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.

llvm-svn: 174054

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 1f5548f7798..ae0abde86ad 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -256,6 +256,25 @@ void MCObjectFileInfo::InitELFMCObjectFileInfo(Triple T) {
       TTypeEncoding = (CMModel == CodeModel::Small)
         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
     }
+  }  else if (T.getArch() ==  Triple::aarch64) {
+    FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
+
+    // The small model guarantees static code/data size < 4GB, but not where it
+    // will be in memory. Most of these could end up >2GB away so even a signed
+    // pc-relative 32-bit address is insufficient, theoretically.
+    if (RelocM == Reloc::PIC_) {
+      PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
+        dwarf::DW_EH_PE_sdata8;
+      LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
+      FDEEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
+      TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
+        dwarf::DW_EH_PE_sdata8;
+    } else {
+      PersonalityEncoding = dwarf::DW_EH_PE_absptr;
+      LSDAEncoding = dwarf::DW_EH_PE_absptr;
+      FDEEncoding = dwarf::DW_EH_PE_udata4;
+      TTypeEncoding = dwarf::DW_EH_PE_absptr;
+    }
   } else if (T.getArch() == Triple::ppc64) {
     PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
       dwarf::DW_EH_PE_udata8;