[Git][ghc/ghc][wip/ghc-8.10-backports] 5 commits: macOS: Load frameworks without stating them first.
Ben Gamari
gitlab at gitlab.haskell.org
Sun Nov 22 12:30:09 UTC 2020
Ben Gamari pushed to branch wip/ghc-8.10-backports at Glasgow Haskell Compiler / GHC
Commits:
3571cc41 by Matthias Andreas Benkard at 2020-11-19T15:36:22-05:00
macOS: Load frameworks without stating them first.
macOS Big Sur makes the following change to how frameworks are shipped
with the OS:
> New in macOS Big Sur 11 beta, the system ships with a built-in
> dynamic linker cache of all system-provided libraries. As part of
> this change, copies of dynamic libraries are no longer present on
> the filesystem. Code that attempts to check for dynamic library
> presence by looking for a file at a path or enumerating a directory
> will fail. Instead, check for library presence by attempting to
> dlopen() the path, which will correctly check for the library in the
> cache. (62986286)
https://developer.apple.com/documentation/macos-release-notes/macos-big-sur-11-beta-release-notes/
Therefore, the previous method of checking whether a library exists
before attempting to load it makes GHC.Runtime.Linker.loadFramework
fail to find frameworks installed at /System/Library/Frameworks.
GHC.Runtime.Linker.loadFramework now opportunistically loads the
framework libraries without checking for their existence first,
failing only if all attempts to load a given framework from any of the
various possible locations fail.
- - - - -
57b5f130 by Matthias Andreas Benkard at 2020-11-19T15:36:22-05:00
loadFramework: Output the errors collected in all loading attempts.
With the recent change away from first finding and then loading a
framework, loadFramework had no way of communicating the real reason
why loadDLL failed if it was any reason other than the framework
missing from the file system. It now collects all loading attempt
errors into a list and concatenates them into a string to return to
the caller.
- - - - -
07c5acae by Matthias Andreas Benkard at 2020-11-19T15:36:22-05:00
Document loadFramework changes. (#18446)
Adds commentary on the rationale for the changes made in merge request
!3689.
- - - - -
bde58de9 by Ömer Sinan Ağacan at 2020-11-22T07:29:28-05:00
Fix and enable object unloading in GHCi
Fixes #16525 by tracking dependencies between object file symbols and
marking symbol liveness during garbage collection
See Note [Object unloading] in CheckUnload.c for details.
(cherry picked from commit c34a4b98b1f09ea3096d39a839a86f2d7185c796)
- - - - -
180f58cf by Viktor Dukhovni at 2020-11-22T07:29:28-05:00
8.10 - dirty MVAR after mutating TSO queue head
While the original head and tail of the TSO queue may be in the same
generation as the MVAR, interior elements of the queue could be younger
after a GC run and may then be exposed by putMVar operation that updates
the queue head.
Resolves #18919
(cherry picked from commit 699facec0bc8dd7d5b82cc537fbf131b74f5bd2c)
- - - - -
27 changed files:
- compiler/ghci/Linker.hs
- rts/CheckUnload.c
- rts/CheckUnload.h
- rts/Hash.c
- rts/Hash.h
- rts/Linker.c
- rts/LinkerInternals.h
- rts/PrimOps.cmm
- rts/RtsStartup.c
- rts/Threads.c
- rts/linker/Elf.c
- rts/linker/LoadArchive.c
- rts/linker/MachO.c
- rts/linker/PEi386.c
- rts/linker/elf_got.c
- rts/sm/Evac.c
- rts/sm/GC.c
- rts/sm/GC.h
- testsuite/tests/ghci/T16525a/T16525a.script
- testsuite/tests/ghci/T16525a/T16525a.stdout
- testsuite/tests/ghci/T16525a/all.T
- + testsuite/tests/ghci/T16525b/A.hs
- + testsuite/tests/ghci/T16525b/B.hs
- + testsuite/tests/ghci/T16525b/T16525b.script
- + testsuite/tests/ghci/T16525b/T16525b.stdout
- + testsuite/tests/ghci/T16525b/all.T
- testsuite/tests/rts/linker/linker_error.c
Changes:
=====================================
compiler/ghci/Linker.hs
=====================================
@@ -1134,14 +1134,15 @@ unload_wkr hsc_env keep_linkables pls at PersistentLinkerState{..} = do
where
unloadObjs :: Linkable -> IO ()
unloadObjs lnk
+ -- The RTS's PEi386 linker currently doesn't support unloading.
+ | isWindowsHost = return ()
+
| dynamicGhc = return ()
-- We don't do any cleanup when linking objects with the
-- dynamic linker. Doing so introduces extra complexity for
-- not much benefit.
