llvm dev - Nov 2012 - [LLVMdev] Instruction does not dominate all uses! <badref> ??

I'm having trouble figuring out what the error "Instruction does not
dominate all uses!" means. I'm trying to construct a call to a function
with two parameters. The printed IR, with error, looks like this:

define i32 @add(i32, i32) {
EntryBlock:
  %2 = add i32 %0, %1
  ret i32 %2
}

define i32 @eval_expr() {
EntryBlock:
  ret i32 <badref>
}

Instruction does not dominate all uses!
  <badref> = call i32 @add(i32 2, i32 3)
  ret i32 <badref>


And the approximate/simplified code I'm using to generate the call,
which would appear at <badref> is:

	llvm::Value * func = module->getFunction( "add" );
	
	std::vector<llvm::Value*> args;
	args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
*context ), 2 ) );
	args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
*context ), 3 ) );
	
	llvm::ArrayRef<llvm::Value*> ar_args( args );
	return llvm::CallInst::Create( func, ar_args );




-- 
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Hi edA-qa mort-ora-y,

On 02/11/12 10:20, edA-qa mort-ora-y wrote:
> I'm having trouble figuring out what the error "Instruction does
not
> dominate all uses!" means. I'm trying to construct a call to a
function
> with two parameters. The printed IR, with error, looks like this:
>
> define i32 @add(i32, i32) {
> EntryBlock:
>    %2 = add i32 %0, %1
>    ret i32 %2
> }
>
> define i32 @eval_expr() {
> EntryBlock:
>    ret i32 <badref>
> }
>
> Instruction does not dominate all uses!
>    <badref> = call i32 @add(i32 2, i32 3)
>    ret i32 <badref>
Looks like you forgot to add the call instruction to EntryBlock.
>
>
> And the approximate/simplified code I'm using to generate the call,
> which would appear at <badref> is:
>
> 	llvm::Value * func = module->getFunction( "add" );
> 	
> 	std::vector<llvm::Value*> args;
> 	args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
> *context ), 2 ) );
> 	args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
> *context ), 3 ) );
> 	
> 	llvm::ArrayRef<llvm::Value*> ar_args( args );
> 	return llvm::CallInst::Create( func, ar_args );
^ Didn't add it to a basic block.

Ciao, Duncan.
>
>
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

On 02/11/12 11:55, Duncan Sands wrote:
> Looks like you forgot to add the call instruction to EntryBlock.
> ^ Didn't add it to a basic block.
I forget to past that part. This is how I add it to a block:

	auto f = llvm::cast<llvm::Function>( module->getOrInsertFunction(
"eval_expr",
		llvm::Type::getInt32Ty( *context ), (llvm::Type*)0 ) );
		
	auto bb = llvm::BasicBlock::Create( *context, "EntryBlock", f );
	llvm::IRBuilder<true,llvm::NoFolder> builder( bb );
	
	builder.CreateRet( expr_i_showed_before );	

	return f;

Or do I have to create another block to do the calls?


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edA-qa mort-ora-y wrote:
> I'm having trouble figuring out what the error "Instruction does
not
> dominate all uses!" means. I'm trying to construct a call to a
function
> with two parameters. The printed IR, with error, looks like this:
>
> define i32 @add(i32, i32) {
> EntryBlock:
>    %2 = add i32 %0, %1
>    ret i32 %2
> }
>
> define i32 @eval_expr() {
> EntryBlock:
>    ret i32<badref>
> }
>
> Instruction does not dominate all uses!
>    <badref>  = call i32 @add(i32 2, i32 3)
>    ret i32<badref>
It's correct but not entirely helpful. You've got an instruction in 
function @eval_expr whose operand is an instruction in an entirely 
different function (or in no function at all).
> And the approximate/simplified code I'm using to generate the call,
> which would appear at<badref>  is:
>
> 	llvm::Value * func = module->getFunction( "add" );
> 	
> 	std::vector<llvm::Value*>  args;
> 	args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
> *context ), 2 ) );
> 	args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
> *context ), 3 ) );
> 	
> 	llvm::ArrayRef<llvm::Value*>  ar_args( args );
> 	return llvm::CallInst::Create( func, ar_args );
This creates a CallInst but doesn't insert it into any basic block.

Nick

Okay, I've think I understand now. By using a "Value" object (like
a
function call) in another instruction does nothing more than use a
reference to that value. It is still my responsibility to ensure that
value/reference is actually created prior to its use in the block.

On 02/11/12 12:16, Nick Lewycky wrote:
> edA-qa mort-ora-y wrote:
>> I'm having trouble figuring out what the error "Instruction
does not
>> dominate all uses!" means. I'm trying to construct a call to a
function
>> with two parameters. The printed IR, with error, looks like this:
>>
>> define i32 @add(i32, i32) {
>> EntryBlock:
>>    %2 = add i32 %0, %1
>>    ret i32 %2
>> }
>>
>> define i32 @eval_expr() {
>> EntryBlock:
>>    ret i32<badref>
>> }
>>
>> Instruction does not dominate all uses!
>>    <badref>  = call i32 @add(i32 2, i32 3)
>>    ret i32<badref>
> 
> It's correct but not entirely helpful. You've got an instruction in
> function @eval_expr whose operand is an instruction in an entirely
> different function (or in no function at all).
> 
>> And the approximate/simplified code I'm using to generate the call,
>> which would appear at<badref>  is:
>>
>>     llvm::Value * func = module->getFunction( "add" );
>>     
>>     std::vector<llvm::Value*>  args;
>>     args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
>> *context ), 2 ) );
>>     args.push_back( llvm::ConstantInt::get( llvm::Type::getInt32Ty(
>> *context ), 3 ) );
>>     
>>     llvm::ArrayRef<llvm::Value*>  ar_args( args );
>>     return llvm::CallInst::Create( func, ar_args );
> 
> This creates a CallInst but doesn't insert it into any basic block.
> 
> Nick
> 
> 

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