Use is.constant intrinsic for __builtin_constant_p

Summary:
A __builtin_constant_p may end up with a constant after inlining. Use
the is.constant intrinsic if it's a variable that's in a context where
it may resolve to a constant, e.g., an argument to a function after
inlining.

Reviewers: rsmith, shafik

Subscribers: jfb, kristina, cfe-commits, nickdesaulniers, jyknight

Differential Revision: https://reviews.llvm.org/D54355

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@347294 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 3 deletions

diff --git a/include/clang/AST/Expr.h b/include/clang/AST/Expr.h
index 004631019c..57fe192f06 100644
--- a/include/clang/AST/Expr.h
+++ b/include/clang/AST/Expr.h
@@ -901,10 +901,15 @@ public:
 
 /// ConstantExpr - An expression that occurs in a constant context.
 class ConstantExpr : public FullExpr {
-public:
   ConstantExpr(Expr *subexpr)
     : FullExpr(ConstantExprClass, subexpr) {}
 
+public:
+  static ConstantExpr *Create(const ASTContext &Context, Expr *E) {
+    assert(!isa<ConstantExpr>(E));
+    return new (Context) ConstantExpr(E);
+  }
+
   /// Build an empty constant expression wrapper.
   explicit ConstantExpr(EmptyShell Empty)
     : FullExpr(ConstantExprClass, Empty) {}
@@ -3091,8 +3096,8 @@ inline Expr *Expr::IgnoreImpCasts() {
   while (true)
     if (ImplicitCastExpr *ice = dyn_cast<ImplicitCastExpr>(e))
       e = ice->getSubExpr();
-    else if (ConstantExpr *ce = dyn_cast<ConstantExpr>(e))
-      e = ce->getSubExpr();
+    else if (FullExpr *fe = dyn_cast<FullExpr>(e))
+      e = fe->getSubExpr();
     else
       break;
   return e;