Commit Graph

20 Commits

Author SHA1 Message Date
Andrea Di Biagio 45685a1fc4 [MCA] Simplify the rounding logic used in TimelineView::printWaitTimeEntry.
This is related to PR51392.

Before this patch, the timeline view was rounding doubles to the first decimal,
using a logic similar to this:

```
  double AverageTime = (double)Input / CumulativeExecutions;
  double Result = floor((AverageTime * 10) + 0.5) / 10
```

Here, Input and CumulativeExecutions are both unsigned integers.
The last operation is what effectively performs the rounding of AverageTime.

PR51392 has been raised because - under specific -m32 configurations of GCC -
one of the timeline tests reports slighlty different values (due to a different
rounding choice).

This patch tries to minimise the propagation of floating-point error by
hoisting the multiply by 10, so that it is performed on the unsigned.

```
  double AverageTime = (double)(Input * 10) / CumulativeExecutions;
  floor(AverageTime + 0.5) / 10
```

So we are trading a floating point multiply for a integer multiply (which can be
expanded using a simple MUL or using an `ADD + LEA` sequence). This decrease in
floating point operations executed should also help with decreasing the error in
the computation..

Strictly speaking, that computation will always be potentially subject to error
(depending on what values are passed in input). However, this patch should
improve the situation and make bug like PR51392 less frequent.
2021-08-07 11:59:41 +01:00
Jay Foad beebe5a056 [MCA] Allow unlimited cycles in the timeline view
Change --max-timeline-cycles=0 to mean no limit on the number of cycles.
Use this in AMDGPU tests to show all instructions in the timeline view
instead of having it arbitrarily truncated.

Differential Revision: https://reviews.llvm.org/D104846
2021-06-24 12:54:57 +01:00
Patrick Holland 70040de32d [MCA][TimelineView] Fixed a bug that was causing instructions outside of the timeline-max-cycles to still be printed.
Differential Revision: https://reviews.llvm.org/D104815
2021-06-23 15:05:49 -07:00
Patrick Holland d03736455c [MCA] [In-order pipeline] Fix for 0 latency instruction causing assertion to fail.
0 latency instructions now get processed and retired properly within the in-order pipeline. Had to fix a bug within TimelineView.cpp as well that would show up when a 0 latency instruction was the first instruction in the source.

Differential Revision: https://reviews.llvm.org/D104675
2021-06-22 10:18:39 -07:00
Andrew Savonichev 292da93d59 [MCA] Disable RCU for InOrderIssueStage
This is a follow-up for:
D98604 [MCA] Ensure that writes occur in-order

When instructions are aligned by the order of writes, they retire
in-order naturally. There is no need for an RCU, so it is disabled.

Differential Revision: https://reviews.llvm.org/D98628
2021-03-24 13:54:04 +03:00
Wolfgang Pieb d38be2ba0e [llvm-mca] Initial implementation of serialization using JSON. The views
implemented at this time are Summary, Timeline, ResourcePressure and InstructionInfo.
Use --json on the command line to obtain JSON output.
2021-01-21 15:15:54 -08:00
Wolfgang Pieb e02920fe55 [llvm-mca][NFC] Refactor handling of views that examine individual instructions,
including printing them.

Reviewers: andreadb, lebedev.ri

Differential Review: https://reviews.llvm.org/D86390

Introduces a new base class "InstructionView" that such views derive from.
Other views still use the "View" base class.
2020-08-25 12:12:37 -07:00
Fangrui Song aa708763d3 [MC] Add parameter `Address` to MCInstPrinter::printInst
printInst prints a branch/call instruction as `b offset` (there are many
variants on various targets) instead of `b address`.

It is a convention to use address instead of offset in most external
symbolizers/disassemblers. This difference makes `llvm-objdump -d`
output unsatisfactory.

Add `uint64_t Address` to printInst(), so that it can pass the argument to
printInstruction(). `raw_ostream &OS` is moved to the last to be
consistent with other print* methods.

The next step is to pass `Address` to printInstruction() (generated by
tablegen from the instruction set description). We can gradually migrate
targets to print addresses instead of offsets.

In any case, downstream projects which don't know `Address` can pass 0 as
the argument.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D72172
2020-01-06 20:42:22 -08:00
Roman Lebedev a5e65c1cf7 [MCA] Show aggregate over Average Wait times for the whole snippet (PR43219)
Summary:
As disscused in https://bugs.llvm.org/show_bug.cgi?id=43219,
i believe it may be somewhat useful to show //some// aggregates
over all the sea of statistics provided.

Example:
```
Average Wait times (based on the timeline view):
[0]: Executions
[1]: Average time spent waiting in a scheduler's queue
[2]: Average time spent waiting in a scheduler's queue while ready
[3]: Average time elapsed from WB until retire stage

      [0]    [1]    [2]    [3]
0.     3     1.0    1.0    4.7       vmulps     %xmm0, %xmm1, %xmm2
1.     3     2.7    0.0    2.3       vhaddps    %xmm2, %xmm2, %xmm3
2.     3     6.0    0.0    0.0       vhaddps    %xmm3, %xmm3, %xmm4
       3     3.2    0.3    2.3       <total>
```
I.e. we average the averages.

Reviewers: andreadb, mattd, RKSimon

Reviewed By: andreadb

Subscribers: gbedwell, arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68714

llvm-svn: 374361
2019-10-10 14:46:21 +00:00
Rui Ueyama 4d41c332ef Revert r367649: Improve raw_ostream so that you can "write" colors using operator<<
This reverts commit r367649 in an attempt to unbreak Windows bots.

llvm-svn: 367658
2019-08-02 07:22:34 +00:00
Rui Ueyama a52f982f1c Improve raw_ostream so that you can "write" colors using operator<<
1. raw_ostream supports ANSI colors so that you can write messages to
the termina with colors. Previously, in order to change and reset
color, you had to call `changeColor` and `resetColor` functions,
respectively.

