[base] Remove ITERATE_PACK

Replace by a unary right fold using the comma operator. This also
evaluates from left to right, so has the same semantics but uses
standard C++17 syntax.

R=tebbi@chromium.org

Bug: v8:12425
Change-Id: I680800ba07b048ee85d9da4ae32c12825df14e54
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3576131Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79877}

src/base/macros.h

@@ -251,12 +251,6 @@ struct Use {
     (void)unused_tmp_array_for_use_macro;                          \
   } while (false)
 
-// Evaluate the instantiations of an expression with parameter packs.
-// Since USE has left-to-right evaluation order of it's arguments,
-// the parameter pack is iterated from left to right and side effects
-// have defined behavior.
-#define ITERATE_PACK(...) USE(0, ((__VA_ARGS__), 0)...)
-
 }  // namespace base
 }  // namespace v8
 

src/baseline/ia32/baseline-assembler-ia32-inl.h

@@ -316,7 +316,7 @@ void BaselineAssembler::PushReverse(T... vals) {
 
 template <typename... T>
 void BaselineAssembler::Pop(T... registers) {
-  ITERATE_PACK(__ Pop(registers));
+  (__ Pop(registers), ...);
 }
 
 void BaselineAssembler::LoadTaggedPointerField(Register output, Register source,

src/baseline/x64/baseline-assembler-x64-inl.h

@@ -323,7 +323,7 @@ void BaselineAssembler::PushReverse(T... vals) {
 
 template <typename... T>
 void BaselineAssembler::Pop(T... registers) {
-  ITERATE_PACK(__ Pop(registers));
+  (__ Pop(registers), ...);
 }
 
 void BaselineAssembler::LoadTaggedPointerField(Register output, Register source,

src/compiler/bytecode-analysis.cc

@@ -212,9 +212,9 @@ void UpdateInLiveness(BytecodeLivenessState* in_liveness,
   if (BytecodeOperands::WritesAccumulator(implicit_register_use)) {
     in_liveness->MarkAccumulatorDead();
   }
-  ITERATE_PACK(
-      UpdateInLivenessForOutOperand<bytecode, operand_types, operand_index>(
-          in_liveness, iterator));
+  (UpdateInLivenessForOutOperand<bytecode, operand_types, operand_index>(
+       in_liveness, iterator),
+   ...);
 
   if (Bytecodes::WritesImplicitRegister(bytecode)) {
     in_liveness->MarkRegisterDead(Register::FromShortStar(bytecode).index());
@@ -223,9 +223,9 @@ void UpdateInLiveness(BytecodeLivenessState* in_liveness,
   if (BytecodeOperands::ReadsAccumulator(implicit_register_use)) {
     in_liveness->MarkAccumulatorLive();
   }
-  ITERATE_PACK(
-      UpdateInLivenessForInOperand<bytecode, operand_types, operand_index>(
-          in_liveness, iterator));
+  (UpdateInLivenessForInOperand<bytecode, operand_types, operand_index>(
+       in_liveness, iterator),
+   ...);
 }
 
 template <Bytecode bytecode, ImplicitRegisterUse implicit_register_use,

src/compiler/code-assembler.h

@@ -1570,7 +1570,7 @@ class CodeAssemblerParameterizedLabel
             {PhiMachineRepresentationOf<Types>...});
     auto it = phi_nodes.begin();
     USE(it);
-    ITERATE_PACK(AssignPhi(results, *(it++)));
+    (AssignPhi(results, *(it++)), ...);
   }
   template <class T>
   static void AssignPhi(TNode<T>* result, Node* phi) {