Summary:
This patch eliminates many places where we originally needed to pass index
values to represent an instruction. The index is still used as a key, in various parts of
MCA. I'm not comfortable eliminating the index just yet. By burying the index in
the instruction, we can avoid exposing that value in many places.
Eventually, we should consider removing the Instructions list in the Backend
all together, it's only used to hold and reclaim the memory for the allocated
Instruction instances. Instead we could pass around a smart pointer. But that's
a separate discussion/patch.
Reviewers: andreadb, courbet, RKSimon
Reviewed By: andreadb
Subscribers: javed.absar, tschuett, gbedwell, llvm-commits
Differential Revision: https://reviews.llvm.org/D46367
llvm-svn: 331660
This patch also improves the description of a couple of flags in the view
options. With this change, the -help now specifies which views are enabled by
default.
llvm-svn: 331594
Summary:
This change makes the TimelineView source simpler to read and easier to modify in the future.
This patch introduces a class of static chars used as the display values in the TimelineView report, this change just eliminates a few magic characters.
Reviewers: andreadb, courbet, RKSimon
Reviewed By: andreadb
Subscribers: tschuett, gbedwell, llvm-commits
Differential Revision: https://reviews.llvm.org/D46409
llvm-svn: 331540
The logic remains the same. Eventually, I see the RCU acting as its own separate stage in the instruction pipeline.
Differential Revision: https://reviews.llvm.org/D46331
llvm-svn: 331316
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
Differential Revision: https://reviews.llvm.org/D46290
llvm-svn: 331272
This fixes PR37293.
We can have scheduling classes with no write latency entries, that still consume
processor resources. We don't want to treat those instructions as zero-latency
instructions; they still have to be issued to the underlying pipelines, so they
still consume resource cycles.
This is likely to be a regression which I have accidentally introduced at
revision 330807. Now, if an instruction has a non-empty set of write processor
resources, we conservatively treat it as a normal (i.e. non zero-latency)
instruction.
llvm-svn: 331193
Summary: The instruction index was never referenced in the body. Just a minor cleanup.
Reviewers: andreadb
Reviewed By: andreadb
Subscribers: javed.absar, gbedwell, llvm-commits
Differential Revision: https://reviews.llvm.org/D46142
llvm-svn: 331001
With this patch, options to add/tweak views are all grouped together in the
-help output.
The new "View Options" category looks like this:
```
View Options:
-dispatch-stats - Print dispatch statistics
-instruction-info - Print the instruction info view
-instruction-tables - Print instruction tables
-register-file-stats - Print register file statistics
-resource-pressure - Print the resource pressure view
-retire-stats - Print retire control unit statistics
-scheduler-stats - Print scheduler statistics
-timeline - Print the timeline view
-timeline-max-cycles=<uint> - Maximum number of cycles in the timeline view. Defaults to 80 cycles
-timeline-max-iterations=<uint> - Maximum number of iterations to print in timeline view
```
llvm-svn: 330816
The instruction printer used by llvm-mca to generate the performance report now
defaults the output assembly format to the format used for the input assembly
file.
On x86, the asm format can be either AT&T or Intel, depending on the
presence/absence of directive `.intel_syntax`.
Users can still specify a different assembly dialect with the command line flag
-output-asm-variant=<uint>.
llvm-svn: 330733
Zero latency instructions are now scheduled the same way as other instructions.
Before this patch, there was a specialzed code path for those instructions.
All scheduler events are now generated from method `scheduleInstruction()` and
from method `cycleEvent()`. This will make easier to implement a "execution
stage", and let that stage publish all the scheduler events.
No functional change intended.
llvm-svn: 330723
We have a few functions that virtually all command wants to run on
process startup/shutdown. This patch adds InitLLVM class to do that
all at once, so that we don't need to copy-n-paste boilerplate code
to each llvm command's main() function.
Differential Revision: https://reviews.llvm.org/D45602
llvm-svn: 330046
Normally, the Scheduler prioritizes older instructions over younger instructions
during the instruction issue stage. In one particular case where a dependent
instruction had a schedule read-advance associated to one of the input operands,
this rule was not correctly applied.
This patch fixes the issue and adds a test to verify that we don't regress that
particular case.
llvm-svn: 330032
This patch moves part of the logic that notifies dispatch stall events from the
DispatchUnit to the Scheduler.
The main goal of this patch is to remove (yet another) dependency between the
DispatchUnit and the Scheduler. Before this patch, the DispatchUnit had to know
about `Scheduler::Event` and how to classify stalls due to the lack of scheduling
resources. This patch removes that knowledge and simplifies the logic in
DispatchUnit::checkScheduler.
This is another change done in preparation for the work to fix PR36663.
No functional change intended.
llvm-svn: 329835
This patch moves the logic that collects and analyzes dispatch events to the
DispatchStatistics view.
Added flag -dispatch-stats to print statistics related to the dispatch logic.
llvm-svn: 329708
This patch teaches llvm-mca how to parse code comments in search for special
"markers" used to select regions of code.
Example:
# LLVM-MCA-BEGIN My Code Region
....
# LLVM-MCA-END
The MCAsmLexer now delegates to an object of class MCACommentParser (i.e. an
AsmCommentConsumer) the parsing of code comments to search for begin/end code
region markers.
A comment starting with substring "LLVM-MCA-BEGIN" marks the beginning of a new
region of code. A comment starting with substring "LLVM-MCA-END" marks the end
of the last region.
This implementation doesn't allow regions to overlap. Each region can have a
optional description; internally, each region is identified by a range of source
code locations (SMLoc).
