Add AArch64 as an experimental target.

This patch adds support for AArch64 (ARM's 64-bit architecture) to
LLVM in the "experimental" category. Currently, it won't be built
unless requested explicitly.

This initial commit should have support for:
    + Assembly of all scalar (i.e. non-NEON, non-Crypto) instructions
      (except the late addition CRC instructions).
    + CodeGen features required for C++03 and C99.
    + Compilation for the "small" memory model: code+static data <
      4GB.
    + Absolute and position-independent code.
    + GNU-style (i.e. "__thread") TLS.
    + Debugging information.

The principal omission, currently, is performance tuning.

This patch excludes the NEON support also reviewed due to an outbreak of
batshit insanity in our legal department. That will be committed soon bringing
the changes to precisely what has been approved.

Further reviews would be gratefully received.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174054 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/projects/sample/autoconf/configure.ac b/projects/sample/autoconf/configure.ac
index 1763ea2..283bc12 100644
--- a/projects/sample/autoconf/configure.ac
+++ b/projects/sample/autoconf/configure.ac
@@ -304,6 +304,7 @@
   sparc*-*)               llvm_cv_target_arch="Sparc" ;;
   powerpc*-*)             llvm_cv_target_arch="PowerPC" ;;
   arm*-*)                 llvm_cv_target_arch="ARM" ;;
+  aarch64*-*)             llvm_cv_target_arch="AArch64" ;;
   mips-* | mips64-*)      llvm_cv_target_arch="Mips" ;;
   mipsel-* | mips64el-*)  llvm_cv_target_arch="Mips" ;;
   xcore-*)                llvm_cv_target_arch="XCore" ;;
@@ -474,6 +475,7 @@
     PowerPC)     AC_SUBST(TARGET_HAS_JIT,1) ;;
     x86_64)      AC_SUBST(TARGET_HAS_JIT,1) ;;
     ARM)         AC_SUBST(TARGET_HAS_JIT,1) ;;
+    AArch64)     AC_SUBST(TARGET_HAS_JIT,0) ;;
     Mips)        AC_SUBST(TARGET_HAS_JIT,1) ;;
     XCore)       AC_SUBST(TARGET_HAS_JIT,0) ;;
     MSP430)      AC_SUBST(TARGET_HAS_JIT,0) ;;
@@ -596,7 +598,7 @@
   enableval=host
 fi
 case "$enableval" in
-  all) TARGETS_TO_BUILD="X86 Sparc PowerPC ARM Mips XCore MSP430 Hexagon CppBackend MBlaze NVPTX" ;;
+  all) TARGETS_TO_BUILD="X86 Sparc PowerPC ARM AArch64 Mips XCore MSP430 Hexagon CppBackend MBlaze NVPTX" ;;
   *)for a_target in `echo $enableval|sed -e 's/,/ /g' ` ; do
       case "$a_target" in
         x86)      TARGETS_TO_BUILD="X86 $TARGETS_TO_BUILD" ;;
@@ -604,6 +606,7 @@
         sparc)    TARGETS_TO_BUILD="Sparc $TARGETS_TO_BUILD" ;;
         powerpc)  TARGETS_TO_BUILD="PowerPC $TARGETS_TO_BUILD" ;;
         arm)      TARGETS_TO_BUILD="ARM $TARGETS_TO_BUILD" ;;
+        aarch64)  TARGETS_TO_BUILD="AArch64 $TARGETS_TO_BUILD" ;;
         mips)     TARGETS_TO_BUILD="Mips $TARGETS_TO_BUILD" ;;
         xcore)    TARGETS_TO_BUILD="XCore $TARGETS_TO_BUILD" ;;
         msp430)   TARGETS_TO_BUILD="MSP430 $TARGETS_TO_BUILD" ;;
@@ -617,6 +620,7 @@
             Sparc)       TARGETS_TO_BUILD="Sparc $TARGETS_TO_BUILD" ;;
             PowerPC)     TARGETS_TO_BUILD="PowerPC $TARGETS_TO_BUILD" ;;
             ARM)         TARGETS_TO_BUILD="ARM $TARGETS_TO_BUILD" ;;
+            AArch64)     TARGETS_TO_BUILD="AArch64 $TARGETS_TO_BUILD" ;;
             Mips)        TARGETS_TO_BUILD="Mips $TARGETS_TO_BUILD" ;;
             MBlaze)      TARGETS_TO_BUILD="MBlaze $TARGETS_TO_BUILD" ;;
             XCore)       TARGETS_TO_BUILD="XCore $TARGETS_TO_BUILD" ;;