used it. Fixes an unused variable warning from GCC on release builds.

llvm-svn: 142799

llvm-svn: 142798

llvm-svn: 142797

llvm-svn: 142796

llvm-svn: 142795

Add a test case for the edge case that triggers this. Thanks to Chandler for bringing this to my attention.

llvm-svn: 142794

introduce no-return or unreachable heuristics.

The return heuristics from the Ball and Larus paper don't work well in
practice as they pessimize early return paths. The only good hitrate
return heuristics are those for:
 - NULL return
 - Constant return
 - negative integer return

Only the last of these three can possibly require significant code for
the returning block, and even the last is fairly rare and usually also
a constant. As a consequence, even for the cold return paths, there is
little code on that return path, and so little code density to be gained
by sinking it. The places where sinking these blocks is valuable (inner
loops) will already be weighted appropriately as the edge is a loop-exit
branch.

All of this aside, early returns are nearly as common as all three of
these return categories, and should actually be predicted as taken!
Rather than muddy the waters of the static predictions, just remain
silent on returns and let the CFG itself dictate any layout or other
issues.

However, the return heuristic was flagging one very important case:
unreachable. Unfortunately it still gave a 1/4 chance of the
branch-to-unreachable occuring. It also didn't do a rigorous job of
finding those blocks which post-dominate an unreachable block.

This patch builds a more powerful analysis that should flag all branches
to blocks known to then reach unreachable. It also has better worst-case
runtime complexity by not looping through successors for each block. The
previous code would perform an N^2 walk in the event of a single entry
block branching to N successors with a switch where each successor falls
through to the next and they finally fall through to a return.

Test case added for noreturn heuristics. Also doxygen comments improved
along the way.

llvm-svn: 142793

llvm-svn: 142792

llvm-svn: 142791

  Enhance SCEV's brute force loop analysis to handle multiple PHI nodes in the
  loop header when computing the trip count.

  With this, we now constant evaluate:
    struct ListNode { const struct ListNode *next; int i; };
    static const struct ListNode node1 = {0, 1};
    static const struct ListNode node2 = {&node1, 2};
    static const struct ListNode node3 = {&node2, 3};
    int test() {
      int sum = 0;
      for (const struct ListNode *n = &node3; n != 0; n = n->next)
        sum += n->i;
      return sum;
    }

llvm-svn: 142790

two more subtle routines to the bottom and expand on their cautionary
comments a bit. No functionality or actual interface change here.

llvm-svn: 142789

state. Furthermore, they might not have two operands. This fixes the underlying
issue behind the crashes introduced in r142781.

llvm-svn: 142788

instructions.

This doesn't introduce any optimizations we weren't doing before (except
potentially due to pass ordering issues), now passes will eliminate them sooner
as part of their own cleanups.

llvm-svn: 142787

  Assertion `i_nocapture < OperandTraits<PHINode>::operands(this) && "getOperand() out of range!"' failed.
coming out of indvars.

llvm-svn: 142786

llvm-svn: 142785

to match the CMakeLists.txt change in r142782; this should fix the CMake
build.

llvm-svn: 142784

a single class. Previously it was split between two classes, one
internal and one external. The concern seemed to center around exposing
the weights used, but those can remain confined to the implementation
file.

Having a single class to maintain the state and analyses in use will
also simplify several of the enhancements I want to make to our static
heuristics.

llvm-svn: 142783

Rename AnalysisContext to AnalysisDeclContext.  Not only is this name more accurate, but it frees up the name AnalysisContext for other uses.

llvm-svn: 142782

loop header when computing the trip count.

With this, we now constant evaluate:
  struct ListNode { const struct ListNode *next; int i; };
  static const struct ListNode node1 = {0, 1};
  static const struct ListNode node2 = {&node1, 2};
  static const struct ListNode node3 = {&node2, 3};
  int test() {
    int sum = 0;
    for (const struct ListNode *n = &node3; n != 0; n = n->next)
      sum += n->i;
    return sum;
  }

llvm-svn: 142781

extraneous whitespace. Trying to clean-up this pass as much as I can
before I start making functional changes.

llvm-svn: 142780

llvm-svn: 142779

to bring it under direct test instead of merely indirectly testing it in
the BlockFrequencyInfo pass.

The next step is to start adding tests for the various heuristics
employed, and to start fixing those heuristics once they're under test.

llvm-svn: 142778

These are remainders of the switch to the newer isl version. At the point of
switching I did not test with PoCC support. I should have done. ;-)

llvm-svn: 142777

The recommanded and supported way to use Polly is to load it into clang.
Documentation for this is available on the website under
http://polly.grosser.es/example_load_Polly_into_clang.html

llvm-svn: 142776

This also documents the new option on the website.

llvm-svn: 142775

This removes the separate prevector options for the Pluto and isl scheduler.

llvm-svn: 142774

llvm-svn: 142773

The option -polly-no-optimizer disables the scheduling optimizer.

llvm-svn: 142772

llvm-svn: 142771

llvm-svn: 142770

llvm-svn: 142769

llvm-svn: 142768

llvm-svn: 142767

Similar changes for polly-only-viewer, polly-printer and polly-only-printer.

llvm-svn: 142766

llvm-svn: 142765

llvm-svn: 142764

llvm-svn: 142763

to get important constant branch probabilities and use them for finding
the best branch out of a set of possibilities.

llvm-svn: 142762

llvm-svn: 142761

llvm-svn: 142760