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

llvm-svn: 161147

The height on an instruction is the minimum number of cycles from the
instruction is issued to the end of the trace. Heights are computed for
all instructions in and below the trace center block.

The method for computing heights is different from the depth
computation. As we visit instructions in the trace bottom-up, heights of
used instructions are pushed upwards. This way, we avoid scanning long
use lists, looking for uses in the current trace.

At each basic block boundary, a list of live-in registers and their
minimum heights is saved in the trace block info. These live-in lists
are used when restarting depth computations on a trace that
converges with an already computed trace. They will also be used to
accurately compute the critical path length.

llvm-svn: 161138

failures in the debug testsuite and possibly PR13486.

llvm-svn: 161121

llvm-svn: 161115

llvm-svn: 161110

Use stable_sort instead of sort. Follow-up to r161062.

rdar://11980766

llvm-svn: 161075

Assuming infinite issue width, compute the earliest each instruction in
the trace can issue, when considering the latency of data dependencies.
The issue cycle is record as a 'depth' from the beginning of the trace.

This is half the computation required to find the length of the critical
path through the trace. Heights are next.

llvm-svn: 161074

llvm-svn: 161072

One motivating example is to sink an instruction from a basic block which has
two successors: one outside the loop, the other inside the loop. We should try
to sink the instruction outside the loop.

rdar://11980766

llvm-svn: 161062

llvm-svn: 161061

llvm-svn: 161053

We are extending live ranges, so kill flags are not accurate. They
aren't needed until they are recomputed after RA anyway.

<rdar://problem/11950722>

llvm-svn: 161023

We branch to the successor with higher edge weight first.
Convert from
     je    LBB4_8  --> to outer loop
     jmp   LBB4_14 --> to inner loop
to
     jne   LBB4_14
     jmp   LBB4_8

PR12750
rdar: 11393714

llvm-svn: 161018

llvm-svn: 161010

llvm-svn: 161007

llvm-svn: 161004

This lets traces include the final iteration of a nested loop above the
center block, and the first iteration of a nested loop below the center
block.

We still don't allow traces to contain backedges, and traces are
truncated where they would leave a loop, as seen from the center block.

llvm-svn: 161003

llvm-svn: 160997

When computing a trace, all the candidates for pred/succ must have been
visited. Filter out back-edges first, though. The PO traversal ignores
them.

Thanks to Andy for spotting this in review.

llvm-svn: 160995

By overriding Pass::verifyAnalysis(), the pass contents will be verified
by the pass manager.

llvm-svn: 160994

Consider address spaces for hashing and CSEing DAG nodes.  Otherwise two loads from different x86 segments but the same address would get CSEd

llvm-svn: 160987

This is a cleaned up version of the isFree() function in
MachineTraceMetrics.cpp.

Transient instructions are very unlikely to produce any code in the
final output. Either because they get eliminated by RegisterCoalescing,
or because they are pseudo-instructions like labels and debug values.

llvm-svn: 160977

This function verifies the consistency of cached data in the
MachineTraceMetrics analysis.

llvm-svn: 160976

The MachineTraceMetrics analysis must be invalidated before modifying
the CFG. This will catch some of the violations of that rule.

llvm-svn: 160969

A->isPredecessor(B) is the same as B->isSuccessor(A), but it can
tolerate a B that is null or dangling. This shouldn't happen normally,
but it it useful for verification code.

llvm-svn: 160968