Intrinsify String.length() and String.isEmpty() as HIR.

Use HArrayLength for String.length() in anticipation of
changing the String.charAt() to HBoundsCheck+HArrayGet to
allow the existing BCE to seamlessly work for strings.
Use HArrayLength+HEqual for String.isEmpty().

We previously relied on inlining but we now want to apply
the new intrinsics even when we do not inline, i.e. when
compiling debuggable (as is currently the case for boot
image) or when we hit inlining limits, i.e. depth, size,
or the number of accumulated dex registers.

Bug: 28330359
Change-Id: Iab9d2f6d2967bdd930a72eb461f27efe8f37c103

1 files changed, 5 insertions, 0 deletions

diff --git a/compiler/optimizing/code_generator.h b/compiler/optimizing/code_generator.h
index d69c41055b..6e75e3bb2e 100644
--- a/compiler/optimizing/code_generator.h
+++ b/compiler/optimizing/code_generator.h
@@ -340,6 +340,11 @@ class CodeGenerator : public DeletableArenaObject<kArenaAllocCodeGenerator> {
   // Pointer variant for ArtMethod and ArtField arrays.
   size_t GetCachePointerOffset(uint32_t index);
 
+  // Helper that returns the offset of the array's length field.
+  // Note: Besides the normal arrays, we also use the HArrayLength for
+  // accessing the String's `count` field in String intrinsics.
+  static uint32_t GetArrayLengthOffset(HArrayLength* array_length);
+
   void EmitParallelMoves(Location from1,
                          Location to1,
                          Primitive::Type type1,