This patch adds !nosanitize metadata to FixedMetadataKinds.def, !nosanitize indicates that LLVM should not insert any sanitizer instrumentation.
Reviewed By: vitalybuka
Differential Revision: https://reviews.llvm.org/D126294
The OpenMPIRBuilder has a bug. Specifically, suppose you have two nested openmp parallel regions (writing with MLIR for ease)
```
omp.parallel {
%a = ...
omp.parallel {
use(%a)
}
}
```
As OpenMP only permits pointer-like inputs, the builder will wrap all of the inputs into a stack allocation, and then pass this
allocation to the inner parallel. For example, we would want to get something like the following:
```
omp.parallel {
%a = ...
%tmp = alloc
store %tmp[] = %a
kmpc_fork(outlined, %tmp)
}
```
However, in practice, this is not what currently occurs in the context of nested parallel regions. Specifically to the OpenMPIRBuilder,
the entirety of the function (at the LLVM level) is currently inlined with blocks marking the corresponding start and end of each
region.
```
entry:
...
parallel1:
%a = ...
...
parallel2:
use(%a)
...
endparallel2:
...
endparallel1:
...
```
When the allocation is inserted, it presently inserted into the parent of the entire function (e.g. entry) rather than the parent
allocation scope to the function being outlined. If we were outlining parallel2, the corresponding alloca location would be parallel1.
This causes a variety of bugs, including https://github.com/llvm/llvm-project/issues/54165 as one example.
This PR allows the stack allocation to be created at the correct allocation block, and thus remedies such issues.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D121061
Make the penalty for splitting a region more accurately reflect the cost
of materializing all of the inputs/outputs to/from the region.
This almost entirely eliminates code growth within functions which
undergo splitting in key internal frameworks, and reduces the size of
those frameworks between 2.6% to 3%.
rdar://49167240
Patch by: Vedant Kumar(@vsk)
Reviewers: hiraditya,rjf,t.p.northover
Reviewed By: hiraditya,rjf
Differential Revision: https://reviews.llvm.org/D59715
This is the first in a series of patches that attempts to migrate
existing cost instructions to return a new InstructionCost class
in place of a simple integer. This new class is intended to be
as light-weight and simple as possible, with a full range of
arithmetic and comparison operators that largely mirror the same
sets of operations on basic types, such as integers. The main
advantage to using an InstructionCost is that it can encode a
particular cost state in addition to a value. The initial
implementation only has two states - Normal and Invalid - but these
could be expanded over time if necessary. An invalid state can
be used to represent an unknown cost or an instruction that is
prohibitively expensive.
This patch adds the new class and changes the getInstructionCost
interface to return the new class. Other cost functions, such as
getUserCost, etc., will be migrated in future patches as I believe
this to be less disruptive. One benefit of this new class is that
it provides a way to unify many of the magic costs in the codebase
where the cost is set to a deliberately high number to prevent
optimisations taking place, e.g. vectorization. It also provides
a route to represent the extremely high, and unknown, cost of
scalarization of scalable vectors, which is not currently supported.
Differential Revision: https://reviews.llvm.org/D91174
This broke Chromium's PGO build, it seems because hot-cold-splitting got turned
on unintentionally. See comment on the code review for repro etc.
> This patch adds -f[no-]split-cold-code CC1 options to clang. This allows
> the splitting pass to be toggled on/off. The current method of passing
> `-mllvm -hot-cold-split=true` to clang isn't ideal as it may not compose
> correctly (say, with `-O0` or `-Oz`).
>
> To implement the -fsplit-cold-code option, an attribute is applied to
> functions to indicate that they may be considered for splitting. This
> removes some complexity from the old/new PM pipeline builders, and
> behaves as expected when LTO is enabled.
>
> Co-authored by: Saleem Abdulrasool <compnerd@compnerd.org>
> Differential Revision: https://reviews.llvm.org/D57265
> Reviewed By: Aditya Kumar, Vedant Kumar
> Reviewers: Teresa Johnson, Aditya Kumar, Fedor Sergeev, Philip Pfaffe, Vedant Kumar
This reverts commit 273c299d5d.
