[cfe-commits] r91073 - in /cfe/trunk: lib/Sema/SemaDecl.cpp test/Sema/return.c

[Mike Stump]

On Dec 10, 2009, at 4:08 PM, Chris Lattner wrote:
> On Dec 10, 2009, at 2:57 PM, Mike Stump wrote:
> 
>> Author: mrs
>> Date: Thu Dec 10 16:57:48 2009
>> New Revision: 91073
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=91073&view=rev
>> Log:
>> Don't complain about falling off the end of a function with an asm
>> block, if the function is supposed to return a value as we don't know
>> exactly what the asm code does.
> 
> Why?

Because people write code like:

  void* t4(void) { __asm mov eax, fs:[0x10] }

> A fix to silence the warning is to use __builtin_unreachable() after the asm.

But that point is reachable.

Also, int foo() { asm("a: jump a"); } doesn't fall off the end.  Essentially, trying to understand what is inside the asm is a dangerous thing.