This is a simple, cheap infrastructure for analyzing the shape of a
DAG. It recognizes uniform DAGs that take the shape of bottom-up
subtrees, such as the included matrix multiplication example. This is
useful for heuristics that balance register pressure with ILP. Two
canonical expressions of the heuristic are implemented in scheduling
modes: -misched-ilpmin and -misched-ilpmax.
llvm-svn: 168773
This fixes a hole in the "cheap" alias analysis logic implemented within
the DAG builder itself, regardless of whether proper alias analysis is
enabled. It now handles this pattern produced by LSR+CodeGenPrepare.
%sunkaddr1 = ptrtoint * %obj to i64
%sunkaddr2 = add i64 %sunkaddr1, %lsr.iv
%sunkaddr3 = inttoptr i64 %sunkaddr2 to i32*
store i32 %v, i32* %sunkaddr3
llvm-svn: 168768
This adds support for weak DAG edges to the general scheduling
infrastructure in preparation for MachineScheduler support for
heuristics based on weak edges.
llvm-svn: 167738
the MachineInstr MayLoad/MayLoad flags are based on the tablegen implementation.
For inline assembly, however, we need to compute these based on the constraints.
Revert r166929 as this is no longer needed, but leave the test case in place.
rdar://12033048 and PR13504
llvm-svn: 167040
incorrect instruction sequence due to it not being aware that an
inline assembly instruction may reference memory.
This patch fixes the problem by causing the scheduler to always assume that any
inline assembly code instruction could access memory. This is necessary because
the internal representation of the inline instruction does not include
any information about memory accesses.
This should fix PR13504.
llvm-svn: 166929
Allows the new machine model to be used for NumMicroOps and OutputLatency.
Allows the HazardRecognizer to be disabled along with itineraries.
llvm-svn: 165603
This wasn't contributing anything significant to postRA heuristics except compile time (by my measurements) and will be replaced by a more general heuristic for cross-region dependencies within the scheduler itself.
llvm-svn: 165563
Ordered memory operations are more constrained than volatile loads and
stores because they must be ordered with respect to all other memory
operations.
llvm-svn: 162861
The logic for recomputing latency based on a ScheduleDAG edge was
shady. This bypasses the problem by requiring the client to provide
operand indices. This ensures consistent use of the machine model's
API.
llvm-svn: 162420
For store->load dependencies that may alias, we should always use
TrueMemOrderLatency, which may eventually become a subtarget hook. In
effect, we should guarantee at least TrueMemOrderLatency on at least
one DAG path from a store to a may-alias load.
This should fix the standard mode as well as -enable-aa-sched-mi".
llvm-svn: 158380
There are some that I didn't remove this round because they looked like
obvious stubs. There are dead variables in gtest too, they should be
fixed upstream.
llvm-svn: 158090
No functional change intended.
Sorry for the churn. The iterator classes are supposed to help avoid
giant commits like this one in the future. The TableGen-produced
register lists are getting quite large, and it may be necessary to
change the table representation.
This makes it possible to do so without changing all clients (again).
llvm-svn: 157854
This feature avoids creating edges in the scheduler's dependence graph
for non-aliasing memory operations according to whichever alias
analysis is available. It has been fully tested in Hexagon. Before
making this default, it needs to be extended to handle multiple
MachineMemOperands, compile time needs more evaluation, and
benchmarking on X86 and ARM is needed.
Patch by Sergei Larin!
llvm-svn: 156842
This nicely handles the most common case of virtual register sets, but
also handles anticipated cases where we will map pointers to IDs.
The goal is not to develop a completely generic SparseSet
template. Instead we want to handle the expected uses within llvm
without any template antics in the client code. I'm adding a bit of
template nastiness here, and some assumption about expected usage in
order to make the client code very clean.
The expected common uses cases I'm designing for:
- integer keys that need to be reindexed, and may map to additional
data
- densely numbered objects where we want pointer keys because no
number->object map exists.
llvm-svn: 155227
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
These edges are not really necessary, but it is consistent with the
way we currently create physreg edges. Scheduler heuristics that
expect a DAG edge to the block terminator could benefit from this
change. Although in the future I hope we have a better mechanism for
modeling latency across scheduling regions.
llvm-svn: 152895
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
ScheduleDAGInstrs will be the main interface for MI-level
schedulers. Make sure it's readable: one page of protected fields, one
page of public methids.
llvm-svn: 152258
ScheduleDAG is responsible for the DAG: SUnits and SDeps. It provides target hooks for latency computation.
ScheduleDAGInstrs extends ScheduleDAG and defines the current scheduling region in terms of MachineInstr iterators. It has access to the target's scheduling itinerary data. ScheduleDAGInstrs provides the logic for building the ScheduleDAG for the sequence of MachineInstrs in the current region. Target's can implement highly custom schedulers by extending this class.
ScheduleDAGPostRATDList provides the driver and diagnostics for current postRA scheduling. It maintains a current Sequence of scheduled machine instructions and logic for splicing them into the block. During scheduling, it uses the ScheduleHazardRecognizer provided by the target.
Specific changes:
- Removed driver code from ScheduleDAG. clearDAG is the only interface needed.
- Added enterRegion/exitRegion hooks to ScheduleDAGInstrs to delimit the scope of each scheduling region and associated DAG. They should be used to setup and cleanup any region-specific state in addition to the DAG itself. This is necessary because we reuse the same ScheduleDAG object for the entire function. The target may extend these hooks to do things at regions boundaries, like bundle terminators. The hooks are called even if we decide not to schedule the region. So all instructions in a block are "covered" by these calls.
- Added ScheduleDAGInstrs::begin()/end() public API.
- Moved Sequence into the driver layer, which is specific to the scheduling algorithm.
llvm-svn: 152208
