MemCpyOpt: When merging memsets also merge the trivial case of two memsets with the same destination.

The testcase is from PR19092, but I think the bug described there is actually a clang issue.

llvm-svn: 203489

This requires a number of steps.
1) Move value_use_iterator into the Value class as an implementation
   detail
2) Change it to actually be a *Use* iterator rather than a *User*
   iterator.
3) Add an adaptor which is a User iterator that always looks through the
   Use to the User.
4) Wrap these in Value::use_iterator and Value::user_iterator typedefs.
5) Add the range adaptors as Value::uses() and Value::users().
6) Update *all* of the callers to correctly distinguish between whether
   they wanted a use_iterator (and to explicitly dig out the User when
   needed), or a user_iterator which makes the Use itself totally
   opaque.

Because #6 requires churning essentially everything that walked the
Use-Def chains, I went ahead and added all of the range adaptors and
switched them to range-based loops where appropriate. Also because the
renaming requires at least churning every line of code, it didn't make
any sense to split these up into multiple commits -- all of which would
touch all of the same lies of code.

The result is still not quite optimal. The Value::use_iterator is a nice
regular iterator, but Value::user_iterator is an iterator over User*s
rather than over the User objects themselves. As a consequence, it fits
a bit awkwardly into the range-based world and it has the weird
extra-dereferencing 'operator->' that so many of our iterators have.
I think this could be fixed by providing something which transforms
a range of T&s into a range of T*s, but that *can* be separated into
another patch, and it isn't yet 100% clear whether this is the right
move.

However, this change gets us most of the benefit and cleans up
a substantial amount of code around Use and User. =]

llvm-svn: 203364

No functionality change.

llvm-svn: 203288

This compiles with no changes to clang/lld/lldb with MSVC and includes
overloads to various functions which are used by those projects and llvm
which have OwningPtr's as parameters. This should allow out of tree
projects some time to move. There are also no changes to libs/Target,
which should help out of tree targets have time to move, if necessary.

llvm-svn: 203083

obviously coupled to the IR.

llvm-svn: 203064

already lives.

llvm-svn: 203046

already lives.

llvm-svn: 203038

to ensure we don't mess up any of the overrides. Necessary for cleaning
up the Value use iterators and enabling range-based traversing of use
lists.

llvm-svn: 202958

llvm-svn: 202953

hardcoded to use IR BasicBlocks.

llvm-svn: 202835

IR types.

llvm-svn: 202827

Move the test for this class into the IR unittests as well.

This uncovers that ValueMap too is in the IR library. Ironically, the
unittest for ValueMap is useless in the Support library (honestly, so
was the ValueHandle test) and so it already lives in the IR unittests.
Mmmm, tasty layering.

llvm-svn: 202821

obviously is coupled to the IR.

llvm-svn: 202818

abstracting between a CallInst and an InvokeInst, both of which are IR
concepts.

llvm-svn: 202816

name might indicate, it is an iterator over the types in an instruction
in the IR.... You see where this is going.

Another step of modularizing the support library.

llvm-svn: 202815

business.

This header includes Function and BasicBlock and directly uses the
interfaces of both classes. It has to do with the IR, it even has that
in the name. =] Put it in the library it belongs to.

This is one step toward making LLVM's Support library survive a C++
modules bootstrap.

llvm-svn: 202814

No functionality change.

llvm-svn: 202751

It's not needed anymore.

llvm-svn: 202748

remove_if that its predicate is adaptable. We don't actually need this,
we can write a generic adapter for any predicate.

This lets us remove some very wrong std::function usages. We should
never be using std::function for predicates to algorithms. This incurs
an *indirect* call overhead for every evaluation of the predicate, and
makes it very hard to inline through.

llvm-svn: 202742

This also switches the users in LLVM to ensure this functionality is tested.

llvm-svn: 202705

operand_values. The first provides a range view over operand Use
objects, and the second provides a range view over the Value*s being
used by those operands.

The naming is "STL-style" rather than "LLVM-style" because we have
historically named iterator methods STL-style, and range methods seem to
have far more in common with their iterator counterparts than with
"normal" APIs. Feel free to bikeshed on this one if you want, I'm happy
to change these around if people feel strongly.

I've switched code in SROA and LCG to exercise these mostly to ensure
they work correctly -- we don't really have an easy way to unittest this
and they're trivial.

llvm-svn: 202687

The old implementation is no longer needed in C++11.

llvm-svn: 202644

Remove the old functions.

llvm-svn: 202636

llvm-svn: 202621

directly, and remove the macro.

llvm-svn: 202612

No intended functionality change.

llvm-svn: 202588

Patch by Michael Zolotukhin!

llvm-svn: 202273

address spaces.

This isn't really a correctness issue (the values are truncated) but its
much cleaner.

Patch by Matt Arsenault!

llvm-svn: 202252

the default.

Based on the patch by Matt Arsenault, D1764!

