[LLVMdev] Need help in converting int to double
James Molloy
James.Molloy at arm.com
Fri Sep 23 00:49:39 PDT 2011
Hi Duncan,
Sorry, I haven't had my early morning coffee yet. I meant ptr-to-ptr or ptr-to-vector/vice-versa.
James
-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On Behalf Of Duncan Sands
Sent: 23 September 2011 08:39
To: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] Need help in converting int to double
Hi James,
> The docs are slightly hazy on that - they do mention type-to-type if same size, but the examples are only between pointers and integers, not floats.
you can't use bitcast to convert a pointer to an integer or vice-versa. You
must use ptrtoint/inttoptr.
Ciao, Duncan.
Would it be worthwhile my updating the documentation to explicitly state that
or is it just me?
>
> Cheers,
>
> James
>
> -----Original Message-----
> From: John McCall [mailto:rjmccall at apple.com]
> Sent: 23 September 2011 00:06
> To: James Molloy
> Cc: sarath chandra; llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] Need help in converting int to double
>
> On Sep 22, 2011, at 3:32 AM, James Molloy wrote:
>> It's in trouble by this point because it needs to do a fptosi on a double operand, but you've got an i64 operand and you can't reinterpret-cast ints to floats in LLVM IR (AFAIK)
>
> You can bitcast ints to floats and vice-versa if they're the same size - for example, i32 to float and i64 to double.
>
> John.
>
>
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