[x64] Fix code generation of testw and add tests

BUG=v8:5798
R=epertoso@chromium.org
LOG=N

Review-Url: https://codereview.chromium.org/2619263002
Cr-Commit-Position: refs/heads/master@{#42148}

src/x64/assembler-x64.cc

@@ -2103,11 +2103,12 @@ void Assembler::testb(const Operand& op, Register reg) {
 void Assembler::testw(Register dst, Register src) {
   EnsureSpace ensure_space(this);
   emit(0x66);
-  if (src.low_bits() == 4) {
-    emit_rex_32(src, dst);
+  if (!dst.is_byte_register() || !src.is_byte_register()) {
+    // Register is not one of al, bl, cl, dl.  Its encoding needs REX.
+    emit_rex_32(dst, src);
   }
   emit(0x85);
-  emit_modrm(src, dst);
+  emit_modrm(dst, src);
 }
 
 void Assembler::testw(Register reg, Immediate mask) {
@@ -2118,7 +2119,7 @@ void Assembler::testw(Register reg, Immediate mask) {
     emit(0xA9);
     emitw(mask.value_);
   } else {
-    if (reg.low_bits() == 4) {
+    if (!reg.is_byte_register()) {
       emit_rex_32(reg);
     }
     emit(0xF7);

test/cctest/test-assembler-x64.cc

@@ -201,6 +201,167 @@ TEST(AssemblerX64ImulOperation) {
   CHECK_EQ(-1, result);
 }
 
+TEST(AssemblerX64testbwOperation) {
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+  // Allocate an executable page of memory.
+  size_t actual_size;
+  byte* buffer = static_cast<byte*>(v8::base::OS::Allocate(
+      Assembler::kMinimalBufferSize, &actual_size, true));
+  CHECK(buffer);
+  Assembler assm(CcTest::i_isolate(), buffer, static_cast<int>(actual_size));
+
+  __ pushq(rbx);
+  __ pushq(rdi);
+  __ pushq(rsi);
+  __ pushq(r12);
+  __ pushq(r13);
+  __ pushq(r14);
+  __ pushq(r15);
+
+  // Assemble a simple function that tests testb and testw
+  Label bad;
+  Label done;
+
+  // Test immediate testb and testw
+  __ movq(rax, Immediate(2));
+  __ movq(rbx, Immediate(4));
+  __ movq(rcx, Immediate(8));
+  __ movq(rdx, Immediate(16));
+  __ movq(rsi, Immediate(32));
+  __ movq(rdi, Immediate(64));
+  __ movq(r10, Immediate(128));
+  __ movq(r11, Immediate(0));
+  __ movq(r12, Immediate(0));
+  __ movq(r13, Immediate(0));
+  __ testb(rax, Immediate(2));
+  __ j(zero, &bad);
+  __ testb(rbx, Immediate(4));
+  __ j(zero, &bad);
+  __ testb(rcx, Immediate(8));
+  __ j(zero, &bad);
+  __ testb(rdx, Immediate(16));
+  __ j(zero, &bad);
+  __ testb(rsi, Immediate(32));
+  __ j(zero, &bad);
+  __ testb(rdi, Immediate(64));
+  __ j(zero, &bad);
+  __ testb(r10, Immediate(128));
+  __ j(zero, &bad);
+  __ testw(rax, Immediate(2));
+  __ j(zero, &bad);
+  __ testw(rbx, Immediate(4));
+  __ j(zero, &bad);
+  __ testw(rcx, Immediate(8));
+  __ j(zero, &bad);
+  __ testw(rdx, Immediate(16));
+  __ j(zero, &bad);
+  __ testw(rsi, Immediate(32));
+  __ j(zero, &bad);
+  __ testw(rdi, Immediate(64));
+  __ j(zero, &bad);
+  __ testw(r10, Immediate(128));
+  __ j(zero, &bad);
+
+  // Test reg, reg testb and testw
+  __ movq(rax, Immediate(2));
+  __ movq(rbx, Immediate(2));
+  __ testb(rax, rbx);
+  __ j(zero, &bad);
+  __ movq(rbx, Immediate(4));
+  __ movq(rax, Immediate(4));
+  __ testb(rbx, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(8));
+  __ testb(rcx, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(16));
+  __ testb(rdx, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(32));
+  __ testb(rsi, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(64));
+  __ testb(rdi, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(128));
+  __ testb(r10, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(2));
+  __ movq(rbx, Immediate(2));
+  __ testw(rax, rbx);
+  __ j(zero, &bad);
+  __ movq(rbx, Immediate(4));
+  __ movq(rax, Immediate(4));
+  __ testw(rbx, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(8));
+  __ testw(rcx, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(16));
+  __ testw(rdx, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(32));
+  __ testw(rsi, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(64));
+  __ testw(rdi, rax);
+  __ j(zero, &bad);
+  __ movq(rax, Immediate(128));
+  __ testw(r10, rax);
+  __ j(zero, &bad);
+
+  // Test diffrrent extended register coding combinations.
+  __ movq(rax, Immediate(5));
+  __ movq(r11, Immediate(5));
+  __ testb(r11, rax);
+  __ j(zero, &bad);
+  __ testb(rax, r11);
+  __ j(zero, &bad);
+  __ testw(r11, rax);
+  __ j(zero, &bad);
+  __ testw(rax, r11);
+  __ j(zero, &bad);
+  __ movq(r11, Immediate(3));
+  __ movq(r12, Immediate(3));
+  __ movq(rdi, Immediate(3));
+  __ testb(r12, rdi);
+  __ j(zero, &bad);
+  __ testb(rdi, r12);
+  __ j(zero, &bad);
+  __ testb(r12, r11);
+  __ j(zero, &bad);
+  __ testb(r11, r12);
+  __ j(zero, &bad);
+  __ testw(r12, r11);
+  __ j(zero, &bad);
+  __ testw(r11, r12);
+  __ j(zero, &bad);
+
+  // All tests passed
+  __ movq(rax, Immediate(1));
+  __ jmp(&done);
+
+  __ bind(&bad);
+  __ movq(rax, Immediate(0));
+  __ bind(&done);
+
+  __ popq(r15);
+  __ popq(r14);
+  __ popq(r13);
+  __ popq(r12);
+  __ popq(rsi);
+  __ popq(rdi);
+  __ popq(rbx);
+
+  __ ret(0);
+
+  CodeDesc desc;
+  assm.GetCode(&desc);
+  // Call the function from C++.
+  int result = FUNCTION_CAST<F2>(buffer)(0, 0);
+  CHECK_EQ(1, result);
+}
 
 TEST(AssemblerX64XchglOperations) {
   CcTest::InitializeVM();