Ping. On Friday, September 01 2017, I wrote:
> On Wednesday, August 23 2017, Pedro Alves wrote: > >> On 08/23/2017 05:17 AM, Sergio Durigan Junior wrote: >>> Hi there, >>> >>> This is a series of two patches, one for GDB and one for GCC, which aims >>> to improve the detection and handling of triplets present on compiler >>> names. The motivation for this series was mostly the fact that GDB's >>> "compile" command is broken on Debian unstable, as can be seen here: >>> >>> <https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=851146> >>> >>> The reason for the failure is the fact that Debian compiles GCC using >>> the --program-{prefix,suffix} options from configure in order to name >>> the compiler using the full triplet (i.e., Debian's GCC is not merely >>> named "gcc", but e.g. "x86_64-linux-gnu-gcc-7"), which end up naming the >>> C_COMPILER_NAME and CP_COMPILER_NAME defines with the specified prefix >>> and suffix. Therefore, the regexp being used to match the compiler name >>> is wrong because it doesn't take into account the fact that the defines >>> may already contain the triplets. >> >> As discussed on IRC, I think the problem is that C_COMPILER_NAME >> in libcc1 includes the full triplet in the first place. I think >> that it shouldn't. I think that C_COMPILER_NAME should always >> be "gcc". >> >> The problem is in bootstrapping code, before there's a plugin >> yet -- i.e.., in the code that libcc1 uses to find the compiler (which >> then loads a plugin that libcc1 talks with). >> >> Please bear with me while I lay down my rationale, so that we're >> in the same page. >> >> C_COMPILER_NAME seems to include the prefix currently in an attempt >> to support cross debugging, or more generically, --enable-targets=all >> in gdb, but the whole thing doesn't really work as intended if >> C_COMPILER_NAME already includes a target prefix. >> >> IIUC the libcc1/plugin design, a single "libcc1.so" (what gdb loads, >> not the libcc1plugin compiler plugin) should work with any compiler in >> the PATH, in case you have several in the system. E.g., one for >> each arch. >> >> Let me expand. >> >> The idea is that gdb always dlopens "libcc1.so", by that name exactly. >> Usually that'll open the libcc1.so installed in the system, e.g., >> "/usr/lib64/libcc1.so", which for convenience was originally built from the >> same source tree as the systems's compiler was built. You could force gdb to >> load some other libcc1.so, e.g., by tweaking LD_LIBRARY_PATH of course, >> but you shouldn't need to. >> >> libcc1.so is responsible for finding a compiler that targets the >> architecture of the inferior that the user is debugging in gdb. >> E.g., say you're cross debugging for arm-none-eabi, on a >> x86-64 Fedora host. GDB knows the target inferior's architecture, and passes >> down to (the system) libcc1 a triplet regex like "arm*-*eabi*" or >> similar to libcc1,. libcc1 appends "-" + C_COMPILER_NAME to that regex, >> generating something like "arm*-*eabi*-gcc", and then looks for binaries >> in PATH that match that regex. When one is found, e.g., "arm-none-eabi-gcc", >> libcc1 forks/execs that compiler, passing it "-fplugin=libcc1plugin". >> libcc1 then communicates with that compiler's libcc1plugin plugin >> via a socket. >> >> In this scheme, "libcc1.so", the library that gdb loads, has no >> target-specific logic at all. It should work with any compiler >> in the system, for any target/arch. All it does is marshall the gcc/gdb >> interface between the gcc plugin and gdb, it is not linked against gcc. >> That boundary is versioned, and ABI-stable. So as long as the >> libcc1.so that gdb loads understands the same API version of the gcc/gdb >> interface API as gdb understands, it all should work. (The APIs >> are always extended keeping backward compatibility.) >> >> So in this scheme, having the "C_COMPILER_NAME" macro in libcc1 >> include the target prefix for the --target that the plugin that >> libcc1 is built along with, seems to serve no real purpose, AFAICT. >> It's just getting in the way. >> >> I.e., something like: >> >> "$gdb_specified_triplet_re" + "-" + C_COMPILER_NAME >> >> works if C_COMPILER_NAME is exactly "gcc", but not if C_COMPILER_NAME is >> already: >> >> "$whatever_triplet_libcc1_happened_to_be_built_with" + "-gcc" >> >> because we end up with: >> >> "$gdb_specified_triplet_re" + "-" >> "$whatever_triplet_libcc1_happened_to_be_built_with" + "-gcc" >> >> which is the problem case. >> >> In sum, I think the libcc1.so (not the plugin) should _not_ have baked >> in target awareness, and thus C_COMPILER_NAME should always be "gcc", and >> then libcc1's regex should be adjusted to also tolerate a suffix in >> the final compiler binary name regex. >> >> WDYT? > > As I replied before, I agree with Pedro's rationale here and his idea > actually makes my initial patch much simpler. By renaming > C_COMPILER_NAME (and the new CP_COMPILER_NAME) to just "gcc" (or "g++"), > the Debian bug I was fixing is solved and we don't have to bother with > breaking compatibility with older gdb's packaged by the distros, because > they will also keep working with this change. > > So I would like to propose this new patch, only for GCC, which makes > C_COMPILER_NAME and CP_COMPILER_NAME have "gcc" and "g++" as hardcoded > names, respectively. In the commit log, I intend to include Pedro's > rationale (above). > > What do you guys think of this new version? It doesn't need any GDB > patch, and works with both Fedora and Debian. > > Thanks, > > -- > Sergio > GPG key ID: 237A 54B1 0287 28BF 00EF 31F4 D0EB 7628 65FC 5E36 > Please send encrypted e-mail if possible > http://sergiodj.net/ > > libcc1/ChangeLog: > 2017-09-01 Sergio Durigan Junior <sergi...@redhat.com> > Pedro Alves <pal...@redhat.com> > > * Makefile.am: Remove references to c-compiler-name.h and > cp-compiler-name.h > * Makefile.in: Regenerate. > * compiler-name.hh: New file. > * libcc1.cc: Don't include c-compiler-name.h. Include > compiler-name.hh. > * libcp1.cc: Don't include cp-compiler-name.h. Include > compiler-name.hh. > > diff --git a/libcc1/Makefile.am b/libcc1/Makefile.am > index 5e61a92a26b..cdba5a50b23 100644 > --- a/libcc1/Makefile.am > +++ b/libcc1/Makefile.am > @@ -45,24 +45,6 @@ plugin_LTLIBRARIES = libcc1plugin.la libcp1plugin.la > cc1lib_LTLIBRARIES = libcc1.la > endif > > -BUILT_SOURCES = c-compiler-name.h cp-compiler-name.h > -MOSTLYCLEANFILES = c-compiler-name.h cp-compiler-name.h > - > -# Put this in a header so we don't run sed for each compilation. This > -# is also simpler to debug as one can easily see the constant. > -# FIXME: compute it in configure.ac and output it in config.status, or > -# introduce timestamp files for some indirection to avoid rebuilding it > -# every time. > -c-compiler-name.h: Makefile > - -rm -f $@T > - echo "#define C_COMPILER_NAME \"`echo gcc | sed '$(transform)'`\"" > $@T > - mv $@T $@ # $(SHELL) $(srcdir)/../move-if-change $@T $@ > - > -cp-compiler-name.h: Makefile > - -rm -f $@T > - echo "#define CP_COMPILER_NAME \"`echo g++ | sed '$(transform)'`\"" > > $@T > - mv $@T $@ # $(SHELL) $(srcdir)/../move-if-change $@T $@ > - > shared_source = callbacks.cc callbacks.hh connection.cc connection.hh \ > marshall.cc marshall.hh rpc.hh status.hh > > diff --git a/libcc1/Makefile.in b/libcc1/Makefile.in > index 54babb02a49..47be10025ad 100644 > --- a/libcc1/Makefile.in > +++ b/libcc1/Makefile.in > @@ -307,8 +307,6 @@ plugindir = > $(libdir)/gcc/$(target_noncanonical)/$(gcc_version)/plugin > cc1libdir = $(libdir)/$(libsuffix) > @ENABLE_PLUGIN_TRUE@plugin_LTLIBRARIES = libcc1plugin.la libcp1plugin.la > @ENABLE_PLUGIN_TRUE@cc1lib_LTLIBRARIES = libcc1.la > -BUILT_SOURCES = c-compiler-name.h cp-compiler-name.h > -MOSTLYCLEANFILES = c-compiler-name.h cp-compiler-name.h > shared_source = callbacks.cc callbacks.hh connection.cc connection.hh \ > marshall.cc marshall.hh rpc.hh status.hh > > @@ -344,7 +342,7 @@ libcc1_la_LINK = $(LIBTOOL) --tag=CXX $(AM_LIBTOOLFLAGS) \ > $(LIBTOOLFLAGS) --mode=link $(CXXLD) $(AM_CXXFLAGS) \ > $(CXXFLAGS) $(libcc1_la_LDFLAGS) $(LTLDFLAGS) -o $@ > > -all: $(BUILT_SOURCES) cc1plugin-config.h > +all: cc1plugin-config.h > $(MAKE) $(AM_MAKEFLAGS) all-am > > .SUFFIXES: > @@ -567,15 +565,13 @@ GTAGS: > distclean-tags: > -rm -f TAGS ID GTAGS GRTAGS GSYMS GPATH tags > check-am: all-am > -check: $(BUILT_SOURCES) > - $(MAKE) $(AM_MAKEFLAGS) check-am > +check: check-am > all-am: Makefile $(LTLIBRARIES) cc1plugin-config.h > installdirs: > for dir in "$(DESTDIR)$(cc1libdir)" "$(DESTDIR)$(plugindir)"; do \ > test -z "$$dir" || $(MKDIR_P) "$$dir"; \ > done > -install: $(BUILT_SOURCES) > - $(MAKE) $(AM_MAKEFLAGS) install-am > +install: install-am > install-exec: install-exec-am > install-data: install-data-am > uninstall: uninstall-am > @@ -595,7 +591,6 @@ install-strip: > "INSTALL_PROGRAM_ENV=STRIPPROG='$(STRIP)'" install; \ > fi > mostlyclean-generic: > - -test -z "$(MOSTLYCLEANFILES)" || rm -f $(MOSTLYCLEANFILES) > > clean-generic: > > @@ -606,7 +601,6 @@ distclean-generic: > maintainer-clean-generic: > @echo "This command is intended for maintainers to use" > @echo "it deletes files that may require special tools to rebuild." > - -test -z "$(BUILT_SOURCES)" || rm -f $(BUILT_SOURCES) > clean: clean-am > > clean-am: clean-cc1libLTLIBRARIES clean-generic clean-libtool \ > @@ -681,7 +675,7 @@ ps-am: > > uninstall-am: uninstall-cc1libLTLIBRARIES uninstall-pluginLTLIBRARIES > > -.MAKE: all check install install-am install-strip > +.MAKE: all install-am install-strip > > .PHONY: CTAGS GTAGS all all-am am--refresh check check-am clean \ > clean-cc1libLTLIBRARIES clean-generic clean-libtool \ > @@ -702,21 +696,6 @@ uninstall-am: uninstall-cc1libLTLIBRARIES > uninstall-pluginLTLIBRARIES > override CXXFLAGS := $(filter-out -fsanitize=address,$(CXXFLAGS)) > override LDFLAGS := $(filter-out -fsanitize=address,$(LDFLAGS)) > > -# Put this in a header so we don't run sed for each compilation. This > -# is also simpler to debug as one can easily see the constant. > -# FIXME: compute it in configure.ac and output it in config.status, or > -# introduce timestamp files for some indirection to avoid rebuilding it > -# every time. > -c-compiler-name.h: Makefile > - -rm -f $@T > - echo "#define C_COMPILER_NAME \"`echo gcc | sed '$(transform)'`\"" > $@T > - mv $@T $@ # $(SHELL) $(srcdir)/../move-if-change $@T $@ > - > -cp-compiler-name.h: Makefile > - -rm -f $@T > - echo "#define CP_COMPILER_NAME \"`echo g++ | sed '$(transform)'`\"" > > $@T > - mv $@T $@ # $(SHELL) $(srcdir)/../move-if-change $@T $@ > - > # Tell versions [3.59,3.63) of GNU make to not export all variables. > # Otherwise a system limit (for SysV at least) may be exceeded. > .NOEXPORT: > diff --git a/libcc1/compiler-name.hh b/libcc1/compiler-name.hh > new file mode 100644 > index 00000000000..30cdc41838b > --- /dev/null > +++ b/libcc1/compiler-name.hh > @@ -0,0 +1,29 @@ > +/* The names of the compilers we use. > + Copyright (C) 2017 Free Software Foundation, Inc. > + > +This file is part of GCC. > + > +GCC is free software; you can redistribute it and/or modify it under > +the terms of the GNU General Public License as published by the Free > +Software Foundation; either version 3, or (at your option) any later > +version. > + > +GCC is distributed in the hope that it will be useful, but WITHOUT ANY > +WARRANTY; without even the implied warranty of MERCHANTABILITY or > +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License > +for more details. > + > +You should have received a copy of the GNU General Public License > +along with GCC; see the file COPYING3. If not see > +<http://www.gnu.org/licenses/>. */ > + > +#ifndef COMPILER_NAME_H > +#define COMPILER_NAME_H > + > +// C compiler name. > +#define C_COMPILER_NAME "gcc" > + > +// C++ compiler name. > +#define CP_COMPILER_NAME "g++" > + > +#endif // ! COMPILER_NAME_H > diff --git a/libcc1/libcc1.cc b/libcc1/libcc1.cc > index 0ef6c112dae..1a20dd941a4 100644 > --- a/libcc1/libcc1.cc > +++ b/libcc1/libcc1.cc > @@ -37,7 +37,7 @@ along with GCC; see the file COPYING3. If not see > #include "libiberty.h" > #include "xregex.h" > #include "findcomp.hh" > -#include "c-compiler-name.h" > +#include "compiler-name.hh" > #include "intl.h" > > struct libcc1; > diff --git a/libcc1/libcp1.cc b/libcc1/libcp1.cc > index bbd8488af93..b4f9710e0e2 100644 > --- a/libcc1/libcp1.cc > +++ b/libcc1/libcp1.cc > @@ -37,7 +37,7 @@ along with GCC; see the file COPYING3. If not see > #include "libiberty.h" > #include "xregex.h" > #include "findcomp.hh" > -#include "cp-compiler-name.h" > +#include "compiler-name.hh" > #include "intl.h" > > struct libcp1; -- Sergio GPG key ID: 237A 54B1 0287 28BF 00EF 31F4 D0EB 7628 65FC 5E36 Please send encrypted e-mail if possible http://sergiodj.net/
