passes including LoopInfoWrapperPass, ScalarEvolutionWrapperPass and LoopAccessLegacyAnalysis. Therefore, I implement the following code based on LLVM 9.0.0: ===================================================================== bool LoopInformationCollect::runOnLoop(Loop *L, LPPassManager &) { auto &SE =

Dear all, Hi! I noticed an interesting situation when using getUnsignedRange and getSignedRange of SCEV for URem instruction. Here is an example with 2 IR instructions: %rem.lhs.trunc = trunc i32 %i15.082 to i8 --> getUnsignedRange --> [1,50) %rem81 = urem i8 %rem.lhs.trunc, 3 --> getUnsignedRange --> [-47,50) The problems are: 1) From my

Dear all, Hi! I encounter an interesting assertion failure when implementing my Pass, which is defined with the member functions shown below: ======================My Pass====================================== bool MYPass::runOnModule(Module &M) { for (auto &F : M) { SE = &getAnalysis<ScalarEvolutionWrapperPass>(F).getSE(); ......

Dear Momchil, Thanks a lot for your prompt reply and kindly suggestion. The code will truly lead to some automatic unrolling with GCC and increase the number of operations in the assembly code. However, I am focus on the the IR optimization and the calculation of the array element offest, which may need multiplication if the IR instruction GEP is lowered to arithmetic operations. The

Dear LLVMers, I am trying to implement a particular type of loop optimization, but I am having problems with global variables. To solve this problem, I would like to know if LLVM has some pass that moves loads outside loops. I will illustrate with an example. I want to transform this code below. I am writing in C for readability, but I am analysing LLVM IR: int *vectorE; void foo (int n) {

Dear all, Hi! Recently, I try to combine the passes SeparateConstOffsetFromGEP and LoopStrengthReduction to transform the multiplication in the lowered GEP IRs into addition. However, it seems LoopStrengthReduction is unable to remove all the multiplications for the element offset calculation. My test code is shown below and thanks a lot in advance for your time and suggestion!

Hello All, I have a question about a May-alias case. Let's look at one simple C example. char *buf[4]; char c; void test(int idx) {   char *a = buf[3 - idx];   char *b = buf[idx];   *a = *b;   c++;   *a = *b; } We can imagine the second "*a = *b" could be removed. Let's look at the IR snippet with -O3 for above example.   1 define void @test(i32 %idx) {   2 entry:  

Hi, Look at the following code: Look at the following C code seqence: unsigned char mainGtU ( unsigned int i1, unsigned int i2, unsigned char* block) { unsigned char c1, c2; c1 = block[i1]; c2 = block[i2]; if (c1 != c2) return (c1 > c2); i1++; i2++; c1 = block[i1]; c2 = block[i2]; if (c1 != c2) return (c1 > c2); i1++; i2++; .. ..

Hi Devs, I am looking at the bug https://bugs.llvm.org/show_bug.cgi?id=43953 and found that following piece of ir %arrayidx = getelementptr inbounds float, float* %Vec0, i64 %idxprom %0 = load float, float* %arrayidx, align 4, !tbaa !2 %arrayidx2 = getelementptr inbounds float, float* %Vec1, i64 %idxprom %1 = load float, float* %arrayidx2, align 4, !tbaa !2 %sub = fsub fast float %0, %1

----- Original Message ----- > From: "Hal Finkel" <hfinkel at anl.gov> > To: "Chandler Carruth" <chandlerc at google.com> > Cc: llvmdev at cs.uiuc.edu > Sent: Thursday, July 16, 2015 1:58:02 AM > Subject: Re: [LLVMdev] Improving loop vectorizer support for loops > with a volatile iteration variable > ----- Original Message ----- > >

I've actually got an implementation of this as an arbitrary precision integer extension that I've written up an RFC for (but not submitted). Below is my copy/pasted RFC (again, not reviewed, but I DO have an implementation of it that I need to prepare for review). I suspect my implementation will do what you need out of it. Its actually more significant than just adding a normal

Hi all, I'm looking into resolving a FIXME in the LoopDataPrefetch (and FalkorMarkStridedAccesses) pass by marking both of these passes as preserving the ScalarEvolution analysis. Unfortunately, when this change is made, LSR will generate different code. One of the root causes seems to be that SCEV will return different nsw/nuw flags for the same Value, depending on what order the

Hi Andrew, The issue below refers to LSR, so I'll appreciate your feedback. It also refers to instruction combining and might impact backends other than X86, so if you know of others that might be interested you are more than welcome to add them. Thanks, Anat _____________________________________________ From: Shemer, Anat Sent: Tuesday, February 18, 2014 15:07 To: 'llvmdev at

Hi, Mehdi, For example, I have this very simple source code: void foo( int n, int array_x[]) { for (int i=0; i < n; i++) array_x[i] = i; } After I use "clang -emit-llvm -o bc_from_clang.bc -c try.cc", I get bc_from_clang.bc. With my code (using LLVM IRbuilder API), I get bc_from_api.bc. Attachment please find thse two files. I also past the IR here.

Thanks for your point that out. I just add DataLayout in my code such as "mod->setDataLayout("e-m:e-i64:64-f80:128-n8:16:32:64-S128");", still no luck. I'm really confused about this. Do I need to add more passes before -loop-unroll? On Sat, Aug 22, 2015 at 11:36 AM, Mehdi Amini <mehdi.amini at apple.com> wrote: > > On Aug 22, 2015, at 7:27 AM, Xiangyang

Hi Gerolf, I think we have several (perhaps separable) issues here: 1. Do we have a canonical form for loops, preserved through the optimizer, that allows naturally-constructed loop nests to remain separable? 2. Do we forbid non-lowering transformations that turn vectorizable loops into non-vectorizable loops? 3. How do we detect cases where transformations cause a negative answer to either

Hi, all I found in some cases the int variable get promoted to i64, although I think it should i32. I use the online demo (http://llvm.org/demo). And below is the test case. ------------- test case ------------- int test(int x[], int y[], int n) { int i = 0; int sum = 0; for ( ; i < n; i++) { sum += x[i] * y[i]; } return sum; } ------------------------------------- No

On 5 February 2013 17:28, Nadav Rotem <nrotem at apple.com> wrote: > We insert runtime overlap checks only for unidentified objects. The > problem here is that the vectorizer thinks that A,B,C are all pointers to > the same array, so it gives up. If A,B,C were different arrays then it > could have used runtime checks. > Yes, that is exactly the code that creates the

It seems there is no -enable-iv-rewrite now in llvm3.2, and it suggest -enable-load-pre, but it still does not work. So, how to active the transform? -- View this message in context: http://llvm.1065342.n5.nabble.com/indvars-issues-tp4646p58587.html Sent from the LLVM - Dev mailing list archive at Nabble.com.