FileCheck-ize test and make sure more things don't happen.

[probinson]

Summary

Attirbute 'nodebug' means no llvm.dbg.* intrinsics, no !dbg annotations, and no DISubprogram for the function.

[dblaikie]

SGTM

(heh, I don't even remember "llvm.dbg.func.start" - maybe that's from
before my time... yep, 2009)

Maybe it'd be nice to make sure that this test doesn't bitrot the same way
again - have a canary of some kind? (eg: a non-nodebug function and
positively CHECK for the same features - so if those checks ever fail, we
know we've accidentally made the negative tests for dbg/DISubprogram
invalid)

Seems weird - not sure if it's a good idea. Just a thought.

[probinson]

I had a similar thought, but had foolishly suppressed it. Since you had the same thought, it's probably worth paying attention to it.

[dblaikie]

Looks good - alternatively you could phrase this as a single function with
a macro for the nodebug attribute - two clang+FileCheck lines, one passes
-D to enable the nodebug, one passes an empty -D. Might be a more direct
comparison? (& does require two clang invocations, which is a tradeoff)

[probinson]

In D10747#195045, @dblaikie wrote:

Looks good - alternatively you could phrase this as a single function with
a macro for the nodebug attribute - two clang+FileCheck lines, one passes
-D to enable the nodebug, one passes an empty -D. Might be a more direct
comparison? (& does require two clang invocations, which is a tradeoff)

Yeah, but for this it doesn't really seem worthwhile; the functions are pretty trivial and the checks are very generic.
For something more specific/fine-tuned, or bigger test functions, it might be more worth it.

r240747, thanks!

test/CodeGen/attr-nodebug.c

-// RUN: %clang_cc1 -g -emit-llvm -o %t %s
-// RUN: not grep 'call void @llvm.dbg.func.start' %t
+// RUN: %clang_cc1 -g -emit-llvm -o - %s | FileCheck %s
 
 void t1() __attribute__((nodebug));
 
 void t1()
 {
   int a = 10;
-  
   a++;
 }
 
+void t2()
+{
+  int b = 10;
+  b++;
+}
+
+// With nodebug, IR should have no llvm.dbg.* calls, or !dbg annotations.
+// CHECK-LABEL: @t1
+// CHECK-NOT:   dbg
+// CHECK:       }
+
+// For sanity, check those things do occur normally.
+// CHECK-LABEL: @t2
+// CHECK:       call{{.*}}llvm.dbg
+// CHECK:       !dbg
+// CHECK:       }
+
+// We should see a function description for t2 but not t1.
+// CHECK-NOT: DISubprogram(name: "t1"
+// CHECK:     DISubprogram(name: "t2"
+// CHECK-NOT: DISubprogram(name: "t1"
+