commit ee34f594881ac2d859113db33baf5e141f5a58dd
author Elliott Hughes <enh@google.com> Mon Apr 05 18:13:52 2010 -0700
committer Elliott Hughes <enh@google.com> Thu Apr 08 15:53:10 2010 -0700
tree 46054403ccc8b27c821563574f7be6cfe70e50b4
parent 3517705eed1cd8dc9cb0386db952de661623b2df

An InlineNative for String.isEmpty, so it's not slower than length() == 0.

Before:

       benchmark  ns logarithmic runtime
         IsEmpty  115 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
LengthEqualsZero   21 XXXXX||||||||||||||

With C intrinsic:

          IsEmpty  30 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 LengthEqualsZero  20 XXXXXXXXXXXXXXXXXXXX||||||

With assembler intrinsic:

          IsEmpty  15 XXXXXXXXXXXXXXXXXXXX||||||
 LengthEqualsZero  21 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

(All times on passion.)

Change-Id: Ifcc37fe7b8efdd377675a448e0085e490d6767bc

vm/compiler/codegen/arm/Assemble.c

diff --git a/vm/compiler/codegen/arm/Assemble.c b/vm/compiler/codegen/arm/Assemble.c
index 493f95e..61c2338 100644
--- a/vm/compiler/codegen/arm/Assemble.c
+++ b/vm/compiler/codegen/arm/Assemble.c
@@ -651,7 +651,7 @@
                  kFmtBitBlt, 11, 8, kFmtBitBlt, 19, 16, kFmtBitBlt, 3, 0,
                  kFmtShift, -1, -1,
                  IS_QUAD_OP | REG_DEF0_USE12 | SETS_CCODES,
-                 "acds", "r!0d, r!1d, r!2d, shift !3d", 2),
+                 "adcs", "r!0d, r!1d, r!2d, shift !3d", 2),
     ENCODING_MAP(kThumb2AndRRR,  0xea000000,
                  kFmtBitBlt, 11, 8, kFmtBitBlt, 19, 16, kFmtBitBlt, 3, 0,
                  kFmtShift, -1, -1, IS_QUAD_OP | REG_DEF0_USE12,