LLVM Value/Use does and MachineRegisterInfo/MachineOperand does.
This allows constant time for all uses list maintenance operations.

The idea was suggested by Chris. Reviewed by Evan and Dan.
Patch is tested and approved by Dan.

On normal use-cases compilation speed is not affected. On very big basic
blocks there are compilation speedups in the range of 15-20% or even better. 

llvm-svn: 48822

llvm-svn: 48819

This fixes Bugzilla #1835 (http://llvm.org/bugs/show_bug.cgi?id=1835).
This patched is reviewed by Tanya and Dan. Dan tested and approved it.

The reason for the bad performance of the old algorithm is that it is very naive and scans every
time all nodes of the DAG in the worst case.

This patch introduces  a new algorithm based on the paper "Online algorithms
for maintaining the topological order of a directed acyclic graph" by
David J.Pearce and Paul H.J.Kelly. This is the MNR algorithm. It has a
linear time worst-case and performs much better in most situations.

The paper can be found here:
http://fano.ics.uci.edu/cites/Document/Online-algorithms-for-maintaining-the-topological-order-of-a-directed-acyclic-graph.html

The main idea of the new algorithm is to compute the topological ordering of the SNodes in the
DAG and to maintain it even after DAG modifications. The topological ordering allows for very fast 
node reachability checks. 

Tests on very big  input files with tens of thousands of instructions in a BB indicate huge 
speed-ups (up to 10x compilation time improvement) compared to the old version.

llvm-svn: 48817

llvm-svn: 48815

llvm-svn: 48811

llvm-svn: 48809

llvm's output .s files will go through gcc -std=c99
without triggering preprocesser errors.  Approach
suggested by Daveed Vandevoorde.

llvm-svn: 48808

# this is my first commit here, so please be gentle :)

llvm-svn: 48807

will gradually get pruned down, as it doesn't need to be as functional as
'ccc'.

llvm-svn: 48806

llvm-svn: 48805

llvm-svn: 48804

llvm-svn: 48803

llvm-svn: 48802

llvm-svn: 48801

marked read-write. Use const so that they can be allocated in a
read-only segment.

llvm-svn: 48800

llvm-svn: 48797

llvm-svn: 48794

llvm-svn: 48793

Handle a special case xor undef, undef -> 0. Technically this should be transformed to undef. But this is such a common idiom (misuse) we are going to handle it.

llvm-svn: 48792

Handle a special case xor undef, undef -> 0. Technically this should be transformed to undef. But this is such a common idiom (misuse) we are going to handle it.

llvm-svn: 48791

llvm-svn: 48786

the future, RecordTypes.

llvm-svn: 48784

llvm-svn: 48783

Patch by dekruijf@cs.wisc.edu!

llvm-svn: 48782

llvm-svn: 48779

other things, this allows the scheduler to unfold a load operand
in the 2008-01-08-SchedulerCrash.ll testcase, so it now successfully
clones the comparison to avoid a pushf+popf.

llvm-svn: 48777

passing an uninitialized value to a message expresion.

llvm-svn: 48776

llvm-svn: 48775

This adds support for instruction iterators, as well as rewriting the
builder code to use these new functions. This lets us eliminate the C
bindings for moving around the builder.

Patch by Erick Tryzelaar!

llvm-svn: 48774

and message expressions with a specified receiver.

llvm-svn: 48773

object directory.

llvm-svn: 48766

llvm-svn: 48764

OwningPtr<> class.

llvm-svn: 48763

llvm-svn: 48762

and uninitialized values passed-by-value as arguments to message expressions.

llvm-svn: 48760

llvm-svn: 48759

llvm-svn: 48758

llvm-svn: 48757

llvm-svn: 48756

llvm-svn: 48755