The previous implementation of AddAliasScopeMetadata, which adds noalias
metadata to preserve noalias parameter attribute information when inlining had
a flaw: it would add alias.scope metadata to accesses which might have been
derived from pointers other than noalias function parameters. This was
incorrect because even some access known not to alias with all noalias function
parameters could easily alias with an access derived from some other pointer.
Instead, when deriving from some unknown pointer, we cannot add alias.scope
metadata at all. This fixes a miscompile of the test-suite's tramp3d-v4.
Furthermore, we cannot add alias.scope to functions unless we know they
access only argument-derived pointers (currently, we know this only for
memory intrinsics).

Also, we fix a theoretical problem with using the NoCapture attribute to skip
the capture check. This is incorrect (as explained in the comment added), but
would not matter in any code generated by Clang because we get only inferred
nocapture attributes in Clang-generated IR.

This functionality is not yet enabled by default.

llvm-svn: 216818

llvm-svn: 216817

consider: (and (icmp X, Y), (and Z, (icmp A, B)))
It may be possible to combine (icmp X, Y) with (icmp A, B).
If we successfully combine, create an 'and' instruction with Z.

This fixes PR20814.

N.B. There is room for improvement after this change but I'm not
convinced it's worth chasing yet.

llvm-svn: 216814

llvm-svn: 216741

This reverts commit r216523 and r216598; people have reported
regressions.

llvm-svn: 216698

Don't promote byval pointer arguments when when their size in bits is
not equal to their alloc size in bits. This can happen for x86_fp80,
where the size in bits is 80 but the alloca size in bits in 128.
Promoting these types can break passing unions of x86_fp80s and other
types.

Patch by Thomas Jablin!

Reviewed By: rnk

Differential Revision: http://reviews.llvm.org/D5057

llvm-svn: 216693

InstSimplify already handles icmp (X+Y), X (and things like it)
appropriately.  The first thing that InstCombine does is run
InstSimplify on the instruction.

llvm-svn: 216659

For a detailed description of the problem see the comment in the test file.
The problematic moveBefore() calls are not required anymore because the new
scheduling algorithm ensures a correct ordering anyway.

llvm-svn: 216656

Several combines involving icmp (shl C2, %X) C1 can be simplified
without introducing any new instructions.  Move them to InstSimplify;
while we are at it, make them more powerful.

llvm-svn: 216642

We try to perform this transform in InstSimplify but we aren't always
able to.  Sometimes, we need to insert a bitcast if X and Y don't have
the same time.

llvm-svn: 216598

llvm-svn: 216549

Simplify creation of a bunch of ArrayRefs by using None, makeArrayRef or just letting them be implicitly created.

llvm-svn: 216525

Fix some cases were ArrayRefs were being passed by reference. Also remove 'const' from some other ArrayRef uses since its implicitly const already.

llvm-svn: 216524

We supported transforming:
(gep i8* X, -(ptrtoint Y))

to:
(inttoptr (sub (ptrtoint X), (ptrtoint Y)))

However, this only fired if 'X' had type i8*.  Generalize this to
support various types of different sizes.  This results in much better
CodeGen, especially for pointers to packed structs.

llvm-svn: 216523

PR 20642.

llvm-svn: 216475

(X >> Z) & (Y >> Z)  -> (X&Y) >> Z  for all shifts.
(X >> Z) | (Y >> Z)  -> (X|Y) >> Z  for all shifts.
(X >> Z) ^ (Y >> Z)  -> (X^Y) >> Z  for all shifts.

These patterns were previously handled separately in visitAnd()/visitOr()/visitXor().

Differential Revision: http://reviews.llvm.org/D4951

llvm-svn: 216443

Also clean up and beef up this grep test for the feature.

llvm-svn: 216425

llvm-svn: 216424

Adding, removing, or changing non-pack parameters can change the ABI
classification of pack parameters. Clang and other frontends encode the
classification in the IR of the call site, but the callee side
determines it dynamically based on the number of registers consumed so
far. Changing the prototype affects the number of registers consumed
would break such code.

Dead argument elimination performs a similar task and already has a
similar check to avoid this problem.

Patch by Thomas Jablin!

llvm-svn: 216421

Take a StringRef instead of a "const char *".
Take a "std::error_code &" instead of a "std::string &" for error.

A create static method would be even better, but this patch is already a bit too
big.

llvm-svn: 216393

GlobalDCE deletes global vars and updates their initializers to nullptr
while leaving underlying constants to be cleaned up later by its uses.
The clean up may never happen, fix this by forcing it every time it's
safe to destroy constants.

