[AST] CastExpr: BasePathSize is not large enough.

Summary:
rC337815 / D49508 had to cannibalize one bit of `CastExprBitfields::BasePathSize` in order to squeeze `PartOfExplicitCast` boolean.
That reduced the maximal value of `PartOfExplicitCast` from 9 bits (~512) down to 8 bits (~256).
Apparently, that mattered. Too bad there weren't any tests.
It caused [[ https://bugs.llvm.org/show_bug.cgi?id=38356 | PR38356 ]].

So we need to increase `PartOfExplicitCast` back at least to 9 bits, or a bit more.
For obvious reasons, we can't do that in `CastExprBitfields` - that would blow up the size of every `Expr`.
So we need to either just add a variable into the `CastExpr` (as done here),
or use `llvm::TrailingObjects`. The latter does not seem to be straight-forward.
Perhaps, that needs to be done not for the `CastExpr` itself, but for all of it's `final` children.

Reviewers: rjmccall, rsmith, erichkeane

Reviewed By: rjmccall

Subscribers: bricci, hans, cfe-commits, waddlesplash

Differential Revision: https://reviews.llvm.org/D50050

llvm-svn: 338489

1 files changed, 24 insertions, 8 deletions

diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index e913a852f68..93d68ec8e0b 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -559,7 +559,9 @@ CXXStaticCastExpr *CXXStaticCastExpr::Create(const ASTContext &C, QualType T,
                                              SourceLocation RParenLoc,
                                              SourceRange AngleBrackets) {
   unsigned PathSize = (BasePath ? BasePath->size() : 0);
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   auto *E =
       new (Buffer) CXXStaticCastExpr(T, VK, K, Op, PathSize, WrittenTy, L,
                                      RParenLoc, AngleBrackets);
@@ -571,7 +573,9 @@ CXXStaticCastExpr *CXXStaticCastExpr::Create(const ASTContext &C, QualType T,
 
 CXXStaticCastExpr *CXXStaticCastExpr::CreateEmpty(const ASTContext &C,
                                                   unsigned PathSize) {
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   return new (Buffer) CXXStaticCastExpr(EmptyShell(), PathSize);
 }
 
@@ -584,7 +588,9 @@ CXXDynamicCastExpr *CXXDynamicCastExpr::Create(const ASTContext &C, QualType T,
                                                SourceLocation RParenLoc,
                                                SourceRange AngleBrackets) {
   unsigned PathSize = (BasePath ? BasePath->size() : 0);
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   auto *E =
       new (Buffer) CXXDynamicCastExpr(T, VK, K, Op, PathSize, WrittenTy, L,
                                       RParenLoc, AngleBrackets);
@@ -596,7 +602,9 @@ CXXDynamicCastExpr *CXXDynamicCastExpr::Create(const ASTContext &C, QualType T,
 
 CXXDynamicCastExpr *CXXDynamicCastExpr::CreateEmpty(const ASTContext &C,
                                                     unsigned PathSize) {
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   return new (Buffer) CXXDynamicCastExpr(EmptyShell(), PathSize);
 }
 
@@ -641,7 +649,9 @@ CXXReinterpretCastExpr::Create(const ASTContext &C, QualType T,
                                SourceLocation RParenLoc,
                                SourceRange AngleBrackets) {
   unsigned PathSize = (BasePath ? BasePath->size() : 0);
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   auto *E =
       new (Buffer) CXXReinterpretCastExpr(T, VK, K, Op, PathSize, WrittenTy, L,
                                           RParenLoc, AngleBrackets);
@@ -653,7 +663,9 @@ CXXReinterpretCastExpr::Create(const ASTContext &C, QualType T,
 
 CXXReinterpretCastExpr *
 CXXReinterpretCastExpr::CreateEmpty(const ASTContext &C, unsigned PathSize) {
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   return new (Buffer) CXXReinterpretCastExpr(EmptyShell(), PathSize);
 }
 
@@ -676,7 +688,9 @@ CXXFunctionalCastExpr::Create(const ASTContext &C, QualType T, ExprValueKind VK,
                               const CXXCastPath *BasePath,
                               SourceLocation L, SourceLocation R) {
   unsigned PathSize = (BasePath ? BasePath->size() : 0);
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   auto *E =
       new (Buffer) CXXFunctionalCastExpr(T, VK, Written, K, Op, PathSize, L, R);
   if (PathSize)
@@ -687,7 +701,9 @@ CXXFunctionalCastExpr::Create(const ASTContext &C, QualType T, ExprValueKind VK,
 
 CXXFunctionalCastExpr *
 CXXFunctionalCastExpr::CreateEmpty(const ASTContext &C, unsigned PathSize) {
-  void *Buffer = C.Allocate(totalSizeToAlloc<CXXBaseSpecifier *>(PathSize));
+  void *Buffer =
+      C.Allocate(totalSizeToAlloc<CastExpr::BasePathSizeTy, CXXBaseSpecifier *>(
+          PathSize ? 1 : 0, PathSize));
   return new (Buffer) CXXFunctionalCastExpr(EmptyShell(), PathSize);
 }