Ping^2. On Friday, September 15 2017, I wrote:
> 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/ -- Sergio GPG key ID: 237A 54B1 0287 28BF 00EF 31F4 D0EB 7628 65FC 5E36 Please send encrypted e-mail if possible http://sergiodj.net/
