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Commit Graph

23 Commits

Author SHA1 Message Date
Dan Gohman
7e48e82adb When scheduling a block in parts, keep track of the overall
instruction index across each part. Instruction indices are used
to make live range queries, and live ranges can extend beyond
scheduling region boundaries.

Refactor the ScheduleDAGSDNodes class some more so that it
doesn't have to worry about this additional information.

llvm-svn: 64288
2009-02-11 04:27:20 +00:00
Dan Gohman
f2b9543ee5 Factor out more code for computing register live-range informationfor
scheduling, and generalize is so that preserves state across
scheduling regions. This fixes incorrect live-range information around
terminators and labels, which are effective region boundaries.

In place of looking for terminators to anchor inter-block dependencies,
introduce special entry and exit scheduling units for this purpose.

llvm-svn: 64254
2009-02-10 23:27:53 +00:00
Dan Gohman
2d402dd7cd Move ScheduleDAGInstrs.h to be a private header. Front-ends
that used this header to select a scheduling policy should
use SchedulerRegistry.h instead (llvm-gcc and clang were
updated a while ago).

llvm-svn: 63934
2009-02-06 17:12:10 +00:00
Dan Gohman
50283ce80b Fix a post-RA scheduling dependency bug.
If a MachineInstr doesn't have a memoperand but has an opcode that
is known to load or store, assume its memory reference may alias
*anything*, including stack slots which the compiler completely
controls.

To partially compensate for this, teach the ScheduleDAG building
code to do basic getUnderlyingValue analysis. This greatly
reduces the number of instructions that require restrictive
dependencies. This code will need to be revisited when we start
doing real alias analysis, but it should suffice for now.

llvm-svn: 63370
2009-01-30 02:49:14 +00:00
Dan Gohman
3d0633627d Instead of adding dependence edges between terminator instructions
and every other instruction in their blocks to keep the terminator
instructions at the end, teach the post-RA scheduler how to operate
on ranges of instructions, and exclude terminators from the range
of instructions that get scheduled.

Also, exclude mid-block labels, such as EH_LABEL instructions, and
schedule code before them separately from code after them. This
fixes problems with the post-RA scheduler moving code past
EH_LABELs.

llvm-svn: 62366
2009-01-16 22:10:20 +00:00
Dan Gohman
6fcee67989 Move a few containers out of ScheduleDAGInstrs::BuildSchedGraph
and into the ScheduleDAGInstrs class, so that they don't get
destructed and re-constructed for each block. This fixes a
compile-time hot spot in the post-pass scheduler.

To help facilitate this, tidy and do some minor reorganization
in the scheduler constructor functions.

llvm-svn: 62275
2009-01-15 19:20:50 +00:00
Dan Gohman
a0f1fc06c4 Clean up the atomic opcodes in SelectionDAG.
This removes all the _8, _16, _32, and _64 opcodes and replaces each
group with an unsuffixed opcode. The MemoryVT field of the AtomicSDNode
is now used to carry the size information. In tablegen, the size-specific
opcodes are replaced by size-independent opcodes that utilize the
ability to compose them with predicates.

This shrinks the per-opcode tables and makes the code that handles
atomics much more concise.

llvm-svn: 61389
2008-12-23 21:37:04 +00:00
Dan Gohman
6bee7ef264 Rename BuildSchedUnits to BuildSchedGraph, and refactor the
code in ScheduleDAGSDNodes' BuildSchedGraph into separate functions.

llvm-svn: 61376
2008-12-23 18:36:58 +00:00
Dan Gohman
1c1b281cd5 Use isTerminator() instead of isBranch()||isReturn() in
several places. isTerminator() returns true for a superset
of cases, and includes things like FP_REG_KILL, which are
nither return or branch but aren't safe to move/remat/etc.

llvm-svn: 61373
2008-12-23 17:28:50 +00:00
Dan Gohman
c3e24d559b Add initial support for back-scheduling address computations,
especially in the case of addresses computed from loop induction
variables.

llvm-svn: 61075
2008-12-16 03:35:01 +00:00
Dan Gohman
40a40dd7c1 Fix some register-alias-related bugs in the post-RA scheduler liveness
computation code. Also, avoid adding output-depenency edges when both
defs are dead, which frequently happens with EFLAGS defs.

