[Python-checkins] gh-101282: Apply BOLT optimizations to libpython for shared builds (#104709)
erlend-aasland
webhook-mailer at python.org
Mon May 22 07:45:27 EDT 2023
https://github.com/python/cpython/commit/5360cb3d5608ab375de6cd8c0b408459f3fa953a
commit: 5360cb3d5608ab375de6cd8c0b408459f3fa953a
branch: main
author: Gregory Szorc <gregory.szorc at gmail.com>
committer: erlend-aasland <erlend.aasland at protonmail.com>
date: 2023-05-22T13:45:20+02:00
summary:
gh-101282: Apply BOLT optimizations to libpython for shared builds (#104709)
Apply BOLT optimizations to libpython for shared builds. Most of the C
code is in libpython so it is critical to apply BOLT there fully realize
BOLT benefits.
This change also reworks how BOLT instrumentation is applied. It
effectively removes the readelf based logic added in gh-101525 and
replaces it with a mechanism that saves a copy of the pre-bolt binary
and restores that copy when necessary. This allows us to perform BOLT
optimizations without having to manually delete the output binary to
force a new bolt run.
Also:
- add a clean-bolt target for purging BOLT files and hook that up to the
clean target
- .gitignore BOLT related files
Before and after this refactor, `make` will no-op after a previous run.
Both versions should also share common make DAG deficiencies where
targets fail to trigger as often as they need to or can trigger
prematurely in certain scenarios. e.g. after this change you may need to
`rm profile-bolt-stamp` to force a BOLT run because there aren't
appropriate non-phony targets for BOLT's make target to depend on.
To make it easier to iterate on custom BOLT settings, the flags to pass
to instrumentation and application are now defined in configure and can
be overridden by passing BOLT_INSTRUMENT_FLAGS and BOLT_APPLY_FLAGS.
files:
A Misc/NEWS.d/next/Build/2023-05-20-16-09-59.gh-issue-101282.FvRARb.rst
M .gitignore
M Doc/using/configure.rst
M Makefile.pre.in
M configure
M configure.ac
diff --git a/.gitignore b/.gitignore
index d9c4a7972f07..ef7642b09bc5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -23,6 +23,10 @@
*.gc??
*.profclang?
*.profraw
+# Copies of binaries before BOLT optimizations.
+*.prebolt
+# BOLT profile data.
+*.fdata
*.dyn
.gdb_history
.purify
@@ -124,6 +128,7 @@ Tools/unicode/data/
/platform
/profile-clean-stamp
/profile-run-stamp
+/profile-bolt-stamp
/Python/deepfreeze/*.c
/pybuilddir.txt
/pyconfig.h
diff --git a/Doc/using/configure.rst b/Doc/using/configure.rst
index ce858ab2c8d7..fbe280d64131 100644
--- a/Doc/using/configure.rst
+++ b/Doc/using/configure.rst
@@ -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
diff --git a/Makefile.pre.in b/Makefile.pre.in
index da3a8f6c13f9..eb79c9c4ca18 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -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
@@ -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; \
$(MAKE) profile-removal; \
fi
diff --git a/Misc/NEWS.d/next/Build/2023-05-20-16-09-59.gh-issue-101282.FvRARb.rst b/Misc/NEWS.d/next/Build/2023-05-20-16-09-59.gh-issue-101282.FvRARb.rst
new file mode 100644
index 000000000000..cc70d47c6c16
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2023-05-20-16-09-59.gh-issue-101282.FvRARb.rst
@@ -0,0 +1,4 @@
+BOLT optimization is now applied to the libpython shared library if building
+a shared library. BOLT instrumentation and application settings can now be
+influenced via the ``BOLT_INSTRUMENT_FLAGS`` and ``BOLT_APPLY_FLAGS``
+configure variables.
diff --git a/configure b/configure
index 7aad4fe89e3c..2b863be108be 100755
--- a/configure
+++ b/configure
@@ -883,10 +883,11 @@ CFLAGS_NODIST
BASECFLAGS
CFLAGS_ALIASING
OPT
+BOLT_APPLY_FLAGS
+BOLT_INSTRUMENT_FLAGS
+BOLT_BINARIES
MERGE_FDATA
LLVM_BOLT
-ac_ct_READELF
-READELF
PREBOLT_RULE
LLVM_PROF_FOUND
LLVM_PROFDATA
@@ -1105,6 +1106,8 @@ CPPFLAGS
CPP
HOSTRUNNER
PROFILE_TASK
+BOLT_INSTRUMENT_FLAGS
+BOLT_APPLY_FLAGS
LIBUUID_CFLAGS
LIBUUID_LIBS
LIBFFI_CFLAGS
@@ -1916,6 +1919,10 @@ Some influential environment variables:
HOSTRUNNER Program to run CPython for the host platform
PROFILE_TASK
Python args for PGO generation task
+ BOLT_INSTRUMENT_FLAGS
+ Arguments to llvm-bolt when instrumenting binaries
+ BOLT_APPLY_FLAGS
+ Arguments to llvm-bolt when creating a BOLT optimized binary
LIBUUID_CFLAGS
C compiler flags for LIBUUID, overriding pkg-config
LIBUUID_LIBS
@@ -8106,112 +8113,6 @@ if test "$Py_BOLT" = 'true' ; then
DEF_MAKE_ALL_RULE="bolt-opt"
DEF_MAKE_RULE="build_all"
-
- if test -n "$ac_tool_prefix"; then
- for ac_prog in readelf
- do
- # Extract the first word of "$ac_tool_prefix$ac_prog", so it can be a program name with args.
