llvm dev - Jan 2013 - [LLVMdev] Inconsistent label syntax in LLVM assembly

Is there a way to get the sizeof a type? Say I've created a struct type
without any explicit attribtues, and I want to call malloc() to allocate space
for it. Can I get the size as an llvm::Constant* (or other llvm::Value*) given
an llvm::StructType* or other llvm::Type*?

TIA,

-- 
Rick

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu]
> On Behalf Of Rick Mann
> Subject: [LLVMdev] Sizeof a type?
> Is there a way to get the sizeof a type?
Look at the methods of the DataLayout class.

 - Chuck 


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On Jan 19, 2013, at 22:32 , "Caldarale, Charles R" <Chuck.Caldarale
at unisys.com> wrote:
> Look at the methods of the DataLayout class.
Thanks! I seem to be able to do this

    llvm::DataLayout* dl = new llvm::DataLayout(module());
    uint64_t myStructSuze = dl->getTypeStoreSize(myStructType);

Is that the correct usage?

-- 
Rick

Hi all,

i'm writing a TXL (http://www.txl.ca) grammar and a revamp of  
bison/flex grammar for LLVM.

I've noticed an inconsistency regarding label naming conventions.

For instance, the following is a segment of legit LLVM assembly  
(human-readable) IR:

   br i1 %38, label %17, label %39
; <label>:39                                      ; preds = %._crit_edge
   ret void

However, ";" is a comment-line character. How is this interpreted, as
a meta-comment? (a semantically important comment)?

Other branches appear using regular conventions:

   br i1 %exitcond, label %._crit_edge, label %.lr.ph
._crit_edge:             ; preds = %.lr.ph, %.preheader

So, naturally I have some questions:

1) What is the differences among the branch labels? Differences in the  
formation (e.g. emitted by different passes?)

2) How to normalize the appearance of branch labels? I.e. is it  
possible to not emit the strange ; <label>:39 like ones?

3) Why <label>:39 and not 39: ?

4) Why not prefixing all labels with <label>?

Best regards
Nikolaos Kavvadias

Hi Rick,

On 20/01/13 06:23, Rick Mann wrote:
> Is there a way to get the sizeof a type? Say I've created a struct type
without any explicit attribtues, and I want to call malloc() to allocate space
for it. Can I get the size as an llvm::Constant* (or other llvm::Value*) given
an llvm::StructType* or other llvm::Type*?
if you have DataLayout available, use the getTypeAllocSize method.  If you
don't
have information about the target then you can use ConstantExpr::getSizeOf.  The
advantage of DataLayout is that it returns a number (eg: 8) while getSizeOf
returns a mysterious expression (the optimizers will simplify it to a number,
the same as getTypeAllocSize returns, if you provide them with DataLayout).

Ciao, Duncan.

On Jan 20, 2013, at 3:21 , Duncan Sands <baldrick at free.fr> wrote:
> if you have DataLayout available, use the getTypeAllocSize method.  If you
don't
> have information about the target then you can use ConstantExpr::getSizeOf.
The
> advantage of DataLayout is that it returns a number (eg: 8) while getSizeOf
> returns a mysterious expression (the optimizers will simplify it to a
number,
> the same as getTypeAllocSize returns, if you provide them with DataLayout).
Thanks, Duncan. What's the difference between DataLayout::getTypeAllocSize
and DataLayout::getTypeStoreSize?

-- 
Rick