Final patch by Rafael Espindola
http://reviews.llvm.org/D4931

<rdar://problem/17523868>

llvm-svn: 216390

cmpAPFloat has been renamed to cmpAPFloats (multiple form).

llvm-svn: 216376

cmpAPInt has been renamed to cmpAPInts (multiple form).

llvm-svn: 216375

cmpType has been renamed to cmpTypes (multiple form).

llvm-svn: 216374

cmpGEP has been renamed to cmpGEPs (multiple form).

llvm-svn: 216373

This patch adds support to recognize division by uniform power of 2 and modifies the cost table to vectorize division by uniform power of 2 whenever possible.
Updates Cost model for Loop and SLP Vectorizer.The cost table is currently only updated for X86 backend.
Thanks to Hal, Andrea, Sanjay for the review. (http://reviews.llvm.org/D4971)

llvm-svn: 216371

llvm-svn: 216351

CFE, with -03, would turn:
bool f(unsigned x) {
  bool a = x & 1;
  bool b = x & 2;
  return a | b;
}

into:
  %1 = lshr i32 %x, 1
  %2 = or i32 %1, %x
  %3 = and i32 %2, 1
  %4 = icmp ne i32 %3, 0

This sort of thing exposes a nasty pathology in GCC, ICC and LLVM.

Instead, we would rather want:
  %1 = and i32 %x, 3
  %2 = icmp ne i32 %1, 0

Things get a bit more interesting in the following case:
  %1 = lshr i32 %x, %y
  %2 = or i32 %1, %x
  %3 = and i32 %2, 1
  %4 = icmp ne i32 %3, 0

Replacing it with the following sequence is better:
  %1 = shl nuw i32 1, %y
  %2 = or i32 %1, 1
  %3 = and i32 %2, %x
  %4 = icmp ne i32 %3, 0

This sequence is preferable because %1 doesn't involve %x and could
potentially be hoisted out of loops if it is invariant; only perform
this transform in the non-constant case if we know we won't increase
register pressure.

llvm-svn: 216343

Summary:
Fixes PR20425.

During slice building, if all of the incoming values of a PHI node are the same, replace the PHI node with the common value. This simplification makes alloca's used by PHI nodes easier to promote.

Test Plan: Added three more tests in phi-and-select.ll

Reviewers: nlewycky, eliben, meheff, chandlerc

Reviewed By: chandlerc

Subscribers: zinovy.nis, hfinkel, baldrick, llvm-commits

Differential Revision: http://reviews.llvm.org/D4659

llvm-svn: 216299

Consider:
  %add = add nuw i32 %a, -16777216
  %and = and i32 %add, 255

Regardless of whether or not we demand the sign bit of %add, we cannot
replace -16777216 with 2130706432 without also removing 'nuw' from the
instruction.

llvm-svn: 216273

We can preserve nsw during this transform if -C won't overflow.

llvm-svn: 216269

Consider:
  %add = add nsw i32 %a, -16777216
  %and = and i32 %add, 255

Regardless of whether or not we demand the sign bit of %add, we cannot
replace -16777216 with 2130706432 without also removing 'nsw' from the
instruction.

This fixes PR20377.

llvm-svn: 216261

In unreachable blocks it's legal to have instructions like "%x = op %x".
Such instuctions are not schedulable. Therefore the SLPVectorizer has to check for
unreachable blocks and ignore them.

Fixes bug 20646.

llvm-svn: 216256

We now use a std::vector instead of a DenseSet to store the list of
label checks so that we can iterate over it deterministically.

llvm-svn: 216255

In this case, we are creating an x86_fp80 slice for a union from C where
the padding bytes may contain real data. An x86_fp80 alloca is 16 bytes,
and that's just fine. We can't, however, use regular loads and stores to
access the slice, because the store size is only 10 bytes / 80 bits.
Instead, use memcpy and memset.

Fixes PR18726.

Reviewed By: chandlerc

Differential Revision: http://reviews.llvm.org/D5012

llvm-svn: 216248

Use DILexicalBlockFile, rather than DILexicalBlock, to track discriminator changes to ensure discriminator changes don't introduce new DWARF DW_TAG_lexical_blocks.

Somewhat unnoticed in the original implementation of discriminators, but
it could cause instructions to end up in new, small,
DW_TAG_lexical_blocks due to the use of DILexicalBlock to track
discriminator changes.

Instead, use DILexicalBlockFile which we already use to track file
changes without introducing new scopes, so it works well to track
discriminator changes in the same way.

llvm-svn: 216239

This will avoid code duplication in the next commit which calls it directly
from the gold plugin.

llvm-svn: 216211

llvm-svn: 216203

No functionality change.

llvm-svn: 216178

llvm-svn: 216176