From 4b105f53082bba3a34d4b4585cdd4da13fc0be81 Mon Sep 17 00:00:00 2001
From: Don Hinton <hintonda@gmail.com>
Date: Sat, 18 May 2019 20:46:35 +0000
Subject: [PATCH] [CommandLine] Reduce size of Option class

Summary:
Reduce size of Option class from 184 bytes to 136 bytes by
placing more member variables in Bit Field (16 bytes), and
reducing the initial sizes of Categories and Subs to 1 (32 bytes).

Saves about 48k for bin/opt.

Reviewed By: beanz

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62091

llvm-svn: 361107
---
 llvm/include/llvm/Support/CommandLine.h | 27 +++++++++++++------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/llvm/include/llvm/Support/CommandLine.h b/llvm/include/llvm/Support/CommandLine.h
index d144c9b0f0f2..3cc2c3c0121b 100644
--- a/llvm/include/llvm/Support/CommandLine.h
+++ b/llvm/include/llvm/Support/CommandLine.h
@@ -265,27 +265,27 @@ class Option {
   // Out of line virtual function to provide home for the class.
   virtual void anchor();
 
-  int NumOccurrences = 0; // The number of times specified
+  uint16_t NumOccurrences; // The number of times specified
   // Occurrences, HiddenFlag, and Formatting are all enum types but to avoid
   // problems with signed enums in bitfields.
-  unsigned Occurrences : 3; // enum NumOccurrencesFlag
+  uint16_t Occurrences : 3; // enum NumOccurrencesFlag
   // not using the enum type for 'Value' because zero is an implementation
   // detail representing the non-value
-  unsigned Value : 2;
-  unsigned HiddenFlag : 2; // enum OptionHidden
-  unsigned Formatting : 2; // enum FormattingFlags
-  unsigned Misc : 5;
-  unsigned Position = 0;       // Position of last occurrence of the option
-  unsigned AdditionalVals = 0; // Greater than 0 for multi-valued option.
+  uint16_t Value : 2;
+  uint16_t HiddenFlag : 2; // enum OptionHidden
+  uint16_t Formatting : 2; // enum FormattingFlags
+  uint16_t Misc : 5;
+  uint16_t FullyInitialized : 1; // Has addArgument been called?
+  uint16_t Position;             // Position of last occurrence of the option
+  uint16_t AdditionalVals;       // Greater than 0 for multi-valued option.
 
 public:
   StringRef ArgStr;   // The argument string itself (ex: "help", "o")
   StringRef HelpStr;  // The descriptive text message for -help
   StringRef ValueStr; // String describing what the value of this option is
-  SmallVector<OptionCategory *, 2>
+  SmallVector<OptionCategory *, 1>
       Categories;                    // The Categories this option belongs to
-  SmallPtrSet<SubCommand *, 4> Subs; // The subcommands this option belongs to.
-  bool FullyInitialized = false; // Has addArgument been called?
+  SmallPtrSet<SubCommand *, 1> Subs; // The subcommands this option belongs to.
 
   inline enum NumOccurrencesFlag getNumOccurrencesFlag() const {
     return (enum NumOccurrencesFlag)Occurrences;
@@ -341,8 +341,9 @@ public:
 protected:
   explicit Option(enum NumOccurrencesFlag OccurrencesFlag,
                   enum OptionHidden Hidden)
-      : Occurrences(OccurrencesFlag), Value(0), HiddenFlag(Hidden),
-        Formatting(NormalFormatting), Misc(0) {
+      : NumOccurrences(0), Occurrences(OccurrencesFlag), Value(0),
+        HiddenFlag(Hidden), Formatting(NormalFormatting), Misc(0),
+        FullyInitialized(false), Position(0), AdditionalVals(0) {
     Categories.push_back(&GeneralCategory);
   }