So, if you print out "error: " in red, for example, you had to do
something like this:

  OS.changeColor(raw_ostream::RED);
  OS << "error: ";
  OS.resetColor();

With this patch, you can write the same code as follows:

  OS << raw_ostream::RED << "error: " << raw_ostream::RESET;

2. Add a boolean flag to raw_ostream so that you can disable colored
output. If you disable colors, changeColor, operator<<(Color),
resetColor and other color-related functions have no effect.

Most LLVM tools automatically prints out messages using colors, and
you can disable it by passing a flag such as `--disable-colors`.
This new flag makes it easy to write code that works that way.

Differential Revision: https://reviews.llvm.org/D65564

llvm-svn: 367649
2019-08-02 04:48:30 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Fangrui Song 5a8fd65700 [llvm-mca] Move namespace mca inside llvm::
Summary: This allows to remove `using namespace llvm;` in those *.cpp files

When we want to revisit the decision (everything resides in llvm::mca::*) in the future, we can move things to a nested namespace of llvm::mca::, to conceptually make them separate from the rest of llvm::mca::*

Reviewers: andreadb, mattd

Reviewed By: andreadb

Subscribers: javed.absar, tschuett, gbedwell, llvm-commits

Differential Revision: https://reviews.llvm.org/D53407

llvm-svn: 345612
2018-10-30 15:56:08 +00:00
Andrea Di Biagio 84d0051310 [llvm-mca] Removed dependency on mca::SourcMgr in some Views. NFC
llvm-svn: 345376
2018-10-26 10:48:04 +00:00
Andrea Di Biagio 7be45b0f85 [llvm-mca] Refactor class SourceMgr. NFCI
Added begin()/end() methods to allow the usage of SourceMgr in foreach loops.
With this change, method getMCInstFromIndex() (as well as a couple of other
methods) are now redundant, and can be removed from the public interface.

llvm-svn: 345147
2018-10-24 15:06:27 +00:00
Andrea Di Biagio 7f2230ff16 [llvm-mca] correctly initialize field 'CycleRetired' in the TimelineView.
This fixes a [-Wmissing-field-initializers] warning reported by buildbot
lld-x86_64-darwin13, build #25152.

llvm-svn: 341056
2018-08-30 11:17:58 +00:00
Andrea Di Biagio 8b647dcf4b [llvm-mca] Report the number of dispatched micro opcodes in the DispatchStatistics view.
This patch introduces the following changes to the DispatchStatistics view:
 * DispatchStatistics now reports the number of dispatched opcodes instead of
   the number of dispatched instructions.
 * The "Dynamic Dispatch Stall Cycles" table now also reports the percentage of
   stall cycles against the total simulated cycles.

This change allows users to easily compare dispatch group sizes with the
processor DispatchWidth.
Before this change, it was difficult to correlate the two numbers, since
DispatchStatistics view reported numbers of instructions (instead of opcodes).
DispatchWidth defines the maximum size of a dispatch group in terms of number of
micro opcodes.

The other change introduced by this patch is related to how DispatchStage
generates "instruction dispatch" events.
In particular:
 * There can be multiple dispatch events associated with a same instruction
 * Each dispatch event now encapsulates the number of dispatched micro opcodes.

The number of micro opcodes declared by an instruction may exceed the processor
DispatchWidth. Therefore, we cannot assume that instructions are always fully
dispatched in a single cycle.
DispatchStage knows already how to handle instructions declaring a number of
opcodes bigger that DispatchWidth. However, DispatchStage always emitted a
single instruction dispatch event (during the first simulated dispatch cycle)
for instructions dispatched.

With this patch, DispatchStage now correctly notifies multiple dispatch events
for instructions that cannot be dispatched in a single cycle.

A few views had to be modified. Views can no longer assume that there can only
be one dispatch event per instruction.

Tests (and docs) have been updated.

Differential Revision: https://reviews.llvm.org/D51430

llvm-svn: 341055
2018-08-30 10:50:20 +00:00
Andrea Di Biagio 4269d64b20 [llvm-mca] Initialize each element in vector TimelineView::UsedBuffers to a default invalid buffer descriptor. NFCI
Also change the default buffer size for UsedBuffer entries to -1 (i.e. "unknown
size"). No functional change intended.

llvm-svn: 340830
2018-08-28 15:07:11 +00:00
Andrea Di Biagio d17d371c40 [llvm-mca][TimelineView] Force the same number of executions for every entry in the 'wait-times' table.
This patch also uses colors to highlight problematic wait-time entries.
A problematic entry is an entry with an high wait time that tends to match (or
exceed) the size of the scheduler's buffer.

Color RED is used if an instruction had to wait an average number of cycles
which is bigger than (or equal to) the size of the underlying scheduler's
buffer.
Color YELLOW is used if the time (in cycles) spend waiting for the
operands or pipeline resources is bigger than half the size of the underlying
scheduler's buffer.
Color MAGENTA is used if an instruction does not consume buffer resources
according to the scheduling model.

llvm-svn: 340825
2018-08-28 14:27:01 +00:00
Matt Davis 10aa09f008 [llvm-mca] Move views and stats into a Views subdir. NFC.
llvm-svn: 340645
2018-08-24 20:24:53 +00:00