AArch64: Fix the usage of Thread Register for arm64
This patch cleans-up the usage of x18 as TR for Arm64. As described in
the Arm64 Procedure Call Standard, the recommended usage for x18 is to
carry inter-procedural state (i.e. ART thread information).
However, since x18 is a temporary register there is no guarantee that on
calls to external functions x18 is preserved. Thus on JNI calls we need
to save and restore x18 before coming back to managed runtime. For the
JNI compiler trampoline we move x18 (temporary register - caller saved)
to x19 (ETR, callee saved) before calling into native code, and
restore it on the way back.
Change-Id: If24091018d640027a497517a9238bf4a80d013aa
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>
3 files changed