Implement __builtin_LINE() et. al. to support source location capture.

Summary:
This patch implements the source location builtins `__builtin_LINE(), `__builtin_FUNCTION()`, `__builtin_FILE()` and `__builtin_COLUMN()`. These builtins are needed to implement [`std::experimental::source_location`](https://rawgit.com/cplusplus/fundamentals-ts/v2/main.html#reflection.src_loc.creation).

With the exception of `__builtin_COLUMN`, GCC also implements these builtins, and Clangs behavior is intended to match as closely as possible. 

Reviewers: rsmith, joerg, aaron.ballman, bogner, majnemer, shafik, martong

Reviewed By: rsmith

Subscribers: rnkovacs, loskutov, riccibruno, mgorny, kunitoki, alexr, majnemer, hfinkel, cfe-commits

Differential Revision: https://reviews.llvm.org/D37035

llvm-svn: 360937

1 files changed, 18 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index fddbe1443ce..b274f45867a 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -22,6 +22,7 @@
 #include "EHScopeStack.h"
 #include "VarBypassDetector.h"
 #include "clang/AST/CharUnits.h"
+#include "clang/AST/CurrentSourceLocExprScope.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/ExprOpenMP.h"
@@ -1393,6 +1394,12 @@ private:
   SourceLocation LastStopPoint;
 
 public:
+  /// Source location information about the default argument or member
+  /// initializer expression we're evaluating, if any.
+  CurrentSourceLocExprScope CurSourceLocExprScope;
+  using SourceLocExprScopeGuard =
+      CurrentSourceLocExprScope::SourceLocExprScopeGuard;
+
   /// A scope within which we are constructing the fields of an object which
   /// might use a CXXDefaultInitExpr. This stashes away a 'this' value to use
   /// if we need to evaluate a CXXDefaultInitExpr within the evaluation.
@@ -1413,11 +1420,12 @@ public:
 
   /// The scope of a CXXDefaultInitExpr. Within this scope, the value of 'this'
   /// is overridden to be the object under construction.
-  class CXXDefaultInitExprScope {
+  class CXXDefaultInitExprScope  {
   public:
-    CXXDefaultInitExprScope(CodeGenFunction &CGF)
-      : CGF(CGF), OldCXXThisValue(CGF.CXXThisValue),
-        OldCXXThisAlignment(CGF.CXXThisAlignment) {
+    CXXDefaultInitExprScope(CodeGenFunction &CGF, const CXXDefaultInitExpr *E)
+        : CGF(CGF), OldCXXThisValue(CGF.CXXThisValue),
+          OldCXXThisAlignment(CGF.CXXThisAlignment),
+          SourceLocScope(E, CGF.CurSourceLocExprScope) {
       CGF.CXXThisValue = CGF.CXXDefaultInitExprThis.getPointer();
       CGF.CXXThisAlignment = CGF.CXXDefaultInitExprThis.getAlignment();
     }
@@ -1430,6 +1438,12 @@ public:
     CodeGenFunction &CGF;
     llvm::Value *OldCXXThisValue;
     CharUnits OldCXXThisAlignment;
+    SourceLocExprScopeGuard SourceLocScope;
+  };
+
+  struct CXXDefaultArgExprScope : SourceLocExprScopeGuard {
+    CXXDefaultArgExprScope(CodeGenFunction &CGF, const CXXDefaultArgExpr *E)
+        : SourceLocExprScopeGuard(E, CGF.CurSourceLocExprScope) {}
   };
 
   /// The scope of an ArrayInitLoopExpr. Within this scope, the value of the