In SjLj EH, the jump to the landing pad is not done explicitly through a branch
statement. The EH landing pad is added as a successor to the throwing
BB. Because of that however, the branch folding pass could mistakenly think that
it could merge the throwing BB with another BB. This isn't safe to do.
<rdar://problem/10334833>

llvm-svn: 142891

Four entry register lists.

llvm-svn: 142882

llvm-svn: 142880

llvm-svn: 142878

llvm-svn: 142877

Three entry register list variation.

llvm-svn: 142876

More fixes and improvements to MachO relocation pretty-printing, particular for x86 and x86_64 relocations with addends.

llvm-svn: 142875

llvm-svn: 142871

table. A hidden variable could potentially end up in both lists.
<rdar://problem/10336715>

llvm-svn: 142869

llvm-svn: 142867

One and two length register list variants.

llvm-svn: 142861

Split am6offset into fixed and register offset variants so the instruction
encodings are explicit rather than relying an a magic reg0 marker.
Needed to being able to parse these.

llvm-svn: 142853

llvm-svn: 142852

when deciding that the loop has stopped evolving. Fixes miscompile in the gcc
torture testsuite!

llvm-svn: 142843

llvm-svn: 142841

llvm-svn: 142840

llvm-svn: 142822

llvm-svn: 142821

Fix a NEON disassembly case that was broken in the recent refactorings.  As more of this code gets refactored, a lot of these manual decoding hooks should get smaller and/or go away entirely.

llvm-svn: 142817

physreg dependencies, and upcoming codegen changes will require proper
physreg dependence handling.

llvm-svn: 142816

llvm-svn: 142815

use of Sched::ILP instead, as Sched::Latency is going away.

llvm-svn: 142813

as the Latency scheduler is going away.

llvm-svn: 142811

is going away.

llvm-svn: 142810

PR11220

llvm-svn: 142801

llvm-svn: 142800

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

llvm-svn: 142799

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

  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

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

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

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

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