path: root/dev-lang/ghc/files/ghc-7.6.3-trac-3333-weak-syms.patch

The patch set adds support for weak symbols to ghci.

For gentoo it fixes nonworking ghci / template haskell
for package base.

Steps to reproduce:
    1. CFLAGS=-Os emerge ghc
    2. ghci -package base
    Loading package base ... linking ... ghc: /usr/lib64/ghc-7.6.3/base-4.6.0.1/HSbase-4.6.0.1.o: unknown symbol `stat'

When built with -O2 weak 'stat' resolved to '__xstat' and we don't see any errors.
But on olwer optimization levels 'stat' remains.

Patches-by: akio
Gentoo-bug: http://bugs.gentoo.org/452442
Upstream-bug: http://ghc.haskell.org/trac/ghc/ticket/3333

From 500d57d3a18412c78cab5abc4d91f1564edc964d Mon Sep 17 00:00:00 2001
From: Takano Akio <aljee@hyper.cx>
Date: Sat, 29 Dec 2012 11:47:22 +0900
Subject: [PATCH 1/3] Linker.c: remove stablehash, which is no longer used

---
 includes/rts/Linker.h |    3 ---
 rts/Linker.c          |   31 ++-----------------------------
 2 files changed, 2 insertions(+), 32 deletions(-)

diff --git a/includes/rts/Linker.h b/includes/rts/Linker.h
index e900e85..d20ebc2 100644
--- a/includes/rts/Linker.h
+++ b/includes/rts/Linker.h
@@ -23,9 +23,6 @@ typedef char    pathchar;
 /* initialize the object linker */
 void initLinker( void );
 
-/* insert a stable symbol in the hash table */
-void insertStableSymbol(pathchar* obj_name, char* key, StgPtr data);
-
 /* insert a symbol in the hash table */
 void insertSymbol(pathchar* obj_name, char* key, void* data);
 
diff --git a/rts/Linker.c b/rts/Linker.c
index fa1de89..513fe3f 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -30,1 +30,0 @@
-#include "Stable.h"
@@ -150,9 +149,6 @@ int dynamicByDefault = 0;
 /* Hash table mapping symbol names to Symbol */
 static /*Str*/HashTable *symhash;
 
-/* Hash table mapping symbol names to StgStablePtr */
-static /*Str*/HashTable *stablehash;
-
 /* List of currently loaded objects */
 ObjectCode *objects = NULL;     /* initially empty */
 
@@ -1126,1 +1126,0 @@ typedef struct _RtsSymbolVal {
-      SymI_HasProto(insertStableSymbol)                 \
@@ -1488,7 +1483,6 @@ initLinker( void )
 #if defined(THREADED_RTS) && (defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO))
     initMutex(&dl_mutex);
 #endif
-    stablehash = allocStrHashTable();
     symhash = allocStrHashTable();
 
     /* populate the symbol table with stuff from the RTS */
@@ -1817,17 +1811,6 @@ error:
 }
 
 /* -----------------------------------------------------------------------------
- * insert a stable symbol in the hash table
- */
-
-void
-insertStableSymbol(pathchar* obj_name, char* key, StgPtr p)
-{
-  ghciInsertStrHashTable(obj_name, stablehash, key, getStablePtr(p));
-}
-
-
-/* -----------------------------------------------------------------------------
  * insert a symbol in the hash table
  */
 void
@@ -4749,8 +4732,6 @@ do_Elf_Rel_relocations ( ObjectCode* oc, char* ehdrC,
 #ifdef i386_HOST_ARCH
       Elf_Addr  value;
 #endif
-      StgStablePtr stablePtr;
-      StgPtr stableVal;
 #ifdef arm_HOST_ARCH
       int is_target_thm=0, T=0;
 #endif
@@ -4773,16 +4754,8 @@ do_Elf_Rel_relocations ( ObjectCode* oc, char* ehdrC,
 
