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Add some comments about undef. 

llvm-svn: 103834
This commit is contained in:
Dan Gohman 2010-05-14 23:01:02 +00:00
parent cb78e5558b
commit 62c70559bc
1 changed files with 6 additions and 1 deletions
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7
llvm/include/llvm/Constants.h
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@ -923,7 +923,11 @@ DEFINE_TRANSPARENT_CASTED_OPERAND_ACCESSORS(ConstantExpr, Constant)
/// UndefValue - 'undef' values are things that do not have specified contents.
/// These are used for a variety of purposes, including global variable
/// initializers and operands to instructions. 'undef' values can occur with
/// any type.
/// any first-class type.
///
/// Undef values aren't exactly constants; if they have multiple uses, they
/// can appear to have different bit patterns at each use. See
/// LangRef.html#undefvalues for details.
///
class UndefValue : public Constant {
friend struct ConstantCreator<UndefValue, Type, char>;
@ -954,6 +958,7 @@ public:
return V->getValueID() == UndefValueVal;
}
};
} // End llvm namespace
#endif