Summary:
This patch mostly copies the existing Instruction Flow, and stage descriptions
from the mca README. I made a few text tweaks, but no semantic changes,
and made reference to the "default pipeline." I also removed the internals
references (e.g., reference to class names and header files). I did leave the
LSUnit name around, but only as an abbreviated word for the load-store unit.
Reviewers: andreadb, courbet, RKSimon, gbedwell, filcab
Reviewed By: andreadb
Subscribers: tschuett, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D49692
llvm-svn: 338319
This makes it easier for someone to copy-paste this line, change the path, and run the command.
Differential Revision: https://reviews.llvm.org/D49201
llvm-svn: 338254
This should make the semantics of DIExpressions within llvm.dbg.{addr,
declare, value} easier to understand.
Differential Revision: https://reviews.llvm.org/D49572
llvm-svn: 338182
In light of the recent changes to SmallVector in r335421, r337514, and
r337820, document its advantages over std::vector (see r175906 and
r266909).
Also add a release note.
https://reviews.llvm.org/D49748
llvm-svn: 338071
Violating the invariants specified by attributes is undefined behavior.
Maybe we could use poison instead for some of the parameter attributes,
but I don't think it's worthwhile.
Differential Revision: https://reviews.llvm.org/D49041
llvm-svn: 337947
This new JIT event listener supports generating profiling data for
the linux 'perf' profiling tool, allowing it to generate function and
instruction level profiles.
Currently this functionality is not enabled by default, but must be
enabled with LLVM_USE_PERF=yes. Given that the listener has no
dependencies, it might be sensible to enable by default once the
initial issues have been shaken out.
I followed existing precedent in registering the listener by default
in lli. Should there be a decision to enable this by default on linux,
that should probably be changed.
Please note that until https://reviews.llvm.org/D47343 is resolved,
using this functionality with mcjit rather than orcjit will not
reliably work.
Disregarding the previous comment, here's an example:
$ cat /tmp/expensive_loop.c
bool stupid_isprime(uint64_t num)
{
if (num == 2)
return true;
if (num < 1 || num % 2 == 0)
return false;
for(uint64_t i = 3; i < num / 2; i+= 2) {
if (num % i == 0)
return false;
}
return true;
}
int main(int argc, char **argv)
{
int numprimes = 0;
for (uint64_t num = argc; num < 100000; num++)
{
if (stupid_isprime(num))
numprimes++;
}
return numprimes;
}
$ clang -ggdb -S -c -emit-llvm /tmp/expensive_loop.c -o
/tmp/expensive_loop.ll
$ perf record -o perf.data -g -k 1 ./bin/lli -jit-kind=mcjit /tmp/expensive_loop.ll 1
$ perf inject --jit -i perf.data -o perf.jit.data
$ perf report -i perf.jit.data
- 92.59% lli jitted-5881-2.so [.] stupid_isprime
stupid_isprime
main
llvm::MCJIT::runFunction
llvm::ExecutionEngine::runFunctionAsMain
main
__libc_start_main
0x4bf6258d4c544155
+ 0.85% lli ld-2.27.so [.] do_lookup_x
And line-level annotations also work:
│ for(uint64_t i = 3; i < num / 2; i+= 2) {
│1 30: movq $0x3,-0x18(%rbp)
0.03 │1 38: mov -0x18(%rbp),%rax
0.03 │ mov -0x10(%rbp),%rcx
│ shr $0x1,%rcx
3.63 │ ┌──cmp %rcx,%rax
│ ├──jae 6f
│ │ if (num % i == 0)
0.03 │ │ mov -0x10(%rbp),%rax
│ │ xor %edx,%edx
89.00 │ │ divq -0x18(%rbp)
│ │ cmp $0x0,%rdx
0.22 │ │↓ jne 5f
│ │ return false;
│ │ movb $0x0,-0x1(%rbp)
│ │↓ jmp 73
│ │ }
3.22 │1 5f:│↓ jmp 61
│ │ for(uint64_t i = 3; i < num / 2; i+= 2) {
Subscribers: mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D44892
llvm-svn: 337789
Summary: The original text was lifted from the MCA README. I re-ran the dot-product example and updated the output seen in the docs. I also added a few paragraphs discussing the instruction issued and retired histograms, as well as discussing the register file stats.
