freebsd-skq/share/mk/bsd.linker.mk
arichardson ed1f8eba30 Only compute the X_COMPILER_*/X_LINKER_* variables when needed
When building CheriBSD we have to set XLD/XCC/XCFLAGS on the command line.
This triggers the $XCC != $CC case in bsd.compiler.mk (and the same for LD
in bsd.linker.mk) which causes it to call ${XCC} --version and
${XLD} --version (plus various awk+sed+echo calls) in every subdirectory.
For incremental builds and stages that only walk the source tree this is
often the majority of the time spent in that directory.

By only computing the value of the X_COMPILER_*/X_LINKER_* variables if
_WANT_TOOLCHAIN_CROSS_VARS is set we can reduce the number of cc/ld calls
to once per build stage instead of once per recursive make.

With this change (and no changes to the sources) the `make includes` stage
now takes 28 seconds at -j1 instead of 86 seconds.

Approved By:	brooks (mentor)
Differential Revision: https://reviews.freebsd.org/D17046
2018-10-23 06:31:25 +00:00

117 lines
3.5 KiB
Makefile

# $FreeBSD$
# Setup variables for the linker.
#
# LINKER_TYPE is the major type of linker. Currently binutils and lld support
# automatic detection.
#
# LINKER_VERSION is a numeric constant equal to:
# major * 10000 + minor * 100 + tiny
# It too can be overridden on the command line.
#
# LINKER_FEATURES may contain one or more of the following, based on
# linker support for that feature:
#
# - build-id: support for generating a Build-ID note
# - retpoline: support for generating PLT with retpoline speculative
# execution vulnerability mitigation
#
# LINKER_FREEBSD_VERSION is the linker's internal source version.
#
# These variables with an X_ prefix will also be provided if XLD is set.
#
# This file may be included multiple times, but only has effect the first time.
#
.if !target(__<bsd.linker.mk>__)
__<bsd.linker.mk>__:
_ld_vars=LD $${_empty_var_}
.if !empty(_WANT_TOOLCHAIN_CROSS_VARS)
# Only the toplevel makefile needs to compute the X_LINKER_* variables.
_ld_vars+=XLD X_
.endif
.for ld X_ in ${_ld_vars}
.if ${ld} == "LD" || !empty(XLD)
# Try to import LINKER_TYPE and LINKER_VERSION from parent make.
# The value is only used/exported for the same environment that impacts
# LD and LINKER_* settings here.
_exported_vars= ${X_}LINKER_TYPE ${X_}LINKER_VERSION ${X_}LINKER_FEATURES \
${X_}LINKER_FREEBSD_VERSION
${X_}_ld_hash= ${${ld}}${MACHINE}${PATH}
${X_}_ld_hash:= ${${X_}_ld_hash:hash}
# Only import if none of the vars are set somehow else.
_can_export= yes
.for var in ${_exported_vars}
.if defined(${var})
_can_export= no
.endif
.endfor
.if ${_can_export} == yes
.for var in ${_exported_vars}
.if defined(${var}.${${X_}_ld_hash})
${var}= ${${var}.${${X_}_ld_hash}}
.endif
.endfor
.endif
.if ${ld} == "LD" || (${ld} == "XLD" && ${XLD} != ${LD})
.if !defined(${X_}LINKER_TYPE) || !defined(${X_}LINKER_VERSION)
_ld_version!= (${${ld}} --version || echo none) | sed -n 1p
.if ${_ld_version} == "none"
.warning Unable to determine linker type from ${ld}=${${ld}}
.endif
.if ${_ld_version:[1..2]} == "GNU ld"
${X_}LINKER_TYPE= bfd
${X_}LINKER_FREEBSD_VERSION= 0
_v= ${_ld_version:M[1-9].[0-9]*:[1]}
.elif ${_ld_version:[1]} == "LLD"
${X_}LINKER_TYPE= lld
_v= ${_ld_version:[2]}
${X_}LINKER_FREEBSD_VERSION!= \
${${ld}} --version | \
awk '$$3 ~ /FreeBSD/ {print substr($$4, 1, length($$4)-1)}'
.else
.warning Unknown linker from ${ld}=${${ld}}: ${_ld_version}, defaulting to bfd
${X_}LINKER_TYPE= bfd
_v= 2.17.50
.endif
${X_}LINKER_VERSION!= echo "${_v:M[1-9].[0-9]*}" | \
awk -F. '{print $$1 * 10000 + $$2 * 100 + $$3;}'
.undef _ld_version
.undef _v
${X_}LINKER_FEATURES=
.if ${${X_}LINKER_TYPE} != "bfd" || ${${X_}LINKER_VERSION} > 21750
${X_}LINKER_FEATURES+= build-id
${X_}LINKER_FEATURES+= ifunc
.endif
.if ${${X_}LINKER_TYPE} != "lld" || ${${X_}LINKER_VERSION} >= 50000
${X_}LINKER_FEATURES+= filter
.endif
.if ${${X_}LINKER_TYPE} == "lld" && ${${X_}LINKER_VERSION} >= 60000
${X_}LINKER_FEATURES+= retpoline
.endif
.endif
.else
# Use LD's values
X_LINKER_TYPE= ${LINKER_TYPE}
X_LINKER_VERSION= ${LINKER_VERSION}
X_LINKER_FEATURES= ${LINKER_FEATURES}
X_LINKER_FREEBSD_VERSION= ${LINKER_FREEBSD_VERSION}
.endif # ${ld} == "LD" || (${ld} == "XLD" && ${XLD} != ${LD})
# Export the values so sub-makes don't have to look them up again, using the
# hash key computed above.
.for var in ${_exported_vars}
${var}.${${X_}_ld_hash}:= ${${var}}
.export-env ${var}.${${X_}_ld_hash}
.undef ${var}.${${X_}_ld_hash}
.endfor
.endif # ${ld} == "LD" || !empty(XLD)
.endfor # .for ld in LD XLD
.endif # !target(__<bsd.linker.mk>__)