diff options
author | Rupert Swarbrick <rswarbrick@lowrisc.org> | 2020-02-27 13:20:41 +0000 |
---|---|---|
committer | Rupert Swarbrick <rswarbrick@lowrisc.org> | 2020-02-27 13:43:58 +0000 |
commit | 2efea60720650c57649aec6ceef1756b892eec9b (patch) | |
tree | 9ad49487b943fdb3908f26fdf73de705c997141f /configure | |
parent | 157143b5038ef2b92b1c70d445b566d57b6f5096 (diff) | |
download | spike-2efea60720650c57649aec6ceef1756b892eec9b.zip spike-2efea60720650c57649aec6ceef1756b892eec9b.tar.gz spike-2efea60720650c57649aec6ceef1756b892eec9b.tar.bz2 |
Allow overriding CFLAGS and similar when building
Before this patch, I don't think it was possible to change (say)
CFLAGS as part of running the make command. Nor did setting them when
running configure do anything. Getting this right is a little fiddly:
for example, see Automake's approach at [1] ("AM_CFLAGS" and friends).
This patch adds an "mcppbs-" prefix, and sets things up properly for
CFLAGS, CPPFLAGS, CXXFLAGS and LDFLAGS. Note that the bulk of the
patch is either the auto-generated configure script or the ax_*.m4
files vendored in from the autoconf archive (needed to handle
--export-dynamic correctly without trashing settings from the user
running configure).
What's supposed to happen is as follows:
- Base compilation flags that should apply to everything (standard
optimisation flags, warning flags etc.) are defined in
Makefile.in.
- When the user runs configure, they can set compilation flags on
the command line. These end up as environment variables in the
shell script.
- Compilation flags that can only be decided when we run
configure (this is currently just whether we support
-Wl,--export-dynamic) are appended to the configure-time LDFLAGS
environment variable.
- At the end of the configure script, these environment variables
are spliced into Makefile.in to fill out the corresponding
@<varname>@ entries.
- When running make, the user might again override compilation
flags. These will get appended to the flags found so far.
As a concrete example:
mkdir build
cd build
../configure CXXFLAGS='-O3'
make CXXFLAGS='-O0'
will result in c++ compile commands that look like this:
g++ -MMD -MP \
-DPREFIX=\"/usr/local\" -Wall -Wno-unused -g -O2 -std=c++11 \
-O3 \
-O0 \
-I. -I.. -I../fesvr -I../riscv -I../dummy_rocc -I../softfloat \
-I../spike_main -fPIC -c ../fesvr/elfloader.cc
(I've added some newlines to wrap the long line).
Note that we have the base flags from Makefile.in (called
$(default-CXXFLAGS) there) first. Then we have the -O3 from the
configure command. Finally we have the -O0 from the Make command line.
And I can finally run "make CXXFLAGS='-O0 -g3'". Phew!
[1] https://www.gnu.org/software/automake/manual/html_node/Flag-Variables-Ordering.html
Diffstat (limited to 'configure')
-rwxr-xr-x | configure | 166 |
1 files changed, 154 insertions, 12 deletions
@@ -2205,6 +2205,74 @@ case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac # =========================================================================== +# https://www.gnu.org/software/autoconf-archive/ax_require_defined.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_REQUIRE_DEFINED(MACRO) +# +# DESCRIPTION +# +# AX_REQUIRE_DEFINED is a simple helper for making sure other macros have +# been defined and thus are available for use. This avoids random issues +# where a macro isn't expanded. Instead the configure script emits a +# non-fatal: +# +# ./configure: line 1673: AX_CFLAGS_WARN_ALL: command not found +# +# It's like AC_REQUIRE except it doesn't expand the required macro. +# +# Here's an example: +# +# AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG]) +# +# LICENSE +# +# Copyright (c) 2014 Mike Frysinger <vapier@gentoo.org> +# +# Copying and distribution of this file, with or without modification, are +# permitted in any medium without royalty provided the copyright notice +# and this notice are preserved. This file is offered as-is, without any +# warranty. + +#serial 2 + + +# =========================================================================== +# https://www.gnu.org/software/autoconf-archive/ax_append_flag.