See PR3160 for details

llvm-svn: 60604

llvm-svn: 60594

llvm-svn: 60588

This fixes many bugs. I will add more test cases in a separate check-in.

Some day, the code that manipulates CFG and updates dom. info could use refactoring help.

llvm-svn: 60554

llvm-svn: 60534

llvm-svn: 60514

llvm-svn: 60508

llvm-svn: 60506

llvm-svn: 60501

llvm-svn: 60494

1) have it fold "br undef", which does occur with
   surprising frequency as jump threading iterates.
2) teach j-t to delete dead blocks.  This removes the successor
   edges, reducing the in-edges of other blocks, allowing 
   recursive simplification.
3) Fold things like:
     br COND, BBX, BBY
  BBX:
     br COND, BBZ, BBW

   which also happens because jump threading iterates.

llvm-svn: 60470

llvm-svn: 60469

llvm-svn: 60468

unconditionally delete the block.  All likely clients will
do the checking anyway.

llvm-svn: 60464

DeleteBlockIfDead method.

llvm-svn: 60463

llvm-svn: 60442

llvm-svn: 60431

straight-forward implementation.  This does not require any extra
alias analysis queries beyond what we already do for non-local loads.

Some programs really really like load PRE.  For example, SPASS triggers
this ~1000 times, ~300 times in 255.vortex, and ~1500 times on 403.gcc.

The biggest limitation to the implementation is that it does not split
critical edges.  This is a huge killer on many programs and should be
addressed after the initial patch is enabled by default.

The implementation of this should incidentally speed up rejection of 
non-local loads because it avoids creating the repl densemap in cases 
when it won't be used for fully redundant loads.

This is currently disabled by default.
Before I turn this on, I need to fix a couple of miscompilations in
the testsuite, look at compile time performance numbers, and look at
perf impact.  This is pretty close to ready though.

llvm-svn: 60408

llvm-svn: 60403

llvm-svn: 60402

llvm-svn: 60401

  constant. If X is a constant, then this is folded elsewhere.

- Added a note to Target/README.txt to indicate that we'd like to implement
  this when we're able.

llvm-svn: 60399

llvm-svn: 60398

- No need to do a swap on a canonicalized pattern.

No functionality change.

llvm-svn: 60397

llvm-svn: 60395

a new value numbering set after splitting a critical edge.  This increases
the number of instances of PRE on 403.gcc from ~60 to ~570.

llvm-svn: 60393

figuring out the base of the IV.  This produces better
code in the example.  (Addresses use (IV) instead of 
(BASE,IV) - a significant improvement on low-register
machines like x86).

llvm-svn: 60374

llvm-svn: 60370

llvm-svn: 60369

integer is "minint".

llvm-svn: 60366

don't have overlapping bits.

llvm-svn: 60344

llvm-svn: 60343

llvm-svn: 60341

Move pattern check outside of the if-then statement. This prevents us from fiddling with constants unless we have to.

llvm-svn: 60340

llvm-svn: 60339

that it isn't reallocated all the time.  This is a tiny speedup for
GVN: 3.90->3.88s

llvm-svn: 60338

llvm-svn: 60337

instead of std::sort.  This shrinks the release-asserts LSR.o file
by 1100 bytes of code on my system.

We should start using array_pod_sort where possible.

llvm-svn: 60335

This is a lot cheaper and conceptually simpler.

llvm-svn: 60332

DeadInsts ivar, just use it directly.

llvm-svn: 60330