Fix rdar://6257721 by tightening up the block "snapshot" check, and
move it to its own predicate to make it more clear.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@57796 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index c8610da..563718c 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -309,6 +309,36 @@
StringToks[NumStringToks-1].getLocation());
}
+/// ShouldSnapshotBlockValueReference - Return true if a reference inside of
+/// CurBlock to VD should cause it to be snapshotted (as we do for auto
+/// variables defined outside the block) or false if this is not needed (e.g.
+/// for values inside the block or for globals).
+///
+/// FIXME: This will create BlockDeclRefExprs for global variables,
+/// function references, etc which is suboptimal :) and breaks
+/// things like "integer constant expression" tests.
+static bool ShouldSnapshotBlockValueReference(BlockSemaInfo *CurBlock,
+ ValueDecl *VD) {
+ // If the value is defined inside the block, we couldn't snapshot it even if
+ // we wanted to.
+ if (CurBlock->TheDecl == VD->getDeclContext())
+ return false;
+
+ // If this is an enum constant or function, it is constant, don't snapshot.
+ if (isa<EnumConstantDecl>(VD) || isa<FunctionDecl>(VD))
+ return false;
+
+ // If this is a reference to an extern, static, or global variable, no need to
+ // snapshot it.
+ // FIXME: What about 'const' variables in C++?
+ if (const VarDecl *Var = dyn_cast<VarDecl>(VD))
+ return Var->hasLocalStorage();
+
+ return true;
+}
+
+
+
/// ActOnIdentifierExpr - The parser read an identifier in expression context,
/// validate it per-C99 6.5.1. HasTrailingLParen indicates whether this
/// identifier is used in a function call context.
@@ -397,16 +427,16 @@
// Only create DeclRefExpr's for valid Decl's.
if (VD->isInvalidDecl())
return true;
-
- // FIXME: This will create BlockDeclRefExprs for global variables,
- // function references, etc which is suboptimal :) and breaks
- // things like "integer constant expression" tests.
+
+ // If the identifier reference is inside a block, and it refers to a value
+ // that is outside the block, create a BlockDeclRefExpr instead of a
+ // DeclRefExpr. This ensures the value is treated as a copy-in snapshot when
+ // the block is formed.
//
- if (CurBlock && (CurBlock->TheDecl != VD->getDeclContext()) &&
- !isa<EnumConstantDecl>(VD)) {
- // If we are in a block and the variable is outside the current block,
- // bind the variable reference with a BlockDeclRefExpr.
-
+ // We do not do this for things like enum constants, global variables, etc,
+ // as they do not get snapshotted.
+ //
+ if (CurBlock && ShouldSnapshotBlockValueReference(CurBlock, VD)) {
// The BlocksAttr indicates the variable is bound by-reference.
if (VD->getAttr<BlocksAttr>())
return new BlockDeclRefExpr(VD, VD->getType(), Loc, true);