Reviewers: andreadb, RKSimon, courbet, gbedwell, filcab
Reviewed By: andreadb
Subscribers: tschuett
Differential Revision: https://reviews.llvm.org/D49614
llvm-svn: 337648
For the most part, these changes were from the RFC. I made a few minor
word/structure changes, but nothing significant. I also regenerated the
example output, and adjusted the text accordingly.
Differential Revision: https://reviews.llvm.org/D49527
llvm-svn: 337496
Add some quick words for unroll and jam to the list of passes and add
unroll_and_jam metadata to the language ref.
Differential Revision: https://reviews.llvm.org/D49349
llvm-svn: 337448
Summary:
Updated and reorganized. Made the following additions:
1) How to see if ld.gold is installed, and whether it is the current
default.
2) How to install ld.gold as the default or alternatively use
-fuse-ld=gold.
3) Move the part about installing the newly built ld-new as the default
to the prior section and how to use --enable-gold=default to do it
automatically on install.
4) Add a note about ld.bfd supporting plugins but indicate that it is
not tested by the LLVM project and gold is the recommended linker for
use with the gold plugin.
Fixes PR32760.
Reviewers: davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D49490
llvm-svn: 337404
a Spectre v1 mitigation.
This was initially posted w/ the patch implementing this, got some basic
review there. Also, it is generated from a the Google doc that I shared
as part of the Speculative Load Hardening RFC and which has seen pretty
widespread review at this point.
However, as the patches are landing in LLVM, I wanted to land the docs
as well. But it seemed like a bad idea to have them in the same commit
in case of reverts or other things. So the docs are split out here.
Thanks for all the review so far, and further review and improvements to
the documentation here welcome. Please feel free to keep hammering on
the code review or Google document.
Note that this is a markdown document which Sphinx doesn't yet process.
But we can add support for that after and this should get picked up
(and I'm preparing patches for that). Also, this gets the document
itself into a nice shared place where we can iterate on it.
Differential Revision: https://reviews.llvm.org/D49433
llvm-svn: 337391
We need to explicitly state what happens when an invariant promised by
load metadata is violated at runtime, since it's come up repeatedly.
It's possible we want to specify that the result of the load is poison
in some cases, rather than undefined behavior, if the constraint is
violated. That would allow preserving the metadata when the load is
hoisted, but doesn't allow propagating metadata based on control flow.
We currently do transforms based on control flow for nonnull metadata
(in PromoteMemToReg).
Differential Revision: https://reviews.llvm.org/D47854
llvm-svn: 337325
Clarify that violating nnan and ninf can lead to undefined behavior.
This allows more aggressive optimizations based on those assumptions.
Differential Revision: https://reviews.llvm.org/D47963
llvm-svn: 337323
We're going to work on this in a separate review focusing more on documenting
the View and probably removing some of the less-interesting/less-useful pieces.
This reverts r337219,337225
llvm-svn: 337295
As discussed here:
http://lists.llvm.org/pipermail/llvm-dev/2018-May/123292.htmlhttp://lists.llvm.org/pipermail/llvm-dev/2018-July/124400.html
We want to add rotate intrinsics because the IR expansion of that pattern is 4+ instructions,
and we can lose pieces of the pattern before it gets to the backend. Generalizing the operation
by allowing 2 different input values (plus the 3rd shift/rotate amount) gives us a "funnel shift"
operation which may also be a single hardware instruction.
