This is mostly for the benefit of the LBR latency mode.
Right now, it performs no checking. If this is run on non-supported hardware, it will produce all zeroes for latency.
Differential Revision: https://reviews.llvm.org/D85254
New change: Updated lit.local.cfg to use pass the right argument to llvm-exegesis to actually request the LBR mode.
Differential Revision: https://reviews.llvm.org/D88670
This reverts commit 4fcd1a8e65 as
`llvm/test/tools/llvm-exegesis/X86/lbr/mov-add.s` failed on hosts
without LBR supported if the build has LIBPFM enabled. On that host,
`perf_event_open` fails with `EOPNOTSUPP` on LBR config. That change's
basic assumption
> If this is run on a non-supported hardware, it will produce all zeroes for latency.
could not stand as `perf_event_open` system call will fail if the
underlying hardware really don't have LBR supported.
This is mostly for the benefit of the LBR latency mode.
Right now, it performs no checking. If this is run on non-supported hardware, it will produce all zeroes for latency.
Differential Revision: https://reviews.llvm.org/D85254
LBR contains (up to) 16 entries for last x branches and the X86LBRCounter (from D77422) should be able to return all those.
Currently, it just returns the latest entry, which could lead to mis-leading measurements.
This patch aslo changes the LatencyBenchmarkRunner to accommodate multi-value readings.
https://reviews.llvm.org/D81050
Summary:
Using a .data() member on a StringRef was discarding the StringRef
size, breaking llvm-exegesis on machines with counter sums (e.g.
Zen2).
Reviewers: oontvoo
Subscribers: mstojanovic, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D80982
Summary:
Currently, we only have nice exploration for LEA instruction,
while for the rest, we rely on `randomizeUnsetVariables()`
to sometimes generate something interesting.
While that works, it isn't very reliable in coverage :)
Here, i'm making an assumption that while we may want to explore
multi-instruction configs, we are most interested in the
characteristics of the main instruction we were asked about.
Which we can do, by taking the existing `randomizeMCOperand()`,
and turning it on it's head - instead of relying on it to randomly fill
one of the interesting values, let's pregenerate all the possible interesting
values for the variable, and then generate as much `InstructionTemplate`
combinations of these possible values for variables as needed/possible.
Of course, that requires invasive changes to no longer pass just the
naked `Instruction`, but sometimes partially filled `InstructionTemplate`.
As it can be seen from the test, this allows us to explore
`X86::OperandType::OPERAND_COND_CODE` for instructions
that take such an operand.
I'm hoping this will greatly simplify exploration.
Reviewers: courbet, gchatelet
Reviewed By: gchatelet
Subscribers: orodley, mgorny, sdardis, tschuett, jrtc27, atanasyan, mstojanovic, andreadb, RKSimon, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74156
Summary: Commit 141915963b was reverted in
abe01e17f6 because it broke builds testing
without libpfm. A preparatory commit <commit_sha1> was added to enable
this recommit.
Original commit message:
Followup to D74085.
Replace the use of `report_fatal_error()` with returning the error to
`llvm-exegesis.cpp` and handling it there.
Differential Revision: https://reviews.llvm.org/D74113
It broke e.g. all tests under tools/llvm-exegesis/X86/ when libpfm is
not available, see comment on D74085.
This reverts commit b3576f60eb and
141915963b.
Followup to D74085.
Replace the use of `report_fatal_error()` with returning the error to
`llvm-exegesis.cpp` and handling it there.
Differential Revision: https://reviews.llvm.org/D74113
Summary:
... instead of crashing.
On typical exmaple is when there are no available registers.
Reviewers: gchatelet
Subscribers: tschuett, mstojanovic, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73196
Summary:
Right now when picking a back-to-back instruction at random, we might select
instructions that we do not know how to handle.
Add a ExegesisTarget hook to possibly filter instructions.
Reviewers: gchatelet
Subscribers: tschuett, mstojanovic, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73161
The addition of `inverse_throughput` mode highlighted the disjointedness
of snippet generators and benchmark runners because it used the
`UopsSnippetGenerator` with the `LatencyBenchmarkRunner`.
To keep the code consistent tie the snippet generators to
parallelization/serialization rather than their benchmark runners.
Renaming `LatencySnippetGenerator` -> `SerialSnippetGenerator`.
