Such passes can be used to tweak the register assignments in a
target-dependent way, for example to avoid write-after-write
dependencies.

llvm-svn: 159209

Implicitly defined virtual registers can simply have the <undef> bit set
on all uses, and copies can be turned into implicit defs recursively.

Physical registers are a bit trickier. We handle the common case where a
physreg def is used by a nearby instruction in the same basic block. For
more complicated cases, just leave the IMPLICIT_DEF instruction in.

llvm-svn: 159149

OK, not really. We don't want to reintroduce the old rewriter hacks.

This patch extracts virtual register rewriting as a separate pass that
runs after the register allocator. This is possible now that
CodeGen/Passes.cpp can configure the full optimizing register allocator
pipeline.

The rewriter pass uses register assignments in VirtRegMap to rewrite
virtual registers to physical registers, and it inserts kill flags based
on live intervals.

These finalization steps are the same for the optimizing register
allocators: RABasic, RAGreedy, and PBQP.

llvm-svn: 158244

Besides adding the new insertPass function, this patch uses it to
enhance the existing -print-machineinstrs so that the MachineInstrs
after a specific pass can be printed.

Patch by Bin Zeng!

llvm-svn: 157655

The TargetPassManager's default constructor wants to initialize the PassManager
to 'null'. But it's illegal to bind a null reference to a null l-value. Make the
ivar a pointer instead.
PR12468

llvm-svn: 155902

This is mostly to test the waters. I'd like to get results from FNT
build bots and other bots running on non-x86 platforms.

This feature has been pretty heavily tested over the last few months by
me, and it fixes several of the execution time regressions caused by the
inlining work by preventing inlining decisions from radically impacting
block layout.

I've seen very large improvements in yacr2 and ackermann benchmarks,
along with the expected noise across all of the benchmark suite whenever
code layout changes. I've analyzed all of the regressions and fixed
them, or found them to be impossible to fix. See my email to llvmdev for
more details.

I'd like for this to be in 3.1 as it complements the inliner changes,
but if any failures are showing up or anyone has concerns, it is just
a flag flip and so can be easily turned off.

I'm switching it on tonight to try and get at least one run through
various folks' performance suites in case SPEC or something else has
serious issues with it. I'll watch bots and revert if anything shows up.

llvm-svn: 154816

Some targets still mess up the liveness information, but that isn't
verified after MRI->invalidateLiveness().

The verifier can still check other useful things like register classes
and CFG, so it should be enabled after all passes.

llvm-svn: 153615

The late scheduler depends on accurate liveness information if it is
breaking anti-dependencies, so we should be able to verify it.

Relax the terminator checking in the machine code verifier so it can
handle the basic blocks created by if conversion.

llvm-svn: 153614

llvm-svn: 153599

Branch folding invalidates liveness and disables liveness verification
on some targets.

llvm-svn: 153597

New flags: -misched-topdown, -misched-bottomup. They can be used with
the default scheduler or with -misched=shuffle. Without either
topdown/bottomup flag -misched=shuffle now alternates scheduling
direction.

LiveIntervals update is unimplemented with bottom-up scheduling, so
only -misched-topdown currently works.

Capped the ScheduleDAG hierarchy with a concrete ScheduleDAGMI class.
ScheduleDAGMI is aware of the top and bottom of the unscheduled zone
within the current region. Scheduling policy can be plugged into
the ScheduleDAGMI driver by implementing MachineSchedStrategy.
ConvergingScheduler is now the default scheduling algorithm.
It exercises the new driver but still does no reordering.

llvm-svn: 152700

ecx = mov eax
al  = mov ch
The second copy is not a nop because the sub-indices of ecx,ch is not the
same of that of eax/al.

