Reduce stack usage of TreeTransform.

Without this patch, TreeTransform::TransformExpr uses a ridiculous amount of
stack space (around 5000 bytes).  Preventing inlining brings the stack usage
down to something sane.

On a testcase I have, on my computer, this allows changing -ftemplate-depth
from 210 to around 750 before we crash.  I'm not sure I should commit the
testcase, though: I don't want to cause test failures on platforms with less
stack space available.

<rdar://problem/14098189>.

llvm-svn: 190114

clang/lib/Sema/TreeTransform.h

@@ -598,14 +598,19 @@ public:
   ExprResult TransformDependentScopeDeclRefExpr(DependentScopeDeclRefExpr *E,
                                                 bool IsAddressOfOperand);
 
+// FIXME: We use LLVM_ATTRIBUTE_NOINLINE because inlining causes a ridiculous
+// amount of stack usage with clang.
 #define STMT(Node, Parent)                        \
+  LLVM_ATTRIBUTE_NOINLINE \
   StmtResult Transform##Node(Node *S);
 #define EXPR(Node, Parent)                        \
+  LLVM_ATTRIBUTE_NOINLINE \
   ExprResult Transform##Node(Node *E);
 #define ABSTRACT_STMT(Stmt)
 #include "clang/AST/StmtNodes.inc"
 
 #define OPENMP_CLAUSE(Name, Class)                        \
+  LLVM_ATTRIBUTE_NOINLINE \
   OMPClause *Transform ## Class(Class *S);
 #include "clang/Basic/OpenMPKinds.def"