[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

1 files changed, 9 insertions, 0 deletions

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";