- -- Code unloading currently disabled due to instability.
- -- See #16841.
- | False -- otherwise
+ | otherwise
= mapM_ (unloadObj hsc_env) [f | DotO f <- linkableUnlinked lnk]
-- The components of a BCO linkable may contain
-- dot-o files. Which is very confusing.
@@ -1149,7 +1150,6 @@ unload_wkr hsc_env keep_linkables pls at PersistentLinkerState{..} = do
-- But the BCO parts can be unlinked just by
-- letting go of them (plus of course depopulating
-- the symbol table which is done in the main body)
- | otherwise = return () -- see #16841
{- **********************************************************************
@@ -1679,6 +1679,38 @@ addEnvPaths name list
-- ----------------------------------------------------------------------------
-- Loading a dynamic library (dlopen()-ish on Unix, LoadLibrary-ish on Win32)
+{-
+Note [macOS Big Sur dynamic libraries]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+macOS Big Sur makes the following change to how frameworks are shipped
+with the OS:
+
+> New in macOS Big Sur 11 beta, the system ships with a built-in
+> dynamic linker cache of all system-provided libraries. As part of
+> this change, copies of dynamic libraries are no longer present on
+> the filesystem. Code that attempts to check for dynamic library
+> presence by looking for a file at a path or enumerating a directory
+> will fail. Instead, check for library presence by attempting to
+> dlopen() the path, which will correctly check for the library in the
+> cache. (62986286)
+
+(https://developer.apple.com/documentation/macos-release-notes/macos-big-sur-11-beta-release-notes/)
+
+Therefore, the previous method of checking whether a library exists
+before attempting to load it makes GHC.Runtime.Linker.loadFramework
+fail to find frameworks installed at /System/Library/Frameworks.
+Instead, any attempt to load a framework at runtime, such as by
+passing -framework OpenGL to runghc or running code loading such a
+framework with GHCi, fails with a 'not found' message.
+
+GHC.Runtime.Linker.loadFramework now opportunistically loads the
+framework libraries without checking for their existence first,
+failing only if all attempts to load a given framework from any of the
+various possible locations fail. See also #18446, which this change
+addresses.
+-}
+
-- Darwin / MacOS X only: load a framework
-- a framework is a dynamic library packaged inside a directory of the same
-- name. They are searched for in different paths than normal libraries.
@@ -1689,17 +1721,29 @@ loadFramework hsc_env extraPaths rootname
Left _ -> []
Right dir -> [dir </> "Library/Frameworks"]
ps = extraPaths ++ homeFrameworkPath ++ defaultFrameworkPaths
- ; mb_fwk <- findFile ps fwk_file
- ; case mb_fwk of
- Just fwk_path -> loadDLL hsc_env fwk_path
- Nothing -> return (Just "not found") }
- -- Tried all our known library paths, but dlopen()
- -- has no built-in paths for frameworks: give up
+ ; errs <- findLoadDLL ps []
+ ; return $ fmap (intercalate ", ") errs
+ }
where
fwk_file = rootname <.> "framework" </> rootname
- -- sorry for the hardcoded paths, I hope they won't change anytime soon:
+
+ -- sorry for the hardcoded paths, I hope they won't change anytime soon:
defaultFrameworkPaths = ["/Library/Frameworks", "/System/Library/Frameworks"]
+ -- Try to call loadDLL for each candidate path.
+ --
+ -- See Note [macOS Big Sur dynamic libraries]
+ findLoadDLL [] errs =
+ -- Tried all our known library paths, but dlopen()
+ -- has no built-in paths for frameworks: give up
+ return $ Just errs
+ findLoadDLL (p:ps) errs =
+ do { dll <- loadDLL hsc_env (p </> fwk_file)
+ ; case dll of
+ Nothing -> return Nothing
+ Just err -> findLoadDLL ps ((p ++ ": " ++ err):errs)
+ }
+
{- **********************************************************************
Helper functions
=====================================
rts/CheckUnload.c
=====================================
@@ -17,43 +17,99 @@
#include "CheckUnload.h"
#include "sm/Storage.h"
#include "sm/GCThread.h"
+#include "sm/HeapUtils.h"
//
-// Code that we unload may be referenced from:
-// - info pointers in heap objects and stack frames
-// - pointers to static objects from the heap
-// - StablePtrs to static objects
-// - pointers to cost centres from the cost centre tree
+// Note [Object unloading]
+// ~~~~~~~~~~~~~~~~~~~~~~~
//
-// We can find live static objects after a major GC, so we don't have
-// to look at every closure pointer in the heap. However, we do have
-// to look at every info pointer. So this is like a heap census
-// traversal: we look at the header of every object, but not its
-// contents.
