[PATCH][PowerPC] Fix BlockAddress access on ppc64

[Ulrich Weigand]

Hello,

Anton noticed that code using the GCC extension to take the address of a
block label (which is used e.g. in Linux kernel code):

  __label__ here;
here:
  printf ("current address: %p\n", &&here);

is miscompiled on ppc64 since it directly accesses the label value via @l /
@ha, which fails if the code is linked to an address > 2GB.

The attached patch fixes this by loading such values from the TOC, as is
done for any other global symbol.
(See attached file: diff-llvm-ppc64-blockaddress)

OK for mainline?


Mit freundlichen Gruessen / Best Regards

Ulrich Weigand

--
  Dr. Ulrich Weigand | Phone: +49-7031/16-3727
  STSM, GNU/Linux compilers and toolchain
  IBM Deutschland Research & Development GmbH
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