[Git][ghc/ghc][wip/sym-type] rts/linker: Clearly define SymType
Ben Gamari (@bgamari)
gitlab at gitlab.haskell.org
Mon Oct 23 23:28:34 UTC 2023
Ben Gamari pushed to branch wip/sym-type at Glasgow Haskell Compiler / GHC
Commits:
13a6f3f1 by Ben Gamari at 2023-10-23T19:28:18-04:00
rts/linker: Clearly define SymType
Previously SymType was both an enumeration of three symbol types *and*
an orthogonal flag (`DUP_DISCARD`, introduced in !9475). This was quite
fragile as it meant that to extract the symbol type one had to careful
mask out the flag. Naturally this wasn't done consistently.
Fix this by renaming the field to `flags` and adding an accessor.
Fixes #24117.
- - - - -
5 changed files:
- rts/Linker.c
- rts/LinkerInternals.h
- rts/linker/Elf.c
- rts/linker/MachO.c
- rts/linker/PEi386.c
Changes:
=====================================
rts/Linker.c
=====================================
@@ -226,7 +226,7 @@ static void ghciRemoveSymbolTable(StrHashTable *table, const SymbolName* key,
static const char *
symbolTypeString (SymType type)
{
- switch (type & ~SYM_TYPE_DUP_DISCARD) {
+ switch (type) {
case SYM_TYPE_CODE: return "code";
case SYM_TYPE_DATA: return "data";
case SYM_TYPE_INDIRECT_DATA: return "indirect-data";
@@ -262,6 +262,7 @@ int ghciInsertSymbolTable(
SymbolAddr* data,
SymStrength strength,
SymType type,
+ uint16_t flags,
ObjectCode *owner)
{
RtsSymbolInfo *pinfo = lookupStrHashTable(table, key);
@@ -271,21 +272,21 @@ int ghciInsertSymbolTable(
pinfo->value = data;
pinfo->owner = owner;
pinfo->strength = strength;
- pinfo->type = type;
+ pinfo->flags = (uint16_t) type | flags;
insertStrHashTable(table, key, pinfo);
return 1;
}
- else if (pinfo->type ^ type)
+ else if (getRtsSymbolType(pinfo) != type)
{
/* We were asked to discard the symbol on duplicates, do so quietly. */
- if (!(type & SYM_TYPE_DUP_DISCARD))
+ if (!(flags & SYM_FLAG_DUP_DISCARD))
{
debugBelch("Symbol type mismatch.\n");
debugBelch("Symbol %s was defined by %" PATH_FMT " to be a %s symbol.\n",
key, obj_name, symbolTypeString(type));
debugBelch(" yet was defined by %" PATH_FMT " to be a %s symbol.\n",
pinfo->owner ? pinfo->owner->fileName : WSTR("<builtin>"),
- symbolTypeString(pinfo->type));
+ symbolTypeString(getRtsSymbolType(pinfo)));
}
return 1;
}
@@ -466,7 +467,7 @@ initLinker_ (int retain_cafs)
for (const RtsSymbolVal *sym = rtsSyms; sym->lbl != NULL; sym++) {
if (! ghciInsertSymbolTable(WSTR("(GHCi built-in symbols)"),
symhash, sym->lbl, sym->addr,
- sym->strength, sym->type, NULL)) {
+ sym->strength, sym->type, 0, NULL)) {
barf("ghciInsertSymbolTable failed");
}
IF_DEBUG(linker, debugBelch("initLinker: inserting rts symbol %s, %p\n", sym->lbl, sym->addr));
