8000 gh-101282: Apply BOLT optimisations to libpython for shared builds by indygreg · Pull Request #104709 · python/cpython · GitHub
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gh-101282: Apply BOLT optimisations to libpython for shared builds #104709

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Merged
merged 4 commits into from
May 22, 2023
Merged

gh-101282: Apply BOLT optimisations to libpython for shared builds #104709

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555686d
gh-101282: rework the BOLT build process
indygreg May 20, 2023
52a266e
Fixup doc formatting
erlend-aasland May 21, 2023
3cf0f36
M4 style nits
erlend-aasland May 21, 2023
972dcb2
Remove extra backtick
erlend-aasland May 21, 2023
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5 changes: 5 additions & 0 deletions .gitignore
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Expand Up @@ -23,6 +23,10 @@
*.gc??
*.profclang?
*.profraw
# Copies of binaries before BOLT optimizations.
*.prebolt
# BOLT profile data.
*.fdata
*.dyn
.gdb_history
.purify
Expand Down Expand Up @@ -124,6 +128,7 @@ Tools/unicode/data/
/platform
/profile-clean-stamp
/profile-run-stamp
/profile-bolt-stamp
/Python/deepfreeze/*.c
/pybuilddir.txt
/pyconfig.h
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7 changes: 7 additions & 0 deletions Doc/using/configure.rst
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Expand Up @@ -314,6 +314,13 @@ also be used to improve performance.
is dependent on a combination of the build environment + the other
optimization configure args + the CPU architecture, and not all combinations
are supported.
BOLT versions before LLVM 16 are known to crash BOLT under some scenarios.
Use of LLVM 16 or newer for BOLT optimization is strongly encouraged.

The :envvar:`!BOLT_INSTRUMENT_FLAGS` and :envvar:`!BOLT_APPLY_FLAGS`
:program:`configure` variables can be defined to override the default set of
arguments for :program:`llvm-bolt` to instrument and apply BOLT data to
binaries, respectively.

.. versionadded:: 3.12

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65 changes: 50 additions & 15 deletions Makefile.pre.in
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Expand Up @@ -672,21 +672,55 @@ profile-opt: profile-run-stamp
-rm -f profile-clean-stamp
$(MAKE) @DEF_MAKE_RULE@ CFLAGS_NODIST="$(CFLAGS_NODIST) $(PGO_PROF_USE_FLAG)" LDFLAGS_NODIST="$(LDFLAGS_NODIST)"

.PHONY: bolt-opt
bolt-opt: @PREBOLT_RULE@
# List of binaries that BOLT runs on.
BOLT_BINARIES := @BOLT_BINARIES@

BOLT_INSTRUMENT_FLAGS := @BOLT_INSTRUMENT_FLAGS@
BOLT_APPLY_FLAGS := @BOLT_APPLY_FLAGS@

.PHONY: clean-bolt
clean-bolt:
# Profile data.
rm -f *.fdata
@if $(READELF) -p .note.bolt_info $(BUILDPYTHON) | grep BOLT > /dev/null; then\
echo "skip: $(BUILDPYTHON) is already BOLTed."; \
else \
@LLVM_BOLT@ ./$(BUILDPYTHON) -instrument -instrumentation-file-append-pid -instrumentation-file=$(abspath $(BUILDPYTHON).bolt) -o $(BUILDPYTHON).bolt_inst; \
./$(BUILDPYTHON).bolt_inst $(PROFILE_TASK) || true; \
@MERGE_FDATA@ $(BUILDPYTHON).*.fdata > $(BUILDPYTHON).fdata; \
@LLVM_BOLT@ ./$(BUILDPYTHON) -o $(BUILDPYTHON).bolt -data=$(BUILDPYTHON).fdata -update-debug-sections -reorder-blocks=ext-tsp -reorder-functions=hfsort+ -split-functions -icf=1 -inline-all -split-eh -reorder-functions-use-hot-size -peepholes=none -jump-tables=aggressive -inline-ap -indirect-call-promotion=all -dyno-stats -use-gnu-stack -frame-opt=hot; \
rm -f *.fdata; \
rm -f $(BUILDPYTHON).bolt_inst; \
mv $(BUILDPYTHON).bolt $(BUILDPYTHON); \
fi
# Pristine binaries before BOLT optimization.
rm -f *.prebolt
# BOLT instrumented binaries.
rm -f *.bolt_inst