Compute Depth and Height lazily, and always in terms of edge latency
values. For the schedulers that don't care about latency, edge latencies
are set to 1.

Eliminate Cycle and CycleBound, and LatencyPriorityQueue's Latencies array.
These are all subsumed by the Depth and Height fields.

llvm-svn: 61073
2008-12-16 03:25:46 +00:00
Dan Gohman
67e694b0ea Add a simple target-independent heuristic to allow targets with no
instruction itinerary data to back-schedule loads.

llvm-svn: 61070
2008-12-16 02:38:22 +00:00
Dan Gohman
036cc300ad Rewrite the SDep class, and simplify some of the related code.
The Cost field is removed. It was only being used in a very limited way,
to indicate when the scheduler should attempt to protect a live register,
and it isn't really needed to do that. If we ever want the scheduler to
start inserting copies in non-prohibitive situations, we'll have to
rethink some things anyway.

A Latency field is added. Instead of giving each node a single
fixed latency, each edge can have its own latency. This will eventually
be used to model various micro-architecture properties more accurately.

The PointerIntPair class and an internal union are now used, which
reduce the overall size.

llvm-svn: 60806
2008-12-09 22:54:47 +00:00
Dan Gohman
6f3258586e Fix the top-level comments, and fix some 80-column violations.
llvm-svn: 60707
2008-12-08 17:50:35 +00:00
Dan Gohman
f8e215d4b1 Add minimal support for disambiguating memory references. Currently
the main thing this covers is spills to distinct spill slots.

llvm-svn: 60517
2008-12-04 01:35:46 +00:00
Dan Gohman
6dcf3a7c22 Pass the isAntiDep argument.
llvm-svn: 59968
2008-11-24 17:24:27 +00:00
Dan Gohman
fd0ae4a637 Correctly set the isCtrl flag for chain dependencies.
llvm-svn: 59837
2008-11-21 19:17:25 +00:00
Dan Gohman
4a7eec40e8 Update comments.
llvm-svn: 59836
2008-11-21 19:16:58 +00:00
Dan Gohman
79202c165e Set the isAntiDep flag in the MachineInstr scheduler.
llvm-svn: 59787
2008-11-21 02:38:21 +00:00
Dan Gohman
fe33ecd2d3 Use ComputeLatency in the MachineInstr scheduler.
llvm-svn: 59777
2008-11-21 01:44:51 +00:00
Dan Gohman
60693dacec Implement ComputeLatency for MachineInstr ScheduleDAGs. Factor
some of the latency computation logic out of the SDNode
ScheduleDAG code into a TargetInstrItineraries helper method
to help with this.

llvm-svn: 59761
2008-11-21 00:12:10 +00:00
Dan Gohman
fd06b62f9c Treat mid-block labels the same as terminators when building the
MachineInstr scheduling DAG, meaning they implicitly depend on all
preceding defs. This fixes Benchmarks/Shootout-C++/except and
Regression/C++/EH/simple_rethrow in
  -relocation-model=pic -disable-post-RA-scheduler=false
mode.

llvm-svn: 59747
2008-11-20 19:58:35 +00:00
Dan Gohman
f4b2751ee6 Experimental post-pass scheduling support. Post-pass scheduling
is currently off by default, and can be enabled with
-disable-post-RA-scheduler=false.

This doesn't have a significant impact on most code yet because it doesn't
yet do anything to address anti-dependencies and it doesn't attempt to
disambiguate memory references. Also, several popular targets
don't have pipeline descriptions yet.

The majority of the changes here are splitting the SelectionDAG-specific
code out of ScheduleDAG, so that ScheduleDAG can be moved to
libLLVMCodeGen.a. The interface between ScheduleDAG-using code and
the rest of the scheduling code is somewhat rough and will evolve.

llvm-svn: 59676
2008-11-19 23:18:57 +00:00