          } else {
             symbol = strtab + sym.st_name;
-            stablePtr = (StgStablePtr)lookupHashTable(stablehash, (StgWord)symbol);
-            if (NULL == stablePtr) {
-              /* No, so look up the name in our global table. */
-              S_tmp = lookupSymbol( symbol );
-              S = (Elf_Addr)S_tmp;
-            } else {
-              stableVal = deRefStablePtr( stablePtr );
-              S_tmp = stableVal;
-              S = (Elf_Addr)S_tmp;
-            }
+            S_tmp = lookupSymbol( symbol );
+            S = (Elf_Addr)S_tmp;
          }
          if (!S) {
             errorBelch("%s: unknown symbol `%s'", oc->fileName, symbol);
-- 
1.7.9.5

From 2e5e0f7a90dd390adc5ae5fb2a3bc6e879aa42d6 Mon Sep 17 00:00:00 2001
From: Takano Akio <aljee@hyper.cx>
Date: Sat, 29 Dec 2012 11:59:34 +0900
Subject: [PATCH 2/3] ghci: add support for ELF weak symbols

---
 rts/Linker.c |  102 ++++++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 78 insertions(+), 24 deletions(-)

diff --git a/rts/Linker.c b/rts/Linker.c
index 513fe3f..5105085 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -146,7 +146,13 @@ int dynamicByDefault = 1;
 int dynamicByDefault = 0;
 #endif
 
-/* Hash table mapping symbol names to Symbol */
+typedef struct _RtsSymbolInfo {
+    void *value;
+    const ObjectCode *owner;
+    HsBool weak;
+} RtsSymbolInfo;
+
+/* Hash table mapping symbol names to RtsSymbolInfo */
 static /*Str*/HashTable *symhash;
 
 /* List of currently loaded objects */
@@ -1415,15 +1421,31 @@ static RtsSymbolVal rtsSyms[] = {
  * Insert symbols into hash tables, checking for duplicates.
  */
 
-static void ghciInsertStrHashTable ( pathchar* obj_name,
-                                     HashTable *table,
-                                     char* key,
-                                     void *data
-                                   )
+static void ghciInsertSymbolTable(
+   pathchar* obj_name,
+   HashTable *table,
+   char* key,
+   void *data,
+   HsBool weak,
+   ObjectCode *owner)
 {
-   if (lookupHashTable(table, (StgWord)key) == NULL)
+   RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
+   if (!pinfo) /* new entry */
+   {
+      pinfo = stgMallocBytes(sizeof (*pinfo), "ghciInsertToSymbolTable");
+      pinfo->value = data;
+      pinfo->owner = owner;
+      pinfo->weak = weak;
+      insertStrHashTable(table, key, pinfo);
+      return;
+   } else if ((!pinfo->weak || pinfo->value) && weak) {
+     return; /* duplicate weak symbol, throw it away */
+   } else if (pinfo->weak) /* weak symbol is in the table */
    {
-      insertStrHashTable(table, (StgWord)key, data);
+      /* override the weak definition with the non-weak one */
+      pinfo->value = data;
+      pinfo->owner = owner;
+      pinfo->weak = HS_BOOL_FALSE;
       return;
    }
    debugBelch(
@@ -1444,6 +1466,32 @@ static void ghciInsertStrHashTable ( pathchar* obj_name,
    );
    stg_exit(1);
 }
+
+static HsBool ghciLookupSymbolTable(HashTable *table,
+    const char *key, void **result)
+{
+    RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
+    if (!pinfo) {
+        *result = NULL;
+        return HS_BOOL_FALSE;
+    }
+    if (pinfo->weak)
+        IF_DEBUG(linker, debugBelch("lookup: promoting %s\n", key));
+    /* Once it's looked up, it can no longer be overridden */
+    pinfo->weak = HS_BOOL_FALSE;
+
+    *result = pinfo->value;
+    return HS_BOOL_TRUE;
+}
+
+static void ghciRemoveSymbolTable(HashTable *table, const char *key,
+    ObjectCode *owner)
+{
+    RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
+    if (!pinfo || owner != pinfo->owner) return;
+    removeStrHashTable(table, key, NULL);
+    stgFree(pinfo);
+}
 /* -----------------------------------------------------------------------------
  * initialize the object linker
  */
@@ -1487,8 +1535,8 @@ initLinker( void )
 
