Ensure we evaluate VLA bounds if a variably-modified type is used as the

argument to __builtin_va_arg. Patch by Rahul Jain, some test massaging and
IR emission order changes by me.

llvm-svn: 206223

2 files changed, 12 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 5f932b08b55..08e410be013 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -3199,6 +3199,10 @@ Value *ScalarExprEmitter::VisitChooseExpr(ChooseExpr *E) {
 }
 
 Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
+  QualType Ty = VE->getType();
+  if (Ty->isVariablyModifiedType())
+    CGF.EmitVariablyModifiedType(Ty);
+
   llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
   llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
 
diff --git a/clang/test/CodeGen/varargs.c b/clang/test/CodeGen/varargs.c
index b6973d8337d..3e2cce07938 100644
--- a/clang/test/CodeGen/varargs.c
+++ b/clang/test/CodeGen/varargs.c
@@ -1,5 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck %s
-
+// RUN: %clang_cc1 -triple i386-unknown-unknown -emit-llvm -o - %s | FileCheck %s
 
 // PR6433 - Don't crash on va_arg(typedef).
 typedef double gdouble;
@@ -15,3 +14,10 @@ void function_as_vararg() {
   // CHECK-NOT: llvm.trap
   vararg(0, focus_changed_cb);
 }
+
+void vla(int n, ...)
+{
+  __builtin_va_list ap;
+  void *p;
+  p = __builtin_va_arg(ap, typeof (int (*)[++n])); // CHECK: add nsw i32 {{.*}}, 1
+}