SimplifyCFG: Track the number of used icmps when turning a icmp chain into a switch. If we used only one icmp, don't turn it into a switch.

Also prevent the switch-to-icmp transform from creating identity adds, noticed by Marius Wachtler.

llvm-svn: 125056

SimplifyCFG: Also transform switches that represent a range comparison but are not sorted into sub+icmp.

This transforms another 1000 switches in gcc.c.

llvm-svn: 124826

This makes the job of the later optzn passes easier, allowing the vast amount of
icmp transforms to chew on it.

We transform 840 switches in gcc.c, leading to a 16k byte shrink of the resulting
binary on i386-linux.

The testcase from README.txt now compiles into
  decl  %edi
  cmpl  $3, %edi
  sbbl  %eax, %eax
  andl  $1, %eax
  ret

llvm-svn: 124724

llvm-svn: 124526

llvm-svn: 124522

Re-commit r124462 with fixes. Tail recursion elim will now dup ret into unconditional predecessor to enable TCE on demand.

llvm-svn: 124518

llvm-svn: 124478

  branches. PR8575, rdar://5134905, rdar://8911460.
- Allow codegen tail duplication to dup small return blocks after register
  allocation is done.

llvm-svn: 124462

code.

llvm-svn: 124100

llvm-svn: 124099

on test-suite + SPEC2000 & SPEC2006.

llvm-svn: 124068

llvm-svn: 123732

function. This seems to be about a 1.5% speedup of -scalarrepl on test-suite
with SPEC2000 and SPEC2006.

llvm-svn: 123731

dominance and post-dominance frontiers.

llvm-svn: 123725

llvm-svn: 123724

checks enabled:

1) Use '<' to compare integers in a comparison function rather than '<='.

2) Use the uniqued set DefBlocks rather than Info.DefiningBlocks to initialize
the priority queue.

The speedup of scalarrepl on test-suite + SPEC2000 + SPEC2006 is a bit less, at
just under 16% rather than 17%.

llvm-svn: 123662

llvm-svn: 123618

eliminating a potentially quadratic data structure, this also gives a 17%
speedup when running -scalarrepl on test-suite + SPEC2000 + SPEC2006. My initial
experiment gave a greater speedup around 25%, but I moved the dominator tree
level computation from dominator tree construction to PromoteMemToReg.

Since this approach to computing IDFs has a much lower overhead than the old
code using precomputed DFs, it is worth looking at using this new code for the
second scalarrepl pass as well.

llvm-svn: 123609

to use it.

llvm-svn: 123501

"promote a bunch of load and stores" logic, allowing the code to
be shared and reused.

llvm-svn: 123456

llvm-svn: 123426

DT->changeImmediateDominator() trivially ignores identity updates, so there is
really no need for the uniqueing provided by SmallPtrSet.

I expect this to fix PR8954.

llvm-svn: 123286

llvm-svn: 123247

Factor the actual simplification out of SimplifyIndirectBrOnSelect and into a new helper function so it can be reused in e.g. an upcoming SimplifySwitchOnSelect.
No functional change.

llvm-svn: 123234

is floating around in the ether.

llvm-svn: 123223

phi nodes.  It is called from MergeBlockIntoPredecessor which is 
called from GVN, which claims to preserve these.

I'm skeptical that this is the actual problem behind PR8954, but
this is a stab in the right direction.

llvm-svn: 123222

llvm-svn: 123221

loop info.

llvm-svn: 123074

llvm-svn: 123071

they all ready do). This removes two dominator recomputations prior to isel,
which is a 1% improvement in total llc time for 403.gcc.

The only potentially suspect thing is making GCStrategy recompute dominators if
it used a custom lowering strategy.

llvm-svn: 123064

1. Take a flags argument instead of a bool.  This makes
   it more clear to the reader what it is used for.
2. Add a flag that says that "remapping a value not in the
   map is ok".
3. Reimplement MapValue to share a bunch of code and be a lot
   more efficient.  For lookup failures, don't drop null values
   into the map.
4. Using the new flag a bunch of code can vaporize in LinkModules
   and LoopUnswitch, kill it.

No functionality change.

llvm-svn: 123058

llvm-svn: 123025

InstructionSimplify on instructions that didn't change since the
last time round the loop.

llvm-svn: 122745

so that Dominators.h is *just* domtree.  Also prune #includes a bit.

llvm-svn: 122714

in the PR, the pass could break LCSSA form when inserting preheaders.  It probably
would be easy enough to fix this, but since currently we always go into LCSSA form
after running this pass, doing so is not urgent.

llvm-svn: 122695

operands are visited before the instructions themselves.

llvm-svn: 122647

llvm-svn: 122645

llvm-svn: 122642

BuildLibCalls: Nuke EmitMemCpy, EmitMemMove and EmitMemSet. They are dead and superseded by IRBuilder.

llvm-svn: 122576

llvm-svn: 122556