     /* populate the symbol table with stuff from the RTS */
     for (sym = rtsSyms; sym->lbl != NULL; sym++) {
-        ghciInsertStrHashTable(WSTR("(GHCi built-in symbols)"),
-                               symhash, sym->lbl, sym->addr);
+        ghciInsertSymbolTable(WSTR("(GHCi built-in symbols)"),
+                               symhash, sym->lbl, sym->addr, HS_BOOL_FALSE, NULL);
         IF_DEBUG(linker, debugBelch("initLinker: inserting rts symbol %s, %p\n", sym->lbl, sym->addr));
     }
 #   if defined(OBJFORMAT_MACHO) && defined(powerpc_HOST_ARCH)
@@ -1816,7 +1864,7 @@ error:
 void
 insertSymbol(pathchar* obj_name, char* key, void* data)
 {
-  ghciInsertStrHashTable(obj_name, symhash, key, data);
+  ghciInsertSymbolTable(obj_name, symhash, key, data, HS_BOOL_FALSE, NULL);
 }
 
 /* -----------------------------------------------------------------------------
@@ -1829,9 +1877,8 @@ lookupSymbol( char *lbl )
     IF_DEBUG(linker, debugBelch("lookupSymbol: looking up %s\n", lbl));
     initLinker() ;
     ASSERT(symhash != NULL);
-    val = lookupStrHashTable(symhash, lbl);
 
-    if (val == NULL) {
+    if (!ghciLookupSymbolTable(symhash, lbl, &val)) {
         IF_DEBUG(linker, debugBelch("lookupSymbol: symbol not found\n"));
 #       if defined(OBJFORMAT_ELF)
         return internal_dlsym(dl_prog_handle, lbl);
@@ -1903,7 +1950,7 @@ void ghci_enquire ( char* addr )
          if (sym == NULL) continue;
          a = NULL;
          if (a == NULL) {
-            a = lookupStrHashTable(symhash, sym);
+            ghciLookupSymbolTable(symhash, sym, (void **)&a);
          }
          if (a == NULL) {
              // debugBelch("ghci_enquire: can't find %s\n", sym);
@@ -2715,7 +2762,7 @@ unloadObj( pathchar *path )
                 int i;
                 for (i = 0; i < oc->n_symbols; i++) {
                    if (oc->symbols[i] != NULL) {
-                       removeStrHashTable(symhash, oc->symbols[i], NULL);
+                       ghciRemoveSymbolTable(symhash, oc->symbols[i], oc);
                    }
                 }
             }
@@ -3802,7 +3849,8 @@ ocGetNames_PEi386 ( ObjectCode* oc )
          ASSERT(i >= 0 && i < oc->n_symbols);
          /* cstring_from_COFF_symbol_name always succeeds. */
          oc->symbols[i] = (char*)sname;
-         ghciInsertStrHashTable(oc->fileName, symhash, (char*)sname, addr);
+         ghciInsertSymbolTable(oc->fileName, symhash, (char*)sname, addr,
+            HS_BOOL_FALSE, oc);
       } else {
 #        if 0
          debugBelch(
@@ -4595,6 +4643,7 @@ ocGetNames_ELF ( ObjectCode* oc )
       for (j = 0; j < nent; j++) {
 
          char  isLocal = FALSE; /* avoids uninit-var warning */
+         HsBool isWeak = HS_BOOL_FALSE;
          char* ad      = NULL;
          char* nm      = strtab + stab[j].st_name;
          int   secno   = stab[j].st_shndx;
@@ -4615,6 +4664,7 @@ ocGetNames_ELF ( ObjectCode* oc )
          else
          if ( ( ELF_ST_BIND(stab[j].st_info)==STB_GLOBAL
                 || ELF_ST_BIND(stab[j].st_info)==STB_LOCAL
+                || ELF_ST_BIND(stab[j].st_info)==STB_WEAK
               )
               /* and not an undefined symbol */
               && stab[j].st_shndx != SHN_UNDEF
@@ -4638,7 +4688,8 @@ ocGetNames_ELF ( ObjectCode* oc )
             ad = ehdrC + shdr[ secno ].sh_offset + stab[j].st_value;
             if (ELF_ST_BIND(stab[j].st_info)==STB_LOCAL) {
                isLocal = TRUE;
-            } else {
+               isWeak = FALSE;
+            } else { /* STB_GLOBAL or STB_WEAK */
 #ifdef ELF_FUNCTION_DESC
                /* dlsym() and the initialisation table both give us function
                 * descriptors, so to be consistent we store function descriptors
@@ -4649,6 +4700,7 @@ ocGetNames_ELF ( ObjectCode* oc )
                IF_DEBUG(linker,debugBelch( "addOTabName(GLOB): %10p  %s %s\n",
                                       ad, oc->fileName, nm ));
                isLocal = FALSE;
+               isWeak = (ELF_ST_BIND(stab[j].st_info)==STB_WEAK);
             }
          }
 
