This is a complex change that resulted from a great deal of
experimentation with several different benchmarks. The one which proved
the most useful is included as a test case, but I don't know that it
captures all of the relevant changes, as I didn't have specific
regression tests for each, they were more the result of reasoning about
what the old algorithm would possibly do wrong. I'm also failing at the
moment to craft more targeted regression tests for these changes, if
anyone has ideas, it would be welcome.

The first big thing broken with the old algorithm is the idea that we
can take a basic block which has a loop-exiting successor and a looping
successor and use the looping successor as the layout top in order to
get that particular block to be the bottom of the loop after layout.
This happens to work in many cases, but not in all.

The second big thing broken was that we didn't try to select the exit
which fell into the nearest enclosing loop (to which we exit at all). As
a consequence, even if the rotation worked perfectly, it would result in
one of two bad layouts. Either the bottom of the loop would get
fallthrough, skipping across a nearer enclosing loop and thereby making
it discontiguous, or it would be forced to take an explicit jump over
the nearest enclosing loop to earch its successor. The point of the
rotation is to get fallthrough, so we need it to fallthrough to the
nearest loop it can.

The fix to the first issue is to actually layout the loop from the loop
header, and then rotate the loop such that the correct exiting edge can
be a fallthrough edge. This is actually much easier than I anticipated
because we can handle all the hard parts of finding a viable rotation
before we do the layout. We just store that, and then rotate after
layout is finished. No inner loops get split across the post-rotation
backedge because we check for them when selecting the rotation.

That fix exposed a latent problem with our exitting block selection --
we should allow the backedge to point into the middle of some inner-loop
chain as there is no real penalty to it, the whole point is that it
*won't* be a fallthrough edge. This may have blocked the rotation at all
in some cases, I have no idea and no test case as I've never seen it in
practice, it was just noticed by inspection.

Finally, all of these fixes, and studying the loops they produce,
highlighted another problem: in rotating loops like this, we sometimes
fail to align the destination of these backwards jumping edges. Fix this
by actually walking the backwards edges rather than relying on loopinfo.

This fixes regressions on heapsort if block placement is enabled as well
as lots of other cases where the previous logic would introduce an
abundance of unnecessary branches into the execution.

llvm-svn: 154783

llvm-svn: 154782

llvm-svn: 154781

Spacing fixes and 80 column fixes. Use 0 instead of 0x80 for undef indices in vpermps/vpermd. Hardware only looks at lower 3-bits.

llvm-svn: 154780

llvm-svn: 154778

Use non-vex instructions for SSE4.

llvm-svn: 154770

As an example, attach range info to the "invalid instruction" message:

$ clang -arch arm -c asm.c
asm.c:2:11: error: invalid instruction
  __asm__("foo r0");
          ^
<inline asm>:1:2: note: instantiated into assembly here
        foo r0
        ^~~

llvm-svn: 154765

llvm-svn: 154764

llvm-svn: 154761

llvm-svn: 154759

llvm-svn: 154758

thinking of generalizing it to be able to specify other freedoms beyond accuracy
(such as that NaN's don't have to be respected).  I'd like the 3.1 release (the
first one with this metadata) to have the more generic name already rather than
having to auto-upgrade it in 3.2.

llvm-svn: 154744

When vectorizing pointer types it is important to realize that potential
pairs cannot be connected via the address pointer argument of a load or store.
This is because even after vectorization, the address is still a scalar because
the address of the higher half of the pair is implicit from the address of the
lower half (it need not be, and should not be, explicitly computed).

llvm-svn: 154735

llvm-svn: 154734

This is a special flag for targets that really want their block
terminators in the DAG. The default scheduler cannot handle this
correctly, so it becomes the specialized scheduler's responsibility to
schedule terminators.

llvm-svn: 154712

llvm-svn: 154705

llvm-svn: 154703

llvm-svn: 154700

llvm-svn: 154696

llvm-svn: 154695

- Don't copy offsets into HashData, the underlying vector won't change once the table is finalized.
- Allocate HashData and HashDataContents in a BumpPtrAllocator.
- Allocate string map entries in the same allocator.
- Random cleanups.

llvm-svn: 154694

llvm-svn: 154689

llvm-svn: 154687

targets so if the branch target has the high bit set it does not get printed as:
	 beq     0xffffffff8008c404

llvm-svn: 154685

their argument as "escape" points for objc_retainBlock optimization.
This fixes rdar://11229925.

llvm-svn: 154682

As has been suggested by Duncan and others, Early-CSE and GVN should
do similar redundancy elimination, but Early-CSE is much less expensive.
Most of my autovectorization benchmarks show a performance regresion, but
all of these are < 0.1%, and so I think that it is still worth using
the less expensive pass.

llvm-svn: 154673

llvm-svn: 154661

Silence various build warnings from Hexagon backend that show up in release builds. Mostly converting 'assert(0)' to 'llvm_unreachable' to silence warnings about missing returns. Also fold some variable declarations into asserts to prevent the variables from being unused in release builds.

llvm-svn: 154660

library return value optimization for phi uses. Even when the
phi itself is not dominated, the specific use may be dominated.

llvm-svn: 154647

obviously cannot know that this code is present, let alone used. So prevent the
internalize pass from internalizing those global values which code-gen may
insert.

llvm-svn: 154645

optimizing autorelease calls on phi nodes with null operands.
This fixes rdar://11207070.

llvm-svn: 154642

as Eli noticed.

llvm-svn: 154641

directly instead of a user Instruction. This allows them to test
whether a def dominates a particular operand if the user instruction
is a PHI.

llvm-svn: 154631

symbolic operands added when using the C disassembler API.

llvm-svn: 154628

llvm-svn: 154622

llvm-svn: 154620

llvm-svn: 154616

of zero-initialized sections, virtual sections and common symbols
and preventing the loading of sections which are not required for
execution such as debug information.

Patch by Andy Kaylor!

llvm-svn: 154610

Generalize r153635 to deal with TokenFactor chains; also clean up the logic and fix the tests. rdar://11069732, rdar://11236106

llvm-svn: 154604

llvm-svn: 154597