Widen EHScope::ClenupBitFields::FixupDepth to avoid overflowing it (PR23490)

It currently only takes 2048 gotos to overflow the FixupDepth bitfield,
causing silent miscompilation. Apparently some parser generators run into
this (see PR).

I don't know that that data structure is terribly size sensitive anyway,
and since there's no room to widen the bitfield, let's just use a separate
word in EHCatchScope for it.

Differential Revision: http://reviews.llvm.org/D21566

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@273434 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 0 deletions

diff --git a/test/CodeGen/fixup-depth-overflow.c b/test/CodeGen/fixup-depth-overflow.c
new file mode 100644
index 0000000000..be8f54284e
--- /dev/null
+++ b/test/CodeGen/fixup-depth-overflow.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -O1 -disable-llvm-optzns -emit-llvm -o - %s | FileCheck %s
+
+#define M if (x) goto L1;
+#define M10 M M M M M M M M M M
+#define M100 M10 M10 M10 M10 M10 M10 M10 M10 M10 M10
+#define M1000 M100 M100 M100 M100 M100 M100 M100 M100 M100 M100
+
+void f(int x) {
+  int h;
+
+  // Many gotos to not-yet-emitted labels would cause EHScope's FixupDepth
+  // to overflow (PR23490).
+  M1000 M1000 M1000
+
+  if (x == 5) {
+    // This will cause us to emit a clean-up of the stack variable. If the
+    // FixupDepths are broken, fixups will erroneously get threaded through it.
+    int i;
+  }
+
+L1:
+  return;
+}
+
+// CHECK-LABEL: define void @f
+// CHECK-NOT: cleanup