From 28276a728852835d03fb3df76559c807cf8710a2 Mon Sep 17 00:00:00 2001
From: Oguz Ulgen <oulgen@fb.com>
Date: Mon, 25 Jul 2022 20:55:58 -0700
Subject: [PATCH] Use struct bit packing

Summary: Instead of implementing two bits by hand, lets use proper packing

Reviewed By: ricklavoie

Differential Revision: D38119000

fbshipit-source-id: 406c6d97c16001eac0dd4ea2527a943b3f798794
---
 hphp/runtime/vm/func-emitter.cpp | 7 +++----
 hphp/runtime/vm/func-inl.h       | 5 +----
 hphp/runtime/vm/func.cpp         | 3 +--
 hphp/runtime/vm/func.h           | 7 ++++---
 4 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/hphp/runtime/vm/func-emitter.cpp b/hphp/runtime/vm/func-emitter.cpp
index d16ecad0d44..c5b15aedd38 100644
--- a/hphp/runtime/vm/func-emitter.cpp
+++ b/hphp/runtime/vm/func-emitter.cpp
@@ -300,8 +300,7 @@ Func* FuncEmitter::create(Unit& unit, PreClass* preClass /* = NULL */) const {
     ex->m_allFlags.m_returnByValue = false;
     ex->m_allFlags.m_isMemoizeWrapper = false;
     ex->m_allFlags.m_isMemoizeWrapperLSB = false;
-    ex->m_allFlags.m_memoizeICTypeBit0 = false;
-    ex->m_allFlags.m_memoizeICTypeBit1 = false;
+    ex->m_allFlags.m_memoizeICType = Func::MemoizeICType::NoIC;
 
     if (!coeffectRules.empty()) ex->m_coeffectRules = coeffectRules;
     ex->m_coeffectEscapes = coeffectsInfo.second;
@@ -379,8 +378,8 @@ Func* FuncEmitter::create(Unit& unit, PreClass* preClass /* = NULL */) const {
     auto const it = userAttributes.find(attrName.get());
     if (it != userAttributes.end()) {
       auto const ic_type = getICType(it->second);
-      f->shared()->m_allFlags.m_memoizeICTypeBit0 = ic_type & 1;
-      f->shared()->m_allFlags.m_memoizeICTypeBit1 = (ic_type >> 1) & 1;
+      assertx((ic_type & 0x3) == ic_type);
+      f->shared()->m_allFlags.m_memoizeICType = ic_type;
     }
   }
 
diff --git a/hphp/runtime/vm/func-inl.h b/hphp/runtime/vm/func-inl.h
index f4819d3dc98..5b0c43ce8ea 100644
--- a/hphp/runtime/vm/func-inl.h
+++ b/hphp/runtime/vm/func-inl.h
@@ -560,10 +560,7 @@ inline bool Func::isMemoizeWrapperLSB() const {
 
 inline Func::MemoizeICType Func::memoizeICType() const {
   assertx(isMemoizeWrapper());
-  return static_cast<MemoizeICType>(
-    shared()->m_allFlags.m_memoizeICTypeBit0 |
-    (shared()->m_allFlags.m_memoizeICTypeBit1 << 1)
-  );
+  return shared()->m_allFlags.m_memoizeICType;
 }
 
 inline bool Func::isNoICMemoize() const {
diff --git a/hphp/runtime/vm/func.cpp b/hphp/runtime/vm/func.cpp
index d2a3b2b75cc..ecf1ff3f3db 100644
--- a/hphp/runtime/vm/func.cpp
+++ b/hphp/runtime/vm/func.cpp
@@ -721,8 +721,7 @@ Func::SharedData::SharedData(BCPtr bc, Offset bclen,
   m_allFlags.m_returnByValue = false;
   m_allFlags.m_isMemoizeWrapper = false;
   m_allFlags.m_isMemoizeWrapperLSB = false;
-  m_allFlags.m_memoizeICTypeBit0 = false;
-  m_allFlags.m_memoizeICTypeBit1 = false;
+  m_allFlags.m_memoizeICType = Func::MemoizeICType::NoIC;
   m_allFlags.m_isPhpLeafFn = isPhpLeafFn;
   m_allFlags.m_hasReifiedGenerics = false;
   m_allFlags.m_hasParamsWithMultiUBs = false;
diff --git a/hphp/runtime/vm/func.h b/hphp/runtime/vm/func.h
index 5828fb9a020..43f9bde42be 100644
--- a/hphp/runtime/vm/func.h
+++ b/hphp/runtime/vm/func.h
@@ -706,8 +706,10 @@ public:
 
   /*
    * What kind of memoized function is this?
+   * NB: MemoizeICType must be a unsigned char in order to enable
+   * struct bit packing.
    */
-  enum MemoizeICType {
+  enum MemoizeICType : unsigned char {
     NoIC = 0,
     KeyedByIC = 1,
     MakeICInaccessible = 2,
@@ -1341,8 +1343,7 @@ private:
         bool m_returnByValue : true; // only for builtins
         bool m_isMemoizeWrapper : true;
         bool m_isMemoizeWrapperLSB : true;
-        bool m_memoizeICTypeBit0 : true;
-        bool m_memoizeICTypeBit1 : true;
+        MemoizeICType m_memoizeICType : 2;
         bool m_isPhpLeafFn : true;
         bool m_hasReifiedGenerics : true;
         bool m_hasParamsWithMultiUBs : true;
-- 
2.11.4.GIT