similar to: [LLVMdev] [LLVM, loop-unswitch tests] preserve-analyses.ll, strange PHI instruction.

OK. Thanks. And if I removed "case 4:" for example. Need I scan all phi nodes and fix it, by removing one predecessor (if it exists) to switch's parent block? -Stepan. Nick Lewycky wrote: > Stepan Dyatkovskiy wrote: >> Hi all. >> >> Looking at test/Transforms/LoopUnswitch/preserve-analyses.ll, I found >> improper phi instruction at string #122: >>

Stepan Dyatkovskiy wrote: > Hi all. > > Looking at test/Transforms/LoopUnswitch/preserve-analyses.ll, I found > improper phi instruction at string #122: > %call.i25.lcssa48 = phi i8* [ %call.i25, %if.then31.i.i ], [ %call.i25, > %if.then31.i.i ] ;<i8*> [#uses=0] > Is it trick or mistake? What's improper about it? The block may have two predecessors, both of which

Hi all. By now loops with switch instruction are unswitched value-by-value. For example for case range [0..9] we need to run unswitch process 10 times! I want try to optimize that case. Is there any hidden problems that blocks this improvement? Regards, Stepan.

Cool, thanks for debugging this issue and letting us know. We have a few patches to fix this issue: - Introduce freeze in IR: https://reviews.llvm.org/D29011 - Lowering freeze: https://reviews.llvm.org/D29014 - Fix loop unswitch: https://reviews.llvm.org/D29015 Bonus patches to recover perf: - Be less conservative in loop unswitching: https://reviews.llvm.org/D29016 - Instcombine support

The issue blocks another optimization patch and Wei has spent huge amount of effort isolating the the bootstrap failure to this same problem. I agree with Wei that other developers may also get hit by the same issue and the cost of leaving this issue open for long can be very high to the community. David On Mon, Jul 17, 2017 at 10:01 AM, Wei Mi <wmi at google.com> wrote: > Sanjoy and

This is a bug found by internal compiler bootstrap, and possibly it is the root cause of https://bugs.llvm.org/show_bug.cgi?id=33652 and https://bugs.llvm.org/show_bug.cgi?id=33626. Here is the testcase 1.c. The original code is at MemorySSA.cpp:586 for rL307764. ------------------------- 1.c --------------------------- long a, c, d, e, f, m, cnt, i_hasval; volatile long b; void goo(long); void

Hello: When I use SPSS I execute the AGGREGATE DATA comand for the next data: 2112141123212213212213334 3143244113442312121213344 2114141123112214212113344 2112211122212413421213221 3114444123442414343413344 2312231223212222323223322 2143241123212313131213234 2113241113212313222213333 2113141123112214212113344 2114141123412111114413344 2113211122342314222313234 2114141123112414212113344

As came up recently in other threads, loop passes really get in the way. Here are some of the ways: - There is only one Loop analysis pass - IVUsers. It seems unlikely that the loop nest walk is critical to computing this or preserving it. - Almost all of the things we think of as "required" and dependencies are actually *transforms* that canonicalize the form of a loop into particular

On Mon, Jul 17, 2017 at 5:11 PM, Wei Mi <wmi at google.com> wrote: > On Mon, Jul 17, 2017 at 2:09 PM, Sanjoy Das > <sanjoy at playingwithpointers.com> wrote: >> Hi, >> >> On Mon, Jul 17, 2017 at 1:56 PM, Daniel Berlin via llvm-dev >> <llvm-dev at lists.llvm.org> wrote: >>> >>> >>> On Mon, Jul 17, 2017 at 1:53 PM, Wei Mi

Hi, I have a general question on LoopUnswtich pass. Consider the following IR snippet: define i32 @test(i1 %cond) { br label %loop_begin loop_begin: br i1 %cond, label %loop_body, label %loop_exit loop_body: br label %do_something do_something: call void @some_func() noreturn nounwind br label %loop_begin loop_exit: ret i32 0 } declare void @some_func() noreturn After running

Hi, On Mon, Jul 17, 2017 at 1:56 PM, Daniel Berlin via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > > On Mon, Jul 17, 2017 at 1:53 PM, Wei Mi <wmi at google.com> wrote: >> >> It seems MemorySSA.cpp is the only real code where we found the >> problem happening. > > > This is doubtful, ¸FWIW :) > >> >> Is it possible to change the

On Wed, Jan 22, 2014 at 12:33 AM, Andrew Trick <atrick at apple.com> wrote: > > There appear to be two chunks of "functionality" provided by loop passes: > > > > 1) A worklist of loops to process. This is very rarely used: > > 1.1) LoopSimplify and LoopUnswitch add loops to the queue. > > I’m making this up without much thought, but we may benefit

On Wed, Nov 29, 2017 at 9:48 AM, Philip Reames <listmail at philipreames.com> wrote: > There's already a LoopSimplifyCFG which is a loop-pass (and thus can iterate > with other loop passes) and eliminates trivial branches. Having a simple > pass which just strips unreachable blocks and converts conditional branches > to unconditional ones while updating appropriate analyzes

On 07/18/2017 06:03 PM, David Majnemer via llvm-dev wrote: > I doubt it is possible for us to try and make any fix which is > predicated on eagerly treating undef in a particular way, refinement > will always cause these problems to come about... > > Given what I've seen in LLVM (and what I've learned from other > compilers), we probably have two choices: > 1.

On Sep 29, 2010, at 8:35 AMPDT, Ralf Karrenberg wrote: > Hello everybody, > > I have stumbled upon a test case (the attached module is a slightly > reduced version) that shows extremely reduced performance on linux > compared to windows when executed using LLVM's JIT. > > We narrowed the problem down to the actual code being generated, the > source IR on both systems

There's already a LoopSimplifyCFG which is a loop-pass (and thus can iterate with other loop passes) and eliminates trivial branches.  Having a simple pass which just strips unreachable blocks and converts conditional branches to unconditional ones while updating appropriate analyzes (LoopInfo, DomTree, LCSSA, etc..) seems very reasonable.  This could also be a utility function called

Hello everybody, I have stumbled upon a test case (the attached module is a slightly reduced version) that shows extremely reduced performance on linux compared to windows when executed using LLVM's JIT. We narrowed the problem down to the actual code being generated, the source IR on both systems is the same. Try compiling the attached module: llc -O3 -filetype=asm -o BAD.s BAD.ll Under

Hi all, hope someone can help me out with this. Background Introduction I have a data set consisting of data collected from a questionnaire that I wish to validate. I have chosen to use confirmatory factor analysis to analyse this data set. Instrument The instrument consists of 11 subscales. There is a total of 68 items in the 11 subscales. Each item is scored on an integer scale between 1 to 4.

On Mon, Jul 17, 2017 at 11:18 AM, Sanjoy Das via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi, > > On Mon, Jul 17, 2017 at 10:32 AM, Xinliang David Li <davidxl at google.com> > wrote: > > The issue blocks another optimization patch and Wei has spent huge > amount of > > effort isolating the the bootstrap failure to this same problem. I agree > >

Is there any written description of what "non trivialness" is there? On Sun, Apr 29, 2018, 2:49 PM Chandler Carruth via llvm-dev < llvm-dev at lists.llvm.org> wrote: > One of the last big missing pieces for the new PM is enabling non-trivial > loop unswitch at O3. > > The pass is now working well and passing all the testing I have done as > well as some others'