similar to: [LLVMdev] Does a recursive call have side effects?

Hi Nadav, > I almost missed your email because you replied only to the list. I understand your argument. I think that my fix addresses a part of it. It says that instructions that do not return should not be removed. > The current implementation of mayReturn is to check the 'noreturn' function attribute. Are you suggesting to add a new attribute that is called 'mustreturn'

On 19.03.2016 16:25, Mehdi Amini wrote: > Hi, > > Can you elaborate what is the impact at the IR level? > If the point is just about how you lower for you target, why are you needing an IR level attribute? You backend if free to specialize the lowering for any intrinsic regardless the IR level attributes. As I explained in my reply to Philip, what I really need is a way to get

Hi, All CallInsts should return true for Instruction::mayHaveSideEffects() because functions are not guaranteed to halt. Inliner::runOnSCC calls isInstructionTriviallyDead to determine whether code can be dead code eliminated. isInstructionTriviallyDead returns true if Instruction::mayHaveSideEffects() returns false. A function that potentially runs forever based on its input but does not write

Does any real code benefit from dead code eliminating read-only functions? Tom ----- Original Message ----- From: "Reid Kleckner" <rnk at mit.edu> To: "Thomas B. Jablin" <tjablin at CS.Princeton.EDU> Cc: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu> Sent: Monday, May 10, 2010 9:38:47 PM GMT -05:00 US/Canada Eastern Subject: Re: [LLVMdev]

> On Mar 21, 2016, at 9:14 PM, Mehdi Amini via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > >> On Mar 21, 2016, at 8:58 AM, Nicolai Hähnle <nhaehnle at gmail.com> wrote: >> >> On 19.03.2016 16:25, Mehdi Amini wrote: >>> Hi, >>> >>> Can you elaborate what is the impact at the IR level? >>> If the point is just about

LLVM today does not clearly specify if a function specified to not write to memory (i.e. readonly or readnone) is allowed to throw exceptions. LangRef is ambiguous on this issue. The normative statement is "[readnone/readonly functions] cannot unwind exceptions by calling the C++ exception throwing methods" which does not decide an answer for non C++ languages. It used to say (h/t

While improving ADCE, i notice that for declare i32 @strlen(i8*) readnone define i32 @test() { ; invoke of pure function should not be deleted! invoke i32 @strlen( i8* null ) readnone to label %Cont unwind label %Other ; <i32>:1 [#uses=0] Cont: ; preds = %0 ret i32 0 Other: ; preds = %0 %exn = landingpad {i8*, i32} personality i32 (...)* @__gxx_personality_v0

Hi I am currently trying to schedule instructions with my own algorithm. For that i need to get the data dependency between the instructions. So currently i am dooing s.t. like: for(BasicBlock::iterator j=B.begin(),bbe=B.end();j!=bbe;++j) { InstructionList.push_back(j); if (const AllocaInst *AI = dyn_cast<AllocaInst>(j)) {

On Fri, 12 May 2006, Silken Tiger wrote: > To find the first instructions which are not depending on others results. So > far it seems to be working but i am missing instructions like: > %tmp.1 = seteq int %argc, 2 ; <bool> [#uses=1] > There seems only an function like llvm::Instruction::mayWriteToMemory > but nothing like llvm::Instruction::mayReadFromMemory or

On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: > On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at gcc.gnu.org> > wrote: >> >> On Aug 21, 2009, at 7:31 PM, Eli Friedman wrote: >> >>> On Fri, Aug 21, 2009 at 2:06 PM, Jakub Staszak<kuba at gcc.gnu.org> >>> wrote: >>>> >>>> Hello, >>>>

The Instruction::mayWriteToMemory() member function is quite useful (I'm currently writing code that will break up basic blocks at read/write instructions). Is there a safe way to do the same thing for reads from memory? It's easy enough to check for the relevant instructions, but I thought this might be a nice-to-have in a future version because it separates code like mine from

On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote: > On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> > wrote: >> >> On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: >> >>> On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at gcc.gnu.org> >>> wrote: >>>> >>>> On Aug 21, 2009, at 7:31 PM, Eli

On Aug 21, 2009, at 10:27 PM, Eli Friedman wrote: > On Fri, Aug 21, 2009 at 5:05 PM, Jakub Staszak<kuba at gcc.gnu.org> > wrote: >> >> On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote: >> >>> On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> >>> wrote: >>>> >>>> On Aug 21, 2009, at 8:46 PM, Eli

Hi everyone, I am puzzled by several instruction defines in MSP430. 1 def MOV16rr : Pseudo<(outs GR16:$dst), (ins GR16:$src), "mov.w\t{$src, $dst}", [ ]>; Because it's an empty dag pattern[ ], by what does instuction selector select intruction 'MOV16rr'? 2 let canFoldAsLoad = 1, isReMaterializable = 1, mayHaveSideEffects =

On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: > > On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: > >> On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: >>> >>> On Aug 21, 2009, at 7:31 PM, Eli Friedman wrote: >>> >>>> On Fri, Aug 21, 2009 at 2:06 PM, Jakub Staszak<kuba at

Hi Chuck, > I need to figure out all LLVM Instructions that may write to memory. I->mayWriteToMemory() Ciao, Duncan.

Duncan, I looked at this function even before starting the discussions. I think it respects LLVM's principle that only Loads and Stores (+VAArg, and maybe Call) that can access global memory, but doesn't address the issues of accessing stack frames or stack objects. Thank you for the hint. Chuck On 1/22/2011 6:17 AM, Duncan Sands wrote: > Hi Chuck, > >> I need to figure

2012/2/3 Patrik Hägglund <patrik.h.hagglund at ericsson.com>: > Hi, > > I've tracked the first problem (mentioned in my previous email, quoted > below) down further, ending up in the handling of alloca in > LoopRotation.cpp (from trunk): > >      // If the instruction's operands are invariant and it doesn't read > or write >      // memory, then it is

On Fri, Aug 21, 2009 at 5:05 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: > > On Aug 21, 2009, at 10:02 PM, Eli Friedman wrote: > >> On Fri, Aug 21, 2009 at 4:53 PM, Jakub Staszak<kuba at gcc.gnu.org> wrote: >>> >>> On Aug 21, 2009, at 8:46 PM, Eli Friedman wrote: >>> >>>> On Fri, Aug 21, 2009 at 3:29 PM, Jakub Staszak<kuba at

Prakash Prabhu wrote: > Hi all, > > Would it be correct to say that the only instructions in LLVM IR that > modify/access memory potentially are the following: > I believe that every instruction has a mayWriteToMemory()/mayReadToMemory() method that you can use to determine this information. See http://llvm.org/doxygen/classllvm_1_1Instruction.html (the LLVM doxygen info on