20040709-1.c from the gcc testsuite.  I was using the size of a
pointer instead of the pointee.  This fixes rdar://8713376

llvm-svn: 120519

llvm-svn: 120498

may-aliasing stores that partially overlap with different base
pointers.  This implements PR6043 and the non-variable part of
PR8657

llvm-svn: 120485

llvm-svn: 120476

llvm-svn: 120474

llvm-svn: 120471

the code.  We now get accurate sizes on Loads, though it surely doesn't
matter in practice.

llvm-svn: 120469

1. if the underlying pointer passed in can be resolved
   to any argument or alloca, then we don't need to scan.
   Previously we would only avoid the scan if the alloca
   or byval was actually considered dead.
2. The dead store processing code is itself completely
   dead and didn't handle volatile stores right anyway,
   so delete it.  This allows simplifying the interface
   to RemoveAccessedObjects.

llvm-svn: 120467

made sense to me.  We now have a set of dead stack objects, and
they become live when loaded.  Fix a theoretical problem where
we'd pass in the wrong pointer to the alias query.

llvm-svn: 120465

If the call might read all the allocas, stop scanning early.
Convert a vector to smallvector, shrink SmallPtrSet to 16 instead
of 64 to avoid crazy linear scans.

llvm-svn: 120463

there should be a better way to do this.  PR 8679.

llvm-svn: 120457

llvm-svn: 120454

AA and MD pass info instead of using getAnalysis<> all over.

llvm-svn: 120453

llvm-svn: 120452

now that DSE hacks on them.  This fixes a regression I introduced,
by generalizing DSE to hack on transfers.

llvm-svn: 120445

about pairs of AA::Location's instead of looking for MemDep's
"Def" predicate.  This is more powerful and general, handling
memset/memcpy/store all uniformly, and implementing PR8701 and
probably obsoleting parts of memcpyoptimizer.

This also fixes an obscure bug with init.trampoline and i8
stores, but I'm not surprised it hasn't been hit yet.  Enhancing
init.trampoline to carry the size that it stores would allow
DSE to be much more aggressive about optimizing them.

llvm-svn: 120406

llvm-svn: 120398

llvm-svn: 120391

remove an actively-wrong comment.

llvm-svn: 120378

It can be seriously improved, but at least now it isn't intertwined
with the other logic.

llvm-svn: 120377

contains "ref".

Enhance DSE to use a modref query instead of a store-specific hack
to generalize the "ignore may-alias stores" optimization to handle
memset and memcpy.

llvm-svn: 120368

stores, fix and add a testcase.

llvm-svn: 120363

1. Don't bother trying to optimize:

lifetime.end(ptr)
store(ptr)

as it is undefined, and therefore shouldn't exist.

2. Move the 'storing a loaded pointer' xform up, simplifying
  the may-aliased store code.

llvm-svn: 120359

llvm-svn: 120347

llvm-svn: 120325

by my recent GVN improvement.  Looking through a single layer of
PHI nodes when attempting to sink GEPs, we need to iteratively
look through arbitrary PHI nests.

llvm-svn: 120202

whether the pointer can be replaced with the global variable it is a copy of.
Fixes PR8680.

llvm-svn: 120126

in two places that are really interested in simplified instructions, not
constants.

llvm-svn: 120044

(which does constant folding and more) is called a few lines
later.

llvm-svn: 120042

llvm-svn: 119948

method in MemDep instead of inserting an instruction, doing a query,
then removing it.  Neither operation is effectively cached.

llvm-svn: 119930

llvm-svn: 119927

allowing the memcpy to be eliminated.

Unfortunately, the requirements on byval's without explicit 
alignment are really weak and impossible to predict in the 
mid-level optimizer, so this doesn't kick in much with current
frontends.  The fix is to change clang to set alignment on all
byval arguments.

llvm-svn: 119916

llvm-svn: 119908

llvm-svn: 119865

if all the operands of the PHI are equivalent.  This allows CodeGenPrepare to undo
unprofitable PRE transforms.

llvm-svn: 119853

preserves LCSSA form out of ScalarEvolution and into the LoopInfo
class.  Use it to check that SimplifyInstruction simplifications
are not breaking LCSSA form.  Fixes PR8622.

llvm-svn: 119727

Completely rework the datastructure GVN uses to represent the value number to leader mapping.  Previously,
this was a tree of hashtables, and a query recursed into the table for the immediate dominator ad infinitum
if the initial lookup failed.  This led to really bad performance on tall, narrow CFGs.

We can instead replace it with what is conceptually a multimap of value numbers to leaders (actually
represented by a hashtable with a list of Value*'s as the value type), and then
determine which leader from that set to use very cheaply thanks to the DFS numberings maintained by
DominatorTree.  Because there are typically few duplicates of a given value, this scan tends to be
quite fast.  Additionally, we use a custom linked list and BumpPtr allocation to avoid any unnecessary
allocation in representing the value-side of the multimap.

This change brings with it a 15% (!) improvement in the total running time of GVN on 403.gcc, which I
think is pretty good considering that includes all the "real work" being done by MemDep as well.

The one downside to this approach is that we can no longer use GVN to perform simple conditional progation,
but that seems like an acceptable loss since we now have LVI and CorrelatedValuePropagation to pick up
the slack.  If you see conditional propagation that's not happening, please file bugs against LVI or CVP.

llvm-svn: 119714

saying "it would be bad", give an example of what is going on.

llvm-svn: 119695

refusing to optimize two memcpy's like this:

copy A <- B
copy C <- A

if it couldn't prove that noalias(B,C).  We can eliminate
the copy by producing a memmove instead of memcpy.

llvm-svn: 119694