This patch adds -f[no-]split-cold-code CC1 options to clang. This allows
the splitting pass to be toggled on/off. The current method of passing
`-mllvm -hot-cold-split=true` to clang isn't ideal as it may not compose
correctly (say, with `-O0` or `-Oz`).
To implement the -fsplit-cold-code option, an attribute is applied to
functions to indicate that they may be considered for splitting. This
removes some complexity from the old/new PM pipeline builders, and
behaves as expected when LTO is enabled.
Co-authored by: Saleem Abdulrasool <compnerd@compnerd.org>
Differential Revision: https://reviews.llvm.org/D57265
Reviewed By: Aditya Kumar, Vedant Kumar
Reviewers: Teresa Johnson, Aditya Kumar, Fedor Sergeev, Philip Pfaffe, Vedant Kumar
This reverts commit 20797989ea.
This patch (https://reviews.llvm.org/D69257) cannot complete a stage2
build due to the change:
```
CI->getCalledFunction()->getName().contains("longjmp")
```
There are several concrete issues here:
- The callee may not be a function, so `getCalledFunction` can assert.
- The called value may not have a name, so `getName` can assert.
- There's no distinction made between "my_longjmp_test_helper" and the
actual longjmp libcall.
At a higher level, there's a serious layering problem here. The
splitting pass makes policy decisions in a general way (e.g. based on
attributes or profile data). Special-casing certain names breaks the
layering. It subverts the work of library maintainers (who may now need
to opt-out of unexpected optimization behavior for any affected
functions) and can lead to inconsistent optimization behavior (as not
all llvm passes special-case ".*longjmp.*" in the same way).
The patch may need significant revision to address these issues.
But the immediate issue is that this crashes while compiling llvm's unit
tests in a stage2 build (due to the `getName` problem).
Add support for (if enabled) splitting cold functions into a separate section
in order to further boost locality of hot code.
Authored by: rjf (Ruijie Fang)
Reviewed by: hiraditya,rcorcs,vsk
Differential Revision: https://reviews.llvm.org/D85331
A function marked `noreturn` may contain unreachable terminators: these
should not be considered cold, as the function may be a trampoline.
rdar://58068594
Summary:
This cropped up in the Linux kernel where cold code was placed in an
incompatible section.
Reviewers: compnerd, vsk, tejohnson
Reviewed By: vsk
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70925
This file lists every pass in LLVM, and is included by Pass.h, which is
very popular. Every time we add, remove, or rename a pass in LLVM, it
caused lots of recompilation.
I found this fact by looking at this table, which is sorted by the
number of times a file was changed over the last 100,000 git commits
multiplied by the number of object files that depend on it in the
current checkout:
recompiles touches affected_files header
342380 95 3604 llvm/include/llvm/ADT/STLExtras.h
314730 234 1345 llvm/include/llvm/InitializePasses.h
307036 118 2602 llvm/include/llvm/ADT/APInt.h
213049 59 3611 llvm/include/llvm/Support/MathExtras.h
170422 47 3626 llvm/include/llvm/Support/Compiler.h
162225 45 3605 llvm/include/llvm/ADT/Optional.h
158319 63 2513 llvm/include/llvm/ADT/Triple.h
140322 39 3598 llvm/include/llvm/ADT/StringRef.h
137647 59 2333 llvm/include/llvm/Support/Error.h
131619 73 1803 llvm/include/llvm/Support/FileSystem.h
Before this change, touching InitializePasses.h would cause 1345 files
to recompile. After this change, touching it only causes 550 compiles in
an incremental rebuild.
Reviewers: bkramer, asbirlea, bollu, jdoerfert
Differential Revision: https://reviews.llvm.org/D70211
Factor out CodeExtractor's analysis of allocas (for shrinkwrapping
purposes), and allow the analysis to be reused.