+// Overview of object unloading:
//
-// On the assumption that there aren't many different info pointers in
-// a typical heap, we insert addresses into a hash table. The
-// first time we see an address, we check it against the pending
-// unloadable objects and if it lies within any of them, we mark that
-// object as referenced so that it won't get unloaded in this round.
+// - In a major GC, for every static object we mark the object's object code and
+// its dependencies as 'live'. This is done by `markObjectCode`, called by
+// `evacuate`.
//
-
-// Note [Speeding up checkUnload]
-// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-// In certain circumstances, there may be a lot of unloaded ObjectCode structs
-// chained in `unloaded_objects` (such as when users `:load` a module in a very
-// big repo in GHCi). To speed up checking whether an address lies within any of
-// these objects, we populate the addresses of their mapped sections in
-// an array sorted by their `start` address and do binary search for our address
-// on that array. Note that this works because the sections are mapped to mutual
-// exclusive memory regions, so we can simply find the largest lower bound among
-// the `start` addresses of the sections and then check if our address is inside
-// that section. In particular, we store the start address and end address of
-// each mapped section in a OCSectionIndex, arrange them all on a contiguous
-// memory range and then sort by start address. We then put this array in an
-// OCSectionIndices struct to be passed into `checkAddress` to do binary search
-// on.
+// - Marking object code is done using a global "section index table"
+// (global_s_indices below). When we load an object code we add its section
+// indices to the table. `markObjectCode` does binary search on this table to
+// find object code for the marked object, and mark it and its dependencies.
+//
+// Dependency of an object code is simply other object code that the object
+// code refers to in its code. We know these dependencies by the relocations
+// present in the referent. This is recorded by lookupSymbolDependent.
+//
+// - global_s_indices is updated as we load and unload objects. When we load an
+// object code we add its section indices to the table, we remove those
+// indices when we unload.
+//
+// The table is sorted and old indices are removed in `checkUnload`, instead
+// on every load/unload, to avoid quadratic behavior when we load a list of
+// objects.
+//
+// - After a major GC `checkUnload` unloads objects that are (1) explicitly
+// asked for unloading (via `unloadObj`) and (2) are not marked during GC.
+//
+// Note that, crucially, we don't unload an object code even if it's not
+// reachable from the heap, unless it's explicitly asked for unloading (via
+// `unloadObj`). This is a feature and not a but! Two use cases:
+//
+// - The user might request a symbol from a loaded object at any point with
+// lookupSymbol (e.g. GHCi might do this).
+//
+// - Sometimes we load objects that are not Haskell objects.
+//
+// To avoid unloading objects that are unreachable but are not asked for
+// unloading we maintain a "root set" of object code, `loaded_objects` below.
+// `loadObj` adds the loaded objects (and its dependencies) to the list.
+// `unloadObj` removes. After a major GC, `checkUnload` first marks the root set
+// (`loaded_objects`) to avoid unloading objects that are not asked for
+// unloading.
+//
+// Two other lists `objects` and `old_objects` are similar to large object lists
+// in GC. Before a major GC we move `objects` to `old_objects`, and move marked
+// objects back to `objects` during evacuation and when marking roots in
+// `checkUnload`. Any objects in `old_objects` after that is unloaded.
+//
+// TODO: We currently don't unload objects when non-moving GC is enabled. The
+// implementation would be similar to `nonmovingGcCafs`:
+//
+// - Maintain a "snapshot":
+//
+// - Copy `loaded_objects` as the root set of the snapshot
+//
+// - Stash `objects` to `old_objects` as the snapshot. We don't need a new
+// list for this as `old_objects` won't be used by any other code when
+// non-moving GC is enabled.
+//
+// - Copy `global_s_indices` table to be able to mark objects while mutators
+// call `loadObj_` and `unloadObj_` concurrently.
+//
+// - Don't mark object code in `evacuate`, marking will be done in the
+// non-moving collector.
//
+// - After preparation, bump the object code mark bit (`object_code_mark_bit`
+// below) and mark static objects using a version of `markObjectCode` that
+// basically does the same thing but:
+//
+// - Needs to update `objects` list in a thread-safe way, as mutators will be
+// concurrently calling `loadObj_` and add new stuff to `objects`.
+// (alternatively we could have a new list for non-moving GC's objects list,
+// and then merge it to the global list in the pause before moving to
+// concurrent sweep phase)
+//
+// - Needs to use the copied `global_s_indices`
+//
+// - After marking anything left in `old_objects` are unreachable objects within
+// the snapshot, unload those. The unload loop will be the same as in
+// `checkUnload`. This step needs to happen in the final sync (before sweep
+// begins) to avoid races when updating `global_s_indices`.
