[tablegen] !strconcat accepts more than two arguments but this wasn't documented or tested.

Summary:
* Updated the documentation
* Added a test for >2 arguments
* Added a check for the lexical concatenation
* Made the existing test a bit stricter.

Reviewers: t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, llvm-commits

Differential Revision: http://reviews.llvm.org/D3485

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207865 91177308-0d34-0410-b5e6-96231b3b80d8
llvm-cov: Fix handling of line zero appearing in a line table

Reading line tables in llvm-cov was pretty broken, but would happen to
work as long as no line in the table was 0. It's not clear to me
whether a line of zero *should* show up in these tables, but deciding
to read a string in the middle of the line table is certainly the
wrong thing to do if it does.

I've also added some comments, as trying to figure out what this block
of code was doing was fairly unpleasant.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207866 91177308-0d34-0410-b5e6-96231b3b80d8
Clean up constructor logic and member access for LoopVectorizeHints.

There are public functions that mutate various members as well as
another private member already, so make all the members private to
avoid the discontinuity and add accessors for the values. Should
be no functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207868 91177308-0d34-0410-b5e6-96231b3b80d8
Aliases are always definitions. Delete dead code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207869 91177308-0d34-0410-b5e6-96231b3b80d8
Satisfy GCC's urgent need for parentheses around ‘&&’ within ‘||’.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207871 91177308-0d34-0410-b5e6-96231b3b80d8
[sanitizers] Propagate the sanitizer options through to the lit context.
This makes it *really* easy to debug leaks FYI:

ASAN_OPTIONS=detect_leaks=1 ./bin/llvm-lit -v <path to test>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207874 91177308-0d34-0410-b5e6-96231b3b80d8
Try simplifying LexicalScopes ownership again.

Committed initially in r207724-r207726 and reverted due to compiler-rt
crashes in r207732.

Instead, fix this harder with unordered_map and store the LexicalScopes
by value in the map. This did necessitate moving the definition of
LexicalScope above the definition of LexicalScopes.

Let's see how the buildbots/compilers tolerate unordered_map::emplace +
std::piecewise_construct + std::forward_as_tuple...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207876 91177308-0d34-0410-b5e6-96231b3b80d8
[LSR] Add llc testcase for r207271/r207569.

See PR19608 for the details but to summarize it was easy to modify the .ll
file to get the desired def-use ordering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207887 91177308-0d34-0410-b5e6-96231b3b80d8
Fold selects when the non-selected elements are undef from shufflevectors

If we have a select whose operands are two shufflevectors and we know the
non-selected elements are undef, replace the instruction with a
shufflevector from the source vectors of the shufflevectors.

Added test cases.