[LLVMdev] Seeing a crash with ConstantFP::get

[Chuck Rose III]

Hola Dale,

Bumping it up to 3 bits makes everything work hunky dory on the PC side
of my project.  Would you like me to commit that?

Also, after speaking with some VStudio folks, it looks like that issue
will likely remain for VS2k8 as well.

Another trick that was suggested to me was to try something along these
lines:

Enum E : unsigned int { A, B, C, D };

...

Class ... {

E e : 2;

Unsigned int pad : 30;

};

Presumably you could reduce the pad size by switching it to an unsigned
char.  If you had 8 bits total worth of enums, presumably they could all
fit into one.  

I didn't try that one out since your suggestion was simpler and worked.
:-)

Chuck.

-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
On Behalf Of Neil Booth
Sent: Thursday, September 06, 2007 8:18 AM
To: LLVM Developers Mailing List
Subject: Re: [LLVMdev] Seeing a crash with ConstantFP::get

Dale Johannesen wrote:-

> You might argue with that one if you didn't feel like changing your
> compiler, but 9 .6p4 is quite explicit:
> 
> ... If the value of an enumerator is stored into a bitfield
> of the same enumeration type and the number of bits in the bitfield
> is large enough to hold all the values of that enumeration type, the
> original enumerator value and the value of the bitfield
> shall compare equal. [Example:
> enum BOOL { f=0, t=1 };
> struct A {
> BOOL b:1;
> };
> A a;
> void f() {
> a.b = t;
> if (a.b == t) // shall yield true
> { /* ... */ }
> }
> ?end example]
> 
> Looks just like your code.

Good job finding that, thanks. :)
 
> > It would be pretty sad indeed if
> > assigning an enum of that type to the bitfield didn't then compare
> > equal to itself :)
> 
> I agree.  So did the committee.

One they got right then :)

Neil.
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