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

1 files changed, 24 insertions, 0 deletions

diff --git a/test/CodeGen/AArch64/atomic-ops-not-barriers.ll b/test/CodeGen/AArch64/atomic-ops-not-barriers.ll
new file mode 100644
index 0000000..f383d76
--- /dev/null
+++ b/test/CodeGen/AArch64/atomic-ops-not-barriers.ll
@@ -0,0 +1,24 @@
+; RUN: llc -march=aarch64 < %s | FileCheck %s
+
+define i32 @foo(i32* %var, i1 %cond) {
+; CHECK: foo:
+  br i1 %cond, label %atomic_ver, label %simple_ver
+simple_ver:
+  %oldval = load i32* %var
+  %newval = add nsw i32 %oldval, -1
+  store i32 %newval, i32* %var
+  br label %somewhere
+atomic_ver:
+  %val = atomicrmw add i32* %var, i32 -1 seq_cst
+  br label %somewhere
+; CHECK: dmb
+; CHECK: ldxr
+; CHECK: dmb
+  ; The key point here is that the second dmb isn't immediately followed by the
+  ; simple_ver basic block, which LLVM attempted to do when DMB had been marked
+  ; with isBarrier. For now, look for something that looks like "somewhere".
+; CHECK-NEXT: mov
+somewhere:
+  %combined = phi i32 [ %val, %atomic_ver ], [ %newval, %simple_ver]
+  ret i32 %combined
+}