@@ -476,7 +477,7 @@ initLinker_ (int retain_cafs)
if (! ghciInsertSymbolTable(WSTR("(GHCi built-in symbols)"), symhash,
MAYBE_LEADING_UNDERSCORE_STR("newCAF"),
retain_cafs ? newRetainedCAF : newGCdCAF,
- HS_BOOL_FALSE, SYM_TYPE_CODE, NULL)) {
+ HS_BOOL_FALSE, SYM_TYPE_CODE, 0, NULL)) {
barf("ghciInsertSymbolTable failed");
}
@@ -864,7 +865,7 @@ HsBool removeLibrarySearchPath(HsPtr dll_path_index)
HsInt insertSymbol(pathchar* obj_name, SymbolName* key, SymbolAddr* data)
{
return ghciInsertSymbolTable(obj_name, symhash, key, data, HS_BOOL_FALSE,
- SYM_TYPE_CODE, NULL);
+ SYM_TYPE_CODE, 0, NULL);
}
/* -----------------------------------------------------------------------------
@@ -961,7 +962,7 @@ SymbolAddr* lookupDependentSymbol (SymbolName* lbl, ObjectCode *dependent, SymTy
if (strcmp(lbl, "__fini_array_start") == 0) { return (SymbolAddr *) &RTS_NO_FINI; }
if (type) {
// This is an assumption
- *type = pinfo->type;
+ *type = getRtsSymbolType(pinfo);
}
if (dependent) {
@@ -1696,7 +1697,7 @@ int ocTryLoad (ObjectCode* oc) {
&& !ghciInsertSymbolTable(oc->fileName, symhash, symbol.name,
symbol.addr,
isSymbolWeak(oc, symbol.name),
- symbol.type, oc)) {
+ symbol.type, 0, oc)) {
return 0;
}
}
=====================================
rts/LinkerInternals.h
=====================================
@@ -55,17 +55,27 @@ typedef struct _Section Section;
/* What kind of thing a symbol identifies. We need to know this to determine how
* to process overflowing relocations. See Note [Processing overflowed relocations].
- * This is bitfield however only the option SYM_TYPE_DUP_DISCARD can be combined
- * with the other values. */
+ */
typedef enum _SymType {
SYM_TYPE_CODE = 1 << 0, /* the symbol is a function and can be relocated via a jump island */
SYM_TYPE_DATA = 1 << 1, /* the symbol is data */
SYM_TYPE_INDIRECT_DATA = 1 << 2, /* see Note [_iob_func symbol] */
- SYM_TYPE_DUP_DISCARD = 1 << 3, /* the symbol is a symbol in a BFD import library
- however if a duplicate is found with a mismatching
- SymType then discard this one. */
} SymType;
+#define SYM_TYPE_MASK (SYM_TYPE_CODE | SYM_TYPE_DATA | SYM_TYPE_INDIRECT_DATA)
+
+INLINE_HEADER SymType symbolFlagsToSymbolType(uint16_t flags) {
+ return (SymType) (flags & SYM_TYPE_MASK);
+}
+
+/*
+ * The symbol is a symbol in a BFD import library
+ * however if a duplicate is found with a mismatching
+ * SymType then discard this one.
+ *
+ */
+#define SYM_FLAG_DUP_DISCARD (1 << 3)
+
#if defined(OBJFORMAT_ELF)
# include "linker/ElfTypes.h"
@@ -438,9 +448,14 @@ typedef struct _RtsSymbolInfo {
SymbolAddr* value;
ObjectCode *owner;
SymStrength strength;
- SymType type;
+ // This is a bitfield combining SymType with the SYM_FLAG_* flags.