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE]) +# +# DESCRIPTION +# +# FLAG is appended to the FLAGS-VARIABLE shell variable, with a space +# added in between. +# +# If FLAGS-VARIABLE is not specified, the current language's flags (e.g. +# CFLAGS) is used. FLAGS-VARIABLE is not changed if it already contains +# FLAG. If FLAGS-VARIABLE is unset in the shell, it is set to exactly +# FLAG. +# +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. +# +# LICENSE +# +# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de> +# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com> +# +# Copying and distribution of this file, with or without modification, are +# permitted in any medium without royalty provided the copyright notice +# and this notice are preserved. This file is offered as-is, without any +# warranty. + +#serial 8 + + +# =========================================================================== # https://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html # =========================================================================== # @@ -2243,6 +2311,44 @@ case $host_os in *\ *) host_os=`echo "$host_os" | sed 's/ /-/g'`;; esac #serial 6 +# =========================================================================== +# https://www.gnu.org/software/autoconf-archive/ax_append_link_flags.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_APPEND_LINK_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS], [INPUT]) +# +# DESCRIPTION +# +# For every FLAG1, FLAG2 it is checked whether the linker works with the +# flag. If it does, the flag is added FLAGS-VARIABLE +# +# If FLAGS-VARIABLE is not specified, the linker's flags (LDFLAGS) is +# used. During the check the flag is always added to the linker's flags. +# +# If EXTRA-FLAGS is defined, it is added to the linker's default flags +# when the check is done. The check is thus made with the flags: "LDFLAGS +# EXTRA-FLAGS FLAG". This can for example be used to force the linker to +# issue an error when a bad flag is given. +# +# INPUT gives an alternative input source to AC_COMPILE_IFELSE. +# +# NOTE: This macro depends on the AX_APPEND_FLAG and AX_CHECK_LINK_FLAG. +# Please keep this macro in sync with AX_APPEND_COMPILE_FLAGS. +# +# LICENSE +# +# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com> +# +# Copying and distribution of this file, with or without modification, are +# permitted in any medium without royalty provided the copyright notice +# and this notice are preserved. This file is offered as-is, without any +# warranty. + +#serial 7 + + #------------------------------------------------------------------------- # Checks for programs @@ -4403,18 +4509,20 @@ fi # Default compiler flags #------------------------------------------------------------------------- -CFLAGS="-Wall -Wno-unused -g -O2" -CXXFLAGS="-Wall -Wno-unused -g -O2 -std=c++11" -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the linker accepts -Wl,--export-dynamic" >&5 -$as_echo_n "checking whether the linker accepts -Wl,--export-dynamic... " >&6; } -if ${ax_cv_check_ldflags___Wl___export_dynamic+:} false; then : + + +for flag in -Wl,--export-dynamic; do + as_CACHEVAR=`$as_echo "ax_cv_check_ldflags__$flag" | $as_tr_sh` +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the linker accepts $flag" >&5 +$as_echo_n "checking whether the linker accepts $flag... " >&6; } +if eval \${$as_CACHEVAR+:} false; then : $as_echo_n "(cached) " >&6 else ax_check_save_flags=$LDFLAGS - LDFLAGS="$LDFLAGS -Wl,--export-dynamic" + LDFLAGS="$LDFLAGS $flag" cat confdefs.h - <<_ACEOF >conftest.$ac_ext /* end confdefs.h. */ @@ -4427,22 +4535,56 @@ main () } _ACEOF if ac_fn_cxx_try_link "$LINENO"; then : - ax_cv_check_ldflags___Wl___export_dynamic=yes + eval "$as_CACHEVAR=yes" else - ax_cv_check_ldflags___Wl___export_dynamic=no + eval "$as_CACHEVAR=no" fi rm -f core conftest.err conftest.$ac_objext \ conftest$ac_exeext conftest.$ac_ext LDFLAGS=$ax_check_save_flags fi -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_check_ldflags___Wl___export_dynamic" >&5 -$as_echo "$ax_cv_check_ldflags___Wl___export_dynamic" >&6; } -if test "x$ax_cv_check_ldflags___Wl___export_dynamic" = xyes; then : - LDFLAGS="-Wl,--export-dynamic" +eval ac_res=\$$as_CACHEVAR + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5 +$as_echo "$ac_res" >&6; } +if eval test \"x\$"$as_CACHEVAR"\" = x"yes"; then : + +if ${LDFLAGS+:} false; then : + + case " $LDFLAGS " in #( + *" $flag "*) : + { { $as_echo "$as_me:${as_lineno-$LINENO}: : LDFLAGS already contains \$flag"; } >&5 + (: LDFLAGS already contains $flag) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; } ;; #( + *) : + + as_fn_append LDFLAGS " $flag" + { { $as_echo "$as_me:${as_lineno-$LINENO}: : LDFLAGS=\"\$LDFLAGS\""; } >&5 + (: LDFLAGS="$LDFLAGS") 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; } + ;; +esac + +else + + LDFLAGS=$flag + { { $as_echo "$as_me:${as_lineno-$LINENO}: : LDFLAGS=\"\$LDFLAGS\""; } >&5 + (: LDFLAGS="$LDFLAGS") 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; } + +fi + else : fi +done + #------------------------------------------------------------------------- # MCPPBS subproject list |