llvm dev - Sep 2019 - ConstantFP->getType() is not right

Hi, I want to create a double constant from a float constant, here's my
code:

auto* constFloat1
static_cast<llvm::ConstantFP*>(llvm::ConstantFP::get(llvm::Type::getFloatTy(context),
3.1));

  assert(constFloat1->getType() == llvm::Type::getFloatTy(context));


  auto* constFloat2 llvm::ConstantFP::get(llvm::Type::getDoubleTy(context),
constFloat1->getValueAPF());

  assert(constFloat2->getType() == llvm::Type::getDoubleTy(context));

but the second assert failed, the type of constFloat2 is still float, not
double, why?
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The Type passed to llvm::ConstantFP::get is only used to get the context
and to determine if the constant needs to be a vector. The width is taken
from the APFloat passed in. There is an assert in the implementation that
makes sure the scalar type of the type passed in matches the size of the
APFloat. Is your llvm library compiled with asserts enabled?

You can use ConstantExpr::getFPExtend to do what you want.

~Craig


On Wed, Sep 25, 2019 at 7:43 PM Yafei Liu via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi, I want to create a double constant from a float constant, here's my
> code:
>
> auto* constFloat1 >
static_cast<llvm::ConstantFP*>(llvm::ConstantFP::get(llvm::Type::getFloatTy(context),
> 3.1));
>
>   assert(constFloat1->getType() == llvm::Type::getFloatTy(context));
>
>
>   auto* constFloat2 >
llvm::ConstantFP::get(llvm::Type::getDoubleTy(context),
> constFloat1->getValueAPF());
>
>   assert(constFloat2->getType() == llvm::Type::getDoubleTy(context));
>
> but the second assert failed, the type of constFloat2 is still float, not
> double, why?
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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Hi Craig, it works, appreciate your help

On Thu, Sep 26, 2019 at 10:59 AM Craig Topper <craig.topper at gmail.com>
wrote:
> The Type passed to llvm::ConstantFP::get is only used to get the context
> and to determine if the constant needs to be a vector. The width is taken
> from the APFloat passed in. There is an assert in the implementation that
> makes sure the scalar type of the type passed in matches the size of the
> APFloat. Is your llvm library compiled with asserts enabled?
>
> You can use ConstantExpr::getFPExtend to do what you want.
>
> ~Craig
>
>
> On Wed, Sep 25, 2019 at 7:43 PM Yafei Liu via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi, I want to create a double constant from a float constant,
here's my
>> code:
>>
>> auto* constFloat1 >>
static_cast<llvm::ConstantFP*>(llvm::ConstantFP::get(llvm::Type::getFloatTy(context),
>> 3.1));
>>
>>   assert(constFloat1->getType() == llvm::Type::getFloatTy(context));
>>
>>
>>   auto* constFloat2 >>
llvm::ConstantFP::get(llvm::Type::getDoubleTy(context),
>> constFloat1->getValueAPF());
>>
>>   assert(constFloat2->getType() ==
llvm::Type::getDoubleTy(context));
>>
>> but the second assert failed, the type of constFloat2 is still float,
not
>> double, why?
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
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