[ia32] Create field accessors for Operand's members

With these accessors we can remove Assembler as a friend class.

Drive-by cleanup to change DCHECK(!x || y) to DCHECK_IMPLIES(x, y).

Change-Id: I74b7a23e85b50db93bbfe84fdfcc8563527f14d2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3144374Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76757}

src/codegen/ia32/assembler-ia32.cc

@@ -3408,27 +3408,27 @@ void Assembler::emit_operand(XMMRegister reg, Operand adr) {
 
 void Assembler::emit_operand(int code, Operand adr) {
   // Isolate-independent code may not embed relocatable addresses.
-  DCHECK(!options().isolate_independent_code ||
-         adr.rmode_ != RelocInfo::CODE_TARGET);
-  DCHECK(!options().isolate_independent_code ||
-         adr.rmode_ != RelocInfo::FULL_EMBEDDED_OBJECT);
-  DCHECK(!options().isolate_independent_code ||
-         adr.rmode_ != RelocInfo::EXTERNAL_REFERENCE);
-
-  const unsigned length = adr.len_;
+  DCHECK_IMPLIES(options().isolate_independent_code,
+                 adr.rmode() != RelocInfo::CODE_TARGET);
+  DCHECK_IMPLIES(options().isolate_independent_code,
+                 adr.rmode() != RelocInfo::FULL_EMBEDDED_OBJECT);
+  DCHECK_IMPLIES(options().isolate_independent_code,
+                 adr.rmode() != RelocInfo::EXTERNAL_REFERENCE);
+
+  const unsigned length = adr.encoded_bytes().length();
   DCHECK_GT(length, 0);
 
   // Emit updated ModRM byte containing the given register.
-  EMIT((adr.buf_[0] & ~0x38) | (code << 3));
+  EMIT((adr.encoded_bytes()[0] & ~0x38) | (code << 3));
 
   // Emit the rest of the encoded operand.
-  for (unsigned i = 1; i < length; i++) EMIT(adr.buf_[i]);
+  for (unsigned i = 1; i < length; i++) EMIT(adr.encoded_bytes()[i]);
 
   // Emit relocation information if necessary.
-  if (length >= sizeof(int32_t) && !RelocInfo::IsNone(adr.rmode_)) {
+  if (length >= sizeof(int32_t) && !RelocInfo::IsNone(adr.rmode())) {
     pc_ -= sizeof(int32_t);  // pc_ must be *at* disp32
-    RecordRelocInfo(adr.rmode_);
-    if (adr.rmode_ == RelocInfo::INTERNAL_REFERENCE) {  // Fixup for labels
+    RecordRelocInfo(adr.rmode());
+    if (adr.rmode() == RelocInfo::INTERNAL_REFERENCE) {  // Fixup for labels
       emit_label(ReadUnalignedValue<Label*>(reinterpret_cast<Address>(pc_)));
     } else {
       pc_ += sizeof(int32_t);

src/codegen/ia32/assembler-ia32.h

@@ -269,6 +269,9 @@ class V8_EXPORT_PRIVATE Operand {
   // register.
   Register reg() const;
 
+  base::Vector<const byte> encoded_bytes() const { return {buf_, len_}; }
+  RelocInfo::Mode rmode() { return rmode_; }
+
  private:
   // Set the ModRM byte without an encoded 'reg' register. The
   // register is encoded later as part of the emit_operand operation.
@@ -298,9 +301,6 @@ class V8_EXPORT_PRIVATE Operand {
   uint8_t len_ = 0;
   // Only valid if len_ > 4.
   RelocInfo::Mode rmode_ = RelocInfo::NONE;
-
-  // TODO(clemensb): Get rid of this friendship, or make Operand immutable.
-  friend class Assembler;
 };
 ASSERT_TRIVIALLY_COPYABLE(Operand);
 static_assert(sizeof(Operand) <= 2 * kSystemPointerSize,