+//
+// - NOTE: We don't need write barriers in loadObj/unloadObj as we don't
+// introduce a dependency from an already-loaded object to a newly loaded
+// object and we don't delete existing dependencies.
+//
+
+uint8_t object_code_mark_bit = 0;
typedef struct {
W_ start;
@@ -62,20 +118,85 @@ typedef struct {
} OCSectionIndex;
typedef struct {
+ int capacity; // Doubled on resize
int n_sections;
+ bool sorted; // Invalidated on insertion. Sorted in checkUnload.
+ bool unloaded; // Whether we removed anything from the table in
+ // removeOCSectionIndices. If this is set we "compact" the
+ // table (remove unused entries) in `sortOCSectionIndices.
OCSectionIndex *indices;
} OCSectionIndices;
-static OCSectionIndices *createOCSectionIndices(int n_sections)
+// List of currently live objects. Moved to `old_objects` before unload check.
+// Marked objects moved back to this list in `markObjectLive`. Remaining objects
+// are freed at the end of `checkUnload`.
+//
+// Double-linked list to be able to remove marked objects. List formed with
+// `next` and `prev` fields of `ObjectCode`.
+//
+// Not static: used in Linker.c.
+ObjectCode *objects = NULL;
+
+// `objects` list is moved here before unload check. Marked objects are moved
+// back to `objects`. Remaining objects are freed.
+static ObjectCode *old_objects = NULL;
+
+// Number of objects that we want to unload. When this value is 0 we skip static
+// object marking during GC and `checkUnload`.
+//
+// Not static: we use this value to skip static object marking in evacuate when
+// this is 0.
+//
+// Incremented in `unloadObj_`, decremented as we unload objects in
+// `checkUnload`.
+int n_unloaded_objects = 0;
+
+// List of objects that we don't want to unload (i.e. we haven't called
+// unloadObj on these yet). Used as root set for unload check in checkUnload.
+// Objects are added with loadObj_ and removed with unloadObj_.
+//
+// List formed with `next_loaded_object` field of `ObjectCode`.
+//
+// Not static: used in Linker.c.
+ObjectCode *loaded_objects;
+
+// Section index table for currently loaded objects. New indices are added by
+// `loadObj_`, indices of unloaded objects are removed in `checkUnload`. Used to
+// map static closures to their ObjectCode.
+static OCSectionIndices *global_s_indices = NULL;
+
+static OCSectionIndices *createOCSectionIndices(void)
{
- OCSectionIndices *s_indices;
- s_indices = stgMallocBytes(sizeof(OCSectionIndices), "OCSectionIndices");
- s_indices->n_sections = n_sections;
- s_indices->indices = stgMallocBytes(n_sections*sizeof(OCSectionIndex),
+ // TODO (osa): Maybe initialize as empty (without allocation) and allocate
+ // on first insertion?
+ OCSectionIndices *s_indices = stgMallocBytes(sizeof(OCSectionIndices), "OCSectionIndices");
+ int capacity = 1024;
+ s_indices->capacity = capacity;
+ s_indices->n_sections = 0;
+ s_indices->sorted = true;
+ s_indices->unloaded = false;
+ s_indices->indices = stgMallocBytes(capacity * sizeof(OCSectionIndex),
"OCSectionIndices::indices");
return s_indices;
}
+static void freeOCSectionIndices(OCSectionIndices *s_indices)
+{
+ free(s_indices->indices);
+ free(s_indices);
+}
+
+void initUnloadCheck()
+{
+ global_s_indices = createOCSectionIndices();
+}
+
+void exitUnloadCheck()
+{
+ freeOCSectionIndices(global_s_indices);
+ global_s_indices = NULL;
+}
+
static int cmpSectionIndex(const void* indexa, const void *indexb)
{
W_ s1 = ((OCSectionIndex*)indexa)->start;
@@ -88,44 +209,124 @@ static int cmpSectionIndex(const void* indexa, const void *indexb)
return 0;
}
-static OCSectionIndices* buildOCSectionIndices(ObjectCode *ocs)
+static void reserveOCSectionIndices(OCSectionIndices *s_indices, int len)
{
- int cnt_sections = 0;
- ObjectCode *oc;
- for (oc = ocs; oc; oc = oc->next) {
- cnt_sections += oc->n_sections;
+ int current_capacity = s_indices->capacity;
+ int current_len = s_indices->n_sections;
+ if (current_capacity - current_len >= len) {
+ return;
+ }
+
+ // Round up to nearest power of 2
+ int new_capacity = 1 << (int)ceil(log2(current_len + len));
+
+ OCSectionIndex *old_indices = s_indices->indices;
+ OCSectionIndex *new_indices = stgMallocBytes(new_capacity * sizeof(OCSectionIndex),
+ "reserveOCSectionIndices");
+
+ for (int i = 0; i < current_len; ++i) {
+ new_indices[i] = old_indices[i];
}
- OCSectionIndices* s_indices = createOCSectionIndices(cnt_sections);
- int s_i = 0, i;
- for (oc = ocs; oc; oc = oc->next) {
- for (i = 0; i < oc->n_sections; i++) {
- if (oc->sections[i].kind != SECTIONKIND_OTHER) {
- s_indices->indices[s_i].start = (W_)oc->sections[i].start;
- s_indices->indices[s_i].end = (W_)oc->sections[i].start
- + oc->sections[i].size;
- s_indices->indices[s_i].oc = oc;
- s_i++;
+
+ s_indices->capacity = new_capacity;
+ s_indices->indices = new_indices;
+
+ free(old_indices);
+}
+
+// Insert object section indices of a single ObjectCode. Invalidates 'sorted'
+// state.
