basic block.  This is amazingly common in code generated by the C/C++ front-ends.
This change makes it not have to insert ANY phi nodes, whereas before it would insert
a ton of dead ones which DCE would have to clean up.

Thus, this fix improves compile-time performance of these trivial allocas in two ways:
  1. It doesn't have to do the walking and book-keeping for renaming
  2. It does not insert dead phi nodes for them which would have to
     subsequently be cleaned up.

On my favorite testcase from 252.eon, this special case handles 305 out of
356 promoted allocas in the function.  It speeds up the mem2reg pass from 7.5256s
to 1.2505s.  It inserts 677 fewer dead PHI nodes, which speeds up a subsequent
-dce pass from 18.7524s to 2.4806s.

There are still 120 trivially dead PHI nodes being inserted for variables used
in multiple basic blocks, but they are not handled by this patch.

llvm-svn: 8881

llvm-svn: 8865

The VersionNumbers vector is only used during PHI placement.  Turn it into an argument, allowing us to get rid of the vector.

llvm-svn: 8864

*** Revamp the code which handled unreachable code in the function.  Now the
    code is much more efficient for high-degree basic blocks, such as those
    that occur in the 252.eon SPEC benchmark.

For the interested, the time to promote a SINGLE alloca in _ZN7mrScene4ReadERSi
function used to be > 3.5s.  Now it is < .075s.  The function has a LOT of
allocas in it, so it appeared to be infinite looping, this should make it much
nicer.  :)

llvm-svn: 8863

llvm-svn: 8862

work-list of value definitions.  This allows elimination of the explicit
'iterative' step of the algorithm, and also reuses temporary memory better.

llvm-svn: 8861

need to be an instance variable!

llvm-svn: 8860

* Fuse two parallel loops
* Use a more specific type for AllocaLookup

llvm-svn: 8859

 * Do not insert a new entry into NewPhiNodes during the rename pass if there are no PHIs in a block.
 * Do not compute WriteSets in parallel

llvm-svn: 8858

* Eliminate the KillList instance variable, instead, just delete loads and
  stores as they are "renamed", and delete allocas when they are done
* Make the 'visited' set an instance variable to avoid passing it on the stack.

llvm-svn: 8857

llvm-svn: 7944

llvm-svn: 5919

llvm-svn: 5895

llvm-svn: 5824

llvm-svn: 5810

* Make Mem2Reg assign version numbers now for renamed variables instead of
  .mem2reg suffixes.  This produces what people think of as SSA.

llvm-svn: 5771

llvm-svn: 5685

a pass which wraps the function.  This allows other passes to use the functionality

llvm-svn: 5610

llvm-svn: 5608

    setPreservesCFG to be less confusing.

llvm-svn: 4255

    * Renamed StatisticReporter.h/cpp to Statistic.h/cpp
    * Broke constructor to take two const char * arguments instead of one, so
      that indendation can be taken care of automatically.
    * Sort the list by pass name when printing
    * Make sure to print all statistics as a group, instead of randomly when
      the statistics dtors are called.
    * Updated ProgrammersManual with new semantics.

llvm-svn: 4002

llvm-svn: 3917

Clean up code due to auto-insert constructors

llvm-svn: 3665

llvm-svn: 3487

- Cleaned up the interface to AnalysisUsage to take analysis class names
   instead of ::ID's.
 - Pass::getAnalysis<> now no longer takes an optional argument

llvm-svn: 3265

* Add support for different "PassType's"
* Add new RegisterOpt/RegisterAnalysis templates for registering passes that
  are to show up in opt or analyze
* Register Analyses now
* Change optimizations to use RegisterOpt instead of RegisterPass
* Add support for different "PassType's"
* Add new RegisterOpt/RegisterAnalysis templates for registering passes that
  are to show up in opt or analyze
* Register Analyses now
* Change optimizations to use RegisterOpt instead of RegisterPass
* Remove getPassName implementations from various subclasses

llvm-svn: 3113

llvm-svn: 3016

For details, See: docs/2002-06-25-MegaPatchInfo.txt

llvm-svn: 2779

the command line

llvm-svn: 2601

llvm-svn: 2537

Fixed bug: test/Regression/Transforms/Mem2Reg/2002-05-01-ShouldNotPromoteThisAlloca.ll

llvm-svn: 2423

This only requires Type.h anyway

llvm-svn: 2405

llvm-svn: 2397

to make debugging output a lot nicer.

llvm-svn: 2395

Tighten up the AnalysisUsage of lots of passes, primarily to correctly indicate whether or not they invalidate the CFGA

llvm-svn: 2386

llvm-svn: 2378

class.

llvm-svn: 2375

PromoteInstance.  Make them local variables that are passed around as
appropriate.  Especially in the case of CurrentValue, this makes the
code simpler.

llvm-svn: 2374

* Minor cleanup that was missed in last patch

llvm-svn: 2373

Bugfixes will come in the next revision so that the diff is obvious.

llvm-svn: 2372