MCInst objects are added to a region R only if the source location for the
MCInst is in the range of locations specified by R.
By default, the tool allocates an implicit "Default" code region which contains
every source location. See new tests llvm-mca-marker-*.s for a few examples.
A new Backend object is created for every region. So, the analysis is conducted
on every parsed code region. The final report is the union of the reports
generated for every code region. Note that empty regions are skipped.
Special "[#] Code Region - ..." strings are used in the report to mark the
portion which is specific to a code region only. For example, see
llvm-mca-markers-5.s.
Differential Revision: https://reviews.llvm.org/D45433
llvm-svn: 329590
Scheduling models can now describe processor register files and retire control
units. This updates the existing documentation and the README file.
llvm-svn: 329311
This patch adds the ability to describe properties of the hardware retire
control unit.
Tablegen class RetireControlUnit has been added for this purpose (see
TargetSchedule.td).
A RetireControlUnit specifies the size of the reorder buffer, as well as the
maximum number of opcodes that can be retired every cycle.
A zero (or negative) value for the reorder buffer size means: "the size is
unknown". If the size is unknown, then llvm-mca defaults it to the value of
field SchedMachineModel::MicroOpBufferSize. A zero or negative number of
opcodes retired per cycle means: "there is no restriction on the number of
instructions that can be retired every cycle".
Models can optionally specify an instance of RetireControlUnit. There can only
be up-to one RetireControlUnit definition per scheduling model.
Information related to the RCU (RetireControlUnit) is stored in (two new fields
of) MCExtraProcessorInfo. llvm-mca loads that information when it initializes
the DispatchUnit / RetireControlUnit (see Dispatch.h/Dispatch.cpp).
This patch fixes PR36661.
Differential Revision: https://reviews.llvm.org/D45259
llvm-svn: 329304
This is done in preparation for D45259.
With D45259, models can specify the size of the reorder buffer, and the retire
throughput directly via tablegen.
llvm-svn: 329274
Before this patch, the "BackendStatistics" view was responsible for printing the
register file usage (as well as many other statistics).
Now users can enable register file usage statistics using the command line flag
`-register-file-stats`. By default, the tool doesn't print register file
statistics.
llvm-svn: 329083
This patch allows the description of register files in processor scheduling
models. This addresses PR36662.
A new tablegen class named 'RegisterFile' has been added to TargetSchedule.td.
Targets can optionally describe register files for their processors using that
class. In particular, class RegisterFile allows to specify:
- The total number of physical registers.
- Which target registers are accessible through the register file.
- The cost of allocating a register at register renaming stage.
Example (from this patch - see file X86/X86ScheduleBtVer2.td)
def FpuPRF : RegisterFile<72, [VR64, VR128, VR256], [1, 1, 2]>
Here, FpuPRF describes a register file for MMX/XMM/YMM registers. On Jaguar
(btver2), a YMM register definition consumes 2 physical registers, while MMX/XMM
register definitions only cost 1 physical register.
The syntax allows to specify an empty set of register classes. An empty set of
register classes means: this register file models all the registers specified by
the Target. For each register class, users can specify an optional register
cost. By default, register costs default to 1. A value of 0 for the number of
physical registers means: "this register file has an unbounded number of
physical registers".
This patch is structured in two parts.
* Part 1 - MC/Tablegen *
A first part adds the tablegen definition of RegisterFile, and teaches the
SubtargetEmitter how to emit information related to register files.
Information about register files is accessible through an instance of
MCExtraProcessorInfo.
The idea behind this design is to logically partition the processor description
which is only used by external tools (like llvm-mca) from the processor
information used by the llvm machine schedulers.
I think that this design would make easier for targets to get rid of the extra
processor information if they don't want it.
* Part 2 - llvm-mca related *
The second part of this patch is related to changes to llvm-mca.
The main differences are:
1) class RegisterFile now needs to take into account the "cost of a register"
when allocating physical registers at register renaming stage.
2) Point 1. triggered a minor refactoring which lef to the removal of the
"maximum 32 register files" restriction.
3) The BackendStatistics view has been updated so that we can print out extra
details related to each register file implemented by the processor.
The effect of point 3. is also visible in tests register-files-[1..5].s.
Differential Revision: https://reviews.llvm.org/D44980
llvm-svn: 329067
Before, the instruction builder incorrectly assumed that only explicit reads
could have been associated with ReadAdvance entries.
This patch fixes the issue and adds a test to verify it.
llvm-svn: 328972
Summary:
r327219 added wrappers to std::sort which randomly shuffle the container before sorting.
This will help in uncovering non-determinism caused due to undefined sorting
order of objects having the same key.
To make use of that infrastructure we need to invoke llvm::sort instead of std::sort.
Note: This patch is one of a series of patches to replace *all* std::sort to llvm::sort.
Refer the comments section in D44363 for a list of all the required patches.
Reviewers: JDevlieghere, zturner, echristo, dberris, friss
Reviewed By: echristo
Subscribers: gbedwell, llvm-commits
Differential Revision: https://reviews.llvm.org/D45141
llvm-svn: 328943
The tool was passing the wrong operand index to method
MCSubtargetInfo::getReadAdvanceCycles(). That method requires a "UseIdx", and
not the operand index. This was found when testing X86 code where instructions
had a memory folded operand.
This patch fixes the issue and adds test read-advance-1.s to ensure that
the ReadAfterLd (a ReadAdvance of 3cy) information is correctly used.
llvm-svn: 328790
We were incorrectly initializing the array of used registers in method checkRAT.
As a consequence, the number of register file stalls was misreported.
Added a test to cover this case.
llvm-svn: 328629
Matt Davis