[clang] Add storage for APValue in ConstantExpr

Summary:
When using ConstantExpr we often need the result of the expression to be kept in the AST. Currently this is done on a by the node that needs the result and has been done multiple times for enumerator, for constexpr variables... . This patch adds to ConstantExpr the ability to store the result of evaluating the expression. no functional changes expected.

Changes:
 - Add trailling object to ConstantExpr that can hold an APValue or an uint64_t. the uint64_t is here because most ConstantExpr yield integral values so there is an optimized layout for integral values.
 - Add basic* serialization support for the trailing result.
 - Move conversion functions from an enum to a fltSemantics from clang::FloatingLiteral to llvm::APFloatBase. this change is to make it usable for serializing APValues.
 - Add basic* Import support for the trailing result.
 - ConstantExpr created in CheckConvertedConstantExpression now stores the result in the ConstantExpr Node.
 - Adapt AST dump to print the result when present.

basic* : None, Indeterminate, Int, Float, FixedPoint, ComplexInt, ComplexFloat,
the result is not yet used anywhere but for -ast-dump.

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: rnkovacs, hiraditya, dexonsmith, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D62399

llvm-svn: 363493

5 files changed, 127 insertions, 38 deletions

diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
index 5d5e67a8902..1993bba9bd1 100644
--- a/clang/lib/AST/APValue.cpp
+++ b/clang/lib/AST/APValue.cpp
@@ -456,7 +456,8 @@ void APValue::dump(raw_ostream &OS) const {
   llvm_unreachable("Unknown APValue kind!");
 }
 
-void APValue::printPretty(raw_ostream &Out, ASTContext &Ctx, QualType Ty) const{
+void APValue::printPretty(raw_ostream &Out, const ASTContext &Ctx,
+                          QualType Ty) const {
   switch (getKind()) {
   case APValue::None:
     Out << "<out of lifetime>";
@@ -675,7 +676,7 @@ void APValue::printPretty(raw_ostream &Out, ASTContext &Ctx, QualType Ty) const{
   llvm_unreachable("Unknown APValue kind!");
 }
 
-std::string APValue::getAsString(ASTContext &Ctx, QualType Ty) const {
+std::string APValue::getAsString(const ASTContext &Ctx, QualType Ty) const {
   std::string Result;
   llvm::raw_string_ostream Out(Result);
   printPretty(Out, Ctx, Ty);
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 0657528dc1b..b3c9c20d2b3 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -827,6 +827,9 @@ ASTContext::~ASTContext() {
 
   for (const auto &Value : ModuleInitializers)
     Value.second->~PerModuleInitializers();
+
+  for (APValue *Value : APValueCleanups)
+    Value->~APValue();
 }
 
 class ASTContext::ParentMap {
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index b43491d061a..d3c79eac903 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -6376,6 +6376,13 @@ ExpectedStmt ASTNodeImporter::VisitConstantExpr(ConstantExpr *E) {
   Expr *ToSubExpr;
   std::tie(ToSubExpr) = *Imp;
 
+  // TODO : Handle APValue::ValueKind that require importing.
+  APValue::ValueKind Kind = E->getResultAPValueKind();
+  if (Kind == APValue::Int || Kind == APValue::Float ||
+      Kind == APValue::FixedPoint || Kind == APValue::ComplexFloat ||
+      Kind == APValue::ComplexInt)
+    return ConstantExpr::Create(Importer.getToContext(), ToSubExpr,
+                                E->getAPValueResult());
   return ConstantExpr::Create(Importer.getToContext(), ToSubExpr);
 }
 
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 72e1119851b..f5714d93787 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -229,6 +229,110 @@ SourceLocation Expr::getExprLoc() const {
 // Primary Expressions.
 //===----------------------------------------------------------------------===//
 
