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, 94 insertions, 0 deletions

diff --git a/test/CodeGen/AArch64/tail-call.ll b/test/CodeGen/AArch64/tail-call.ll
new file mode 100644
index 0000000000..eed6ae5f04
--- /dev/null
+++ b/test/CodeGen/AArch64/tail-call.ll
@@ -0,0 +1,94 @@
+; RUN: llc -verify-machineinstrs < %s -march=aarch64 -tailcallopt | FileCheck %s
+
+declare fastcc void @callee_stack0()
+declare fastcc void @callee_stack8([8 x i32], i64)
+declare fastcc void @callee_stack16([8 x i32], i64, i64)
+
+define fastcc void @caller_to0_from0() nounwind {
+; CHECK: caller_to0_from0:
+; CHECK-NEXT: // BB
+  tail call fastcc void @callee_stack0()
+  ret void
+; CHECK-NEXT: b callee_stack0
+}
+
+define fastcc void @caller_to0_from8([8 x i32], i64) {
+; CHECK: caller_to0_from8:
+
+  tail call fastcc void @callee_stack0()
+  ret void
+; CHECK: add sp, sp, #16
+; CHECK-NEXT: b callee_stack0
+}
+
+define fastcc void @caller_to8_from0() {
+; CHECK: caller_to8_from0:
+; CHECK: sub sp, sp, #32
+
+; Key point is that the "42" should go #16 below incoming stack
+; pointer (we didn't have arg space to reuse).
+  tail call fastcc void @callee_stack8([8 x i32] undef, i64 42)
+  ret void
+; CHECK: str {{x[0-9]+}}, [sp, #16]
+; CHECK-NEXT: add sp, sp, #16
+; CHECK-NEXT: b callee_stack8
+}
+
+define fastcc void @caller_to8_from8([8 x i32], i64 %a) {
+; CHECK: caller_to8_from8:
+; CHECK: sub sp, sp, #16
+
+; Key point is that the "%a" should go where at SP on entry.
+  tail call fastcc void @callee_stack8([8 x i32] undef, i64 42)
+  ret void
+; CHECK: str {{x[0-9]+}}, [sp, #16]
+; CHECK-NEXT: add sp, sp, #16
+; CHECK-NEXT: b callee_stack8
+}
+
+define fastcc void @caller_to16_from8([8 x i32], i64 %a) {
+; CHECK: caller_to16_from8:
+; CHECK: sub sp, sp, #16
+
+; Important point is that the call reuses the "dead" argument space
+; above %a on the stack. If it tries to go below incoming-SP then the
+; callee will not deallocate the space, even in fastcc.
+  tail call fastcc void @callee_stack16([8 x i32] undef, i64 42, i64 2)
+; CHECK: str {{x[0-9]+}}, [sp, #24]
+; CHECK: str {{x[0-9]+}}, [sp, #16]
+; CHECK: add sp, sp, #16
+; CHECK: b callee_stack16
+  ret void
+}
+
+
+define fastcc void @caller_to8_from24([8 x i32], i64 %a, i64 %b, i64 %c) {
+; CHECK: caller_to8_from24:
+; CHECK: sub sp, sp, #16
+
+; Key point is that the "%a" should go where at #16 above SP on entry.
+  tail call fastcc void @callee_stack8([8 x i32] undef, i64 42)
+  ret void
+; CHECK: str {{x[0-9]+}}, [sp, #32]
+; CHECK-NEXT: add sp, sp, #32
+; CHECK-NEXT: b callee_stack8
+}
+
+
+define fastcc void @caller_to16_from16([8 x i32], i64 %a, i64 %b) {
+; CHECK: caller_to16_from16:
+; CHECK: sub sp, sp, #16
+
+; Here we want to make sure that both loads happen before the stores:
+; otherwise either %a or %b will be wrongly clobbered.
+  tail call fastcc void @callee_stack16([8 x i32] undef, i64 %b, i64 %a)
+  ret void
+
+; CHECK: ldr x0,
+; CHECK: ldr x1,
+; CHECK: str x1,
+; CHECK: str x0,
+
+; CHECK: add sp, sp, #16
+; CHECK: b callee_stack16
+}