+void insertOCSectionIndices(ObjectCode *oc)
+{
+ reserveOCSectionIndices(global_s_indices, oc->n_sections);
+ global_s_indices->sorted = false;
+
+ int s_i = global_s_indices->n_sections;
+ for (int i = 0; i < oc->n_sections; i++) {
+ if (oc->sections[i].kind != SECTIONKIND_OTHER) {
+ global_s_indices->indices[s_i].start = (W_)oc->sections[i].start;
+ global_s_indices->indices[s_i].end = (W_)oc->sections[i].start
+ + oc->sections[i].size;
+ global_s_indices->indices[s_i].oc = oc;
+ s_i++;
+ }
+ }
+
+ global_s_indices->n_sections = s_i;
+
+ // Add object to 'objects' list
+ if (objects != NULL) {
+ objects->prev = oc;
+ }
+ oc->next = objects;
+ objects = oc;
+}
+
+static int findSectionIdx(OCSectionIndices *s_indices, const void *addr);
+
+static void removeOCSectionIndices(OCSectionIndices *s_indices, ObjectCode *oc)
+{
+ // To avoid quadratic behavior in checkUnload we set `oc` fields of indices
+ // of unloaded objects NULL here. Removing unused entries is done in
+ // `sortOCSectionIndices`.
+
+ s_indices->unloaded = true;
+
+ for (int i = 0; i < oc->n_sections; i++) {
+ if (oc->sections[i].kind != SECTIONKIND_OTHER) {
+ int section_idx = findSectionIdx(s_indices, oc->sections[i].start);
+ if (section_idx != -1) {
+ s_indices->indices[section_idx].oc = NULL;
}
}
}
- s_indices->n_sections = s_i;
+}
+
+static void sortOCSectionIndices(OCSectionIndices *s_indices) {
+ if (s_indices->sorted) {
+ return;
+ }
+
qsort(s_indices->indices,
s_indices->n_sections,
sizeof(OCSectionIndex),
cmpSectionIndex);
- return s_indices;
+
+ s_indices->sorted = true;
}
-static void freeOCSectionIndices(OCSectionIndices *section_indices)
-{
- free(section_indices->indices);
- free(section_indices);
+static void removeRemovedOCSections(OCSectionIndices *s_indices) {
+ if (!s_indices->unloaded) {
+ return;
+ }
+
+ int next_free_idx = 0;
+ for (int i = 0; i < s_indices->n_sections; ++i) {
+ if (s_indices->indices[i].oc == NULL) {
+ // free entry, skip
+ } else if (i == next_free_idx) {
+ ++next_free_idx;
+ } else {
+ s_indices->indices[next_free_idx] = s_indices->indices[i];
+ ++next_free_idx;
+ }
+ }
+
+ s_indices->n_sections = next_free_idx;
+ s_indices->unloaded = true;
}
-static ObjectCode *findOC(OCSectionIndices *s_indices, const void *addr) {
+// Returns -1 if not found
+static int findSectionIdx(OCSectionIndices *s_indices, const void *addr) {
+ ASSERT(s_indices->sorted);
+
W_ w_addr = (W_)addr;
- if (s_indices->n_sections <= 0) return NULL;
- if (w_addr < s_indices->indices[0].start) return NULL;
+ if (s_indices->n_sections <= 0) {
+ return -1;
+ }
+ if (w_addr < s_indices->indices[0].start) {
+ return -1;
+ }
int left = 0, right = s_indices->n_sections;
while (left + 1 < right) {
@@ -139,330 +340,125 @@ static ObjectCode *findOC(OCSectionIndices *s_indices, const void *addr) {
}
ASSERT(w_addr >= s_indices->indices[left].start);
if (w_addr < s_indices->indices[left].end) {
- return s_indices->indices[left].oc;
+ return left;
}
- return NULL;
+ return -1;
}
-static void checkAddress (HashTable *addrs, const void *addr,
- OCSectionIndices *s_indices)
-{
- ObjectCode *oc;
-
- if (!lookupHashTable(addrs, (W_)addr)) {
- insertHashTable(addrs, (W_)addr, addr);
+static ObjectCode *findOC(OCSectionIndices *s_indices, const void *addr) {
+ int oc_idx = findSectionIdx(s_indices, addr);
- oc = findOC(s_indices, addr);
- if (oc != NULL) {
- oc->referenced = 1;