Renaming `UopsSnippetGenerator` -> `ParallelSnippetGenerator`.
Differential Revision: https://reviews.llvm.org/D72928
Summary:
This adds a `-max-configs-per-opcode` option to limit the number of
configs per opcode.
Reviewers: gchatelet
Subscribers: tschuett, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68642
llvm-svn: 374054
Summary:
Before this change the Executable function was made by duplicating the
snippet. This change adds a --repetion-mode={loop|duplicate} flag that
allows choosing between this behaviour and wrapping the snippet instructions
in a loop.
The new mode can help measurements when the snippet fits in the DSB by
short-cirtcuiting decoding. The loop adds a dec + jmp to the measurements, but
since these are not part of the critical path, they execute in parallel
with the measured code and do not impact measurements in practice.
Overview of the change:
- New SnippetRepetitor abstraction that handles repeating the snippet.
The assembler delegates repeating the instructions to this class.
- ExegesisTarget learns how to decrement loop counter and jump.
- Some refactoring of the assembler into FunctionFiller/BasicBlockFiller.
Reviewers: gchatelet
Subscribers: mgorny, tschuett, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68125
llvm-svn: 373083
Summary:
D60041 / D60138 refactoring changed how CMOV/SETcc opcodes
are handled. concode is now an immediate, with it's own operand type.
This at least allows to not crash on the opcode.
However, this still won't generate all the snippets
with all the condcode enumerators. D60066 does that.
Reviewers: courbet, gchatelet
Reviewed By: gchatelet
Subscribers: tschuett, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60057
llvm-svn: 357841
Summary:
This prevents "Cannot encode high byte register in REX-prefixed instruction"
from happening on instructions that require REX encoding when AH & co
get selected.
On the down side, these 4 registers can no longer be selected
automatically, but this avoids having to expose all the X86 encoding
complexity.
Reviewers: gchatelet
Subscribers: tschuett, jdoerfert, llvm-commits, bdb
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59821
llvm-svn: 357003
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
Summary:
The pfm counters are now in the ExegesisTarget rather than the
MCSchedModel (PR39165).
This also compresses the pfm counter tables (PR37068).
Reviewers: RKSimon, gchatelet
Subscribers: mgrang, llvm-commits
Differential Revision: https://reviews.llvm.org/D52932
llvm-svn: 345243
Summary:
This allows simplifying references of llvm::foo with foo when the needs
come in the future.
Reviewers: courbet, gchatelet
Reviewed By: gchatelet
Subscribers: javed.absar, tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D53455
llvm-svn: 344922
Summary:
Added function to set a register to a particular value + tests.
Add EFLAGS test, use new setRegTo instead of setRegToConstant.
Reviewers: courbet, javed.absar
Subscribers: llvm-commits, tschuett, mgorny
Differential Revision: https://reviews.llvm.org/D52297
llvm-svn: 342644
rL342465 is breaking the MSVC buildbots, but I need to revert this dependent revision as well.
Summary:
Added function to set a register to a particular value + tests.
Add EFLAGS test, use new setRegTo instead of setRegToConstant.
Reviewers: courbet, javed.absar
Subscribers: mgorny, tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D51856
llvm-svn: 342489
Summary:
Added function to set a register to a particular value + tests.
Add EFLAGS test, use new setRegTo instead of setRegToConstant.
Reviewers: courbet, javed.absar
Subscribers: mgorny, tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D51856
llvm-svn: 342466
Summary:
The snippet-generation part goes to the SnippetGenerator class.
This will allow benchmarking arbitrary code (see PR38437).
Reviewers: gchatelet
Subscribers: mgorny, tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D51979
llvm-svn: 342117
Summary:
This allows targets to override code generation for some instructions.
As an example of override, this also moves ad-hoc instruction filtering
for X86 into the X86 ExegesisTarget.
Reviewers: gchatelet
Subscribers: mgorny, tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D48587
llvm-svn: 335582
Summary:
This ensures that the snippet always sees the same values for registers,
making measurements reproducible.
This will also allow exploring different values.
Reviewers: gchatelet
Subscribers: tschuett, llvm-commits
Differential Revision: https://reviews.llvm.org/D48542
llvm-svn: 335465
Clement Courbet