[LLVMdev] cyclical use between caller and callee

[charles quarra]

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>?