x86_64: Fix neg_double

In a case, when src and dest regs are the same, previous
implementation of the neg_double bytecode returns an
incorrect result.

This implementation uses shifts and xor and works for both
cases.

Change-Id: I137d9a90298ec225d80435d35558da8abb69cd01
Signed-off-by: Alexei Zavjalov <alexei.zavjalov@intel.com>

4 files changed, 38 insertions, 2 deletions

diff --git a/compiler/dex/quick/x86/fp_x86.cc b/compiler/dex/quick/x86/fp_x86.cc
index 20bb7bf..1f05ab9 100644
--- a/compiler/dex/quick/x86/fp_x86.cc
+++ b/compiler/dex/quick/x86/fp_x86.cc
@@ -568,8 +568,11 @@ void X86Mir2Lir::GenNegDouble(RegLocation rl_dest, RegLocation rl_src) {
   rl_src = LoadValueWide(rl_src, kCoreReg);
   rl_result = EvalLocWide(rl_dest, kCoreReg, true);
   if (Gen64Bit()) {
-    LoadConstantWide(rl_result.reg, 0x8000000000000000);
-    OpRegReg(kOpAdd, rl_result.reg, rl_src.reg);
+    OpRegCopy(rl_result.reg, rl_src.reg);
+    // Flip sign bit.
+    NewLIR2(kX86Rol64RI, rl_result.reg.GetReg(), 1);
+    NewLIR2(kX86Xor64RI, rl_result.reg.GetReg(), 1);
+    NewLIR2(kX86Ror64RI, rl_result.reg.GetReg(), 1);
   } else {
     OpRegRegImm(kOpAdd, rl_result.reg.GetHigh(), rl_src.reg.GetHigh(), 0x80000000);
     OpRegCopy(rl_result.reg, rl_src.reg);
diff --git a/test/112-double-math/expected.txt b/test/112-double-math/expected.txt
new file mode 100644
index 0000000..1e10a95
--- /dev/null
+++ b/test/112-double-math/expected.txt
@@ -0,0 +1 @@
+cond_neg_double PASSED
diff --git a/test/112-double-math/info.txt b/test/112-double-math/info.txt
new file mode 100644
index 0000000..a32f4e0
--- /dev/null
+++ b/test/112-double-math/info.txt
@@ -0,0 +1 @@
+This checks the neg_double bytecode.
diff --git a/test/112-double-math/src/Main.java b/test/112-double-math/src/Main.java
new file mode 100644
index 0000000..8172dfa
--- /dev/null
+++ b/test/112-double-math/src/Main.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+public class Main {
+    public static double cond_neg_double(double value, boolean cond) {
+        return cond ? -value : value;
+    }
+
+    public static void main(String args[]) {
+        double result = cond_neg_double(-1.0d, true);
+
+        if (Double.doubleToRawLongBits(result) == 0x3ff0000000000000L) {
+            System.out.println("cond_neg_double PASSED");
+        } else {
+            System.out.println("cond_neg_double FAILED " + result);
+        }
+    }
+}