- return;
- }
+ if (oc_idx == -1) {
+ return NULL;
}
+
+ return s_indices->indices[oc_idx].oc;
}
-static void searchStackChunk (HashTable *addrs, StgPtr sp, StgPtr stack_end,
- OCSectionIndices *s_indices)
-{
- StgPtr p;
- const StgRetInfoTable *info;
+static bool markObjectLive(void *data STG_UNUSED, StgWord key, const void *value STG_UNUSED) {
+ ObjectCode *oc = (ObjectCode*)key;
+ if (oc->mark == object_code_mark_bit) {
+ return true; // for hash table iteration
+ }
+
+ oc->mark = object_code_mark_bit;
+ // Remove from 'old_objects' list
+ if (oc->prev != NULL) {
+ // TODO(osa): Maybe 'prev' should be a pointer to the referencing
+ // *field* ? (instead of referencing *object*)
+ oc->prev->next = oc->next;
+ } else {
+ old_objects = oc->next;
+ }
+ if (oc->next != NULL) {
+ oc->next->prev = oc->prev;
+ }
- p = sp;
- while (p < stack_end) {
- info = get_ret_itbl((StgClosure *)p);
+ // Add it to 'objects' list
+ oc->prev = NULL;
+ oc->next = objects;
+ if (objects != NULL) {
+ objects->prev = oc;
+ }
+ objects = oc;
- switch (info->i.type) {
- case RET_SMALL:
- case RET_BIG:
- checkAddress(addrs, (const void*)info, s_indices);
- break;
+ // Mark its dependencies
+ iterHashTable(oc->dependencies, NULL, markObjectLive);
- default:
- break;
- }
+ return true; // for hash table iteration
+}
+
+void markObjectCode(const void *addr)
+{
+ if (global_s_indices == NULL) {
+ return;
+ }
- p += stack_frame_sizeW((StgClosure*)p);
+ // This should be checked at the call site
+ ASSERT(!HEAP_ALLOCED(addr));
+
+ ObjectCode *oc = findOC(global_s_indices, addr);
+ if (oc != NULL) {
+ // Mark the object code and its dependencies
+ markObjectLive(NULL, (W_)oc, NULL);
}
}
-
-static void searchHeapBlocks (HashTable *addrs, bdescr *bd,
- OCSectionIndices *s_indices)
+// Returns whether or not the GC that follows needs to mark code for potential
+// unloading.
+bool prepareUnloadCheck()
{
- StgPtr p;
- const StgInfoTable *info;
- uint32_t size;
- bool prim;
+ if (global_s_indices == NULL) {
+ return false;
+ }
- for (; bd != NULL; bd = bd->link) {
+ removeRemovedOCSections(global_s_indices);
+ sortOCSectionIndices(global_s_indices);
- if (bd->flags & BF_PINNED) {
- // Assume that objects in PINNED blocks cannot refer to
- continue;
- }
+ ASSERT(old_objects == NULL);
- p = bd->start;
- while (p < bd->free) {
- info = get_itbl((StgClosure *)p);
- prim = false;
-
- switch (info->type) {
-
- case THUNK:
- size = thunk_sizeW_fromITBL(info);
- break;
-
- case THUNK_1_1:
- case THUNK_0_2:
- case THUNK_2_0:
- size = sizeofW(StgThunkHeader) + 2;
- break;
-
- case THUNK_1_0:
- case THUNK_0_1:
- case THUNK_SELECTOR:
- size = sizeofW(StgThunkHeader) + 1;
- break;
-
- case FUN:
- case FUN_1_0:
- case FUN_0_1:
- case FUN_1_1:
- case FUN_0_2:
- case FUN_2_0:
- case CONSTR:
- case CONSTR_NOCAF:
- case CONSTR_1_0:
- case CONSTR_0_1:
- case CONSTR_1_1:
- case CONSTR_0_2:
- case CONSTR_2_0:
- size = sizeW_fromITBL(info);
- break;
-
- case BLACKHOLE:
- case BLOCKING_QUEUE:
- prim = true;
- size = sizeW_fromITBL(info);
- break;
-
- case IND:
- // Special case/Delicate Hack: INDs don't normally
- // appear, since we're doing this heap census right
- // after GC. However, GarbageCollect() also does
- // resurrectThreads(), which can update some
- // blackholes when it calls raiseAsync() on the
- // resurrected threads. So we know that any IND will
- // be the size of a BLACKHOLE.
