Avoid generation of dead code in a few more situations.

 - Emit variable declarations as "simple", we want to avoid forcing the creation
   of a dummy basic block, but still need to make the variable available for
   later use.

 - With that, we can now skip IRgen for other unreachable statements (which
   don't define a label).

 - Anders, I added two fixmes on calls to EmitVLASize, can you check them?


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@76361 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 0 deletions

diff --git a/test/CodeGen/unreachable.c b/test/CodeGen/unreachable.c
new file mode 100644
index 0000000000..ab029b613d
--- /dev/null
+++ b/test/CodeGen/unreachable.c
@@ -0,0 +1,26 @@
+// RUN: clang-cc -emit-llvm -o %t %s &&
+// RUN: grep '@unreachable' %t | count 0
+
+extern int unreachable();
+
+int f0() {
+  return 0;
+  unreachable();
+}
+
+int f1(int i) {
+  goto L0;
+  int a = unreachable();
+ L0:
+  return 0;
+}
+
+int f2(int i) {
+  goto L0;
+  unreachable();
+  int a;
+  unreachable();
+ L0:
+  a = i + 1;
+  return a;
+}