This resolves a quadratic compile-time bug observed when compiling
AMDGPUDisassembler.cpp.o.
Pre-patch (Release + LTO clang):
```
---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name ---
176.5278 ( 57.8%) 0.4915 ( 18.5%) 177.0192 ( 57.4%) 177.4112 ( 57.3%) Hot Cold Splitting
```
Post-patch (ReleaseAsserts clang):
```
---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name ---
1.4051 ( 3.3%) 0.0079 ( 0.3%) 1.4129 ( 3.2%) 1.4129 ( 3.2%) Hot Cold Splitting
```
Testing: check-llvm, and comparing the AMDGPUDisassembler.cpp.o binary
pre- vs. post-patch.
An alternate approach is to hide CodeExtractorAnalysisCache from clients
of CodeExtractor, and to recompute the analysis from scratch inside of
CodeExtractor::extractCodeRegion(). This eliminates some redundant work
in the shrinkwrapping legality check. However, some clients continue to
exhibit O(n^2) compile time behavior as computing the analysis is O(n).
rdar://55912966
Differential Revision: https://reviews.llvm.org/D68616
llvm-svn: 374089
When a cold path is outlined, the value tracking in the assumption cache may be
invalidated due to the code motion. We would previously trip an assertion in
subsequent passes (but required the passes to happen in a single run as the
assumption cache is shared across the passes). Invalidating the cache ensures
that we get the correct information when needed with the legacy pass manager as
well.
llvm-svn: 372667
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
llvm-svn: 369013
Create method `optForNone()` testing for the function level equivalent of
`-O0` and refactor appropriately.
Differential revision: https://reviews.llvm.org/D59852
llvm-svn: 357638
Part 2 of CSPGO changes (mostly related to ProfileSummary).
Note that I use a default parameter in setProfileSummary() and getSummary().
This is to break the dependency in clang. I will make the parameter explicit
after changing clang in a separated patch.
Differential Revision: https://reviews.llvm.org/D54175
llvm-svn: 355131
Splitting can make sanitizer errors harder to understand, as the
trapping instruction may not be in the function where the bug was
detected.
rdar://48142697
llvm-svn: 354931
Summary: Assumption cache's self-updating mechanism does not correctly handle the case when blocks are extracted from the function by the CodeExtractor. As a result function's assumption cache may have stale references to the llvm.assume calls that were moved to the outlined function. This patch fixes this problem by removing extracted llvm.assume calls from the function’s assumption cache.
Reviewers: hfinkel, vsk, fhahn, davidxl, sanjoy
Reviewed By: hfinkel, vsk
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57215
llvm-svn: 353500
Summary:
When compiling with profile data, ensure the split cold function gets
cold function_entry_count metadata (just use 0 since it should be cold).
Otherwise with function sections it will not be placed in the unlikely
text section with other cold code.
Reviewers: vsk
Subscribers: sebpop, hiraditya, davidxl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57900
llvm-svn: 353434
Resumes that are not reachable from a cleanup landing pad are considered
to be unreachable. It’s not safe to split them out.
rdar://47808235
llvm-svn: 353242
The main goal of the model is to avoid *increasing* function size, as
that would eradicate any memory locality benefits from splitting. This
happens when:
- There are too many inputs or outputs to the cold region. Argument
materialization and reloads of outputs have a cost.
- The cold region has too many distinct exit blocks, causing a large
switch to be formed in the caller.
- The code size cost of the split code is less than the cost of a
set-up call.
A secondary goal is to prevent excessive overall binary size growth.
With the cost model in place, I experimented to find a splitting
threshold that works well in practice. To make warm & cold code easily
separable for analysis purposes, I moved split functions to a "cold"
section. I experimented with thresholds between [0, 4] and set the
default to the threshold which minimized geomean __text size.
