similar to: [LLVMdev] Question about shouldMergeGEPs in InstructionCombining

On Mon, Feb 23, 2015 at 2:17 PM, Hal Finkel <hfinkel at anl.gov> wrote: > ----- Original Message ----- > > From: "Francois Pichet" <pichet2000 at gmail.com> > > To: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu> > > Sent: Sunday, February 22, 2015 5:34:11 PM > > Subject: [LLVMdev] Question about shouldMergeGEPs in

----- Original Message ----- > From: "Hal Finkel" <hfinkel at anl.gov> > To: "Francois Pichet" <pichet2000 at gmail.com> > Cc: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu>, "chandlerc" <chandlerc at gmail.com> > Sent: Tuesday, February 24, 2015 11:27:43 PM > Subject: Re: [LLVMdev] Question about

I think it would make sense for (1) and (2). I am not sure if (3) is feasible in instcombine. (I am not too familiar with LoopInfo) For the Octasic's Opus platform, I modified shouldMergeGEPs in our fork to: if (GEP.hasAllZeroIndices() && !Src.hasAllZeroIndices() && !Src.hasOneUse()) return false; return Src.hasAllConstantIndices(); // was return false;

Hi Mark, It is not clear to me at all that preventing the merging is the right solution. There are a large number of analysis, including alias analysis, and optimizations that use GetUnderlyingObject, and related routines to search back through GEPs. They only do this up to some small finite depth (six, IIRC). So reducing the GEP depth is likely the right solution for InstCombine (which has the

----- Original Message ----- > From: "Jingyue Wu" <jingyue at google.com> > To: "Daniel Berlin" <dberlin at dberlin.org>, "Mark Heffernan" <meheff at google.com>, "Hal Finkel" <hfinkel at anl.gov> > Cc: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu> > Sent: Friday, March 13, 2015 1:31:59 PM >

On Fri, Mar 13, 2015 at 10:16 AM Mark Heffernan <meheff at google.com> wrote: > On Thu, Mar 12, 2015 at 2:34 PM, Hal Finkel <hfinkel at anl.gov> wrote: > >> It is not clear to me at all that preventing the merging is the right >> solution. There are a large number of analysis, including alias analysis, >> and optimizations that use GetUnderlyingObject, and

Hi all, I am new to LLVM, and I am learning how to use LLVM for profiling. I need to pass an array to an external method, and insert a call instruction to the method in the code. After reading a few source files, I've tried using GetElementPtrInst to pass an array, but it fails at llvm::GetElementPtrInst::hasAllZeroIndices() const + 0 std::vector<Value*> Args(1);

/Volumes/mrs5/net/llvm/llvm/lib/Transforms/Scalar/ InstructionCombining.cpp: In member function ‘llvm::Instruction*<unnamed>::InstCombiner::visitAnd (llvm::BinaryOperator&)’: /Volumes/mrs5/net/llvm/llvm/lib/Transforms/Scalar/ InstructionCombining.cpp:3597: warning: ‘RHSCC’ may be used uninitialized in this function /Volumes/mrs5/net/llvm/llvm/lib/Transforms/Scalar/

I think I found it. In InstCombiner::ComputeMaskedBits we have the following lines: if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { unsigned Align = GV->getAlignment(); if (Align == 0 && TD && GV->getType()->getElementType()->isSized()) Align = TD->getPrefTypeAlignment(GV->getType()->getElementType()); It assumes that global

Hi, This is regarding a TODO mentioned in getIdentityValue function in InstructionCombining.cpp file. //TODO: We can handle other cases e.g. Instruction::And, Instruction::Or etc. I wanted to know what could be the use cases of implementing these. When I tried implementing these and wrote test cases for the same, the test cases would be optimized in InstructionSimplify before hitting the code

Hi all, The InstructionCombining pass causes alignment of globals to be ignored. I've attached a replacement of Fibonacci.cpp which reproduces this (I used 2.3 release). Here's the x86 code it produces: 03C20019 movaps xmm0,xmmword ptr ds:[164E799h] 03C20020 mulps xmm0,xmmword ptr ds:[164E79Ah] 03C20027 movaps xmmword ptr ds:[164E799h],xmm0 03C2002E

InstCombine says in its getAnalysisUsage that it preserves the CFG, but for the 4th argument in its INITIALIZE_PASS call, it says false, which I believe corresponds to whether it preserves the CFG. Is this a mistake, or is there deeper meaning here? InstructionCombining.cpp:73-82 char InstCombiner::ID = 0; INITIALIZE_PASS(InstCombiner, "instcombine", "Combine

Hi Michael, > InstCombine says in its getAnalysisUsage that it preserves the CFG, > but for the 4th argument in its INITIALIZE_PASS call, it says false, > which I believe corresponds to whether it preserves the CFG. that argument should be set to true if the pass only looks at the CFG, i.e. whatever it computes/does is only a function of the CFG, and doesn't otherwise depend on what

Hi Nicolas, > if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { > > unsigned Align = GV->getAlignment(); > > if (Align == 0 && TD && GV->getType()->getElementType()->isSized()) > > Align = TD->getPrefTypeAlignment(GV->getType()->getElementType()); > > It assumes that global values are always optimally

Hi Duncan, I see. I didn't know GlobalValue had a method for changing the alignment (and that 0 meant natural alignment). Explicitly calling setAlignment works like a charm. So it's not an LLVM bug. Thanks, Nicolas -----Original Message----- From: Duncan Sands [mailto:baldrick at free.fr] Sent: Thursday, 10 July, 2008 14:41 To: llvmdev at cs.uiuc.edu Cc: Nicolas Capens Subject: Re:

On Thursday 10 July 2008 07:46, Nicolas Capens wrote: > Hi Duncan, > > I see. I didn't know GlobalValue had a method for changing the alignment > (and that 0 meant natural alignment). Explicitly calling setAlignment works > like a charm. Nicolas, Where are you explicitly calling setAlignment? From llvm-gcc code? -Dave

Hi Bill- For what it's worth, a simple truth table proves Chris correct. Alastair On 5 Jan 2010, at 02:46, Bill Wendling wrote: > On Jan 3, 2010, at 10:04 PM, Chris Lattner wrote: > >> Author: lattner >> Date: Mon Jan 4 00:03:59 2010 >> New Revision: 92458 >> >> URL: http://llvm.org/viewvc/llvm-project?rev=92458&view=rev >> Log: >>

ISSUE: This code: %bob = type { int } int %alias() { %pbob1 = alloca %bob %pbob2 = getelementptr %bob* %pbob1 ;pbob2 aliases pbob1 %pbobel = getelementptr %bob* %pbob2, long 0, ubyte 0 %rval = load int* %pbobel ret int %rval } Crashes when run through opt -instcombine. InstCombiner visits instructions in reverse declaration order, but

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 Sep 13, 2008, at 1:07 PM, Matthijs Kooijman wrote: > Hi Dan, > >> Changing PromoteCastOfAllocation to not replace aggregate allocas >> with >> non-aggregate allocas if they have GEP users sounds reasonable to me. > This sounds reasonable indeed, but still a bit arbitrary. Haven't > figured out > anything better yet, though. > >> Finding the