+ uint16_t flags;
} RtsSymbolInfo;
+INLINE_HEADER SymType getRtsSymbolType(RtsSymbolInfo *pinfo) {
+ return symbolFlagsToSymbolType(pinfo->flags);
+}
+
#include "BeginPrivate.h"
void exitLinker( void );
@@ -466,6 +481,8 @@ int ghciInsertSymbolTable(
SymbolAddr* data,
SymStrength weak,
SymType type,
+ // One of SYM_FLAG_*
+ uint16_t flags,
ObjectCode *owner);
/* Lock-free version of lookupSymbol. When 'dependent' is not NULL, adds it as a
=====================================
rts/linker/Elf.c
=====================================
@@ -1083,7 +1083,7 @@ ocGetNames_ELF ( ObjectCode* oc )
setWeakSymbol(oc, nm);
}
if (!ghciInsertSymbolTable(oc->fileName, symhash,
- nm, symbol->addr, isWeak, sym_type, oc)
+ nm, symbol->addr, isWeak, sym_type, 0, oc)
) {
goto fail;
}
=====================================
rts/linker/MachO.c
=====================================
@@ -1390,14 +1390,15 @@ ocGetNames_MachO(ObjectCode* oc)
{
IF_DEBUG(linker_verbose, debugBelch("ocGetNames_MachO: inserting %s\n", nm));
SymbolAddr* addr = oc->info->macho_symbols[i].addr;
- // TODO: Make figure out how to determine this from the object file
- SymType sym_type = SYM_TYPE_CODE;
+ // TODO: Figure out how to determine this from the object file
+ const SymType sym_type = SYM_TYPE_CODE;
ghciInsertSymbolTable( oc->fileName
, symhash
, nm
, addr
, HS_BOOL_FALSE
, sym_type
+ , 0
, oc);
oc->symbols[curSymbol].name = nm;
@@ -1440,7 +1441,7 @@ ocGetNames_MachO(ObjectCode* oc)
IF_DEBUG(linker_verbose, debugBelch("ocGetNames_MachO: inserting common symbol: %s\n", nm));
ghciInsertSymbolTable(oc->fileName, symhash, nm,
- (void*)commonCounter, HS_BOOL_FALSE, sym_type, oc);
+ (void*)commonCounter, HS_BOOL_FALSE, sym_type, 0, oc);
oc->symbols[curSymbol].name = nm;
oc->symbols[curSymbol].addr = oc->info->macho_symbols[i].addr;
curSymbol++;
=====================================
rts/linker/PEi386.c
=====================================
@@ -299,7 +299,7 @@
These two issues mean that for GHC we need to take a different approach
to handling import libraries. For normal C libraries we have proper
differentiation between CODE and DATA. For GHC produced import libraries
- we do not. As such the SYM_TYPE_DUP_DISCARD tells the linker that if a
+ we do not. As such the SYM_FLAG_DUP_DISCARD tells the linker that if a
duplicate symbol is found, and we were going to discard it anyway, just do
so quitely. This works because the RTS symbols themselves are provided by
the currently loaded RTS as built-in symbols.
@@ -438,7 +438,7 @@ void initLinker_PEi386(void)
if (!ghciInsertSymbolTable(WSTR("(GHCi/Ld special symbols)"),
symhash, "__image_base__",
GetModuleHandleW (NULL), HS_BOOL_TRUE,
- SYM_TYPE_CODE, NULL)) {
+ SYM_TYPE_CODE, 0, NULL)) {
barf("ghciInsertSymbolTable failed");
}
@@ -1814,9 +1814,8 @@ ocGetNames_PEi386 ( ObjectCode* oc )
sname = strdup (sname);
addr = strdup (addr);
type = has_code_section ? SYM_TYPE_CODE : SYM_TYPE_DATA;
- type |= SYM_TYPE_DUP_DISCARD;
if (!ghciInsertSymbolTable(oc->fileName, symhash, sname,
- addr, false, type, oc)) {
+ addr, false, type, SYM_FLAG_DUP_DISCARD, oc)) {
releaseOcInfo (oc);
stgFree (oc->image);
oc->image = NULL;
@@ -1895,7 +1894,7 @@ ocGetNames_PEi386 ( ObjectCode* oc )
stgFree(tmp);
sname = strdup (sname);
if (!ghciInsertSymbolTable(oc->fileName, symhash, sname,
- addr, false, type, oc))
+ addr, false, type, 0, oc))
return false;
break;
@@ -1918,7 +1917,7 @@ ocGetNames_PEi386 ( ObjectCode* oc )
}
if (! ghciInsertSymbolTable(oc->fileName, symhash, sname, addr,
- isWeak, type, oc))
+ isWeak, type, 0, oc))
return false;
} else {
/* We're skipping the symbol, but if we ever load this
@@ -2321,7 +2320,9 @@ SymbolAddr *lookupSymbol_PEi386(SymbolName *lbl, ObjectCode *dependent, SymType
sym = lookupSymbolInDLLs(lbl, dependent);
return sym; // might be NULL if not found
} else {
- if (type) *type = pinfo->type;
+ if (type) {
+ *type = getRtsSymbolType(pinfo);
+ }
if (pinfo && pinfo->owner && isSymbolImport (pinfo->owner, lbl))
{
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/13a6f3f15895322c96956ef8e48e8a640e866ff6
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/13a6f3f15895322c96956ef8e48e8a640e866ff6
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