Experiment data from building LNT+externals for X86 (N = 639 programs,
all sizes in bytes):
| Configuration | __text geom size | __cold geom size | TEXT geom size |
| **-Os** | 1736.3 | 0, n=0 | 10961.6 |
| -Os, thresh=0 | 1740.53 | 124.482, n=134 | 11014 |
| -Os, thresh=1 | 1734.79 | 57.8781, n=90 | 10978.6 |
| -Os, thresh=2 | ** 1733.85 ** | 65.6604, n=61 | 10977.6 |
| -Os, thresh=3 | 1733.85 | 65.3071, n=61 | 10977.6 |
| -Os, thresh=4 | 1735.08 | 67.5156, n=54 | 10965.7 |
| **-Oz** | 1554.4 | 0, n=0 | 10153 |
| -Oz, thresh=2 | ** 1552.2 ** | 65.633, n=61 | 10176 |
| **-O3** | 2563.37 | 0, n=0 | 13105.4 |
| -O3, thresh=2 | ** 2559.49 ** | 71.1072, n=61 | 13162.4 |
Picking thresh=2 reduces the geomean __text section size by 0.14% at
-Os, -Oz, and -O3 and causes ~0.2% growth in the TEXT segment. Note that
TEXT size is page-aligned, whereas section sizes are byte-aligned.
Experiment data from building LNT+externals for ARM64 (N = 558 programs,
all sizes in bytes):
| Configuration | __text geom size | __cold geom size | TEXT geom size |
| **-Os** | 1763.96 | 0, n=0 | 42934.9 |
| -Os, thresh=2 | ** 1760.9 ** | 76.6755, n=61 | 42934.9 |
Picking thresh=2 reduces the geomean __text section size by 0.17% at
-Os and causes no growth in the TEXT segment.
Measurements were done with D57082 (r352080) applied.
Differential Revision: https://reviews.llvm.org/D57125
llvm-svn: 352228
While a cold invoke itself and its unwind destination can't be
extracted, code which unconditionally executes before/after the invoke
may still be profitable to extract.
With cost model changes from D57125 applied, this gives a 3.5% increase
in split text across LNT+externals on arm64 at -Os.
llvm-svn: 352160
Instead of manually computing DT and PDT, we can get the from the pass
manager, which ideally has them already cached. With the new pass
manager, we could even preserve DT/PDT on a per function basis in a
module pass.
I think this also addresses the TODO about re-using the computed DTs for
BFI. IIUC, GetBFI will fetch the DT from the pass manager and when we
will fetch the cached version later.
Reviewers: vsk, hiraditya, tejohnson, thegameg, sebpop
Reviewed By: vsk
Differential Revision: https://reviews.llvm.org/D57092
llvm-svn: 352036
The splitting pass does not need BFI unless the Module actually has a profile
summary. Do not calcualte BFI unless the summary is present.
For the sqlite3 amalgamation, this reduces time spent in the splitting pass
from 0.4% of the total to under 0.1%.
llvm-svn: 351894
The splitting pass does not need (post)domtrees until after it's found a
cold block. Defer domtree calculation until a cold block is found.
For the sqlite3 amalgamation, this reduces time spent in the splitting
pass from 0.8% of the total to 0.4%.
llvm-svn: 351892
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
If an inherently cold function is found, mark it as cold. For now this
means applying the `cold` and `minsize` attributes.
As a drive-by, revisit and clean up the criteria for considering a
function for splitting. Add tests.
llvm-svn: 351623
Prior to r348205, extracting code regions with live output values was
disabled because of a miscompilation (PR39433). Lift the restriction as
PR39433 has been addressed.
Tested on LNT+externals, on a run of check-llvm in a stage2 build, and
with a full build of iOS (with hot/cold splitting enabled).
As a drive-by, remove an errant TODO.
llvm-svn: 351492
Resuming exception unwinding is roughly as unlikely as throwing an
exception.
Tested on LNT+externals (in particular, the C++ EH regression tests
provide end-to-end test coverage), as well as with a full build of iOS.
llvm-svn: 351491
Enna1