header for now for memset/memcpy opportunities.  It turns out that loop-rotate
is successfully rotating loops, but *DOESN'T MERGE THE BLOCKS*, turning "for 
loops" into 2 basic block loops that loop-idiom was ignoring.

With this fix, we form many *many* more memcpy and memsets than before, including
on the "history" loops in the viterbi benchmark, which look like this:

        for (j=0; j<MAX_history; ++j) {
          history_new[i][j+1] = history[2*i][j];
        }

Transforming these loops into memcpy's speeds up the viterbi benchmark from
11.98s to 3.55s on my machine.  Woo.

llvm-svn: 122685

llvm-svn: 122683

llvm-svn: 122682

size of a loop header instead of its own code size estimator.
This allows it to handle bitcasts etc more precisely.

llvm-svn: 122681

llvm-svn: 122678

maintains the guarantee that the DenseSet expects two elements it contains to
not go from inequal to equal under its nose.

As a side-effect, this also lets us switch from iterating to a fixed-point to
actually maintaining a work queue of functions to look at again, and we don't
add thunks to our work queue so we don't need to detect and ignore them.

llvm-svn: 122677

llvm-svn: 122676

llvm-svn: 122675

loop idiom pass exposed.

llvm-svn: 122674

llvm-svn: 122667

earlyclobber stuff. This should fix PRs 2313 and 8157.

Unfortunately, no testcase, since it'd be dependent on register
assignments.

llvm-svn: 122663

new testcase.

llvm-svn: 122662

is the wrong hammer for this nail, and is probably right.

llvm-svn: 122661

aggressively.  In practice, this doesn't help anything though,
see the todo.

llvm-svn: 122660

should be correct now.

llvm-svn: 122659

llvm-svn: 122658

numbering, in which it considers (for example) "%a = add i32 %x, %y" and
"%b = add i32 %x, %y" to be equal because the operands are equal and the
result of the instructions only depends on the values of the operands.
This has almost no effect (it removes 4 instructions from gcc-as-one-file),
and perhaps slows down compilation: I measured a 0.4% slowdown on the large
gcc-as-one-file testcase, but it wasn't statistically significant.

llvm-svn: 122654

llvm-svn: 122653

llvm-svn: 122652

is necessary for executing the custom command that runs the
assember. Fixes PR8877.

llvm-svn: 122649

operands are visited before the instructions themselves.

llvm-svn: 122647

llvm-svn: 122645

llvm-svn: 122642

Fixes PR8861.

llvm-svn: 122641

llvm-svn: 122638

llvm-svn: 122637

llvm-svn: 122636

with 2-address instructions, for about a 3.5% speedup of StrongPHIElimination on
403.gcc.

llvm-svn: 122635

llvm-svn: 122632

llvm-svn: 122631

llvm-svn: 122630

llvm-svn: 122628

process those instructions that define phi sources. This is a 47% speedup of
StrongPHIElimination compile time on 403.gcc.

llvm-svn: 122627

llvm-svn: 122626

llvm-svn: 122625

llvm-svn: 122624

CMake: Add disabling optimization on MSVC8 and MSVC10 as workaround for some files in Target/ARM and Target/X86.

llvm-svn: 122623

llvm-svn: 122617

llvm-svn: 122616

llvm-svn: 122615