[FileCheck] Suppress old -v/-vv diags if dumping input

The old diagnostic form of the trace produced by -v and -vv looks
like:

```
check1:1:8: remark: CHECK: expected string found in input
CHECK: abc
       ^
<stdin>:1:3: note: found here
; abc def
  ^~~
```

When dumping annotated input is requested (via -dump-input), I find
that this old trace is not useful and is sometimes harmful:

1. The old trace is mostly redundant because the same basic
   information also appears in the input dump's annotations.

2. The old trace buries any error diagnostic between it and the input
   dump, but I find it useful to see any error diagnostic up front.

3. FILECHECK_OPTS=-dump-input=fail requests annotated input dumps only
   for failed FileCheck calls.  However, I have to also add -v or -vv
   to get a full set of annotations, and that can produce massive
   output from all FileCheck calls in all tests.  That's a real
   problem when I run this in the IDE I use, which grinds to a halt as
   it tries to capture all that output.

When -dump-input=fail|always, this patch suppresses the old trace from
-v or -vv.  Error diagnostics still print as usual.  If you want the
old trace, perhaps to see variable expansions, you can set
-dump-input=none (the default).

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D55825

llvm-svn: 351881

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/docs/CommandGuide/FileCheck.rst b/llvm/docs/CommandGuide/FileCheck.rst
index 721d2c2..33d9fe8 100644
--- a/llvm/docs/CommandGuide/FileCheck.rst
+++ b/llvm/docs/CommandGuide/FileCheck.rst
@@ -111,13 +111,16 @@ and from the command line.
 
 .. option:: -v
 
-  Print directive pattern matches.
+  Print good directive pattern matches.  However, if ``-input-dump=fail`` or
+  ``-input-dump=always``, add those matches as input annotations instead.
 
 .. option:: -vv
 
   Print information helpful in diagnosing internal FileCheck issues, such as
   discarded overlapping ``CHECK-DAG:`` matches, implicit EOF pattern matches,
   and ``CHECK-NOT:`` patterns that do not have matches.  Implies ``-v``.
+  However, if ``-input-dump=fail`` or ``-input-dump=always``, just add that
+  information as input annotations instead.
 
 .. option:: --allow-deprecated-dag-overlap