Apply String.equals() optimizations on arm, arm64 and x86-64.

This is a follow-up to
    https://android-review.googlesource.com/174192

Change-Id: Ie71197df22548d6eb0ca773de6f19fcbb975f065

4 files changed, 51 insertions, 36 deletions

diff --git a/compiler/optimizing/intrinsics_arm.cc b/compiler/optimizing/intrinsics_arm.cc
index de04175e38..5e5e9732a5 100644
--- a/compiler/optimizing/intrinsics_arm.cc
+++ b/compiler/optimizing/intrinsics_arm.cc
@@ -1055,17 +1055,22 @@ void IntrinsicCodeGeneratorARM::VisitStringEquals(HInvoke* invoke) {
   // Note that the null check must have been done earlier.
   DCHECK(!invoke->CanDoImplicitNullCheckOn(invoke->InputAt(0)));
 
-  // Check if input is null, return false if it is.
-  __ CompareAndBranchIfZero(arg, &return_false);
-
-  // Instanceof check for the argument by comparing class fields.
-  // All string objects must have the same type since String cannot be subclassed.
-  // Receiver must be a string object, so its class field is equal to all strings' class fields.
-  // If the argument is a string object, its class field must be equal to receiver's class field.
-  __ ldr(temp, Address(str, class_offset));
-  __ ldr(temp1, Address(arg, class_offset));
-  __ cmp(temp, ShifterOperand(temp1));
-  __ b(&return_false, NE);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ CompareAndBranchIfZero(arg, &return_false);
+  }
+
+  if (!optimizations.GetArgumentIsString()) {
+    // Instanceof check for the argument by comparing class fields.
+    // All string objects must have the same type since String cannot be subclassed.
+    // Receiver must be a string object, so its class field is equal to all strings' class fields.
+    // If the argument is a string object, its class field must be equal to receiver's class field.
+    __ ldr(temp, Address(str, class_offset));
+    __ ldr(temp1, Address(arg, class_offset));
+    __ cmp(temp, ShifterOperand(temp1));
+    __ b(&return_false, NE);
+  }
 
   // Load lengths of this and argument strings.
   __ ldr(temp, Address(str, count_offset));
diff --git a/compiler/optimizing/intrinsics_arm64.cc b/compiler/optimizing/intrinsics_arm64.cc
index 6cd1726eb3..30ab111ffd 100644
--- a/compiler/optimizing/intrinsics_arm64.cc
+++ b/compiler/optimizing/intrinsics_arm64.cc
@@ -1327,21 +1327,26 @@ void IntrinsicCodeGeneratorARM64::VisitStringEquals(HInvoke* invoke) {
   // Note that the null check must have been done earlier.
   DCHECK(!invoke->CanDoImplicitNullCheckOn(invoke->InputAt(0)));
 
-  // Check if input is null, return false if it is.
-  __ Cbz(arg, &return_false);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ Cbz(arg, &return_false);
+  }
 
   // Reference equality check, return true if same reference.
   __ Cmp(str, arg);
   __ B(&return_true, eq);
 
-  // Instanceof check for the argument by comparing class fields.
-  // All string objects must have the same type since String cannot be subclassed.
-  // Receiver must be a string object, so its class field is equal to all strings' class fields.
-  // If the argument is a string object, its class field must be equal to receiver's class field.
-  __ Ldr(temp, MemOperand(str.X(), class_offset));
-  __ Ldr(temp1, MemOperand(arg.X(), class_offset));
-  __ Cmp(temp, temp1);
-  __ B(&return_false, ne);
+  if (!optimizations.GetArgumentIsString()) {
+    // Instanceof check for the argument by comparing class fields.
+    // All string objects must have the same type since String cannot be subclassed.
+    // Receiver must be a string object, so its class field is equal to all strings' class fields.
+    // If the argument is a string object, its class field must be equal to receiver's class field.
+    __ Ldr(temp, MemOperand(str.X(), class_offset));
+    __ Ldr(temp1, MemOperand(arg.X(), class_offset));
+    __ Cmp(temp, temp1);
+    __ B(&return_false, ne);
+  }
 
   // Load lengths of this and argument strings.
   __ Ldr(temp, MemOperand(str.X(), count_offset));
diff --git a/compiler/optimizing/intrinsics_x86.cc b/compiler/optimizing/intrinsics_x86.cc
index 99bc40e71e..e530b90066 100644
--- a/compiler/optimizing/intrinsics_x86.cc
+++ b/compiler/optimizing/intrinsics_x86.cc
@@ -1319,11 +1319,11 @@ void IntrinsicCodeGeneratorX86::VisitStringEquals(HInvoke* invoke) {
     __ j(kEqual, &return_false);
   }
 
-  // Instanceof check for the argument by comparing class fields.
-  // All string objects must have the same type since String cannot be subclassed.
-  // Receiver must be a string object, so its class field is equal to all strings' class fields.
-  // If the argument is a string object, its class field must be equal to receiver's class field.
   if (!optimizations.GetArgumentIsString()) {
+    // Instanceof check for the argument by comparing class fields.
+    // All string objects must have the same type since String cannot be subclassed.
+    // Receiver must be a string object, so its class field is equal to all strings' class fields.
+    // If the argument is a string object, its class field must be equal to receiver's class field.
     __ movl(ecx, Address(str, class_offset));
     __ cmpl(ecx, Address(arg, class_offset));
     __ j(kNotEqual, &return_false);
diff --git a/compiler/optimizing/intrinsics_x86_64.cc b/compiler/optimizing/intrinsics_x86_64.cc
index 06e9cc2b28..2b626be040 100644
--- a/compiler/optimizing/intrinsics_x86_64.cc
+++ b/compiler/optimizing/intrinsics_x86_64.cc
@@ -1416,17 +1416,22 @@ void IntrinsicCodeGeneratorX86_64::VisitStringEquals(HInvoke* invoke) {
   // Note that the null check must have been done earlier.
   DCHECK(!invoke->CanDoImplicitNullCheckOn(invoke->InputAt(0)));
 
-  // Check if input is null, return false if it is.
-  __ testl(arg, arg);
-  __ j(kEqual, &return_false);
-
-  // Instanceof check for the argument by comparing class fields.
-  // All string objects must have the same type since String cannot be subclassed.
-  // Receiver must be a string object, so its class field is equal to all strings' class fields.
-  // If the argument is a string object, its class field must be equal to receiver's class field.
-  __ movl(rcx, Address(str, class_offset));
-  __ cmpl(rcx, Address(arg, class_offset));
-  __ j(kNotEqual, &return_false);
+  StringEqualsOptimizations optimizations(invoke);
+  if (!optimizations.GetArgumentNotNull()) {
+    // Check if input is null, return false if it is.
+    __ testl(arg, arg);
+    __ j(kEqual, &return_false);
+  }
+
+  if (!optimizations.GetArgumentIsString()) {
+    // Instanceof check for the argument by comparing class fields.
+    // All string objects must have the same type since String cannot be subclassed.
+    // Receiver must be a string object, so its class field is equal to all strings' class fields.
+    // If the argument is a string object, its class field must be equal to receiver's class field.
+    __ movl(rcx, Address(str, class_offset));
+    __ cmpl(rcx, Address(arg, class_offset));
+    __ j(kNotEqual, &return_false);
+  }
 
   // Reference equality check, return true if same reference.
   __ cmpl(str, arg);