Only currently done if the later store is writing to a power of 2 address or 
has the same alignment as the earlier store as then its likely to not break up
large stores into smaller ones

Fixes <rdar://problem/10140300>

llvm-svn: 143630

elimination on them too.

llvm-svn: 142735

Enhance the memdep interface so that users can tell the difference between a dependency which cannot be calculated and a path reaching the entry point of the function. This patch introduces isNonFuncLocal, which replaces isUnknown in some cases.

Patch by Xiaoyi Guo.

llvm-svn: 141896

llvm-svn: 139571

Try again at r138809 (make DSE more aggressive in removing dead stores at the end of a function), now with less deleting stores before memcpy's.

llvm-svn: 139150

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: 137888

llvm-svn: 136205

llvm-svn: 135375

Add "unknown" results for memdep, which mean "I don't know whether a dependence for the given instruction exists in the given block".  This cleans up all the existing hacks in memdep which represent this concept by returning clobber with various unrelated instructions.

llvm-svn: 133031

Luis Felipe Strano Moraes!

llvm-svn: 129558

  that one of the numbers is signed while the other is unsigned. This could lead
  to a wrong result when the signed was promoted to an unsigned int.

* Add the data layout line to the testcase so that it will test the appropriate
  thing.

Patch by David Terei!

llvm-svn: 128577

Fixes PR9569 and will hopefully make selfhost on ASLR-enabled systems more deterministic.

llvm-svn: 128482

llvm-svn: 128333

There are two ways that a later store can comletely overlap a previous store:

1. They both start at the same offset, but the earlier store's size is <= the
   later's size, or
2. The earlier store's offset is > the later's offset, but it's offset + size
   doesn't extend past the later's offset + size.

llvm-svn: 128332

completely overlaps a previous store, thus mistakenly deleting that store. Check
for this condition.

llvm-svn: 128319

with BasicAA's DecomposeGEPExpression, which recently began
using a TargetData. This fixes PR8968, though the testcase
is awkward to reduce.

Also, update several off GetUnderlyingObject's users
which happen to have a TargetData handy to pass it in.

llvm-svn: 124134

dominance and post-dominance frontiers.

llvm-svn: 123725

function so that it can live in Analysis instead of
VMCore.

llvm-svn: 121885

llvm-svn: 121040

llvm-svn: 121038

memcpy's like:
  memcpy(A, B)
  memcpy(A, C)

we cannot delete the first memcpy as dead if A and C might be aliases.
If so, we actually get:

  memcpy(A, B)
  memcpy(A, A)

which is not correct to transform into:

  memcpy(A, A)

This patch was heavily influenced by Jakub Staszak's patch in PR8728, thanks
Jakub!

llvm-svn: 120974

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: 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

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: 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