Improve code generation for ARM64 VisitArrayGet/Set.

We prefer the code sequence
   add temp, obj, #offset
   ldr out, [temp, index LSL #shift_amount]
to
   add temp, obj, index LSL #shift_amount
   ldr out, [temp, #offset]

Change-Id: I98f51a1b5a5ecd84c677d6dbd4c4bfc0f157f5e2

1 files changed, 9 insertions, 0 deletions

diff --git a/compiler/optimizing/common_arm64.h b/compiler/optimizing/common_arm64.h
index 246fff99ac..f54547534f 100644
--- a/compiler/optimizing/common_arm64.h
+++ b/compiler/optimizing/common_arm64.h
@@ -151,6 +151,15 @@ static inline vixl::MemOperand HeapOperand(const vixl::Register& base, size_t of
   return vixl::MemOperand(base.X(), offset);
 }
 
+static inline vixl::MemOperand HeapOperand(const vixl::Register& base,
+                                           const vixl::Register& regoffset,
+                                           vixl::Shift shift = vixl::LSL,
+                                           unsigned shift_amount = 0) {
+  // A heap reference must be 32bit, so fit in a W register.
+  DCHECK(base.IsW());
+  return vixl::MemOperand(base.X(), regoffset, shift, shift_amount);
+}
+
 static inline vixl::MemOperand HeapOperand(const vixl::Register& base, Offset offset) {
   return HeapOperand(base, offset.SizeValue());
 }