similar to: loop induction variables at IR level

I just subscribed this group. This is my first time to post a question (not sure if this is a right place for discussion) after I have a brief look at LLVM OPT (dev trunk). I would expect loop simplification and induction variable canonicalization pass (IndVarSimplify pass) should be able to convert the following loops into a simple canonical form, i.e., there is a canonical induction variable

But even for a very simple loop: int test1 (int *x, int *y, int *z, int k) { int sum = 0; for (int i = 10; i < k; i++) { z[i] = x[i] / y[i]; } return sum; } The initial value of induction variable is not zero after compiling with -O3 -mcpu=power8 x.cpp -S -c -emit-llvm -fno-unroll-loops (see bottom of the email for IR) Also I can write somewhat more complicated loop where step

Hello . opt -indvars pass does not generate canonical induction variable.  (NULL == loop->getCanonicalInductionVariable();) PLEASE explain why? and how can I fix it? Thanks in advance, Edvard  -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20120724/92a28ed5/attachment.html>

Hi I have the followed code for which I am writing a loop pass. int main() { int i = 0; for (i=0; i<20; i++) { printf ("hello world %d\n", i); } return 0; } In the function runOnLoop, I have the following instruction PHINode *indv = NULL; indv = L->getCanonicalInductionVariable(); However, when I check indv is always set to NULL. Since the code has a canonical

Hello, I need to perform the analysis of loop induction variables. However, as I understood, directly it is possible to extract only a canonical induction variable which is only one. If I have multiple induction variables with the step not one, are there any methods to extract their phi node? int a[10]; int b[10]; for (int i = 0, j = 1; i < 10, j < 10; i++, j+=2) {

On 19 January 2011 13:01, Dan Gohman <gohman at apple.com> wrote: > > On Jan 18, 2011, at 12:32 AM, Nick Lewycky wrote: > > > Hi, > > > > I tracked down a bug in indvars where we weren't updating SCEV properly. > The attached patch shows the fix to this bug with a testcase, but it also > causes five new test failures. > > Indvars isn't

On Jan 19, 2011, at 2:03 PM, Nick Lewycky wrote: > On 19 January 2011 13:01, Dan Gohman <gohman at apple.com> wrote: > > On Jan 18, 2011, at 12:32 AM, Nick Lewycky wrote: > > > Hi, > > > > I tracked down a bug in indvars where we weren't updating SCEV properly. The attached patch shows the fix to this bug with a testcase, but it also causes five new test

I am new to LLVM and I've a question about the optimization passes and in particular about the loop transformation passes. I've setup the LLVM tool-chain with Polly installed. The following example is causing problems with me: http://llvm.org/docs/Passes.html#indvars The input is a .c file with the following loops: # 01 Standard, N=100 for (i=0; i<N; i++) b[i] = a[i] + 5; # 02

Hello, I've just downloaded the latest release of LLVM, and playing with the following simple example: int main() { int r(0); for (int i = 0; i < 100; ++i) r += i; ; return r; } I compile it and then run: analyze -indvars x.bc which prints: Printing analysis 'Induction Variable Analysis' for function 'main': and nothing else. It is a

Hello . I ran opt with -indvars options , got wrong result.  This is my example: test.cc :  int test(int a)                 {      for (int i = 2; i < a; ++i) {                            a += ;      }              return a; } clang -O3 -emit-llvm -S test.cc -o test.ll opt -indvards -S test.ll  -o indvars.ll > /dev/null indvars.ll : ; ModuleID = 'test.ll' target datalayout =

On 01/16/2012 01:19 PM, Pieter Custers wrote: > I am new to LLVM and I've a question about the optimization passes and > in particular about the loop transformation passes. I've setup the LLVM > tool-chain with Polly installed. > > The following example is causing problems with me: > http://llvm.org/docs/Passes.html#indvars > > The input is a .c file with the

Hi Pankaj, On April 14, 2017 at 4:55:16 PM, Chawla, Pankaj (pankaj.chawla at intel.com) wrote: > I have attached the IR I got by compiling with -O2. This is just before we widen the IV. Thanks! > To get the backedge taken count info I ran indvars on it and then replaced zext with sext. > > I think regardless of where we decide to add this transformation in the pipeline, it should

Chris Lattner wrote: > > int main() > > { > > int r(0); > > for (int i = 0; i < 100; ++i) > > r += i; > > ; > > return r; > > } > > When I compiled it, I got the following LLVM code: The code I get is somewhat different: int %main() { entry: %tmp.1.i = load bool* %Initialized.0__ ; <bool> [#uses=1] br

Hi all, It looks like the induction variable simplification pass prefers doing a zero-extension to compute the wider trip count of loops when extending the IV. This can sometimes result in loss of information making ScalarEvolution's analysis conservative which can lead to missed performance opportunities. For example, consider this loopnest- int i, j; for(i=0; i< 40; i++) for(j=0;

Hi, How does LLVM identify induction variables of a loop? Is the algorithm based on SSA graphs? I have a complicated loop and I need to do some analysis around it. Can anyone please point me to source of identification part? -- *Disclaimer: Views, concerns, thoughts, questions, ideas expressed in this mail are of my own and my employer has no take in it. * Thank You. Madhur D. Amilkanthwar

On Wed, 31 Mar 2004, Vladimir Prus wrote: > I've just downloaded the latest release of LLVM, and playing with the > following simple example: > > int main() > { > int r(0); > for (int i = 0; i < 100; ++i) > r += i; > ; > return r; > } When I compiled it, I got the following LLVM code: int %main() { entry: call void %__main( )

Hello LLVM, Can you suggest a good way to use the loops and induction variable passes to map loop exiting BasicBlocks to InductionVariables. That is, can we use these tools to identify the loop condition. What i have tried Function Pass: foreach BB if(terminal is loop exit of containing loop) trace back to instruction producing the cond that the branch branches on -

I call this function and it returns only "i" in my example. Are there any ways to return "j" also? 2017-07-25 19:11 GMT+02:00 Michael Kruse <llvmdev at meinersbur.de>: > There is Loop::getCanonicalInductionVariable() > > You may need to run the "-indvars" (IndVarSimplify) pass before it > returns a value. I am not sure it normalizes the step size

Hello, Recently I've come across two instances where Induction Variable Simplification lead to noticable performance regressions. In one case, the removal of extra IV lead to the inability to reschedule instructions in a tight loop to reduce stalls. In that case, there were enough registers to spare, so using extra register for extra induction variable was preferable since it reduced

Hello . I'm trying to implement FunctionPass for detecting loops in llvm IR. How can I get <condition> for loop from llvm::Loop object.? Is there any example? Thanks in advance, Edvard  -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20120723/85e7f2f9/attachment.html>