similar to: [LLVMdev] Remove identical or redundant basic blocks?

Would it make sense to have a similar pass that operates on llvm main IR? On Sat, May 8, 2010 at 5:15 PM, Dale Johannesen <dalej at apple.com> wrote: > The branch folding pass does this, but it operates later, on the > target-dependent form in llc. > > On May 8, 2010, at 8:48 AM, Heinz Riener wrote: > >> Dear all, >> >> after optimizing a small LLVM example

The branch folding pass does this, but it operates later, on the target-dependent form in llc. On May 8, 2010, at 8:48 AM, Heinz Riener wrote: > Dear all, > > after optimizing a small LLVM example program (i.e., with opt -O3), > the > resulting code contains several basic blocks, which I consider > identical > or redundant. For instance, > > return:

Eugene Toder wrote: > Would it make sense to have a similar pass that operates on llvm main IR? > The unify exit return node (-mergereturn?) pass should take care of the first example. The -simplifycfg option might take care of the second example. Both work on LLVM IR. -- John T. > On Sat, May 8, 2010 at 5:15 PM, Dale Johannesen <dalej at apple.com> wrote: > >>

Dale is totally right, all of these blocks disappear in later target-dependent optimizations. I have not thought about that since eliminating these blocks requires no target-dependent information. However, I guess it is not worth eliminating them earlier. John, I tried your advice and executed opt (after -O3) again with -mergereturn and -simplifycfg: The -mergereturn pass introduces another

Hi Quentin, I have rerun the test case on a recent commit, so the numbers have changed. There are also now a few more basic blocks very small basic blocks in the function, and therefore there are some slight differences. I tried to go back to earlier commits, without success for some reason... This is however very similar, except that there becomes two COPYs back to sibling value after the loop.

Hi Jonas, Thanks for your patience. After spending some time looking at the additional output you gave me, I agree that your fix is the right one. I was worried that this problem may arise because we were spilling not real user, but in fact what I thought was the problem is an optimization we could do :). See my comments inlined for a few nitpicks before you commit. Thanks again, -Quentin On

---------- Forwarded message ---------- From: Ryan Taylor <ryta1203 at gmail.com> Date: Mon, Nov 21, 2011 at 10:30 AM Subject: Re: [LLVMdev] Order of Basic Blocks To: Benjamin Kramer <benny.kra at googlemail.com> This worked, though the RPO_iterator apparently wasn't what I was looking for anyways, it seems it doesn't rreally go top->down. I have a simple example code,

Hi, I'm having problems with the LoopIdiomRegognizer crashing on me with An asserting value handle still pointed to this value! UNREACHABLE executed at ../lib/IR/Value.cpp:695! If I remove AU.addPreserved<LoopInfoWrapperPass>(); or AU.addPreserved<AAResultsWrapperPass>(); everything goes well. The C-code triggering this is void foo(int a[10][10]) { int i, j,

I have what appears to be a bug in LLVM... I'm deeply hesitant to label it a bug, given my lack of experience with LLVM, but the behaviour of this fragment strongly suggests a bug. In particular, compiling and running this fragment using a fresh SVN build yields this stderr: uccello:/tmp clements$ lli a.out.bc 0 lli 0x005e72b6 char const* std::find<char const*,

Hi Haicheng, Originally I ran into this on our out-of-tree target but I managed to reproduce the crash on X86 as well now: build-all/bin/opt -S -sroa -loop-rotate -loop-deletion -licm -loop-idiom ../llvm/bugpoint-reduced-simplified.i8+.ll gives: While deleting: void % An asserting value handle still pointed to this value! UNREACHABLE executed at ../lib/IR/Value.cpp:696! 0 opt

On 08/05/2010 06:46 AM, Wenbin Zhang wrote: > Hi all, > I'm using postDominatorTree to do some program analysis. My code works > well for small tests, but when I run it on real applications, the > following error occurs: > /Inorder PostDominator Tree: DFSNumbers invalid: 0 slow queries. > [1] <<exit node>> {0,21} > [2] %bb1 {1,2} > [2] %bb {3,4} > [2]

Hi, It looks like PDT.getRootNode() returns NULL for: define fastcc void @c974001__lengthy_calculation. 1736(%struct.FRAME.c974001* nocapture %CHAIN.185) noreturn { entry: br label %bb bb: br label %bb } Isn't it a bug in PostDominatorTree? Please note that this crashes: opt -postdomtree -debug dom_crash.bc I think this should be reported as a bug, -Jakub On Sep 3, 2009, at

Jakub Staszak wrote: > Hi, > > It looks like PDT.getRootNode() returns NULL for: > > define fastcc void @c974001__lengthy_calculation. > 1736(%struct.FRAME.c974001* nocapture %CHAIN.185) noreturn { > entry: > br label %bb > > bb: > br label %bb > } > > > Isn't it a bug in PostDominatorTree? > > Please note that this crashes: >

I'll try the trunk, as well as check my code again. If indeed it's not fixed, I'll try to post a triggering case here. Thanks for the advice~ Best, --Wenbin ----- Original Message ----- From: "Tobias Grosser" <grosser at fim.uni-passau.de> To: "Wenbin Zhang" <zhangwen at cse.ohio-state.edu> Cc: <llvmdev at cs.uiuc.edu> Sent: Thursday, August

Hello, Bug is already fixed by Chris (see: http://llvm.org/bugs/show_bug.cgi?id=4915) . I added getRootNode() == NULL condition to my patch. It's not a great solution, but it is enough for now I think. New patch attached. -Jakub -------------- next part -------------- A non-text attachment was scrubbed... Name: dse_ssu-2.patch Type: application/octet-stream Size: 17762 bytes Desc: not

Wenbin Zhang wrote: > I'll try the trunk, as well as check my code again. If indeed it's not > fixed, I'll try to post a triggering case here. > Thanks for the advice~ > Did you run the -mergereturn pass (it might also be called UnifyExitNodes in the source code)? This is the pass that ensures that each function has exactly one basic block that returns control to the

Hi Quentin, I have tried to find a test case for an official target, but failed. It seems to be a rare case. To do it, I added the 'else' clause in the following: ... if (VNI->def == OrigVNI->def) { DEBUG(dbgs() << "orig phi value\n"); SVI->second.DefByOrigPHI = true; SVI->second.AllDefsAreReloads = false; propagateSiblingValue(SVI); continue;

I would like to be able to instrument va_arg, but when I generate a bc file for a test case using: llvm-gcc -O3 -emit-llvm vararg.c -c -o vararg.bc I do not see va_arg. Instead, it seems the args are accessed through %struct.__va_list_tag, which makes things a bit trickier to instrument. Is there a way to force llvm-gcc to use va_arg? Perhaps there is some documentation about va_list_tag or

Hi, I've stumbled upon a case where I think gvn does a bad (wrong) optimization. It's a bit messy to debug though so I'm not sure if I should just write a PR about it a let someone who knows the code look at it instead. Anyway, for the bug to trigger I need to run the following passes in the same opt invocation: -sroa -instcombine -simplifycfg -instcombine -gvn The problem

Dear All, Is there a pass (or set of passes) that will replace a phi whose input operands all compute the same value with an instruction that computes that value? In other words, something that will convert: define internal i32 @function(i32 %x) { ... bb1: %y = add %x, 10 ... bb2: %z = add %x, 10 ... bb3: %phi = [bb1, %y], [bb2, %z] into define internal i32 @function(i32 %x) { ... bb1: ...