@@ -4661,7 +4713,7 @@ ocGetNames_ELF ( ObjectCode* oc )
             if (isLocal) {
                /* Ignore entirely. */
             } else {
-               ghciInsertStrHashTable(oc->fileName, symhash, nm, ad);
+               ghciInsertSymbolTable(oc->fileName, symhash, nm, ad, isWeak, oc);
             }
          } else {
             /* Skip. */
@@ -6306,11 +6358,13 @@ ocGetNames_MachO(ObjectCode* oc)
                     else
                     {
                             IF_DEBUG(linker, debugBelch("ocGetNames_MachO: inserting %s\n", nm));
-                            ghciInsertStrHashTable(oc->fileName, symhash, nm,
+                            ghciInsertSymbolTable(oc->fileName, symhash, nm,
                                                     image
                                                     + sections[nlist[i].n_sect-1].offset
                                                     - sections[nlist[i].n_sect-1].addr
-                                                    + nlist[i].n_value);
+                                                    + nlist[i].n_value,
+                                                    HS_BOOL_FALSE,
+                                                    oc);
                             oc->symbols[curSymbol++] = nm;
                     }
                 }
@@ -6341,8 +6395,8 @@ ocGetNames_MachO(ObjectCode* oc)
                 nlist[i].n_value = commonCounter;
 
                 IF_DEBUG(linker, debugBelch("ocGetNames_MachO: inserting common symbol: %s\n", nm));
-                ghciInsertStrHashTable(oc->fileName, symhash, nm,
-                                       (void*)commonCounter);
+                ghciInsertSymbolTable(oc->fileName, symhash, nm,
+                                       (void*)commonCounter, HS_BOOL_FALSE, oc);
                 oc->symbols[curSymbol++] = nm;
 
                 commonCounter += sz;
@@ -6466,7 +6520,7 @@ machoInitSymbolsWithoutUnderscore(void)
 
 #undef SymI_NeedsProto
 #define SymI_NeedsProto(x)  \
-    ghciInsertStrHashTable("(GHCi built-in symbols)", symhash, #x, *p++);
+    ghciInsertSymbolTable("(GHCi built-in symbols)", symhash, #x, *p++, HS_BOOL_FALSE, NULL);
 
     RTS_MACHO_NOUNDERLINE_SYMBOLS
 
-- 
1.7.9.5

From 916d7713b34b529ae7ec24eaa836a4eaca7724fc Mon Sep 17 00:00:00 2001
From: Takano Akio <aljee@hyper.cx>
Date: Sun, 6 Jan 2013 17:51:19 +0900
Subject: [PATCH 3/3] Linker.c: add dso_handle to the symbol table

---
 rts/Linker.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/rts/Linker.c b/rts/Linker.c
index 5105085..0b2bf63 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -1542,6 +1542,13 @@ initLinker( void )
 #   if defined(OBJFORMAT_MACHO) && defined(powerpc_HOST_ARCH)
     machoInitSymbolsWithoutUnderscore();
 #   endif
+    /* GCC defines a special symbol __dso_handle which is resolved to NULL if
+       referenced from a statically linked module. We need to mimic this, but
+       we cannot use NULL because we use it to mean nonexistent symbols. So we
+       use an arbitrary (hopefully unique) address here.
+    */
+    ghciInsertSymbolTable(WSTR("(GHCi special symbols)"),
+        symhash, "__dso_handle", (void *)0x12345687, HS_BOOL_FALSE, NULL);
 
 #   if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
 #   if defined(RTLD_DEFAULT)
-- 
1.7.9.5