Tree:
29dca8b846
arrv-sc-arrv-sc/snippy-tests
confprec
cs250
cycleh
debug_rom
debug_rom_fence
device_flags
dtm_reset_error
dts_parsing
dynamic
eos18-bringup
factor-out-macros
fetch
fix-bf16
force-rtti
fp-encoding
heterogeneous_mc
hwachav4
increase-stack-size
itrigger-etrigger-cleanup
load_reservation_set_size
log-commits-faster
master
mmio-hack
mvp
no_progbuf
no_progbuf2
nolibfdt
p-ext-0.5.2
plctlab-plct-zce-fix2
plic-clint-endian
plic_uart_v1
priv-1.10
private-l1-caches
pte-info-and-delegation
remove-tests
rivosinc-etrigger_fix_exception_match
rva-profile-support
sanitize
simplify-misaligned
sodor
sparse-mem
speed2
speedup-hacks
static-link
test
tmp
trigger_priority
tweak_debug_rom
whole-archive
zvmm
dummy-tag-for-ci-storage
v1.0.0
v1.1.0
${ noResults }
1 Commits (29dca8b846250a015e84b36e40f4bd1b57bf55fa)
| Author | SHA1 | Message | Date |
|---|---|---|---|
Rupert Swarbrick
|
2efea60720 |
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
|
6 years ago |