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

2 files changed, 18 insertions, 3 deletions

diff --git a/rts/Printer.c b/rts/Printer.c
index 3d77e83282..9bc2984384 100644
--- a/rts/Printer.c
+++ b/rts/Printer.c
@@ -7,6 +7,8 @@
  * ---------------------------------------------------------------------------*/
 
 #include "PosixSource.h"
+#include "ghcconfig.h"
+
 #include "Rts.h"
 #include "rts/Bytecodes.h"  /* for InstrPtr */
 
@@ -664,8 +666,16 @@ const char *lookupGHCName( void *addr )
    disabling this for now.
 */
 #ifdef USING_LIBBFD
-
-#include <bfd.h>
+#    define PACKAGE 1
+#    define PACKAGE_VERSION 1
+/* Those PACKAGE_* defines are workarounds for bfd:
+ *     https://sourceware.org/bugzilla/show_bug.cgi?id=14243
+ * ghc's build system filter PACKAGE_* values out specifically to avoid clashes
+ * with user's autoconf-based Cabal packages.
+ * It's a shame <bfd.h> checks for unrelated fields instead of actually used
+ * macros.
+ */
+#    include <bfd.h>
 
 /* Fairly ad-hoc piece of code that seems to filter out a lot of
  * rubbish like the obj-splitting symbols
@@ -733,7 +743,6 @@ extern void DEBUG_LoadSymbols( char *name )
         for( i = 0; i != number_of_symbols; ++i ) {
             symbol_info info;
             bfd_get_symbol_info(abfd,symbol_table[i],&info);
-            /*debugBelch("\t%c\t0x%x      \t%s\n",info.type,(nat)info.value,info.name); */
             if (isReal(info.type, info.name)) {
                 num_real_syms += 1;
             }
diff --git a/rts/RtsStartup.c b/rts/RtsStartup.c
index 98a43c0586..5e6f9fab54 100644
--- a/rts/RtsStartup.c
+++ b/rts/RtsStartup.c
@@ -19,6 +19,7 @@
 #include "RtsFlags.h"
 #include "RtsUtils.h"
 #include "Prelude.h"
+#include "Printer.h"    /* DEBUG_LoadSymbols */
 #include "Schedule.h"   /* initScheduler */
 #include "Stats.h"      /* initStats */
 #include "STM.h"        /* initSTM */
@@ -162,6 +163,11 @@ hs_init_ghc(int *argc, char **argv[], RtsConfig rts_config)
                       rts_config.rts_opts_enabled, rts_config.rts_opts, rts_config.rts_hs_main);
     }
 
+#ifdef DEBUG
+    /* load debugging symbols for current binary */
+    DEBUG_LoadSymbols((*argv)[0]);
+#endif /* DEBUG */
+
     /* Initialise the stats department, phase 1 */
     initStats1();