-set dummy $ac_tool_prefix$ac_prog; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_READELF+:} false; then :
- $as_echo_n "(cached) " >&6
-else
- if test -n "$READELF"; then
- ac_cv_prog_READELF="$READELF" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
- IFS=$as_save_IFS
- test -z "$as_dir" && as_dir=.
- for ac_exec_ext in '' $ac_executable_extensions; do
- if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
- ac_cv_prog_READELF="$ac_tool_prefix$ac_prog"
- $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
- break 2
- fi
-done
- done
-IFS=$as_save_IFS
-
-fi
-fi
-READELF=$ac_cv_prog_READELF
-if test -n "$READELF"; then
- { $as_echo "$as_me:${as_lineno-$LINENO}: result: $READELF" >&5
-$as_echo "$READELF" >&6; }
-else
- { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-
- test -n "$READELF" && break
- done
-fi
-if test -z "$READELF"; then
- ac_ct_READELF=$READELF
- for ac_prog in readelf
-do
- # Extract the first word of "$ac_prog", so it can be a program name with args.
-set dummy $ac_prog; ac_word=$2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
-$as_echo_n "checking for $ac_word... " >&6; }
-if ${ac_cv_prog_ac_ct_READELF+:} false; then :
- $as_echo_n "(cached) " >&6
-else
- if test -n "$ac_ct_READELF"; then
- ac_cv_prog_ac_ct_READELF="$ac_ct_READELF" # Let the user override the test.
-else
-as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
-for as_dir in $PATH
-do
- IFS=$as_save_IFS
- test -z "$as_dir" && as_dir=.
- for ac_exec_ext in '' $ac_executable_extensions; do
- if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
- ac_cv_prog_ac_ct_READELF="$ac_prog"
- $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
- break 2
- fi
-done
- done
-IFS=$as_save_IFS
-
-fi
-fi
-ac_ct_READELF=$ac_cv_prog_ac_ct_READELF
-if test -n "$ac_ct_READELF"; then
- { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_READELF" >&5
-$as_echo "$ac_ct_READELF" >&6; }
-else
- { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
-
-
- test -n "$ac_ct_READELF" && break
-done
-
- if test "x$ac_ct_READELF" = x; then
- READELF=""notfound""
- else
- case $cross_compiling:$ac_tool_warned in
-yes:)
-{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
-$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
-ac_tool_warned=yes ;;
-esac
- READELF=$ac_ct_READELF
- fi
-fi
-
- if test "$READELF" == "notfound"
- then
- as_fn_error $? "readelf is required for a --enable-bolt build but could not be found." "$LINENO" 5
- fi
-
# -fno-reorder-blocks-and-partition is required for bolt to work.
# Possibly GCC only.
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether C compiler accepts -fno-reorder-blocks-and-partition" >&5
@@ -8474,6 +8375,36 @@ $as_echo "\"Found merge-fdata\"" >&6; }
fi
fi
+
+BOLT_BINARIES='$(BUILDPYTHON)'
+if test "x$enable_shared" = xyes; then :
+
+ BOLT_BINARIES="${BOLT_BINARIES} \$(INSTSONAME)"
+
+fi
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking BOLT_INSTRUMENT_FLAGS" >&5
+$as_echo_n "checking BOLT_INSTRUMENT_FLAGS... " >&6; }
+if test -z "${BOLT_INSTRUMENT_FLAGS}"
+then
+ BOLT_INSTRUMENT_FLAGS=
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $BOLT_INSTRUMENT_FLAGS" >&5
+$as_echo "$BOLT_INSTRUMENT_FLAGS" >&6; }
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking BOLT_APPLY_FLAGS" >&5
+$as_echo_n "checking BOLT_APPLY_FLAGS... " >&6; }
+if test -z "${BOLT_APPLY_FLAGS}"
+then
+ BOLT_APPLY_FLAGS=-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
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $BOLT_APPLY_FLAGS" >&5
+$as_echo "$BOLT_APPLY_FLAGS" >&6; }
+
# XXX Shouldn't the code above that fiddles with BASECFLAGS and OPT be
# merged with this chunk of code?
diff --git a/configure.ac b/configure.ac
index 115998e0753b..786d3414eb0e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2028,13 +2028,6 @@ if test "$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 "$READELF" == "notfound"
- then
- AC_MSG_ERROR([readelf is required for a --enable-bolt build but could not be found.])
- fi
-
# -fno-reorder-blocks-and-partition is required for bolt to work.
# Possibly GCC only.
AX_CHECK_COMPILE_FLAG([-fno-reorder-blocks-and-partition],[
@@ -2067,6 +2060,54 @@ if test "$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?
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