I switched one place to use the more direct pointer type to compute the
desired address space, and I reworked the memcpy rewriting section to
reflect significant refactorings that this patch helped inspire.

Thanks to several of the folks who helped review and improve the patch
as well.

llvm-svn: 202247

to work independently for the slice side and the other side.

This allows us to only compute the minimum of the two when we actually
rewrite to a memcpy that needs to take the minimum, and preserve higher
alignment for one side or the other when rewriting to loads and stores.

This fix was inspired by seeing the result of some refactoring that
makes addrspace handling better.

llvm-svn: 202242

D1764, which in turn set off the other refactorings to make
'getSliceAlign()' a sensible thing.

There are two possible inputs to the required alignment of a memory
transfer intrinsic: the alignment constraints of the source and the
destination. If we are *only* introducing a (potentially new) offset
onto one side of the transfer, we don't need to consider the alignment
constraints of the other side. Use this to simplify the logic feeding
into alignment computation for unsplit transfers.

Also, hoist the clamp of the magical zero alignment for these intrinsics
to the more customary one alignment early. This lets several other
conditions melt away.

No functionality changed. There is a further improvement this exposes
which *will* change functionality, but that's arriving in a separate
patch.

llvm-svn: 202232

rewriting logic: don't pass custom offsets for the adjusted pointer to
the new alloca.

We always passed NewBeginOffset here. Sometimes we spelled it
BeginOffset, but only when they were in fact equal. Whats worse, the API
is set up so that you can't reasonably call it with anything else -- it
assumes that you're passing it an offset relative to the *original*
alloca that happens to fall within the new one. That's the whole point
of NewBeginOffset, it's the clamped beginning offset.

No functionality changed.

llvm-svn: 202231

alignment of the slice being rewritten, not any arbitrary offset.

Every caller is really just trying to compute the alignment for the
whole slice, never for some arbitrary alignment. They are also just
passing a type when they have one to see if we can skip an explicit
alignment in the IR by using the type's alignment. This makes for a much
simpler interface.

Another refactoring inspired by the addrspace patch for SROA, although
only loosely related.

llvm-svn: 202230

consistency with memcpy rewriting, and fix a latent bug in the alignment
management for memset.

The alignment issue is that getAdjustedAllocaPtr is computing the
*relative* offset into the new alloca, but the alignment isn't being set
to the relative offset, it was using the the absolute offset which is
into the old alloca.

I don't think its possible to write a test case that actually reaches
this code where the resulting alignment would be observably different,
but the intent was clearly to use the relative offset within the new
alloca.

llvm-svn: 202229

rather than passing them as arguments.

While I generally prefer actual arguments, in this case the readability
loss is substantial. By using members we avoid repeatedly calculating
the offsets, and once we're using members it is useful to ensure that
those names *always* refer to the original-alloca-relative new offset
for a rewritten slice.

No functionality changed. Follow-up refactoring, all toward getting the
address space patch merged.

llvm-svn: 202228

slice being rewritten.

We had the same code scattered across most of the visits. Instead,
compute the new offsets and the slice size once when we start to visit
a particular slice, and use the member variables from then on. This
reduces quite a bit of code duplication.

No functionality changed. Refactoring inspired to make it easier to
apply the address space patch to SROA.

llvm-svn: 202227

checking in SROA.

The primary change is to just rely on uge for checking that the offset
is within the allocation size. This removes the explicit checks against
isNegative which were terribly error prone (including the reversed logic
that led to PR18615) and prevented us from supporting stack allocations
larger than half the address space.... Ok, so maybe the latter isn't
*common* but it's a silly restriction to have.

Also, we used to try to support a PHI node which loaded from before the
start of the allocation if any of the loaded bytes were within the
allocation. This doesn't make any sense, we have never really supported
loading or storing *before* the allocation starts. The simplified logic
just doesn't care.

We continue to allow loading past the end of the allocation in part to
support cases where there is a PHI and some loads are larger than others
and the larger ones reach past the end of the allocation. We could solve
this a different and more conservative way, but I'm still somewhat
paranoid about this.

llvm-svn: 202224

their inputs come from std::stable_sort and they are not total orders.

I'm not a huge fan of this, but the really bad std::stable_sort is right
at the beginning of Reassociate. After we commit to stable-sort based
consistent respect of source order, the downstream sorts shouldn't undo
that unless they have a total order or they are used in an
order-insensitive way. Neither appears to be true for these cases.
I don't have particularly good test cases, but this jumped out by
inspection when looking for output instability in this pass due to
changes in the ordering of std::sort.

llvm-svn: 202196

implemented this way a long time ago and due to the overwhelming bugs
that surfaced, moved to a much more relaxed variant. Richard Smith would
like to understand the magnitude of this problem and it seems fairly
harmless to keep some flag-controlled logic to get the extremely strict
behavior here. I'll remove it if it doesn't prove useful.

llvm-svn: 202193

Instead, have a DataLayoutPass that holds one. This will allow parts of LLVM
don't don't handle passes to also use DataLayout.

llvm-svn: 202168