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Ahmad Nouralizadeh via llvm-dev

2018-Aug-08 16:29 UTC

[llvm-dev] Error Calling eraseFromParent()

Hi. Thanks. I changed the code but the problem exists. This is my new code
which is again very simple:
...
bool runOnFunction(Function &F) override {

vector<Instruction *> dels;
dels.clear();

for (inst_iterator It = inst_begin(&F), Ie = inst_end(&F); It != Ie;) {
Instruction *I = &*(It++);

if (auto* op = dyn_cast<BinaryOperator>(I)) {
IRBuilder<NoFolder> builder(op);

Value* lhs = op->getOperand(0);
Value* rhs = op->getOperand(1);
Value* mul = builder.CreateMul(lhs, rhs);

for (auto& U : op->uses()) {
  User* user = U.getUser();
  user->setOperand(U.getOperandNo(), mul);
}
//I->eraseFromParent();
dels.push_back(I);
}
}

for (auto &I : dels) {
I->eraseFromParent();
}
...

On Wed, Aug 8, 2018 at 6:16 PM, mayuyu.io <admin at mayuyu.io> wrote:
> Hi:
> As stated in the documentation you shouldn’t modify it while iterating as
> this invalidates the iterator. Try save the pointers to a vector outside
> your loop and perform erasing in a new loop following your current one.
>
> Zhang
>
> 在 2018年8月8日，07:54，Ahmad Nouralizadeh via llvm-dev <llvm-dev at
lists.llvm.org>
> 写道：
>
> Thanks Bjorn! But The problem is still there.
>
> On Wed, Aug 8, 2018 at 2:04 AM, Björn Pettersson A <
> bjorn.a.pettersson at ericsson.com> wrote:
>
>> It looks quite dangerous to erase the instruction I inside the loop
when
>> iterating over all instructions in the function.
>> I guess it depends on how the range based iterator is implemented if
that
>> works or not.
>>
>> I think that you, for example, can change the range based iteration
>>
>>    for (auto &I : instructions(F))
>>
>> into something like this
>>
>>    for (inst_iterator It = inst_begin(&F), Ie = inst_end(&F);
It != Ie;) {
>>       Instruction *I = &*(It++);
>>       ...
>>     }
>>
>> That will make sure that you step the iterator before modifying the
data
>> structure you iterate over.
>>
>> Regards,
>> Björn
>> ________________________________________
>> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of
Ahmad
>> Nouralizadeh via llvm-dev <llvm-dev at lists.llvm.org>
>> Sent: Tuesday, August 7, 2018 22:26
>> To: paul.robinson at sony.com
>> Cc: llvm-dev at lists.llvm.org
>> Subject: Re: [llvm-dev] Error Calling eraseFromParent()
>>
>> The code is really simple. But I can not the reason for the
segmentation
>> fault. I only know that the eraseFromParent() function leads to it. The
>> whole code is:
>> ...
>> bool runOnFunction(Function &F) override {
>>
>> for (auto &I : instructions(F)) {
>>
>> if (auto* op = dyn_cast<BinaryOperator>(&I)) {
>> IRBuilder<> builder(op);
>>
>> Value* lhs = op->getOperand(0);
>> Value* rhs = op->getOperand(1);
>> Value* mul = builder.CreateMul(lhs, rhs);
>>
>> for (auto& U : op->uses()) {
>>   User* user = U.getUser();
>>   user->setOperand(U.getOperandNo(), mul);
>> }
>>
>> I.eraseFromParent();
>>     }
>>
>> }
>> ...
>> And I think that the code worked well with LLVM-3.6.0 that I tested one
>> year ago. Now, I use LLVM-6.0.0.
>> Regards.
>>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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mayuyu.io via llvm-dev

2018-Aug-08 16:33 UTC

head link

[llvm-dev] Error Calling eraseFromParent()

Hmmmm that’s strange. Do you get an assert when you build LLVM with this code in
Debug Mode or is it simply null pointer dereference?
On a side note, usually when doing transforms similar to yours I use IRBuilder’s
CreateXXX followed by a ReplaceInstWithInst which works perfectly fine for me.

