[LLVMdev] r72619

Bill Wendling wendling at apple.com
Fri Dec 4 11:49:33 PST 2009

On Dec 4, 2009, at 12:52 AM, Duncan Sands wrote:

> Hi Bill,
>> There's a problem with your check-in for r72619 is causing "weak  
>> external" symbols to appear in C++ code when it shouldn't. Take  
>> this code for example,
>> #include <stdexcept>
>> void dummysymbol() {
>>  throw(std::runtime_error("string"));
>> }
>> The c'tor for std::string is emitted as code from llvm-gcc. It is  
>> then inlined. And a weak external for the `_S_construct' variable  
>> is created. However, C++ rules stipulate that it shouldn't be,  
>> because of explicit & implicit template instantiation rules that  
>> Doug knows about but which makes my head spin.
> I can't reproduce this on x86-64 linux (but maybe I misunderstood  
> what the
> problem is?).  I've attached the bitcode I get at -O4.
>> I'm going to need to revert at least some of these changes. Could  
>> you take a look at this and let me know your thoughts on it?
> Can you please send me the bitcode you get on darwin.

Here's what I get with TOT compiling with -Os. The orig.ll is what I  
get before r72619. Notice that orig.ll has only one function in it.  
Both the one you sent and duncan.ll have more than one function. It's  
not the fact that more than one function is showing up, but these  
functions in particular shouldn't be there because of the implicit/ 
explicit template instantiation stuff.


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