This changes loop unrolling to use the same mechanism for trip count
computation as indvars. This is a stronger check that tends to unroll
more loops. A very common side-effect is that many single iteration
loops will be removed sooner. The real goal was simply to remove
dependence on canonical IVs.

x86 is break even.
ARM performance changes to expect (+ is good):
External/SPEC/CFP2000/183.equake/183.equake +13%
SingleSource/Benchmarks/Dhrystone/fldry     +21%
MultiSource/Applications/spiff/spiff         +3%
SingleSource/Benchmarks/Stanford/Puzzle     -14%

The Puzzle regression is actually an improvement in loop optimization
that defeats GVN: rdar://problem/10065079.

llvm-svn: 139009

will be valid. This fixes PR10820.

llvm-svn: 139005

Duncan noticed this!

llvm-svn: 138967

Fix an issue with the IR sink pass found by inspection.  (I'm not sure anyone is actually using this, but might as well fix it since I found the issue.)

llvm-svn: 138965

The landingpad instruction is required in the landing pad block. Because we're
not deleting terminating instructions, the invoke may still jump to here (see
Transforms/SCCP/2004-11-16-DeadInvoke.ll). Remove all uses of the landingpad
instruction, but keep it around until code-gen can remove the basic block.

llvm-svn: 138890

ssa, so it has to be run really early in the pipeline. Any replacement
should probably use the SSAUpdater.

llvm-svn: 138841

llvm-svn: 138829

When walking backwards to eliminate final stores to allocas at the end of a function, encountering an unrelated store should not cause us to give up like encountering a load does.

llvm-svn: 138809

llvm-svn: 138651

proper function to do it.

llvm-svn: 138550

getFirstNonPHI so that it will skip over the landingpad instructions as well.

llvm-svn: 138537

llvm-svn: 138481

insertion place.

llvm-svn: 138473

llvm-svn: 138243

llvm-svn: 138242

llvm-svn: 138102

llvm-svn: 138025

known-incremented level, because the two concepts can be used
to prove the saftey of a retain+release removal in different
ways.

llvm-svn: 138016

llvm-svn: 138008

llvm-svn: 137985

Dramatically speedup codegen prepare by a) avoiding use of dominator tree and b) doing a separate pass over dbg.value instructions.

llvm-svn: 137908

llvm-svn: 137888

PRE needs the landing pads to have their critical edges split. Doing this for a
landing pad is non-trivial. Abandon the attempt to perform PRE when we come
across a landing pad. (Reviewed by Owen!)

llvm-svn: 137876

Silly mistake from r137777; restore significant isStructTy() checks.  While here, be a bit more defensive
with unknown instructions.

Fixes PR10687.

llvm-svn: 137836

making random bad assumptions about instructions which are not explicitly listed.  

Includes fix for rdar://9956541, a version of "undef ^ undef should return
0 because it's easier than arguing with users".

llvm-svn: 137777

Minor bug in SCCP found by inspection.  (I don't think it's possible to hit this with a normal pass pipeline, but fixing for completeness.)

llvm-svn: 137755

check for a LandingPadInst.

llvm-svn: 137745

llvm-svn: 137679

llvm-svn: 137648

llvm-svn: 137626

This implements the 'landingpad' instruction. It's used to indicate that a basic
block is a landing pad. There are several restrictions on its use (see
LangRef.html for more detail). These restrictions allow the exception handling
code to gather the information it needs in a much more sane way.

This patch has the definition, implementation, C interface, parsing, and bitcode
support in it.

llvm-svn: 137501

when building with assertions disabled.

llvm-svn: 137460

is returned through a bitcast.

llvm-svn: 137402

the retains and releases all use the same SSA pointer value.

Also, don't let CFG hazards disrupt nested retain+release pair
optimizations.

llvm-svn: 137399

rather than plain postorder, so that CFG constructs like single-exit loops
are reliably visited in a sensible order.

llvm-svn: 137398

SCEV unrolling can unroll loops with arbitrary induction variables. It
is a prerequisite for -disable-iv-rewrite performance. It is also
easily handles loops of arbitrary structure including multiple exits
and is generally more robust.

This is under a temporary option to avoid affecting default
behavior for the next couple of weeks. It is needed so that I can
checkin unit tests for updateUnloop.

llvm-svn: 137384

llvm-svn: 137352

llvm-svn: 137203

SimplifyIndVar utility since it is required.

llvm-svn: 137202

based on ScalarEvolution without changing the induction variable phis.

This utility is the main tool of IndVarSimplifyPass, but the pass also
restructures induction variables in strange ways that are sensitive to
pass ordering. This provides a way for other loop passes to simplify
new uses of induction variables created during transformation. The
utility may be used by any pass that preserves ScalarEvolution. Soon
LoopUnroll will use it.

The net effect in this checkin is to cleanup the IndVarSimplify pass
by factoring out the SimplifyIndVar algorithm into a standalone utility.

llvm-svn: 137197