+static void AssertResultStorageKind(ConstantExpr::ResultStorageKind Kind) {
+  assert((Kind == ConstantExpr::RSK_APValue ||
+          Kind == ConstantExpr::RSK_Int64 || Kind == ConstantExpr::RSK_None) &&
+         "Invalid StorageKind Value");
+}
+
+ConstantExpr::ResultStorageKind
+ConstantExpr::getStorageKind(const APValue &Value) {
+  switch (Value.getKind()) {
+  case APValue::None:
+    return ConstantExpr::RSK_None;
+  case APValue::Int:
+    if (!Value.getInt().needsCleanup())
+      return ConstantExpr::RSK_Int64;
+    LLVM_FALLTHROUGH;
+  default:
+    return ConstantExpr::RSK_APValue;
+  }
+}
+
+void ConstantExpr::DefaultInit(ResultStorageKind StorageKind) {
+  ConstantExprBits.ResultKind = StorageKind;
+  if (StorageKind == RSK_APValue)
+    ::new (getTrailingObjects<APValue>()) APValue();
+}
+
+ConstantExpr::ConstantExpr(Expr *subexpr, ResultStorageKind StorageKind)
+    : FullExpr(ConstantExprClass, subexpr) {
+  DefaultInit(StorageKind);
+}
+
+ConstantExpr *ConstantExpr::Create(const ASTContext &Context, Expr *E,
+                                   ResultStorageKind StorageKind) {
+  assert(!isa<ConstantExpr>(E));
+  AssertResultStorageKind(StorageKind);
+  unsigned Size = totalSizeToAlloc<APValue, uint64_t>(
+      StorageKind == ConstantExpr::RSK_APValue,
+      StorageKind == ConstantExpr::RSK_Int64);
+  void *Mem = Context.Allocate(Size, alignof(ConstantExpr));
+  ConstantExpr *Self = new (Mem) ConstantExpr(E, StorageKind);
+  if (StorageKind == ConstantExpr::RSK_APValue)
+    Context.AddAPValueCleanup(&Self->APValueResult());
+  return Self;
+}
+
+ConstantExpr *ConstantExpr::Create(const ASTContext &Context, Expr *E,
+                                   const APValue &Result) {
+  ResultStorageKind StorageKind = getStorageKind(Result);
+  ConstantExpr *Self = Create(Context, E, StorageKind);
+  Self->SetResult(Result);
+  return Self;
+}
+
+ConstantExpr::ConstantExpr(ResultStorageKind StorageKind, EmptyShell Empty)
+    : FullExpr(ConstantExprClass, Empty) {
+  DefaultInit(StorageKind);
+}
+
+ConstantExpr *ConstantExpr::CreateEmpty(const ASTContext &Context,
+                                        ResultStorageKind StorageKind,
+                                        EmptyShell Empty) {
+  AssertResultStorageKind(StorageKind);
+  unsigned Size = totalSizeToAlloc<APValue, uint64_t>(
+      StorageKind == ConstantExpr::RSK_APValue,
+      StorageKind == ConstantExpr::RSK_Int64);
+  void *Mem = Context.Allocate(Size, alignof(ConstantExpr));
+  ConstantExpr *Self = new (Mem) ConstantExpr(StorageKind, Empty);
+  if (StorageKind == ConstantExpr::RSK_APValue)
+    Context.AddAPValueCleanup(&Self->APValueResult());
+  return Self;
+}
+
+void ConstantExpr::MoveIntoResult(APValue &Value) {
+  assert(getStorageKind(Value) == ConstantExprBits.ResultKind &&
+         "Invalid storage for this value kind");
+  switch (ConstantExprBits.ResultKind) {
+  case RSK_None:
+    return;
+  case RSK_Int64:
+    Int64Result() = *Value.getInt().getRawData();
+    ConstantExprBits.BitWidth = Value.getInt().getBitWidth();
+    ConstantExprBits.IsUnsigned = Value.getInt().isUnsigned();
+    return;
+  case RSK_APValue:
+    APValueResult() = std::move(Value);
+    return;
+  }
+  llvm_unreachable("Invalid ResultKind Bits");
+}
+
+APValue ConstantExpr::getAPValueResult() const {
+  switch (ConstantExprBits.ResultKind) {
+  case ConstantExpr::RSK_APValue:
+    return APValueResult();
+  case ConstantExpr::RSK_Int64:
+    return APValue(
+        llvm::APSInt(llvm::APInt(ConstantExprBits.BitWidth, Int64Result()),
+                     ConstantExprBits.IsUnsigned));
+  case ConstantExpr::RSK_None:
+    return APValue();
+  }
+  llvm_unreachable("invalid ResultKind");
+}
+
 /// Compute the type-, value-, and instantiation-dependence of a
 /// declaration reference
 /// based on the declaration being referenced.
@@ -840,7 +944,7 @@ FloatingLiteral::FloatingLiteral(const ASTContext &C, const llvm::APFloat &V,
 
