search for: loopunswitching

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.

Hi all. Guys in accordance to PR1255 I need to add case-ranges support for passes listed in subject. Who can review some of these passes in nearest future? Thanks! -Stepan.

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 > >

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

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? -Stepan.

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

Hello, some of the patches had conflicts with LLVM head, so I updated them. If you experienced patch failure before then you can try it again. I compiled your code (1.c) with LLVM r308173 with the 5 patches applied, and it generated assembly like this. Now it contains store to c(%rip). It tries to store a(%rip) + b(%rip) to c(%rip). I wish this translation is now correct. ``` 73 .globl hoo

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

It seems MemorySSA.cpp is the only real code where we found the problem happening. Is it possible to change the source of MemorySSA.cpp to hide the problem and buy some time for now? Now we use an empty generic_def_path_iterator with Optional<ListIndex> N being initialized by None as the end of range. Can we initialize the Optional var with a special value instead of None?

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

I've been looking at compilation time issues in the LICM pass, and it looks to me like colorEHFunclets() is probably being called a lot more often than it needs to be for functions that have Windows EH personality functions. For one thing, the funclet coloring is happening when computeLoopSafetyInfo() is called from LoopIdiomRecognize and LoopUnswitch but those passes don't use the

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, Jun 15, 2011 at 3:20 AM, Jimborean Alexandra <xinfinity_a at yahoo.com> wrote: > Thanks , your suggestion was welcome and CloneLoop works without passing the > LPPassManager. > >  However, I reached another problem. When the loop to be cloned has some > subloops, the subloops are not properly cloned. Some clones of the clones > are created and the CFG between the

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, Which optimization passes use profile information? http://llvm.org/docs/Passes.html seems to suggest only block placement uses it, is that correct? Emma. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160715/46cc3ccc/attachment.html>

On Mon, Jan 30, 2017 at 4:59 PM Mehdi Amini <mehdi.amini at apple.com> wrote: > > > Another question is about PGO integration: is it already hooked there? > Should we have a more aggressive threshold in a hot function? (Assuming > we’re willing to spend some binary size there but not on the cold path). > > > I would even wire the *unrolling* the other way: just

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

Hello, We currently generate suboptimal code for this loop: for (int i = 1; i < LEN; i++) { a[i] = a[0] + b[i]; } The largest problem is that we won't vectorize the loop because the loop vectorizer does not grok the independence of a[i] and a[0] (note that i starts at 1 in this loop). While we can probably fix the vectorizer to handle this, I don't think that is the right place for

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: >>