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gh-101525: Check whether to skip functions with computed gotos during BOLT runs #140250

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gh-101525: Check whether to skip functions with computed gotos during BOLT runs #140250

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gh-101525: Add GCC's LTO-generated function clones, with computed got…
stratakis Oct 9, 2025
241a541
gh-101525: Check whether to skip functions with computed gotos during…
stratakis Oct 16, 2025
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28 changes: 27 additions & 1 deletion configure
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31 changes: 26 additions & 5 deletions configure.ac
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Original file line number Diff line number Diff line change
Expand Up @@ -2129,6 +2129,23 @@ if test "$Py_BOLT" = 'true' ; then
AC_MSG_ERROR([llvm-bolt is required for a --enable-bolt build but could not be found.])
fi

# Check BOLT version to determine if we need to skip functions with computed gotos.
AC_MSG_CHECKING([llvm-bolt version])
llvm_bolt_version=$("${LLVM_BOLT}" --version 2>/dev/null | grep -oE '[[0-9]]+\.[[0-9]]+\.[[0-9]]+' | head -1)
AC_MSG_RESULT([${llvm_bolt_version}])

# Parse version
llvm_bolt_major=$(echo "${llvm_bolt_version}" | cut -d. -f1)
llvm_bolt_minor=$(echo "${llvm_bolt_version}" | cut -d. -f2)

bolt_need_skip_computed_goto="yes"
if test -n "${llvm_bolt_major}" && test "${llvm_bolt_major}" -ge 21; then
if test "${llvm_bolt_major}" -gt 21 || test "${llvm_bolt_minor}" -ge 1; then
bolt_need_skip_computed_goto="no"
AC_MSG_RESULT([LLVM ${llvm_bolt_version} supports computed gotos])
fi
fi

AC_SUBST([MERGE_FDATA])
AC_PATH_TOOL([MERGE_FDATA], [merge-fdata], [''], [${llvm_path}])
if test -n "${MERGE_FDATA}" -a -x "${MERGE_FDATA}"
Expand Down Expand Up @@ -2158,14 +2175,18 @@ then
[BOLT_COMMON_FLAGS],
[m4_normalize("
[-update-debug-sections]

dnl At least LLVM 19.x doesn't support computed gotos in PIC compiled code.
dnl Exclude functions containing computed gotos.
dnl TODO this may be fixed in LLVM 20.x via https://github.com/llvm/llvm-project/pull/120267.
[-skip-funcs=_PyEval_EvalFrameDefault,sre_ucs1_match/1,sre_ucs2_match/1,sre_ucs4_match/1]
")]
)

dnl BOLT versions before LLVM 21.1.0 don't support computed gotos in PIC compiled code.
dnl Exclude functions containing computed gotos for older versions.
dnl Fixed in LLVM 21.1.0+ via https://github.com/llvm/llvm-project/pull/120267
dnl GCC's LTO creates .lto_priv.0 clones of these functions.
if test "${bolt_need_skip_computed_goto}" = "yes"; then
BOLT_COMMON_FLAGS="${BOLT_COMMON_FLAGS} -skip-funcs=_PyEval_EvalFrameDefault,sre_ucs1_match/1,sre_ucs2_match/1,sre_ucs4_match/1,sre_ucs1_match.lto_priv.0/1,sre_ucs2_match.lto_priv.0/1,sre_ucs4_match.lto_priv.0/1"
fi
fi
AC_MSG_RESULT([$BOLT_COMMON_FLAGS])

AC_ARG_VAR(
[BOLT_INSTRUMENT_FLAGS],
Expand Down
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