Initially, I thought we needed to define new DAG nodes for these ops, and I spent time working
on that (much larger patch), but then I concluded that we don't need it. At least as a first
step, we have all of the backend support necessary to match these ops...because it was required.
And shepherding these through the IR optimizer is the primary concern, so the IR intrinsics are
likely all that we'll ever need.
There was also a question about converting the intrinsics to the existing ROTL/ROTR DAG nodes
(along with improving the oversized shift documentation). Again, I don't think that's strictly
necessary (as the test results here prove). That can be an efficiency improvement as a small
follow-up patch.
So all we're left with is documentation, definition of the IR intrinsics, and DAG builder support.
Differential Revision: https://reviews.llvm.org/D49242
llvm-svn: 337221
This patch introduces a brief description of the components of MCA. The main
focus is on Views. This is a work in progress, and more descriptions will be
introduced later. I want to flesh-out the Views section more and provide a
detailed description of eventing in MCA. Eventually a brief code example of a
View should accompany the description.
Also, we should consider moving the MCA internals guide elsewhere at some point.
llvm-svn: 337219
As suggested in the review for r337007, this makes cfi-verify abort on unsupported targets instead of producing incorrect results. It also updates the design document to reflect this.
Differential Revision: https://reviews.llvm.org/D49304
llvm-svn: 337181
-v prints all directive pattern matches.
-vv additionally prints info that might be noise to users but that can
be helpful to FileCheck developers.
To maximize code reuse and to make diagnostics more consistent, this
patch also adjusts and extends some of the existing diagnostics.
CHECK-NOT failures now report variables uses. Many more diagnostics
now report the check prefix and kind of directive.
Reviewed By: probinson
Differential Revision: https://reviews.llvm.org/D47114
llvm-svn: 336967
That is, make CHECK-DAG skip matches that overlap the matches of any
preceding consecutive CHECK-DAG directives. This change makes
CHECK-DAG more consistent with other directives, and there is evidence
it makes CHECK-DAG more intuitive and less error-prone. See the RFC
discussion starting at:
http://lists.llvm.org/pipermail/llvm-dev/2018-May/123010.html
Moreover, this behavior enables CHECK-DAG groups for unordered,
non-unique strings or patterns. For example, it is useful for
verifying output or logs from a parallel program, such as the OpenMP
runtime.
This patch also implements the command-line option
-allow-deprecated-dag-overlap, which reverts CHECK-DAG to the old
overlapping behavior. This option should not be used in new tests.
It is meant only for the existing tests that are broken by this change
and that need time to update.
See the following bugzilla issue for tracking of such tests:
https://bugs.llvm.org/show_bug.cgi?id=37532
Patches to add -allow-deprecated-dag-overlap to those tests will
follow immediately.
Reviewed By: probinson
Differential Revision: https://reviews.llvm.org/D47106
llvm-svn: 336847
This reverts commit r306102.
This change was made without any review, and has a couple of issues.
First, AFAIK we do not test the combination of the LLVM gold plugin with
ld.bfd. Second, the change removed documentation for how to build gold
and replaced it with instructions for building ld.bfd.
llvm-svn: 336841
That is, make CHECK-DAG skip matches that overlap the matches of any
preceding consecutive CHECK-DAG directives. This change makes
CHECK-DAG more consistent with other directives, and there is evidence
it makes CHECK-DAG more intuitive and less error-prone. See the RFC
discussion starting at:
http://lists.llvm.org/pipermail/llvm-dev/2018-May/123010.html
Moreover, this behavior enables CHECK-DAG groups for unordered,
non-unique strings or patterns. For example, it is useful for
verifying output or logs from a parallel program, such as the OpenMP
runtime.
This patch also implements the command-line option
-allow-deprecated-dag-overlap, which reverts CHECK-DAG to the old
overlapping behavior. This option should not be used in new tests.
It is meant only for the existing tests that are broken by this change
and that need time to update.