Zhang
> 在 2018年8月9日，00:29，Ahmad Nouralizadeh <ahmadnouralizadeh at gmail.com>
写道：
> 
> Hi. Thanks. I changed the code but the problem exists. This is my new code
which is again very simple:
> ...
> bool runOnFunction(Function &F) override {
> 
> vector<Instruction *> dels;
> dels.clear();
> 
> for (inst_iterator It = inst_begin(&F), Ie = inst_end(&F); It !=
Ie;) {
> 	Instruction *I = &*(It++);
> 
> 	if (auto* op = dyn_cast<BinaryOperator>(I)) {
> 		IRBuilder<NoFolder> builder(op);
> 
> 		Value* lhs = op->getOperand(0);
> 		Value* rhs = op->getOperand(1);
> 		Value* mul = builder.CreateMul(lhs, rhs);
> 
> 		for (auto& U : op->uses()) {
> 		  User* user = U.getUser();
> 		  user->setOperand(U.getOperandNo(), mul);
> 		}
> 		//I->eraseFromParent();
> 		dels.push_back(I);
> 	}
> }	
> 
> for (auto &I : dels) {
> 	I->eraseFromParent();
> }
> ...
> 
>> On Wed, Aug 8, 2018 at 6:16 PM, mayuyu.io <admin at mayuyu.io>
wrote:
>> Hi:
>> As stated in the documentation you shouldn’t modify it while iterating
as this invalidates the iterator. Try save the pointers to a vector outside your
loop and perform erasing in a new loop following your current one.
>> 
>> Zhang
>> 
>>> 在 2018年8月8日，07:54，Ahmad Nouralizadeh via llvm-dev <llvm-dev at
lists.llvm.org> 写道：
>>> 
>>> Thanks Bjorn! But The problem is still there.
>>> 
>>>> On Wed, Aug 8, 2018 at 2:04 AM, Björn Pettersson A
<bjorn.a.pettersson at ericsson.com> wrote:
>>>> It looks quite dangerous to erase the instruction I inside the
loop when iterating over all instructions in the function.
>>>> I guess it depends on how the range based iterator is
implemented if that works or not.
>>>> 
>>>> I think that you, for example, can change the range based
iteration
>>>> 
>>>>    for (auto &I : instructions(F))
>>>> 
>>>> into something like this
>>>> 
>>>>    for (inst_iterator It = inst_begin(&F), Ie =
inst_end(&F); It != Ie;) {
>>>>       Instruction *I = &*(It++);
>>>>       ...
>>>>     }
>>>> 
>>>> That will make sure that you step the iterator before modifying
the data structure you iterate over.
>>>> 
>>>> Regards,
>>>> Björn
>>>> ________________________________________
>>>> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on
behalf of Ahmad Nouralizadeh via llvm-dev <llvm-dev at lists.llvm.org>
>>>> Sent: Tuesday, August 7, 2018 22:26
>>>> To: paul.robinson at sony.com
>>>> Cc: llvm-dev at lists.llvm.org
>>>> Subject: Re: [llvm-dev] Error Calling eraseFromParent()
>>>> 
>>>> The code is really simple. But I can not the reason for the
segmentation fault. I only know that the eraseFromParent() function leads to it.
The whole code is:
>>>> ...
>>>> bool runOnFunction(Function &F) override {
>>>> 
>>>> for (auto &I : instructions(F)) {
>>>> 
>>>> if (auto* op = dyn_cast<BinaryOperator>(&I)) {
>>>> IRBuilder<> builder(op);
>>>> 
>>>> Value* lhs = op->getOperand(0);
>>>> Value* rhs = op->getOperand(1);
>>>> Value* mul = builder.CreateMul(lhs, rhs);
>>>> 
>>>> for (auto& U : op->uses()) {
>>>>   User* user = U.getUser();
>>>>   user->setOperand(U.getOperandNo(), mul);
>>>> }
>>>> 
>>>> I.eraseFromParent();
>>>>     }
>>>> 
>>>> }
>>>> ...
>>>> And I think that the code worked well with LLVM-3.6.0 that I
tested one year ago. Now, I use LLVM-6.0.0.
>>>> Regards.
>>> 
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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Ahmad Nouralizadeh via llvm-dev

2018-Aug-08 17:30 UTC

head link

[llvm-dev] Error Calling eraseFromParent()

LLVM is built in Release mode. The version is 6.0.0. I think that a similar
code worked on verison 3.9.0. It is probably a null pointer dereference
occurring in eraseFromParent(). I checked and reconfirmed that the
instruction had no uses. Perhaps I should rebuild LLVM. Thanks.

