llvm dev - Mar 2013 - [LLVMdev] cyclical use between caller and callee

Hi,

I have two functions in a module, X.foo, which is the callee, and
Y.foo2, which calls X.foo.

If i either try to run llvm::Function::eraseFromParent() on any one of
the functions, i'll
get this assertion error:

F is used in instruction:
  %"calling function" = call i32 @X.foo(i32 %read)
F is used in instruction:
  %"calling function" = call i32 @X.foo(i32 %read)
While deleting: i32 (i32)* %X.foo
Use still stuck around after Def is destroyed:  %"calling function"
call i32 @X.foo(i32 %read)
mytests: Value.cpp:75: virtual llvm::Value::~Value(): Assertion
`use_empty() && "Uses remain when a value is destroyed!"'
failed.

regardless of which one i call first.

What is the appropiate way to delete a function from an existing module?

charles quarra wrote:
> Hi,
>
> I have two functions in a module, X.foo, which is the callee, and
> Y.foo2, which calls X.foo.
>
> If i either try to run llvm::Function::eraseFromParent() on any one of
> the functions, i'll
> get this assertion error:
>
> F is used in instruction:
>    %"calling function" = call i32 @X.foo(i32 %read)
> F is used in instruction:
>    %"calling function" = call i32 @X.foo(i32 %read)
> While deleting: i32 (i32)* %X.foo
> Use still stuck around after Def is destroyed:  %"calling
function" > call i32 @X.foo(i32 %read)
> mytests: Value.cpp:75: virtual llvm::Value::~Value(): Assertion
> `use_empty()&&  "Uses remain when a value is
destroyed!"' failed.
>
> regardless of which one i call first.
>
> What is the appropiate way to delete a function from an existing module?
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.

Nick

2013/3/27 Nick Lewycky <nicholas at mxc.ca>:
> charles quarra wrote:
>>
>> Hi,
>>
>> I have two functions in a module, X.foo, which is the callee, and
>> Y.foo2, which calls X.foo.
>>
>> If i either try to run llvm::Function::eraseFromParent() on any one of
>> the functions, i'll
>> get this assertion error:
>>
>> F is used in instruction:
>>    %"calling function" = call i32 @X.foo(i32 %read)
>> F is used in instruction:
>>    %"calling function" = call i32 @X.foo(i32 %read)
>> While deleting: i32 (i32)* %X.foo
>> Use still stuck around after Def is destroyed:  %"calling
function" >> call i32 @X.foo(i32 %read)
>> mytests: Value.cpp:75: virtual llvm::Value::~Value(): Assertion
>> `use_empty()&&  "Uses remain when a value is
destroyed!"' failed.
>>
>>
>> regardless of which one i call first.
>>
>> What is the appropiate way to delete a function from an existing
module?
>
>
> 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 just tried this, passing the type returned by
llvm::Function::getType(), but i get this assertion failure:

  %"calling function" = call i32 @X.foo(i32 %read)
F is used in instruction:
  %"calling function" = call i32 @X.foo(i32 %read)
mytests:
/home/charlesq/third_party/llvm-3.1.src/include/llvm/ADT/ValueMap.h:220:
void llvm::ValueMapCallbackVH<KeyT, ValueT,
Config>::allUsesReplacedWith(llvm::Value*) [with KeyT = const
llvm::Function*; ValueT = {anonymous}::JITEmitter::EmittedCode; Config
= {anonymous}::JITEmitter::EmittedFunctionConfig]: Assertion
`isa<KeySansPointerT>(new_key) && "Invalid RAUW on key of
ValueMap<>"'
failed.


how do i pass a type for the uses such that isa<KeySansPointerT>?