X86: Implement VarHandle.compareAndSet() for fields.

This commit implements VarHandle compareAndExchange access mode for
fields (both static and instance).

Int64 and Float64 are not implemented because ParallelMove might fail
when moving register pairs.

Test: ART_HEAP_POISONING=true art/test.py --host --32 -r -t 712-varhandle-invocations
Test: ART_HEAP_POISONING=false art/test.py --host --32 -r -t 712-varhandle-invocations
Bug: 65872996
Change-Id: I92e51c348f076c23413e419948f03197c286a619

1 files changed, 17 insertions, 0 deletions

diff --git a/compiler/utils/x86/assembler_x86.cc b/compiler/utils/x86/assembler_x86.cc
index c86b1cd522..981894f321 100644
--- a/compiler/utils/x86/assembler_x86.cc
+++ b/compiler/utils/x86/assembler_x86.cc
@@ -3636,6 +3636,23 @@ X86Assembler* X86Assembler::lock() {
 }
 
 
+void X86Assembler::cmpxchgb(const Address& address, ByteRegister reg) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitUint8(0x0F);
+  EmitUint8(0xB0);
+  EmitOperand(reg, address);
+}
+
+
+void X86Assembler::cmpxchgw(const Address& address, Register reg) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitOperandSizeOverride();
+  EmitUint8(0x0F);
+  EmitUint8(0xB1);
+  EmitOperand(reg, address);
+}
+
+
 void X86Assembler::cmpxchgl(const Address& address, Register reg) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitUint8(0x0F);