Fix for building ARM/linux using clang.

src/include/concurrency_ops.h

Index: src/include/concurrency_ops.h
diff --git a/src/include/concurrency_ops.h b/src/include/concurrency_ops.h
index 7943520907684216afa41e26b2738df64d2c5a29..e826e0f51209157ad74b6e2496d164f0d3d0bada 100644
--- a/src/include/concurrency_ops.h
+++ b/src/include/concurrency_ops.h
@@ -88,8 +88,9 @@ static INLINE void NaClFlushCacheForDoublyMappedCode(uint8_t *writable_addr,
    * does both.  For background, see:
    * http://code.google.com/p/nativeclient/issues/detail?id=2443
    */
-  __builtin___clear_cache(writable_addr, writable_addr + size);
-  __builtin___clear_cache(executable_addr, executable_addr + size);
+  __builtin___clear_cache((char*)writable_addr, (char*)writable_addr + size);

[Mark Seaborn, 2014/07/23 19:13:41]

What version of Clang did you test against?

It looks like Clang has been fixed to use void* and so match GCC:
http://llvm.org/viewvc/llvm-project?view=revision&revision=181810

[Sam Clegg, 2014/07/23 19:21:52]

clang is coming from the chrome tree: third_party/llvm-build/Release+Asserts

I assume its very recent.

[Mark Seaborn, 2014/07/24 18:45:35]

Ah, the issue is that __clear_cache() and __builtin___clear_cache() have
different types:

include/clang/Basic/Builtins.def:BUILTIN(__builtin___clear_cache, "vc*c*", "n")
include/clang/Basic/BuiltinsARM.def:BUILTIN(__clear_cache, "vv*v*", "i")

It should be OK to change this to use __clear_cache() instead.  Aside from the
type, they appear to behave the same on both GCC and Clang.  They both call
libgcc's __clear_cache().

Can you do a standalone change to change this part?

+  __builtin___clear_cache((char*)executable_addr,
+                          (char*)executable_addr + size);
 #else
   /*
    * Give an error in case we ever target a non-gcc compiler for ARM