commit 37af46385e24afddee1b609d9e30750ae06cb84d
author Ulya Trafimovich <skvadrik@google.com> Thu Jan 13 15:27:38 2022 +0000
committer Ulya Trofimovich <skvadrik@google.com> Fri Jan 14 12:29:47 2022 +0000
tree 3abec9cd6a61ddb7730c8bddef9187efedec9ca8
parent bb2643f6ed81872847ee6c45733ff7e25a3f0e90

x86: Implement Unsafe.compareAndSetObject intrinsic.

The implementation is the same as Unsafe.compareAndSwapObject, as the
latter operation has compare-and-set semantics.

Benchmarks improvements (using benchmarks provided by
https://android-review.googlesource.com/1420959):

  benchmark                              before   after
  -----------------------------------------------------
  UnsafeCompareAndSetStaticFieldString   1.442    0.011
  UnsafeCompareAndSetFieldString         1.446    0.009

Bug: 71781600
Test: ART_HEAP_POISONING=true m build-art-host-tests \
        && art/test.py --host -r -t 712-varhandle-invocations --32
Change-Id: I325e1f09d3b4d016d43657604be9a2d5b910e68a

compiler/optimizing/intrinsics_x86.cc

diff --git a/compiler/optimizing/intrinsics_x86.cc b/compiler/optimizing/intrinsics_x86.cc
index 6015a6d..c9c8a5a 100644
--- a/compiler/optimizing/intrinsics_x86.cc
+++ b/compiler/optimizing/intrinsics_x86.cc
@@ -2070,7 +2070,8 @@
   bool can_call = kEmitCompilerReadBarrier &&
       kUseBakerReadBarrier &&
       (invoke->GetIntrinsic() == Intrinsics::kUnsafeCASObject ||
-       invoke->GetIntrinsic() == Intrinsics::kJdkUnsafeCASObject);
+       invoke->GetIntrinsic() == Intrinsics::kJdkUnsafeCASObject ||
+       invoke->GetIntrinsic() == Intrinsics::kJdkUnsafeCompareAndSetObject);
   LocationSummary* locations =
       new (allocator) LocationSummary(invoke,
                                       can_call
@@ -2116,21 +2117,18 @@
 }
 
 void IntrinsicLocationsBuilderX86::VisitJdkUnsafeCASInt(HInvoke* invoke) {
-  CreateIntIntIntIntIntToInt(allocator_, DataType::Type::kInt32, invoke);
+  // `jdk.internal.misc.Unsafe.compareAndSwapObject` has compare-and-set semantics (see javadoc).
+  VisitJdkUnsafeCompareAndSetInt(invoke);
 }
 
 void IntrinsicLocationsBuilderX86::VisitJdkUnsafeCASLong(HInvoke* invoke) {
-  CreateIntIntIntIntIntToInt(allocator_, DataType::Type::kInt64, invoke);
+  // `jdk.internal.misc.Unsafe.compareAndSwapObject` has compare-and-set semantics (see javadoc).
+  VisitJdkUnsafeCompareAndSetLong(invoke);
 }
 
 void IntrinsicLocationsBuilderX86::VisitJdkUnsafeCASObject(HInvoke* invoke) {
-  // The only read barrier implementation supporting the
-  // JdkUnsafeCASObject intrinsic is the Baker-style read barriers.
-  if (kEmitCompilerReadBarrier && !kUseBakerReadBarrier) {
-    return;
-  }
-
-  CreateIntIntIntIntIntToInt(allocator_, DataType::Type::kReference, invoke);
+  // `jdk.internal.misc.Unsafe.compareAndSwapObject` has compare-and-set semantics (see javadoc).
+  VisitJdkUnsafeCompareAndSetObject(invoke);
 }
 
 void IntrinsicLocationsBuilderX86::VisitJdkUnsafeCompareAndSetInt(HInvoke* invoke) {
@@ -2141,6 +2139,15 @@
   CreateIntIntIntIntIntToInt(allocator_, DataType::Type::kInt64, invoke);
 }
 
+void IntrinsicLocationsBuilderX86::VisitJdkUnsafeCompareAndSetObject(HInvoke* invoke) {
+  // The only supported read barrier implementation is the Baker-style read barriers.
+  if (kEmitCompilerReadBarrier && !kUseBakerReadBarrier) {
+    return;
+  }
+
+  CreateIntIntIntIntIntToInt(allocator_, DataType::Type::kReference, invoke);
+}
+
 static void GenPrimitiveLockedCmpxchg(DataType::Type type,
                                       CodeGeneratorX86* codegen,
                                       Location expected_value,
@@ -2378,19 +2385,18 @@
 }
 
 void IntrinsicCodeGeneratorX86::VisitJdkUnsafeCASInt(HInvoke* invoke) {
-  GenCAS(DataType::Type::kInt32, invoke, codegen_);
+  // `jdk.internal.misc.Unsafe.compareAndSwapObject` has compare-and-set semantics (see javadoc).
+  VisitJdkUnsafeCompareAndSetInt(invoke);
 }
 
 void IntrinsicCodeGeneratorX86::VisitJdkUnsafeCASLong(HInvoke* invoke) {
-  GenCAS(DataType::Type::kInt64, invoke, codegen_);
+  // `jdk.internal.misc.Unsafe.compareAndSwapObject` has compare-and-set semantics (see javadoc).
+  VisitJdkUnsafeCompareAndSetLong(invoke);
 }
 
 void IntrinsicCodeGeneratorX86::VisitJdkUnsafeCASObject(HInvoke* invoke) {
-  // The only read barrier implementation supporting the
-  // JdkUnsafeCASObject intrinsic is the Baker-style read barriers.
-  DCHECK(!kEmitCompilerReadBarrier || kUseBakerReadBarrier);
-
-  GenCAS(DataType::Type::kReference, invoke, codegen_);
+  // `jdk.internal.misc.Unsafe.compareAndSwapObject` has compare-and-set semantics (see javadoc).
+  VisitJdkUnsafeCompareAndSetObject(invoke);
 }
 
 void IntrinsicCodeGeneratorX86::VisitJdkUnsafeCompareAndSetInt(HInvoke* invoke) {
@@ -2401,6 +2407,12 @@
   GenCAS(DataType::Type::kInt64, invoke, codegen_);
 }
 
+void IntrinsicCodeGeneratorX86::VisitJdkUnsafeCompareAndSetObject(HInvoke* invoke) {
+  // The only supported read barrier implementation is the Baker-style read barriers.
+  DCHECK(!kEmitCompilerReadBarrier || kUseBakerReadBarrier);
+
+  GenCAS(DataType::Type::kReference, invoke, codegen_);
+}
 
 void IntrinsicLocationsBuilderX86::VisitIntegerReverse(HInvoke* invoke) {
   LocationSummary* locations =
@@ -4840,7 +4852,6 @@
 UNIMPLEMENTED_INTRINSIC(X86, JdkUnsafeGetAndSetInt)
 UNIMPLEMENTED_INTRINSIC(X86, JdkUnsafeGetAndSetLong)
 UNIMPLEMENTED_INTRINSIC(X86, JdkUnsafeGetAndSetObject)
-UNIMPLEMENTED_INTRINSIC(X86, JdkUnsafeCompareAndSetObject)
 
 UNREACHABLE_INTRINSICS(X86)