Differential Revision: https://reviews.llvm.org/D22688

llvm-svn: 276449

A seemingly common use for the walker's getClobberingMemoryAccess
function is:

```
MemoryAccess *getClobber(MemorySSAWalker *W, MemoryUseOrDef *MUD) {
  const Instruction *I = MUD->getMemoryInst();
  return W->getClobberingMemoryAccess(I);
}
```

Which is kind of redundant, since walkers will ultimately query MSSA to
find out which MemoryAccess `I` maps to (...which is always `MUD`).

So, this patch adds an overload of getClobberingMemoryAccess that
accepts MemoryAccesses directly. As a result, the Instruction overload
of getClobberingMemoryAccess becomes a lightweight wrapper around our
new overload.

Additionally, this patch un`virtual`izes the Instruction overload of
getClobberingMemoryAccess, since there doesn't seem to be a walker that
benefits from that being virtual, and I can't think of how else one
would implement it. Happy to make it virtual again if we would benefit
from doing so.

llvm-svn: 276169

As noted in https://reviews.llvm.org/D22537 , we can use this functionality in 
visitSelectInstWithICmp() and InstSimplify, but currently we have duplicated
code.

llvm-svn: 276140

llvm-svn: 276135

This reverts commit r276064, and thus reapplies r275891 and r275883 with
a fix for PR28608.

llvm-svn: 276077

Revert "[LoopSimplify] Update LCSSA after separating nested loops."

This reverts commit r275891.

Revert "[LCSSA] Post-process PHI-nodes created by SSAUpdate when constructing LCSSA form."

This reverts commit r275883.

llvm-svn: 276064

llvm-svn: 276050

Summary: Make MemorySSA::dominates/locallydominates constant time

Reviewers: george.burgess.iv, gberry

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D22527

llvm-svn: 276046

This patch updates MemorySSA's use-optimizing walker to be more
accurate and, in some cases, faster.

Essentially, this changed our core walking algorithm from a
cache-as-you-go DFS to an iteratively expanded DFS, with all of the
caching happening at the end. Said expansion happens when we hit a Phi,
P; we'll try to do the smallest amount of work possible to see if
optimizing above that Phi is legal in the first place. If so, we'll
expand the search to see if we can optimize to the next phi, etc.

An iteratively expanded DFS lets us potentially quit earlier (because we
don't assume that we can optimize above all phis) than our old walker.
Additionally, because we don't cache as we go, we can now optimize above
loops.

As an added bonus, this patch adds a ton of verification (if
EXPENSIVE_CHECKS are enabled), so finding bugs is easier.

Differential Revision: https://reviews.llvm.org/D21777

llvm-svn: 275940

Summary:
Usually LCSSA survives this transformation, but in some cases (see
attached test) it doesn't: values from the original loop after
separating might be used from the outer loop. Before the transformation
it was the same loop, so LCSSA phis were not required.

This fixes PR28272.

Reviewers: sanjoy, hfinkel, chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D21665

llvm-svn: 275891

Summary:
SSAUpdate might insert PHI-nodes inside loops, which can break LCSSA
form unless we fix it up.

This fixes PR28424.

Reviewers: sanjoy, chandlerc, hfinkel

Subscribers: uabelho, llvm-commits

Differential Revision: http://reviews.llvm.org/D21997

llvm-svn: 275883

Summary:
When a pass tries to keep LCSSA form it's often convenient to be able to update
LCSSA for a set of instructions rather than for the entire loop. This patch makes the
processInstruction from LCSSA externally available under a name
formLCSSAForInstruction.

Reviewers: chandlerc, sanjoy, hfinkel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D22378

llvm-svn: 275613

Calling getModRefInfo with a fence resulted in crashes because fences
don't have a memory location.  Add a new predicate to Instruction
called isFenceLike which indicates that the instruction mutates memory
but not any single memory location in particular. In practice, it is a
proxy for the set of instructions which "mayWriteToMemory" but cannot be
used with MemoryLocation::get.

This fixes PR28570.

llvm-svn: 275581

llvm-svn: 275304

Patch by Sunita Marathe

Differential Revision: http://reviews.llvm.org/D21920

llvm-svn: 275284

Chandler pointed out in his review but I forgot to remove before
committing, my bad.

llvm-svn: 274963

While here move simplifyLoop() function to the new header, as
suggested by Chandler in the review.

Differential Revision:  http://reviews.llvm.org/D21404

llvm-svn: 274959

llvm-svn: 274927

llvm-svn: 274796

moved the optimise for size check inside function optimizeFPuts.

llvm-svn: 274758

because fwrite requires more arguments and thus extra MOVs are required.

llvm-svn: 274753

Differential Revision: http://reviews.llvm.org/D22058

llvm-svn: 274679

llvm-svn: 274606

llvm-svn: 274590

Differential Revision: http://reviews.llvm.org/D21636

llvm-svn: 274334

llvm-svn: 273974

NFC.

llvm-svn: 273901

build.

There's a known bug in msvc 2013 that fails to compile do-while loops
inside of ranged for loops.

llvm-svn: 273811

Only minor manual fixes. No functionality change intended.

llvm-svn: 273808

No functional change is intended

llvm-svn: 273780

This reverts commit r273778, it seems to break UBSan :/

llvm-svn: 273779

SimplifyCFG had logic to insert calls to llvm.trap for two very
particular IR patterns: stores and invokes of undef/null.

While InstCombine canonicalizes certain undefined behavior IR patterns
to stores of undef, phase ordering means that this cannot be relied upon
in general.

There are much better tools than llvm.trap: UBSan and ASan.

N.B. I could be argued into reverting this change if a clear argument as
to why it is important that we synthesize llvm.trap for stores, I'd be
hard pressed to see why it'd be useful for invokes...

llvm-svn: 273778

Calling null is undefined behavior, a call to undef can be trivially
treated as a call to null.

llvm-svn: 273776

llvm-svn: 273761

r273711 was reverted by r273743.  The inliner needs to know about any
call sites in the inlined function.  These were obscured if we replaced
a call to undef with an undef but kept the call around.

This fixes PR28298.

llvm-svn: 273753

llvm-svn: 273752

llvm-svn: 273743

This patch moves MSSA's caching walker into MemorySSA, and moves the
actual definition of MSSA's caching walker out of MemorySSA.h. This is
done in preparation for the new walker, which should be out for review
soonish.

Also, this patch removes a field from UpwardsMemoryQuery and has a few
lines of diff from clang-format'ing MemorySSA.cpp.

llvm-svn: 273723

We cannot remove an instruction with no uses just because
SimplifyInstruction succeeds.  It may have side effects.

llvm-svn: 273711

This makes the code a little more concise, no functional change is
intended.

llvm-svn: 273644