- prim = true;
- size = BLACKHOLE_sizeW();
- break;
-
- case BCO:
- prim = true;
- size = bco_sizeW((StgBCO *)p);
- break;
-
- case MVAR_CLEAN:
- case MVAR_DIRTY:
- case TVAR:
- case WEAK:
- case PRIM:
- case MUT_PRIM:
- case MUT_VAR_CLEAN:
- case MUT_VAR_DIRTY:
- prim = true;
- size = sizeW_fromITBL(info);
- break;
-
- case AP:
- prim = true;
- size = ap_sizeW((StgAP *)p);
- break;
-
- case PAP:
- prim = true;
- size = pap_sizeW((StgPAP *)p);
- break;
-
- case AP_STACK:
- {
- StgAP_STACK *ap = (StgAP_STACK *)p;
- prim = true;
- size = ap_stack_sizeW(ap);
- searchStackChunk(addrs, (StgPtr)ap->payload,
- (StgPtr)ap->payload + ap->size, s_indices);
- break;
- }
+ object_code_mark_bit = ~object_code_mark_bit;
+ old_objects = objects;
+ objects = NULL;
+ return true;
+}
- case ARR_WORDS:
- prim = true;
- size = arr_words_sizeW((StgArrBytes*)p);
- break;
-
- case MUT_ARR_PTRS_CLEAN:
- case MUT_ARR_PTRS_DIRTY:
- case MUT_ARR_PTRS_FROZEN_CLEAN:
- case MUT_ARR_PTRS_FROZEN_DIRTY:
- prim = true;
- size = mut_arr_ptrs_sizeW((StgMutArrPtrs *)p);
- break;
-
- case SMALL_MUT_ARR_PTRS_CLEAN:
- case SMALL_MUT_ARR_PTRS_DIRTY:
- case SMALL_MUT_ARR_PTRS_FROZEN_CLEAN:
- case SMALL_MUT_ARR_PTRS_FROZEN_DIRTY:
- prim = true;
- size = small_mut_arr_ptrs_sizeW((StgSmallMutArrPtrs *)p);
- break;
-
- case TSO:
- prim = true;
- size = sizeofW(StgTSO);
- break;
-
- case STACK: {
- StgStack *stack = (StgStack*)p;
- prim = true;
- searchStackChunk(addrs, stack->sp,
- stack->stack + stack->stack_size, s_indices);
- size = stack_sizeW(stack);
- break;
- }
+void checkUnload()
+{
+ if (global_s_indices == NULL) {
+ return;
+ }
- case TREC_CHUNK:
- prim = true;
- size = sizeofW(StgTRecChunk);
- break;
+ // At this point we've marked all dynamically loaded static objects
+ // (including their dependencies) during GC, but not the root set of object
+ // code (loaded_objects). Mark the roots first, then unload any unmarked
+ // objects.
- default:
- barf("searchHeapBlocks, unknown object: %d", info->type);
- }
+ OCSectionIndices *s_indices = global_s_indices;
+ ASSERT(s_indices->sorted);
- if (!prim) {
- checkAddress(addrs,info, s_indices);
- }
-
- p += size;
- }
+ // Mark roots
+ for (ObjectCode *oc = loaded_objects; oc != NULL; oc = oc->next_loaded_object) {
+ markObjectLive(NULL, (W_)oc, NULL);
}
-}
-#if defined(PROFILING)
-//
-// Do not unload the object if the CCS tree refers to a CCS or CC which
-// originates in the object.
-//
-static void searchCostCentres (HashTable *addrs, CostCentreStack *ccs,
- OCSectionIndices* s_indices)
-{
- IndexTable *i;
+ // Free unmarked objects
+ ObjectCode *next = NULL;
+ for (ObjectCode *oc = old_objects; oc != NULL; oc = next) {
+ next = oc->next;
- checkAddress(addrs, ccs, s_indices);
- checkAddress(addrs, ccs->cc, s_indices);
- for (i = ccs->indexTable; i != NULL; i = i->next) {
- if (!i->back_edge) {
- searchCostCentres(addrs, i->ccs, s_indices);
- }
+ removeOCSectionIndices(s_indices, oc);
+
+ // Symbols should be removed by unloadObj_.
