rts: unrust 'libbfd' debug symbols parser

Summary:
Patch does the following:
- fixes detection of working libbfd on modern linux
  platforms (where bfd_uncompress_section_contents is a macro)
- disables 'bfd' by default and adds '--enable-bfd-debug'
  configure option. As bfd's ABI is unstable
  the feature is primarily useful by ghc hackers.

Not done (subject for another patch):
- one-time bfd object memory leak in DEBUG_LoadSymbols
- in '-dynamic' mode debugging symbols are loaded only for
  current executable, not all libraries it is linked against.

Fixes Issue #8790

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

Test Plan: built unregisterised ghc on amd64 and ran './hello +RTS -Di' there

Reviewers: simonmar, austin

Reviewed By: simonmar, austin

Subscribers: thomie, simonmar, ezyang, carter

Differential Revision: https://phabricator.haskell.org/D193

GHC Trac Issues: #8790

1 files changed, 49 insertions, 0 deletions

diff --git a/aclocal.m4 b/aclocal.m4
index a98691ef57..0db231db04 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -2215,4 +2215,53 @@ $2=$HS_CPP_ARGS
 
 ])
 
+# FP_BFD_SUPPORT()
+# ----------------------
+# whether to use libbfd for debugging RTS
+AC_DEFUN([FP_BFD_SUPPORT], [
+    AC_ARG_ENABLE(bfd-debug,
+        [AC_HELP_STRING([--enable-bfd-debug],
+              [Enable symbol resolution for -debug rts ('+RTS -Di') via binutils' libbfd [default=no]])],
+        [
+            # don't pollute general LIBS environment
+            save_LIBS="$LIBS"
+            AC_CHECK_HEADERS([bfd.h])
+            dnl ** check whether this machine has BFD and libiberty installed (used for debugging)
+            dnl    the order of these tests matters: bfd needs libiberty
+            AC_CHECK_LIB(iberty, xmalloc)
+            dnl 'bfd_init' is a rare non-macro in libbfd
+            AC_CHECK_LIB(bfd,    bfd_init)
+
+            AC_TRY_LINK([#include <bfd.h>],
+                        [
+                                /* mimic our rts/Printer.c */
+                                bfd* abfd;
+                                const char * name;
+                                char **matching;
+
+                                name = "some.executable";
+                                bfd_init();
+                                abfd = bfd_openr(name, "default");
+                                bfd_check_format_matches (abfd, bfd_object, &matching);
+                                {
+                                    long storage_needed;
+                                    storage_needed = bfd_get_symtab_upper_bound (abfd);
+                                }
+                                {
+                                    asymbol **symbol_table;
+                                    long number_of_symbols;
+                                    symbol_info info;
+
+                                    number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
+                                    bfd_get_symbol_info(abfd,symbol_table[0],&info);
+                                }
+                        ],
+                        [],dnl bfd seems to work
+                        [AC_MSG_ERROR([can't use 'bfd' library])])
+            LIBS="$save_LIBS"
+        ],
+        []
+    )
+])
+
 # LocalWords:  fi