Re-enabled machine-cp.
PR11940

llvm-svn: 151002

Disable machine copy propagation for now. It's known to be buggy (PR11940) and introduces subtle miscompiles in many places.

llvm-svn: 150703

I'll put MachineLICM back before PEI. All my arm/x86 benchmarks look good, but buildbots don't like it.

llvm-svn: 150568

llvm-svn: 150567

llvm-svn: 150566

llvm-svn: 150565

The llc command line options for enabling/disabling passes are local to CodeGen/Passes.cpp. This patch associates those options with standard pass IDs so they work regardless of how the target configures the passes.

A target has two ways of overriding standard passes:
1) Redefine the pass pipeline (override TargetPassConfig::add%Stage)
2) Replace or suppress individiual passes with TargetPassConfig::substitutePass.

In both cases, the command line options associated with the pass override the target default.

For example, say a target wants to disable machine instruction scheduling by default:

- The target calls disablePass(MachineSchedulerID) but otherwise does not override any TargetPassConfig methods.

- Without any llc options, no scheduler is run.

- With -enable-misched, the standard machine scheduler is run and honors the -misched=... flag to select the scheduler variant, which may be used for performance evaluation or testing.

Sorry overridePass is ugly. I haven't thought of a better way without replacing the cl::opt framework. I hope to do that one day...

I haven't figured out why CodeGen uses char& for pass IDs. AnalysisID is much easier to use and less bug prone. I'm using it wherever I can for internal implementation. Maybe later we can change the global pass ID definitions as well.

llvm-svn: 150563

Added TargetPassConfig::disablePass/substitutePass as a general mechanism to override specific passes.

llvm-svn: 150562

In case the MachineScheduling pass I'm working on doesn't work well
for another target, they can completely override it. This also adds a
hook immediately after the RegAlloc pass to cleanup immediately after
vregs go away. We may want to fold it into the postRA hook later.

llvm-svn: 150298

llvm-svn: 150233

Creates a configurable regalloc pipeline.

Ensure specific llc options do what they say and nothing more: -reglloc=... has no effect other than selecting the allocator pass itself. This patch introduces a new umbrella flag, "-optimize-regalloc", to enable/disable the optimizing regalloc "superpass". This allows for example testing coalscing and scheduling under -O0 or vice-versa.

When a CodeGen pass requires the MachineFunction to have a particular property, we need to explicitly define that property so it can be directly queried rather than naming a specific Pass. For example, to check for SSA, use MRI->isSSA, not addRequired<PHIElimination>.

CodeGen transformation passes are never "required" as an analysis

ProcessImplicitDefs does not require LiveVariables.

We have a plan to massively simplify some of the early passes within the regalloc superpass.

llvm-svn: 150226

Split CodeGen into stages.
Distinguish between optimization and correctness.

llvm-svn: 150122

Moving toward a uniform style of pass definition to allow easier target configuration.
Globally declare Pass ID.
Globally declare pass initializer.
Use INITIALIZE_PASS consistently.
Add a call to the initializer from CodeGen.cpp.
Remove redundant "createPass" functions and "getPassName" methods.

While cleaning up declarations, cleaned up comments (sorry for large diff).

llvm-svn: 150100

llvm-svn: 150099

llvm-svn: 150097

llvm-svn: 150096

llvm-svn: 150095

llvm-svn: 150093

llvm-svn: 150092

llvm-svn: 150091

Passes prior to instructon selection are now split into separate configurable stages.
Header dependencies are simplified.
The bulk of this diff is simply removal of the silly DisableVerify flags.

Sorry for the target header churn. Attempting to stabilize them.

llvm-svn: 149754

llvm-svn: 149753

llvm-svn: 149752

RegAllocGreedy has been the default for six months now.

Deleting RegAllocLinearScan makes it possible to also delete
VirtRegRewriter and clean up the spiller code.

llvm-svn: 144475

llvm-svn: 130582

llvm-svn: 130568

This means that the new register allocator can be used with 'clang -mllvm -regalloc=greedy'.

llvm-svn: 129764

This affects both llvm-gcc and clang.

llvm-svn: 105372

optimization level.

This only really affects llc for now because both the llvm-gcc and clang front
ends override the default register allocator. I intend to remove that code later.

llvm-svn: 104904