[clang] 0cd5cd1 - [Serialization] write expr dependence bits as a single integer

[Sam McCall via cfe-commits]

Author: Sam McCall
Date: 2022-04-25T12:09:40+02:00
New Revision: 0cd5cd19af0eee1d35077de6824b2fe3022d2280

URL: https://github.com/llvm/llvm-project/commit/0cd5cd19af0eee1d35077de6824b2fe3022d2280
DIFF: https://github.com/llvm/llvm-project/commit/0cd5cd19af0eee1d35077de6824b2fe3022d2280.diff

LOG: [Serialization] write expr dependence bits as a single integer

When exprs are written unabbreviated:
  - these were encoded as 5 x vbr6 = 30 bits
  - now they fit exactly into a one-chunk vbr = 6 bits

clangd --check=clangd/AST.cpp reports ~1% reduction in PCH size
(42826720->42474460)

Differential Revision: https://reviews.llvm.org/D124250

Added: 
    

Modified: 
    clang/lib/Serialization/ASTReaderStmt.cpp
    clang/lib/Serialization/ASTWriterDecl.cpp
    clang/lib/Serialization/ASTWriterStmt.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 281385ad9e7d9..77ea1b95d5be5 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -107,8 +107,7 @@ namespace clang {
 
     /// The number of record fields required for the Expr class
     /// itself.
-    static const unsigned NumExprFields =
-        NumStmtFields + llvm::BitWidth<ExprDependence> + 3;
+    static const unsigned NumExprFields = NumStmtFields + 4;
 
     /// Read and initialize a ExplicitTemplateArgumentList structure.
     void ReadTemplateKWAndArgsInfo(ASTTemplateKWAndArgsInfo &Args,
@@ -521,26 +520,7 @@ void ASTStmtReader::VisitCapturedStmt(CapturedStmt *S) {
 void ASTStmtReader::VisitExpr(Expr *E) {
   VisitStmt(E);
   E->setType(Record.readType());
-
-  // FIXME: write and read all DependentFlags with a single call.
-  bool TypeDependent = Record.readInt();
-  bool ValueDependent = Record.readInt();
-  bool InstantiationDependent = Record.readInt();
-  bool ContainsUnexpandedTemplateParameters = Record.readInt();
-  bool ContainsErrors = Record.readInt();
-  auto Deps = ExprDependence::None;
-  if (TypeDependent)
-    Deps |= ExprDependence::Type;
-  if (ValueDependent)
-    Deps |= ExprDependence::Value;
-  if (InstantiationDependent)
-    Deps |= ExprDependence::Instantiation;
-  if (ContainsUnexpandedTemplateParameters)
-    Deps |= ExprDependence::UnexpandedPack;
-  if (ContainsErrors)
-    Deps |= ExprDependence::Error;
-  E->setDependence(Deps);
-
+  E->setDependence(static_cast<ExprDependence>(Record.readInt()));
   E->setValueKind(static_cast<ExprValueKind>(Record.readInt()));
   E->setObjectKind(static_cast<ExprObjectKind>(Record.readInt()));
   assert(Record.getIdx() == NumExprFields &&

diff  --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 4e9e97514de0b..3666d5a6daab8 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -2288,17 +2288,14 @@ void ASTWriter::WriteDeclAbbrevs() {
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
   DeclCXXMethodAbbrev = Stream.EmitAbbrev(std::move(Abv));
 
+  unsigned ExprDependenceBits = llvm::BitWidth<ExprDependence>;
   // Abbreviation for EXPR_DECL_REF
   Abv = std::make_shared<BitCodeAbbrev>();
   Abv->Add(BitCodeAbbrevOp(serialization::EXPR_DECL_REF));
   //Stmt
   // Expr
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //TypeDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ValueDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //InstantiationDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //UnexpandedParamPack
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ContainsErrors
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, ExprDependenceBits));
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetValueKind
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetObjectKind
   //DeclRefExpr
@@ -2318,11 +2315,7 @@ void ASTWriter::WriteDeclAbbrevs() {
   //Stmt
   // Expr
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //TypeDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ValueDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //InstantiationDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //UnexpandedParamPack
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ContainsErrors
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, ExprDependenceBits));
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetValueKind
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetObjectKind
   //Integer Literal
@@ -2337,11 +2330,7 @@ void ASTWriter::WriteDeclAbbrevs() {
   //Stmt
   // Expr
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //TypeDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ValueDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //InstantiationDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //UnexpandedParamPack
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ContainsErrors
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, ExprDependenceBits));
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetValueKind
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetObjectKind
   //Character Literal
@@ -2356,11 +2345,7 @@ void ASTWriter::WriteDeclAbbrevs() {
   // Stmt
   // Expr
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Type
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //TypeDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ValueDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //InstantiationDependent
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //UnexpandedParamPack
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); //ContainsErrors
+  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, ExprDependenceBits));
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetValueKind
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 3)); //GetObjectKind
   // CastExpr

diff  --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 1a4c782d5917d..587aad3f11e06 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -543,11 +543,7 @@ void ASTStmtWriter::VisitCapturedStmt(CapturedStmt *S) {
 void ASTStmtWriter::VisitExpr(Expr *E) {
   VisitStmt(E);
   Record.AddTypeRef(E->getType());
-  Record.push_back(E->isTypeDependent());
-  Record.push_back(E->isValueDependent());
-  Record.push_back(E->isInstantiationDependent());
-  Record.push_back(E->containsUnexpandedParameterPack());
-  Record.push_back(E->containsErrors());
+  Record.push_back(E->getDependence());
   Record.push_back(E->getValueKind());
   Record.push_back(E->getObjectKind());
 }