critical edges in PHIElimination.

This has a huge impact on regalloc performance, and we recover almost all of
the 10% compile time regression that edge splitting introduced.

llvm-svn: 89381

$ svn merge -c -89279 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r89279 into '.':
U    lib/CodeGen/AsmPrinter/DwarfException.cpp
U    lib/Target/TargetLoweringObjectFile.cpp
$ svn merge -c -89270 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r89270 into '.':
G    lib/CodeGen/AsmPrinter/DwarfException.cpp
G    lib/Target/TargetLoweringObjectFile.cpp

llvm-svn: 89379

Fix a small bug.

Fix one case we missed to make sure we reserve registers from
allocation.

llvm-svn: 89376

Add support for spreading register allocation.

Add a -linearscan-skip-count argument (default to 0) that tells the
allocator to remember the last N registers it allocated and skip them
when looking for a register candidate.  This tends to spread out
register usage and free up post-allocation scheduling at the cost of
slightly more register pressure.  The primary benefit is the ability
to backschedule reloads.

This is turned off by default.

llvm-svn: 89356

All spiller calls in RegAllocLinearScan now go through the new Spiller interface.
The "-new-spill-framework" command line option has been removed. To use the trivial in-place spiller you should now pass "-spiller=trivial -rewriter=trivial".
(Note the trivial spiller/rewriter are only meant to serve as examples of the new in-place modification work. Enabling them will yield terrible, though hopefully functional, code).

llvm-svn: 89311

exception table than DataRel.

llvm-svn: 89279

llvm-svn: 89275

Place the EH table in the __TEXT section on MachO. It saves space.

llvm-svn: 89270

the tail of a block may make that block a new candidate for duplication.

llvm-svn: 89264

llvm-svn: 89254

When TwoAddressInstructionPass deletes a dead instruction, make sure that all
register kills are accounted for. The 2-addr register does not get special
treatment.

llvm-svn: 89246

Verify LiveVariables information when present.

llvm-svn: 89241

llvm-svn: 89240

Fixed the in-place spiller and trivial rewriter, which had been broken by the recent SlotIndexes work.

llvm-svn: 89238

llvm-svn: 89225

when LiveVariables is available.

The -split-phi-edges is now gone, and so is the hack to disable it when using
the local register allocator. The PHIElimination pass no longer has
LiveVariables as a prerequisite - that is what broke the local allocator.
Instead we do critical edge splitting when possible - that is when
LiveVariables is available.

llvm-svn: 89213

contents of the block to be duplicated.  Use this for ARM Cortex A8/9 to
be more aggressive tail duplicating indirect branches, since it makes it
much more likely that they will be predicted in the branch target buffer.
Testcase coming soon.

llvm-svn: 89187

llvm-svn: 89167

llvm-svn: 89142

llvm-svn: 89139

llvm-svn: 89130

llvm-svn: 89129

The local register allocator doesn't like it when LiveVariables is run.
We should also disable edge splitting under -O0, but that has to wait a bit.

llvm-svn: 89125

unnecessary.  It is broken because the "isIdenticalTo" check should be
negated.  If that is fixed, this code causes the CodeGen/X86/tail-opts.ll
test to fail, in the dont_merge_oddly function.  And, I confirmed that the
regression is real -- the generated code is worse.  As far as I can tell,
that tail-opts.ll test is checking for what this code is supposed to handle
and we're doing the right thing anyway.

llvm-svn: 89121

llvm-svn: 89114

folding optimizations.

llvm-svn: 89109

It was too difficult to keep the heuristics for merging and duplication
consistent.

llvm-svn: 89105

llvm-svn: 89082

llvm-svn: 89075

llvm-svn: 89066

more than one place. No intended functionality change.

llvm-svn: 89024

llvm-svn: 89021

unconditional branches or fallthroghes. Instcombine/SimplifyCFG
should be simplifying branches with known conditions.

This fixes some problems caused by these transformations not
updating the MachineBasicBlock CFG.

llvm-svn: 89017

uninitialized memory.

llvm-svn: 88985

llvm-svn: 88973

llvm-svn: 88956

llvm-svn: 88953

llvm-svn: 88940

llvm-svn: 88939

llvm-svn: 88932