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Since the "--write-dwp" option has been removed in
[PR](https://github.com/llvm/llvm-project/pull/100771), this patch also
cleans up the corresponding document and test to avoid misleading
issues.
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https://github.com/codespell-project/codespell
```bash
codespell bolt --skip="*.yaml,Maintainers.txt" --write-changes \
--ignore-words-list=acount,alledges,ans,archtype,defin,iself,mis,mmaped,othere,outweight,vas
```
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The pass for inlining memcpy in BOLT was currently X86-specific and was
using the instruction `rep movsb`.
This patch implements a static size analysis system for AArch64 memcpy
inlining that extracts copy sizes from preceding instructions to then
use it to generate the optimal width-specific load/store sequences.
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## Change:
* Added `--dump-dot-func` command-line option that allows users to dump
CFGs only for specific functions instead of dumping all functions (the
current only available option being `--dump-dot-all`)
## Usage:
* Users can now specify function names or regex patterns (e.g.,
`--dump-dot-func=main,helper` or `--dump-dot-func="init.*`") to generate
.dot files only for functions of interest
* Aims to save time when analysing specific functions in large binaries
(e.g., only dumping graphs for performance-critical functions identified
through profiling) and we can now avoid reduce output clutter from
generating thousands of unnecessary .dot files when analysing large
binaries
## Testing
The introduced test `dump-dot-func.test` confirms the new option does
the following:
- [x] 1. `dump-dot-func` can correctly filter a specified functions
- [x] 2. Can achieve the above with regexes
- [x] 3. Can do 1. with a list of functions
- [x] No option specified creates no dot files
- [x] Passing in a non-existent function generates no dumping messages
- [x] `dump-dot-all` continues to work as expected
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Update the documentation accordingly.
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Identical Code Folding (ICF) folds functions that are identical into one
function, and updates symbol addresses to the new address. This reduces
the size of a binary, but can lead to problems. For example when
function pointers are compared. This can be done either explicitly in
the code or generated IR by optimization passes like Indirect Call
Promotion (ICP). After ICF what used to be two different addresses
become the same address. This can lead to a different code path being
taken.
This is where safe ICF comes in. Linker (LLD) does it using address
significant section generated by clang. If symbol is in it, or an object
doesn't have this section symbols are not folded.
BOLT does not have the information regarding which objects do not have
this section, so can't re-use this mechanism.
This implementation scans code section and conservatively marks
functions symbols as unsafe. It treats symbols as unsafe if they are
used in non-control flow instruction. It also scans through the data
relocation sections and does the same for relocations that reference a
function symbol. The latter handles the case when function pointer is
stored in a local or global variable, etc. If a relocation address
points within a vtable these symbols are skipped.
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(#100282)
Enables parallelization for the processing of DWO CUs.
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Fix typo from `alterantive` -> `alternative`
Signed-off-by: Jordan Brantner <brantnej@oregonstate.edu>
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Remove deprecated DeterministicDebugInfo option and its uses.
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Implemented call graph function matching. First, two call graphs are
constructed for both profiled and binary functions. Then functions are
hashed based on the names of their callee/caller functions. Finally,
functions are matched based on these neighbor hashes and the
longest common prefix of their names. The `match-with-call-graph`
flag turns this matching on.
Test Plan: Added match-with-call-graph.test. Matched 164 functions
in a large binary with 10171 profiled functions.
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Emit a mapping in the legend between the characters/buckets and the text
sections, using:
```sh
llvm-heatmap-bolt -print-mappings ..
```
Example:
```
Legend:
..
Sections:
a/A : .init 0x00000100-0x00000200
b/B : .plt 0x00000200-0x00000500
c/C : .text 0x00010000-0x000a0000
d/D : .fini 0x000a0000-0x000f0000
..
```
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A mapping - from namespace to associated binary functions - is used to
match function profiles to binary based on the
'--name-similarity-function-matching-threshold' flag set edit distance
threshold. The flag is set to 0 (exact name matching) by default as it is
expensive, requiring the processing of all BFs.
Test Plan: Added name-similarity-function-matching.test. On a binary
with 5M functions, rewrite passes took ~520s without the flag and
~2018s with the flag set to 20.
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Added flag '--match-profile-with-function-hash' to match functions
based on exact hash. After identical and LTO name matching, more
functions can be recovered for inference with exact hash, in the case
of function renaming with no functional changes. Collisions are
possible in the unlikely case where multiple functions share the same
exact hash. The flag is off by default as it requires the processing of
all binary functions and subsequently is expensive.
Test Plan: added hashing-based-function-matching.test.
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This reverts commit bb5ab1ffe719f5e801ef08ac08be975546aa3266.
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Created using spr 1.3.4
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Reverts llvm/llvm-project#95821
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Using the hashes of binary and profiled functions
to recover functions with changed names.
Test Plan: added
hashing-based-function-matching.test.
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Summary: Functions with high discrepancy
(measured by matched function blocks)
can be ignored with an added command line
argument for better performance.
Test Plan: Added
stale-matching-min-matched-block.test
---------
Co-authored-by: Amir Ayupov <aaupov@fb.com>
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Add .md file documentation with all BOLT options to display it more
conveniently.
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