[LLVMdev] StmtPrinter long double support.

Dale Johannesen dalej at apple.com
Fri Jun 6 09:47:26 PDT 2008

On Jun 6, 2008, at 8:51 AM, Jean-Daniel Dupas wrote:

> Hello,
> I'm playing with llvm/clang and I have a problem when I try to use  
> the -ast-print options for a file that uses long double.
> The Basic/Targets.cpp file defined the x86 (and x86_64) long double  
> type as APFloat::x87DoubleExtended.
> Then, when the AST printer try to write a long double literal value  
> (using VisitFloatingLiteral()), it call FloatingLiteral- 
> >getValueAsDouble() and the later does not support long double, so  
> it try to call convertToDouble() as a fallback and crash due to an  
> invalid assertion. APFloat.cpp:2631: failed assertion `semantics ==  
> (const llvm::fltSemantics*)&IEEEdouble'
> This is a know issue as some there is some comments like "// FIXME:  
> We need something for long double here." in FloatingLiteral- 
> >getValueAsDouble(), and "// FIXME: print value more precisely." in  
> VisitFloatingLiteral().
> I wonder what will be the best way to solve those both issue.  Has  
> somebody planned to add support for long double to APInt and APFloat ?

There are no plans to support the use of host long double anywhere, if  
that's what you mean.

Probably this dumper should use APFloat::convert to get the long  
double into APFloat::IEEEdouble format (with loss of precision; the  
comment claims that's OK), then use convertToDouble on that.  If you  
want full precision, you'll need to print all the bits in hex; see  
EmitGlobalConstant in AsmPrinter.cpp.

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