 FloatingLiteral::FloatingLiteral(const ASTContext &C, EmptyShell Empty)
   : Expr(FloatingLiteralClass, Empty) {
-  setRawSemantics(IEEEhalf);
+  setRawSemantics(llvm::APFloatBase::S_IEEEhalf);
   FloatingLiteralBits.IsExact = false;
 }
 
@@ -855,41 +959,6 @@ FloatingLiteral::Create(const ASTContext &C, EmptyShell Empty) {
   return new (C) FloatingLiteral(C, Empty);
 }
 
-const llvm::fltSemantics &FloatingLiteral::getSemantics() const {
-  switch(FloatingLiteralBits.Semantics) {
-  case IEEEhalf:
-    return llvm::APFloat::IEEEhalf();
-  case IEEEsingle:
-    return llvm::APFloat::IEEEsingle();
-  case IEEEdouble:
-    return llvm::APFloat::IEEEdouble();
-  case x87DoubleExtended:
-    return llvm::APFloat::x87DoubleExtended();
-  case IEEEquad:
-    return llvm::APFloat::IEEEquad();
-  case PPCDoubleDouble:
-    return llvm::APFloat::PPCDoubleDouble();
-  }
-  llvm_unreachable("Unrecognised floating semantics");
-}
-
-void FloatingLiteral::setSemantics(const llvm::fltSemantics &Sem) {
-  if (&Sem == &llvm::APFloat::IEEEhalf())
-    FloatingLiteralBits.Semantics = IEEEhalf;
-  else if (&Sem == &llvm::APFloat::IEEEsingle())
-    FloatingLiteralBits.Semantics = IEEEsingle;
-  else if (&Sem == &llvm::APFloat::IEEEdouble())
-    FloatingLiteralBits.Semantics = IEEEdouble;
-  else if (&Sem == &llvm::APFloat::x87DoubleExtended())
-    FloatingLiteralBits.Semantics = x87DoubleExtended;
-  else if (&Sem == &llvm::APFloat::IEEEquad())
-    FloatingLiteralBits.Semantics = IEEEquad;
-  else if (&Sem == &llvm::APFloat::PPCDoubleDouble())
-    FloatingLiteralBits.Semantics = PPCDoubleDouble;
-  else
-    llvm_unreachable("Unknown floating semantics");
-}
-
 /// getValueAsApproximateDouble - This returns the value as an inaccurate
 /// double.  Note that this may cause loss of precision, but is useful for
 /// debugging dumps, etc.
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index 1998cfaec04..81b3b74f93a 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -223,6 +223,7 @@ void TextNodeDumper::Visit(const Decl *D) {
     return;
   }
 
+  Context = &D->getASTContext();
   {
     ColorScope Color(OS, ShowColors, DeclKindNameColor);
     OS << D->getDeclKindName() << "Decl";
@@ -689,6 +690,14 @@ void TextNodeDumper::VisitCaseStmt(const CaseStmt *Node) {
     OS << " gnu_range";
 }
 
+void TextNodeDumper::VisitConstantExpr(const ConstantExpr *Node) {
+  if (Node->getResultAPValueKind() != APValue::None) {
+    ColorScope Color(OS, ShowColors, ValueColor);
+    OS << " ";
+    Node->getAPValueResult().printPretty(OS, *Context, Node->getType());
+  }
+}
+
 void TextNodeDumper::VisitCallExpr(const CallExpr *Node) {
   if (Node->usesADL())
     OS << " adl";