That particular optimization was probably premature anyway.

llvm-svn: 161541

We filter out MachineLoop back-edges during the trace-building PO
traversals, but it is possible to have CFG cycles that aren't natural
loops, and MachineLoopInfo doesn't include such cycles.

Use a standard visited set to detect such CFG cycles, and completely
ignore them when picking traces.

llvm-svn: 161532

llvm-svn: 161513

Thanks, Andy!

llvm-svn: 161507

llvm-svn: 161470

It caused an assertion failure when compiling consumer-typeset.

llvm-svn: 161463

We perform the following:
1> Use SUB instead of CMP for i8,i16,i32 and i64 in ISel lowering.
2> Modify MachineCSE to correctly handle implicit defs.
3> Convert SUB back to CMP if possible at peephole.

Removed pattern matching of (a>b) ? (a-b):0 and like, since they are handled
by peephole now.

rdar://11873276

llvm-svn: 161462

The getSumForBlock function was quadratic in the number of successors
because getSuccWeight would perform a linear search for an already known
iterator.

llvm-svn: 161460

llvm-svn: 161454

This adds support for TargetIndex operands during isel. The meaning of
these (index, offset, flags) operands is entirely defined by the target.

llvm-svn: 161453

character arrays. This is in line with what GCC does.
<rdar://problem/10529227>

llvm-svn: 161446

A target index operand looks a lot like a constant pool reference, but
it is completely target-defined. It contains the 8-bit TargetFlags, a
32-bit index, and a 64-bit offset. It is preserved by all code generator
passes.

TargetIndex operands can be used to carry target-specific information in
cases where immediate operands won't suffice.

llvm-svn: 161441

llvm-svn: 161437

Compare the critical paths of the two traces through an if-conversion
candidate. If the difference is larger than the branch brediction
penalty, reject the if-conversion. If would never pay.

llvm-svn: 161433

Previously, MBP essentially aligned every branch target it could. This
bloats code quite a bit, especially non-looping code which has no real
reason to prefer aligned branch targets so heavily.

As Andy said in review, it's still a bit odd to do this without a real
cost model, but this at least has much more plausible heuristics.

Fixes PR13265.

llvm-svn: 161409

If the result of a common subexpression is used at all uses of the candidate
expression, CSE should not increase the live range of the common subexpression.

rdar://11393714 and rdar://11819721

llvm-svn: 161396

TwoAddressInstructionPass doesn't remat any more.

llvm-svn: 161285

llvm-svn: 161284

This patch is mostly just refactoring a bunch of copy-and-pasted code, but
it also adds a check that the call instructions are readnone or readonly.
That check was already present for sin, cos, sqrt, log2, and exp2 calls, but
it was missing for the rest of the builtins being handled in this code.

llvm-svn: 161282

No functional change intended, except replacing a DenseMap with a
SmallDenseMap which should behave identically.

llvm-svn: 161281

This is far from complete, and only changes behavior when the
-early-live-intervals flag is passed to llc.

llvm-svn: 161273

This option runs LiveIntervals before TwoAddressInstructionPass which
will eventually learn to exploit and update the analysis.

Eventually, LiveIntervals will run before PHIElimination, and we can get
rid of LiveVariables.

llvm-svn: 161270

Previously, the identity copy would survive through register allocation
before it was removed by the rewriter.

llvm-svn: 161269

The previous change caused fast isel to not attempt handling any calls to
builtin functions.  That included things like "printf" and caused some
noticable regressions in compile time.  I wanted to avoid having fast isel
keep a separate list of functions that had to be kept in sync with what the
code in SelectionDAGBuilder.cpp was handling.  I've resolved that here by
moving the list into TargetLibraryInfo.  This is somewhat redundant in
SelectionDAGBuilder but it will ensure that we keep things consistent.

llvm-svn: 161263

I noticed that SelectionDAGBuilder::visitCall was missing a check for memcmp
in TargetLibraryInfo, so that it would use custom code for memcmp calls even
with -fno-builtin.  I also had to add a new -disable-simplify-libcalls option
to llc so that I could write a test for this.

llvm-svn: 161262

The 'unused' state of a value number can be represented as an invalid
def SlotIndex. This also exposed code that shouldn't have been looking
at unused value VNInfos.

llvm-svn: 161258

Unused VNInfos should be left alone. Their def SlotIndex doesn't point
to anything.

llvm-svn: 161257

llvm-svn: 161256

The only real user of the flag was removeCopyByCommutingDef(), and it
has been switched to LiveIntervals::hasPHIKill().

All the code changed by this patch was only concerned with computing and
propagating the flag.

llvm-svn: 161255

The VNInfo::HAS_PHI_KILL is only half supported. We precompute it in
LiveIntervalAnalysis, but it isn't properly updated by live range
splitting and functions like shrinkToUses().

It is only used in one place: RegisterCoalescer::removeCopyByCommutingDef().

This patch changes that function to use a new LiveIntervals::hasPHIKill()
function that computes the flag for a given value number.

llvm-svn: 161254

llvm-svn: 161242

This functionality was added before we started running
DeadMachineInstructionElim on all targets. It serves no purpose now.

llvm-svn: 161241

Fast isel doesn't currently have support for translating builtin function
calls to target instructions.  For embedded environments where the library
functions are not available, this is a matter of correctness and not
just optimization.  Most of this patch is just arranging to make the
TargetLibraryInfo available in fast isel.  <rdar://problem/12008746>

llvm-svn: 161232

Add more comments and use early returns to reduce nesting in isLoadFoldable.
Also disable folding for V_SET0 to avoid introducing a const pool entry and
a const pool load.

rdar://10554090 and rdar://11873276

llvm-svn: 161207

Whenever both instruction depths and instruction heights are known in a
block, it is possible to compute the length of the critical path as
max(depth+height) over the instructions in the block.

The stored live-in lists make it possible to accurately compute the
length of a critical path that bypasses the current (small) block.

llvm-svn: 161197

Don't cause regunit intervals to be computed just to verify them. Only
check the already cached intervals.

llvm-svn: 161183

LiveRangeEdit::eliminateDeadDefs() can delete a dead instruction that
reads unreserved physregs. This would leave the corresponding regunit
live interval dangling because we don't have shrinkToUses() for physical
registers.

Fix this problem by turning the instruction into a KILL instead of
deleting it. This happens in a landing pad in
test/CodeGen/X86/2012-05-19-CoalescerCrash.ll:

  %vreg27<def,dead> = COPY %EDX<kill>; GR32:%vreg27

becomes:

  KILL %EDX<kill>

An upcoming fix to the machine verifier will catch problems like this by
verifying regunit live intervals.

This fixes PR13498. I am not including the test case from the PR since
we already have one exposing the problem once the verifier is fixed.

llvm-svn: 161182

llvm-svn: 161178

Machine CSE and other optimizations can remove instructions so folding
is possible at peephole while not possible at ISel.

This patch is a rework of r160919 and was tested on clang self-host on my local
machine.

rdar://10554090 and rdar://11873276

llvm-svn: 161152

No functional change.

llvm-svn: 161149