[LLVMdev] if/then/else implement in LLVM

[Jiaye Wu]

I have known. Anyway, thank you!


On Mon, Jun 23, 2014 at 4:17 PM, Jiaye Wu <wujysh at gmail.com> wrote:

> I want to use LLVM APIs to translate own language to IR code. I implement
> it like below. But I got nothing in if_then tag, and if_else is missing too.
>
>
>>> Value* NIfStatement::codeGen(CodeGenContext& context)
>>
>> {
>>
>>     std::cout << "Creating if statement " << std::endl;
>>
>>
>>>     Value *condValue = condition.codeGen(context);
>>
>>     if (condValue == nullptr) return nullptr;
>>
>>
>>>     std::cout << condValue->getType()->getTypeID() << std::endl;
>>
>>     condValue = new FCmpInst(*context.currentBlock(), CmpInst::FCMP_ONE,
>>
>>                              condValue,
>>> ConstantFP::get(getGlobalContext(), APFloat(0.0)));
>>
>>     Function *function = context.currentBlock()->getParent();
>>
>>
>>>     BasicBlock *thenBlock = BasicBlock::Create(getGlobalContext(),
>>> "if.then", function);
>>
>>     BasicBlock *elseBlock = BasicBlock::Create(getGlobalContext(),
>>> "if.else");
>>
>>     BasicBlock *mergeBlock = BasicBlock::Create(getGlobalContext(),
>>> "if.cont");
>>
>>
>>>     BranchInst::Create(thenBlock, elseBlock, condValue,
>>> context.currentBlock());
>>
>>
>>>
>>>     // create then block
>>
>>     context.pushBlock(thenBlock);
>>
>>
>>>     Value *thenValue = conditionCodeGen(context, thenblock);
>>
>>     if (thenValue == nullptr) return nullptr;
>>
>>     BranchInst::Create(mergeBlock, context.currentBlock());
>>
>>
>>>     context.popBlock();
>>
>>
>>>     // create else block
>>
>>     function->getBasicBlockList().push_back(elseBlock);
>>
>>     context.pushBlock(elseBlock);
>>
>>
>>>     Value *elseValue = conditionCodeGen(context, elseblock);
>>
>>     if (elseValue == nullptr) return nullptr;
>>
>>     BranchInst::Create(mergeBlock, context.currentBlock());
>>
>>
>>>     context.popBlock();
>>
>>
>>>     // create PHI node
>>
>>     function->getBasicBlockList().push_back(mergeBlock);
>>
>>     context.pushBlock(mergeBlock);
>>
>>
>>>     PHINode *PN = PHINode::Create(Type::getVoidTy(getGlobalContext()),
>>> 2, "if.tmp", mergeBlock);
>>
>>     PN->addIncoming(thenValue, thenBlock);
>>
>>     PN->addIncoming(elseValue, elseBlock);
>>
>>
>>>     context.popBlock();
>>
>>
>>>     return PN;
>>
>> }
>>
>>
>>> Value* NIfStatement::conditionCodeGen(CodeGenContext& context,
>>> StatementList& block)
>>
>> {
>>
>>     std::cout << "Generate conditional block" << std::endl;
>>
>>     StatementList::const_iterator it;
>>
>>     Value *last = nullptr;
>>
>>     for (it = block.begin(); it != block.end(); it++) {
>>
>>         std::cout << "Generating code for " << typeid(**it).name() << ' '
>>> << std::endl;
>>
>>         last = (**it).codeGen(context);
>>
>>     }
>>
>>     return last;
>>
>> }
>>
>>
>
> AST:
>
>> class NIfStatement : public NStatement {
>>
>> public:
>>
>>     NBinaryOperator& condition;
>>
>>     StatementList thenblock;
>>
>>     StatementList elseblock;
>>
>>     NIfStatement(NBinaryOperator& condition, StatementList& thenblock) :
>>
>>         condition(condition), thenblock(thenblock) {}
>>
>>     NIfStatement(NBinaryOperator& condition, StatementList& thenblock,
>>> StatementList& elseblock) :
>>
>>         condition(condition), thenblock(thenblock), elseblock(elseblock)
>>> {}
>>
>>     virtual llvm::Value* codeGen(CodeGenContext& context);
>>
>>     virtual llvm::Value* conditionCodeGen(CodeGenContext& context,
>>> StatementList& block);
>>
>> };
>>
>>
> Running result:
>
>> define internal i64 @main() {
>>
>> entry:
>>
>>   %x = alloca i64
>>
>>   %y = alloca i64
>>
>>   %z = alloca i64
>>
>>   %str = alloca double
>>
>>   store i64 5, i64* %z
>>
>>   %0 = load i64* %x
>>
>>   %cmptmp = icmp uge i64 %0, 0
>>
>>   %1 = fcmp one double %booltmp, 0.000000e+00
>>
>>   br i1 %1, label %if.then, label %if.else
>>
>>   ret void
>>
>>
>>> if.then:                                          ; preds = %entry
>>
>> }
>>
>>
>>
> Can anyone help me? What's wrong? Thank you!
>
> --
> *Jiaye Wu*
> Donghua University
>



-- 
*Jiaye Wu*
Donghua University
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