Use -iquote instead. This prevents our include paths from messing up
the system headers depended upon by libstdc++. (The specific problem
was syscall.h in fesvr/, which was interfering with libstdc++'s
dependence on the system's syscall.h for SYS_futex.)
Subproject headers can now be included in the following ways:
#include "foo.h" // for a header local to this subproject
#include <bar/baz.h>" // for a header in another subproject
But no longer:
#include <baz.h> // for a header in any subproject
As a special case, libfdt needs itself to be added to the -I path,
because their coding style is to use angle brackets for local headers.
This commit adds the *.pc files for Spike's simulation library,
enabling dynamic and static linking without the need to directly
reference Spike sources. Using Spike as a stand-alone library
provides an interesting option for developing tools
and applications based on Spike.
Otherwise, `ar rcs` will add to the previous archive, creating the
possibility of multiple functions with the same name in the archive.
The linker might not choose the most recent version, resulting in
undefined behavior.
Don't include .a files in other .a files. Doing so trips a sanity
check in the Xcode 14 toolchain, because the included .a files are
not themselves mach-o format, even though their contents are.
1f58b4d869 introduced a link error on my
Mojave machine, because making the Boost include path the highest-priority
one was forcing use of the system's libfdt.h. But the system's libfdt.h
unfortunately lacks the 'extern "C"' linkage modifier, causing link errors
when invoking FDT routines from C++ code.
Fix by making the Boost include path the lowest-priority one.
Precompiled headers were broken because they weren't compiled with
the same -fPIC setting as the rest of the code. Fix by just making
everything use -fPIC.
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
Several people have raised the concern that dynamically linking the
built-in components of Spike causes more headaches than it's worth.
IIRC, the only reason we did this is to better support the
`--extension=libfoo.so` feature.
Andrew Waterman
rbuchner
Jerry Zhao
demin.han
Philipp Tomsich
Wojciech Bartczak
bluew
Scott Johnson
emelcher
Chih-Min Chao
Rupert Swarbrick
Scott Beamer
Palmer Dabbelt
David Craven
Ben Gamari
Tim Newsome
Jonathan Neuschäfer
Andrew Waterman