[llvm-dev] Convert Function Pointer Call to Function Call at the IR Level

[mayuyu.io via llvm-dev]

Yep. We encountered similar issue a while ago due to IR linking. A bitcasted function argument would do

Zhang

> 在 2018年8月17日，19:30，Ahmad Nouralizadeh Khorrami via llvm-dev <llvm-dev at lists.llvm.org> 写道：
> 
> Hi.
> It seems that `struct.demuxer.2657*` is different from `struct.demuxer*`. Should I add something like a `bitcast` before the call?
> Thanks!
> 
>> On 16 August 2018 at 15:45, Ahmad Nouralizadeh Khorrami <ahmad.llvm at gmail.com> wrote:
>> Hi,
>> I want to convert a function pointer call in the IR of MPlayer to a function call. For example, I have the following line:
>> ...
>> %10 = tail call i32 %7(%struct.demuxer* nonnull %0, i32 %1, i8* %2) #7, !dbg !863222
>> ...
>> I want to set the target which is stored in %7 to a real function called "demux_lavf_control()" with the following definition:
>> ...
>> define internal i32 @demux_lavf_control(%struct.demuxer.2657* nocapture readonly, i32, i8* nocapture) #0 !dbg !963916 {
>> ...
>> I wrote a function pass and found the mentioned function pointer call (here, stored in "CallInstr") and set the call target as follows:
>> ...
>> Module *theModule = F.getParent();
>> Function *targetFunc = theModule->getFunction("demux_lavf_control");
>> CalIInstr->setCalledFunction(targetFunc);
>> ...
>> "F" is the function containing the call. But it leads to the following error:
>> ...
>> Call parameter type does not match function signature!
>> %struct.demuxer* %0
>>  %struct.demuxer.2657*  %10 = tail call i32 @demux_lavf_control(%struct.demuxer* nonnull %0, i32 %1, i8* %2) #7, !dbg !863222
>> LLVM ERROR: Broken function found, compilation aborted!
>> ...
>> The [names:types] of call operands before the change is:
>> ...
>> [:%struct.demuxer*] 
>> [:i32] 
>> [:i8*] 
>> [:i32 (%struct.demuxer*, i32, i8*)*] 
>> ...
>> And after the change is:
>> ...
>> [:%struct.demuxer*] 
>> [:i32] 
>> [:i8*] 
>> [demux_lavf_control:i32 (%struct.demuxer.2657*, i32, i8*)*] 
>> ...
>> How can I solve the problem?
>> Thanks in advance!
> 
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