llvm dev - Aug 2018 - Convert Function Pointer Call to Function Call at the IR Level

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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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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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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