profile-bolt-stamp: $(BUILDPYTHON)
# Ensure a pristine, pre-BOLT copy of the binary and no profile data from last run.
for bin in $(BOLT_BINARIES); do \
prebolt="$${bin}.prebolt"; \
if [ -e "$${prebolt}" ]; then \
echo "Restoring pre-BOLT binary $${prebolt}"; \
mv "$${bin}.prebolt" "$${bin}"; \
fi; \
cp "$${bin}" "$${prebolt}"; \
rm -f $${bin}.bolt.*.fdata $${bin}.fdata; \
done
# Instrument each binary.
for bin in $(BOLT_BINARIES); do \
@LLVM_BOLT@ "$${bin}" -instrument -instrumentation-file-append-pid -instrumentation-file=$(abspath $${bin}.bolt) -o $${bin}.bolt_inst $(BOLT_INSTRUMENT_FLAGS); \
mv "$${bin}.bolt_inst" "$${bin}"; \
done
# Run instrumented binaries to collect data.
$(RUNSHARED) ./$(BUILDPYTHON) $(PROFILE_TASK) || true
# Merge all the data files together.
for bin in $(BOLT_BINARIES); do \
@MERGE_FDATA@ $${bin}.*.fdata > "$${bin}.fdata"; \
rm -f $${bin}.*.fdata; \
done
# Run bolt against the merged data to produce an optimized binary.
for bin in $(BOLT_BINARIES); do \
@LLVM_BOLT@ "$${bin}.prebolt" -o "$${bin}.bolt" -data="$${bin}.fdata" $(BOLT_APPLY_FLAGS); \
mv "$${bin}.bolt" "$${bin}"; \
done
touch $@

.PHONY: bolt-opt
bolt-opt:
$(MAKE) @PREBOLT_RULE@
$(MAKE) profile-bolt-stamp

# Compile and run with gcov
.PHONY: coverage
Expand Down Expand Up @@ -2623,10 +2657,11 @@ profile-removal:
rm -f $(COVERAGE_INFO)
rm -rf $(COVERAGE_REPORT)
rm -f profile-run-stamp
rm -f profile-bolt-stamp

.PHONY: clean
clean: clean-retain-profile
@if test @DEF_MAKE_ALL_RULE@ = profile-opt; then \
clean: clean-retain-profile clean-bolt
@if test @DEF_MAKE_ALL_RULE@ = profile-opt -o @DEF_MAKE_ALL_RULE@ = bolt-opt; then \
rm -f profile-gen-stamp profile-clean-stamp; \
$(MAKE) profile-removal; \
fi
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4 changes: 4 additions & 0 deletions Misc/NEWS.d/next/Build/2023-05-20-16-09-59.gh-issue-101282.FvRARb.rst
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@@ -0,0 +1,4 @@
BOLT optimization is now applied to the libpython shared library if building
a shared library. BOLT instrumentation and application settings can now be
influenced via the ``BOLT_INSTRUMENT_FLAGS`` and ``BOLT_APPLY_FLAGS``
configure variables.
147 changes: 39 additions & 108 deletions configure
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55 changes: 48 additions & 7 deletions configure.ac
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Expand Up @@ -2028,13 +2028,6 @@ if test "$Py_BOLT" = 'true' ; then
DEF_MAKE_ALL_RULE="bolt-opt"
DEF_MAKE_RULE="build_all"

AC_SUBST(READELF)
AC_CHECK_TOOLS(READELF, [readelf], "notfound")
if test "$READELF" == "notfound"
then
AC_MSG_ERROR([readelf is required for a --enable-bolt build but could not be found.])
fi

# -fno-reorder-blocks-and-partition is required for bolt to work.
# Possibly GCC only.
AX_CHECK_COMPILE_FLAG([-fno-reorder-blocks-and-partition],[
Expand Down Expand Up @@ -2067,6 +2060,54 @@ if test "$Py_BOLT" = 'true' ; then
fi
fi

dnl Enable BOLT of libpython if built.
AC_SUBST(BOLT_BINARIES)
BOLT_BINARIES='$(BUILDPYTHON)'
AS_VAR_IF([enable_shared], [yes], [
BOLT_BINARIES="${BOLT_BINARIES} \$(INSTSONAME)"
])

AC_ARG_VAR(
[BOLT_INSTRUMENT_FLAGS],
[Arguments to llvm-bolt when instrumenting binaries]
)
AC_MSG_CHECKING([BOLT_INSTRUMENT_FLAGS])
if test -z "${BOLT_INSTRUMENT_FLAGS}"
then
BOLT_INSTRUMENT_FLAGS=
fi
AC_MSG_RESULT([$BOLT_INSTRUMENT_FLAGS])

AC_ARG_VAR(
[BOLT_APPLY_FLAGS],
[Arguments to llvm-bolt when creating a BOLT optimized binary]
)
AC_MSG_CHECKING([BOLT_APPLY_FLAGS])
if test -z "${BOLT_APPLY_FLAGS}"
then
AS_VAR_SET(
[BOLT_APPLY_FLAGS],
[m4_join([ ],
[-update-debug-sections],
[-reorder-blocks=ext-tsp],
[-reorder-functions=hfsort+],
[-split-functions],
[-icf=1],
[-inline-all],
[-split-eh],
[-reorder-functions-use-hot-size],
[-peepholes=none],
[-jump-tables=aggressive],
[-inline-ap],
[-indirect-call-promotion=all],
[-dyno-stats],
[-use-gnu-stack],
[-frame-opt=hot]
)]
)
fi
AC_MSG_RESULT([$BOLT_APPLY_FLAGS])

# XXX Shouldn't the code above that fiddles with BASECFLAGS and OPT be
# merged with this chunk of code?

Expand Down
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