On Wed, Aug 8, 2018 at 9:03 PM, mayuyu.io <admin at mayuyu.io> wrote:
> Hmmmm that’s strange. Do you get an assert when you build LLVM with this
> code in Debug Mode or is it simply null pointer dereference?
> On a side note, usually when doing transforms similar to yours I use
> IRBuilder’s CreateXXX followed by a ReplaceInstWithInst which works
> perfectly fine for me.
>
> Zhang
>
> 在 2018年8月9日，00:29，Ahmad Nouralizadeh <ahmadnouralizadeh at gmail.com>
写道：
>
> Hi. Thanks. I changed the code but the problem exists. This is my new code
> which is again very simple:
> ...
> bool runOnFunction(Function &F) override {
>
> vector<Instruction *> dels;
> dels.clear();
>
> for (inst_iterator It = inst_begin(&F), Ie = inst_end(&F); It !=
Ie;) {
> Instruction *I = &*(It++);
>
> if (auto* op = dyn_cast<BinaryOperator>(I)) {
> IRBuilder<NoFolder> builder(op);
>
> Value* lhs = op->getOperand(0);
> Value* rhs = op->getOperand(1);
> Value* mul = builder.CreateMul(lhs, rhs);
>
> for (auto& U : op->uses()) {
>   User* user = U.getUser();
>   user->setOperand(U.getOperandNo(), mul);
> }
> //I->eraseFromParent();
> dels.push_back(I);
> }
> }
>
> for (auto &I : dels) {
> I->eraseFromParent();
> }
> ...
>
> On Wed, Aug 8, 2018 at 6:16 PM, mayuyu.io <admin at mayuyu.io> wrote:
>
>> Hi:
>> As stated in the documentation you shouldn’t modify it while iterating
as
>> this invalidates the iterator. Try save the pointers to a vector
outside
>> your loop and perform erasing in a new loop following your current one.
>>
>> Zhang
>>
>> 在 2018年8月8日，07:54，Ahmad Nouralizadeh via llvm-dev <
>> llvm-dev at lists.llvm.org> 写道：
>>
>> Thanks Bjorn! But The problem is still there.
>>
>> On Wed, Aug 8, 2018 at 2:04 AM, Björn Pettersson A <
>> bjorn.a.pettersson at ericsson.com> wrote:
>>
>>> It looks quite dangerous to erase the instruction I inside the loop
when
>>> iterating over all instructions in the function.
>>> I guess it depends on how the range based iterator is implemented
if
>>> that works or not.
>>>
>>> I think that you, for example, can change the range based iteration
>>>
>>>    for (auto &I : instructions(F))
>>>
>>> into something like this
>>>
>>>    for (inst_iterator It = inst_begin(&F), Ie =
inst_end(&F); It != Ie;)
>>> {
>>>       Instruction *I = &*(It++);
>>>       ...
>>>     }
>>>
>>> That will make sure that you step the iterator before modifying the
data
>>> structure you iterate over.
>>>
>>> Regards,
>>> Björn
>>> ________________________________________
>>> From: llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf
of Ahmad
>>> Nouralizadeh via llvm-dev <llvm-dev at lists.llvm.org>
>>> Sent: Tuesday, August 7, 2018 22:26
>>> To: paul.robinson at sony.com
>>> Cc: llvm-dev at lists.llvm.org
>>> Subject: Re: [llvm-dev] Error Calling eraseFromParent()
>>>
>>> The code is really simple. But I can not the reason for the
segmentation
>>> fault. I only know that the eraseFromParent() function leads to it.
The
>>> whole code is:
>>> ...
>>> bool runOnFunction(Function &F) override {
>>>
>>> for (auto &I : instructions(F)) {
>>>
>>> if (auto* op = dyn_cast<BinaryOperator>(&I)) {
>>> IRBuilder<> builder(op);
>>>
>>> Value* lhs = op->getOperand(0);
>>> Value* rhs = op->getOperand(1);
>>> Value* mul = builder.CreateMul(lhs, rhs);
>>>
>>> for (auto& U : op->uses()) {
>>>   User* user = U.getUser();
>>>   user->setOperand(U.getOperandNo(), mul);
>>> }
>>>
>>> I.eraseFromParent();
>>>     }
>>>
>>> }
>>> ...
>>> And I think that the code worked well with LLVM-3.6.0 that I tested
one
>>> year ago. Now, I use LLVM-6.0.0.
>>> Regards.
>>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
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llvm dev - Aug 2018 - Error Calling eraseFromParent()

[llvm-dev] Error Calling eraseFromParent()

[llvm-dev] Error Calling eraseFromParent()

[llvm-dev] Error Calling eraseFromParent()