See the following bugzilla issue for tracking of such tests:
https://bugs.llvm.org/show_bug.cgi?id=37532
Patches to add -allow-deprecated-dag-overlap to those tests will
follow immediately.
Reviewed By: probinson
Differential Revision: https://reviews.llvm.org/D47106
llvm-svn: 336830
The aim of this backend is to output everything TableGen knows about
the record set, similarly to the default -print-records backend. But
where -print-records produces output in TableGen's input syntax
(convenient for humans to read), this backend produces it as
structured JSON data, which is convenient for loading into standard
scripting languages such as Python, in order to extract information
from the data set in an automated way.
The output data contains a JSON representation of the variable
definitions in output 'def' records, and a few pieces of metadata such
as which of those definitions are tagged with the 'field' prefix and
which defs are derived from which classes. It doesn't dump out
absolutely every piece of knowledge it _could_ produce, such as type
information and complicated arithmetic operator nodes in abstract
superclasses; the main aim is to allow consumers of this JSON dump to
essentially act as new backends, and backends don't generally need to
depend on that kind of data.
The new backend is implemented as an EmitJSON() function similar to
all of llvm-tblgen's other EmitFoo functions, except that it lives in
lib/TableGen instead of utils/TableGen on the basis that I'm expecting
to add it to clang-tblgen too in a future patch.
To test it, I've written a Python script that loads the JSON output
and tests properties of it based on comments in the .td source - more
or less like FileCheck, except that the CHECK: lines have Python
expressions after them instead of textual pattern matches.
Reviewers: nhaehnle
Reviewed By: nhaehnle
Subscribers: arichardson, labath, mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D46054
llvm-svn: 336771
Let's be conservative here; it matches what we actually implemented, and
it should be rare in practice anyway.
Differential Revision: https://reviews.llvm.org/D49042
llvm-svn: 336744
Summary:
Support for this option is needed for building Linux kernel.
This is a very frequently requested feature by kernel developers.
More details : https://lkml.org/lkml/2018/4/4/601
GCC option description for -fdelete-null-pointer-checks:
This Assume that programs cannot safely dereference null pointers,
and that no code or data element resides at address zero.
-fno-delete-null-pointer-checks is the inverse of this implying that
null pointer dereferencing is not undefined.
This feature is implemented in LLVM IR in this CL as the function attribute
"null-pointer-is-valid"="true" in IR (Under review at D47894).
The CL updates several passes that assumed null pointer dereferencing is
undefined to not optimize when the "null-pointer-is-valid"="true"
attribute is present.
Reviewers: t.p.northover, efriedma, jyknight, chandlerc, rnk, srhines, void, george.burgess.iv
Reviewed By: efriedma, george.burgess.iv
Subscribers: eraman, haicheng, george.burgess.iv, drinkcat, theraven, reames, sanjoy, xbolva00, llvm-commits
Differential Revision: https://reviews.llvm.org/D47895
llvm-svn: 336613
In non-zero address spaces, we were reporting that an object at `null`
always occupies zero bytes. This is incorrect in many cases, so just
return `unknown` in those cases for now.
Differential Revision: https://reviews.llvm.org/D48860
llvm-svn: 336611
Summary:
This adds a new -no-weak flag to nm to hide weak symbols in its output.
This also adds a -W alias for this which is analogous to -U.
Patch by Keith Smiley
Reviewers: kastiglione, enderby, compnerd
Reviewed By: kastiglione
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D48751
llvm-svn: 336126
Summary:
This patch introduce new intrinsic -
strip.invariant.group that was described in the
RFC: Devirtualization v2
Reviewers: rsmith, hfinkel, nlopes, sanjoy, amharc, kuhar
Subscribers: arsenm, nhaehnle, JDevlieghere, hiraditya, xbolva00, llvm-commits
Differential Revision: https://reviews.llvm.org/D47103
Co-authored-by: Krzysztof Pszeniczny <krzysztof.pszeniczny@gmail.com>
llvm-svn: 336073
