search for: undefvalue

2013/3/27 Nick Lewycky <nicholas at mxc.ca>: >The common idiom to delete any Value* is: > > V->replaceAllUsesWith(UndefValue::get(V->getType()); > V->eraseFromParent(); > > Does that work for functions? You may need to make sure the 'undef' has a > pointer to function type instead of the function type. > I tried this code sample, passing the type returned by llvm::Function::getType(), but i...

Hi, At line 2292, lib/VMCore/ConstantFold.cpp (llvm2.7 release) Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode, Constant *C1, Constant *C2) { ... // Handle UndefValue up front. if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) { switch (Opcode) { case Instruction::Xor: if (isa<UndefValue>(C1) && isa<UndefValue>(C2)) // Handle undef ^ undef -> 0 special case. This is a common // idiom (misuse)....

...... > } > int f2 (int y) { > ... > b = f1(smth); > ... > } > > I need delete from module both f1 and f2. They haven't uses in other > part of module, but I can't delete them with eraseFromParent, because > they are use each other. Call X->replaceAllUsesWith(UndefValue::get(X->getType)) before calling X->eraseFromParent(). Nick

How correctly remove function from module? For example: int f1(int x) { ... a = f2(smth); ... } int f2 (int y) { ... b = f1(smth); ... } I need delete from module both f1 and f2. They haven't uses in other part of module, but I can't delete them with eraseFromParent, because they are use each other. Yours sincerely, Kadysev Mikhail -------------- next part

...while (EndInst != BB->begin()) { // Delete the next to last instruction. Instruction *Inst = &*--EndInst->getIterator(); - if (!Inst->use_empty()) + if (!Inst->use_empty() && !Inst->getType()->isTokenTy()) Inst->replaceAllUsesWith(UndefValue::get(Inst->getType())); - if (Inst->isEHPad()) { + if (Inst->isEHPad() || Inst->getType()->isTokenTy()) { EndInst = Inst; @@ -3022,7 +3022,8 @@ static bool prepareICWorklistFromFunction(Function &F, const DataLayout &DL, ++NumDeadInst; Mad...

...e linked with line 364 in LoadValueNumbering.cpp, The error above suggests that "isa<AllocationInst>(whatever)" was invoked, and in current CVS, the only use of AllocationInst in LoadValueNumbering.cpp is on line 305: if (isa<AllocationInst>(I)) RetVals.push_back(UndefValue::get(LI->getType())); I think changing this to if (isa<AllocationInst>(*I)) RetVals.push_back(UndefValue::get(LI->getType())); should work, and be more robust anyway then relying on implicit interator->value conversion anyway. If you'd want to debug this, try compi...

...== 0) { 09794 // Insert a new store to null instruction before the load to indicate 09795 // that this code is not reachable. We do this instead of inserting 09796 // an unreachable instruction directly because we cannot modify the 09797 // CFG. 09798 new StoreInst(UndefValue::get(LI.getType()), 09799 Constant::getNullValue(Op->getType()), &LI); 09800 return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); 09801 } 09802 } First, what happens to the StoreInst? It looks like it is not attached anywhere. Second, I am seein...

Well, line 364 wasn't actually what was holding me up, so it's a bad example, but the problem's still relevant. Using cast<...>(iter), dyn_cast<...>(iter), or isa<...>(iter) results in the error messages mentioned below. ________________________________ When compiling LoadValueNumbering.cpp, I get the following errors:

..... >> b = f1(smth); >> ... >> } >> >> I need delete from module both f1 and f2. They haven't uses in other >> part of module, but I can't delete them with eraseFromParent, because >> they are use each other. > > Call X->replaceAllUsesWith(UndefValue::get(X->getType)) before calling X->eraseFromParent(). > > Nick -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20120422/a1ef5335/attachment.html>

Hi, For a small case, that calls NULL pointer function. LLVM explicitly converts It to a store because it thinks it is not reachable like calling undefvalue. In InstCombineCalls.cpp:930 I think it is not a right approach because calling null pointer function Will segfault the program. Converting to a store will make program pass Silently. This changes the behavior of a program. So we need remove the case if (isa<ConstantPointerNull>(...

> On May 6, 2020, at 21:53, Krzysztof Parzyszek <kparzysz at quicinc.com> wrote: > > You can > 1. extract individual elements of {i8*, i64}, > 2. bitcast the first to some_struct*, > 3. insert them into a new struct of type {some_struct*, i64}. Thanks for the help. I’m thinking the same way. Now I’m stuck with how to create a struct; I know how to create a

...gt;begin()) { > // Delete the next to last instruction. > Instruction *Inst = &*--EndInst->getIterator(); > - if (!Inst->use_empty()) > + if (!Inst->use_empty() && !Inst->getType()->isTokenTy()) > Inst->replaceAllUsesWith(UndefValue::get(Inst->getType())); > - if (Inst->isEHPad()) { > > + if (Inst->isEHPad() || Inst->getType()->isTokenTy()) { > EndInst = Inst; > @@ -3022,7 +3022,8 @@ static bool prepareICWorklistFromFunction(Function > &F, const DataLayout &DL, >...

