similar to: [MemorySSA] inserting or removing memory instructions

In particular, if you want to add support, the right way to know what to rename is (off the top of my head) add a flag or something to have renamepass reset all uses it sees (you only have to change the uses, defs are all linked together and thus already fixed by the updater). Right now it only does that if they have no defining access. Make it skip blocks already in the visited set (the

Hi, I have a question about how llvm MemorySSA works, as seems I misunderstand something. Consider following code snippet and corresponding IR with MemorySSA annotations (got with opt -print-memoryssa) void foo(int* b) { int a = 0; int d = 12; if (b) { a = 42; d = 32; } int c = a; int e = d; } ; Function Attrs: noinline nounwind optnone uwtable

Hi, I am new to MemorySSA and wanted to understand its capabilities. Hence I wrote the following program (test.c): int N; void test(int *restrict a, int *restrict b, int *restrict c, int *restrict d, int *restrict e) { int i; for (i = 0; i < N; i = i + 5) { a[i] = b[i] + c[i]; } for (i = 0; i < N - 5; i = i + 5) { e[i] = a[i] * d[i]; } } I compiled this program using

Hi, try adding some alias analysis to the pipeline: see examples in llvm/test/Analysis/MemorySSA/*.ll for example assume.ll has ; RUN: opt -aa-pipeline=basic-aa -passes='print<memoryssa>,verify<memoryssa>' without basic-aa the memory ssa will safely assume that the stores to %a and %d alias which may be proven disjoint by one of the alias analyses. On Thu, Aug 9, 2018 at 8:37

On Tue, Dec 19, 2017 at 9:10 AM, Siddharth Bhat via llvm-dev < llvm-dev at lists.llvm.org> wrote: > I could be entirely wrong, but from my understanding of memorySSA, each > def defines an "abstract heap state" which has the coarsest possible > definition - any write will be modelled as a "new heap state". > This is true for def-def relationships, but

Hi guys, I think I have run into another CachingMemorySSAWalker cache bug. It's a bit tricky to reproduce, so I'd like to start by trying to show you what is happening when running EarlyCSE with my local changes to use MemorySSA. I've attached a debug log that shows that the value returned by getClobberingMemoryAccess(Inst) after a call to removeMemoryAccess is wrong. The

I suspect something is pulling the RHS of the memorydef and caching it for calls it should not be used for. In particular, i suspect we are about to discover we can't cache the results from both versions of getClobberingMemoryAccess together, or that the cache is not always getting consistently written. On Mon, May 2, 2016 at 11:16 AM, George Burgess IV < george.burgess.iv at

Dear Daniel Berlin, I just tried MemorySSA analysis and get the next IR. However, I feel confused by the result. Specifically, why instruction *%3* relates to a *MemoryDef*. According to my understanding, I think *%3* should be related to a *MemoryUse*, right? ; Function Attrs: uwtable define void @_Z2f1v() #3 personality i32 (...)* @__gxx_personality_v0 { entry: ; 1 = MemoryDef(liveOnEntry)

I've put my changes to EarlyCSE that trigger this case up on phab here: http://reviews.llvm.org/D19821. These changes depend on http://reviews.llvm.org/D19664 so that will need to be applied first. With these changes applied, the original attached .ll file should trigger this bug when compiled with opt -early-cse -early-cse-use-memoryssa On 5/2/2016 2:34 PM, Daniel Berlin wrote: >

Hey All, I've come across what I believe to be a bug in MemorySSA. George, I wasn't sure if this was a known issue that you'll be addressing in your upcoming walker caching changes or not, so I haven't investigated it very much. The test case is attached. The bug is that the defining access for the second load is set to the loop MemoryPhi node instead of being liveOnEntry as

On Mon, Apr 27, 2015 at 4:21 PM, Daniel Berlin <dberlin at dberlin.org> wrote: > You can't win here (believe me, i've tried, and better people than me have > tried, for years :P). > No matter what you do, the partitioning will never be 100% precise. The > only way to solve that in general is to pairwise query over the > partitioning. > > Your basic problem is

Let me try to help. On Thu, Feb 8, 2018 at 12:13 PM, Qiuping Yi via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Thanks for your explanation. > > Do you mean that LLVM will not maintain the def-use chain for atomic > variables? > It is not a variable at the LLVM level. At the source level, it is a variable. At the LLVM IR level, it is lowered into memory operations. All

With regards Bhargav Reddy Godala Software Engineer 2 Bangalore, India E-mail: Bhargav-reddy.Godala at amd.com<mailto:Bhargav-reddy.Godala at amd.com> Ext 30678 On 23-Sep-2017, at 9:27 PM, Daniel Berlin <dberlin at dberlin.org<mailto:dberlin at dberlin.org>> wrote: On Sat, Sep 23, 2017 at 8:38 AM, Godala, Bhargav-reddy via llvm-dev <llvm-dev at

Thanks for your explanation. Do you mean that LLVM will not maintain the def-use chain for atomic variables? So it is impossible to directly catch the fact that the load of x at the statement 'data1 = x; ' dependents on data4 (because of the statement x=data4 )? If I want to get such information, may be the only solution is to traverse all the predecessors of the statement 'data1 =

On 12/20/2017 03:49 PM, Alina Sbirlea via llvm-dev wrote: > +Philip to get his input too. > I've talked with George offline, and here's a summary: > > In D16875 <https://reviews.llvm.org/D16875>, the decision made was: > "The LLVM spec is ambiguous about whether we can hoist a non-volatile > load above a volatile load when the loads alias. It's probably

I understand that changing the starting element to “InsertedPHIs.being() + StartingPHISize” it will be finite but given that InsrtedPHIs is finite. I have a case where one element(same element is appened to InsertedPHIs) is added to InsertedPHIs every time fixupDefs is invoked. I traced the issue why this was happening. template <class RangeType> MemoryAccess

On Sat, Sep 23, 2017 at 9:55 AM, Godala, Bhargav-reddy < Bhargav-reddy.Godala at amd.com> wrote: > > With regards > Bhargav Reddy Godala > Software Engineer 2 > Bangalore, India > E-mail: Bhargav-reddy.Godala at amd.com Ext 30678 > > > > On 23-Sep-2017, at 9:27 PM, Daniel Berlin <dberlin at dberlin.org> wrote: > > > > On Sat, Sep 23, 2017 at

On Sun, Oct 30, 2016 at 4:08 PM, Bryant Wong < 3.14472+reviews.llvm.org at gmail.com> wrote: > > On Sun, Oct 30, 2016 at 6:48 PM, Daniel Berlin <dberlin at dberlin.org> > wrote: > >> In particular: >> " >> I'm not so sure that it's sufficient. Suppose, for instance, that I >> wanted to insert a MemoryDef between 1 and 2 in the below

Hi, Can some one explain the intended behaviour of following loop in void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) function. while (!FixupList.empty()) { unsigned StartingPHISize = InsertedPHIs.size(); fixupDefs(FixupList); FixupList.clear(); // Put any new phis on the fixup list, and process them FixupList.append(InsertedPHIs.end() - StartingPHISize,

This is definitely a caching bug related to this code: 1038 // Don't try to optimize this phi again if we've already tried to do so. 1039 if (!Q.Visited.insert(PHIPair).second) { 1040 ModifyingAccess = CurrAccess; 1041 break; 1042 } We don't differentiate elsewhere between having stopped at a phi because we were path walking and discovered that path