On Dec 20, 2011, at 8:43 AM, Kelly O'Hair wrote:

> On Dec 19, 2011, at 11:39 PM, Alex Strange wrote:
> 
>>> If you are restricting your builders to Mac OS X 10.7 now, you can actually 
>>> cut over to using clang soon, since it has no known bugs compiling the JDK 
>>> (right Alex? I'm not completely hallucinating this right?)
>>> 
>>> Regards,
>>> Mike Swingler
>>> Apple Inc.
>> Clang works fine to compile jdk. However, the build for hotspot is very 
>> unclean and prints thousands of warnings, because clang enables more 
>> warnings by default than gcc. I resorted to building with "clang -w" as 
>> printing all the warnings actually resulted in a slower compile time than 
>> using llvm-gcc.
>> 
>> Cleaning the build up will take some work, but you should look into it as 
>> Clang is a much faster compiler and uses a newer version of the compiler 
>> backend.
> 
> Please don't fall into the trap of 'it compiles fine'. I'm all for using the 
> latest and greatest compilers,
> but when it comes to building something like hotspot, just be very very 
> careful.
> The fact that clang uses a newer compiler backend make me even more nervous 
> for hotspot and everyone's
> code generation playing well together at runtime.

Of course, it needs to be tested - but Apple has a demonstrated history of not 
letting any legacy technologies live on for long, and I want to ensure that 
JDK8 is on a supported compiler when it comes time to ship. Changing compilers 
mid-product cycle is never fun.

Regards,
Mike Swingler
Apple Inc.

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