...<2 x double>* %2 = load <2 x double>* %1, align 4 what I right now doing is: *Assume pInst is *%1 = load double* %arrayidx1, align 4, !tbaa !0 Value *loadValue = pInst->getOperand(0); Type *vecTy = VectorType::get(Type::getDoublePtrTy(currF->getContext()), 2); Value *emptyVec = UndefValue::get(vecTy); Type* u32Ty = Type::getInt32Ty(currF->getContext()); Value *index0 = ConstantInt::get(u32Ty, 0); Value *index1 = ConstantInt::get(u32Ty, 1); Instruction *InsertVal = InsertElementInst::Create(emptyVec, loadValue, index0, ""); InsertVal = InsertElementInst::Create(emptyV...

...908,18 @@ void SCCPSolver::visitBinaryOperator(Instruction &I) { } // If something is undef, wait for it to resolve. - if (!V1State.isOverdefined() && !V2State.isOverdefined()) - return; + if (!V1State.isOverdefined() && !V2State.isOverdefined()) { + Constant *L = UndefValue::get(I.getOperand(0)->getType()); + if (V1State.isConstant()) + L = V1State.getConstant(); + Constant *R = UndefValue::get(I.getOperand(0)->getType()); + if (V2State.isConstant()) + R = V2State.getConstant(); + Constant *C = ConstantExpr::get(I.getOpcode(), L, R); + i...

...GEPI->getPointerAddressSpace() == 0){ // Insert a new store to null instruction before the load to indicate // that this code is not reachable. We do this instead of inserting // an unreachable instruction directly because we cannot modify the // CFG. new StoreInst(UndefValue::get(LI.getType()), Constant::getNullValue(Op->getType()), &LI); return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); } } > > Thanks, > -- Sanjoy > > On Thu, Dec 4, 2014 at 10:09 PM, Sanjoy Das > <sanjoy at playingwithpointers....

...} >>>> >>>> I need delete from module both f1 and f2. They haven't uses in other >>>> part of module, but I can't delete them with eraseFromParent, because >>>> they are use each other. >>> >>> Call X->replaceAllUsesWith(UndefValue::get(X->getType)) before calling >>> X->eraseFromParent(). >>> >>> Nick >> >> >> >> _______________________________________________ >> LLVM Developers mailing list >> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >...

Chris Lattner wrote: > On Wed, 10 May 2006, Nick Lewycky wrote: > >>> Then just run the SCCP pass, and check to see if any operands satisfy >>> the predicate "isa<UndefValue>(V)". LLVM explicitly represents >>> undefined values. >> >> >> I have a case where it doesn't, but perhaps the SCCP pass isn't to blame: >> >> extern void write_char(int); >> >> const char foo[4] = "foo"; >> >...

...naryOperator(Instruction &I) { > } > > // If something is undef, wait for it to resolve. > - if (!V1State.isOverdefined() && !V2State.isOverdefined()) > - return; > + if (!V1State.isOverdefined() && !V2State.isOverdefined()) { > + Constant *L = UndefValue::get(I.getOperand(0)->getType()); > + if (V1State.isConstant()) > + L = V1State.getConstant(); > + Constant *R = UndefValue::get(I.getOperand(0)->getType()); > + if (V2State.isConstant()) > + R = V2State.getConstant(); > + Constant *C = ConstantExpr::ge...

...gt;begin()) { > // Delete the next to last instruction. > Instruction *Inst = &*--EndInst->getIterator(); > - if (!Inst->use_empty()) > + if (!Inst->use_empty() && !Inst->getType()->isTokenTy()) > Inst->replaceAllUsesWith(UndefValue::get(Inst->getType())); > - if (Inst->isEHPad()) { > > + if (Inst->isEHPad() || Inst->getType()->isTokenTy()) { > EndInst = Inst; > @@ -3022,7 +3022,8 @@ static bool prepareICWorklistFromFunction(Function > &F, const DataLayout &DL, >...

...e resulting code after my pass. I just have some questions about LLVM's dce implementation. Well, my transformation is a function pass, and, after the changes are made, some instructions are not needed anymore. In order to easily get rid of those instructions, I'm setting all their uses to UndefValue. This is necessary because some of the instructions I want to erase are inside loops, and, therefore, there might be a circular dependence between the instruction I want to delete and a PHINode, for example, when both of them are not useful anymore. Ok, the problem is: I've always had explicit...