Implement bitLength intrinsic on x64.

runtime/vm/assembler_x64_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/os.h"
 #include "vm/unit_test.h"
@@ skipping 602 matching lines @@
 
 
 ASSEMBLER_TEST_RUN(UnsignedDivideLong, test) {
   typedef uint64_t (*UnsignedDivideLong)();
   EXPECT_EQ(0xf000000000000000,
             reinterpret_cast<UnsignedDivideLong>(test->entry())());
 }
 
 
 ASSEMBLER_TEST_GENERATE(Negate, assembler) {
-  __ movl(RCX, Immediate(42));
-  __ negl(RCX);
-  __ movl(RAX, RCX);
+  __ movq(RCX, Immediate(42));

[Cutch, 2015/01/23 22:10:00]

Good catch.

+  __ negq(RCX);
+  __ movq(RAX, RCX);
   __ ret();
 }
 
 
 ASSEMBLER_TEST_RUN(Negate, test) {
   typedef int (*Negate)();
   EXPECT_EQ(-42, reinterpret_cast<Negate>(test->entry())());
 }
 
 
+ASSEMBLER_TEST_GENERATE(BitScanReverse, assembler) {
+  __ pushq(CallingConventions::kArg1Reg);
+  __ movq(RCX, Address(RSP, 0));
+  __ movq(RAX, Immediate(666));  // Marker for conditional write.
+  __ bsrq(RAX, RCX);
+  __ popq(RCX);
+  __ ret();
+}
+
+
+ASSEMBLER_TEST_RUN(BitScanReverse, test) {
+  typedef int (*Bsr)(int input);
+  Bsr call = reinterpret_cast<Bsr>(test->entry());
+  EXPECT_EQ(666, call(0));
+  EXPECT_EQ(0, call(1));
+  EXPECT_EQ(1, call(2));
+  EXPECT_EQ(1, call(3));
+  EXPECT_EQ(2, call(4));
+  EXPECT_EQ(5, call(42));
+  EXPECT_EQ(31, call(-1));
+}
+
+
 ASSEMBLER_TEST_GENERATE(MoveExtend, assembler) {
   __ movq(RDX, Immediate(0xffff));
   __ movzxb(RAX, RDX);  // RAX = 0xff
   __ movsxw(R8, RDX);   // R8 = -1
   __ movzxw(RCX, RDX);  // RCX = 0xffff
   __ addq(R8, RCX);
   __ addq(RAX, R8);
   __ ret();
 }
 
@@ skipping 2904 matching lines @@
   EXPECT_EQ(ICData::kInt64RangeBit, range_of(Integer::New(kMaxInt64)));
   EXPECT_EQ(ICData::kInt64RangeBit, range_of(Integer::New(kMinInt64)));
 
   EXPECT_EQ(0, range_of(Bool::True().raw()));
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64