+ // NB (osa): If this assertion doesn't hold then freeObjectCode below
+ // will corrupt symhash as keys of that table live in ObjectCodes. If
+ // you see a segfault in a hash table operation in linker (in non-debug
+ // RTS) then it's probably becuse this assertion did not hold.
+ ASSERT(oc->symbols == NULL);
+
+ freeObjectCode(oc);
+ n_unloaded_objects -= 1;
}
-}
-#endif
-//
-// Check whether we can unload any object code. This is called at the
-// appropriate point during a GC, where all the heap data is nice and
-// packed together and we have a linked list of the static objects.
-//
-// The check involves a complete heap traversal, but you only pay for
-// this (a) when you have called unloadObj(), and (b) at a major GC,
-// which is much more expensive than the traversal we're doing here.
-//
-void checkUnload (StgClosure *static_objects)
-{
- uint32_t g, n;
- HashTable *addrs;
- StgClosure* p;
- const StgInfoTable *info;
- ObjectCode *oc, *prev, *next;
- gen_workspace *ws;
- StgClosure* link;
-
- if (unloaded_objects == NULL) return;
-
- ACQUIRE_LOCK(&linker_unloaded_mutex);
-
- OCSectionIndices *s_indices = buildOCSectionIndices(unloaded_objects);
- // Mark every unloadable object as unreferenced initially
- for (oc = unloaded_objects; oc; oc = oc->next) {
- IF_DEBUG(linker, debugBelch("Checking whether to unload %" PATH_FMT "\n",
- oc->fileName));
- oc->referenced = false;
- }
-
- addrs = allocHashTable();
-
- for (p = static_objects; p != END_OF_STATIC_OBJECT_LIST; p = link) {
- p = UNTAG_STATIC_LIST_PTR(p);
- checkAddress(addrs, p, s_indices);
- info = get_itbl(p);
- checkAddress(addrs, info, s_indices);
- link = *STATIC_LINK(info, p);
- }
-
- // CAFs on revertible_caf_list are not on static_objects
- for (p = (StgClosure*)revertible_caf_list;
- p != END_OF_CAF_LIST;
- p = ((StgIndStatic *)p)->static_link) {
- p = UNTAG_STATIC_LIST_PTR(p);
- checkAddress(addrs, p, s_indices);
- }
-
- for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
- searchHeapBlocks (addrs, generations[g].blocks, s_indices);
- searchHeapBlocks (addrs, generations[g].large_objects, s_indices);
-
- for (n = 0; n < n_capabilities; n++) {
- ws = &gc_threads[n]->gens[g];
- searchHeapBlocks(addrs, ws->todo_bd, s_indices);
- searchHeapBlocks(addrs, ws->part_list, s_indices);
- searchHeapBlocks(addrs, ws->scavd_list, s_indices);
- }
- }
-
-#if defined(PROFILING)
- /* Traverse the cost centre tree, calling checkAddress on each CCS/CC */
- searchCostCentres(addrs, CCS_MAIN, s_indices);
-
- /* Also check each cost centre in the CC_LIST */
- CostCentre *cc;
- for (cc = CC_LIST; cc != NULL; cc = cc->link) {
- checkAddress(addrs, cc, s_indices);
- }
-#endif /* PROFILING */
-
- freeOCSectionIndices(s_indices);
- // Look through the unloadable objects, and any object that is still
- // marked as unreferenced can be physically unloaded, because we
- // have no references to it.
- prev = NULL;
- for (oc = unloaded_objects; oc; oc = next) {
- next = oc->next;
- if (oc->referenced == 0) {
- if (prev == NULL) {
- unloaded_objects = oc->next;
- } else {
- prev->next = oc->next;
- }
- IF_DEBUG(linker, debugBelch("Unloading object file %" PATH_FMT "\n",
- oc->fileName));
- freeObjectCode(oc);
- } else {
- IF_DEBUG(linker, debugBelch("Object file still in use: %"
- PATH_FMT "\n", oc->fileName));
- prev = oc;
- }
- }
-
- freeHashTable(addrs, NULL);
-
- RELEASE_LOCK(&linker_unloaded_mutex);
+ old_objects = NULL;
}
=====================================
rts/CheckUnload.h
=====================================
@@ -12,6 +12,34 @@
#include "BeginPrivate.h"
-void checkUnload (StgClosure *static_objects);
+#include "LinkerInternals.h"
+
+// Currently live objects
+extern ObjectCode *objects;
+
+// Root set for object collection
+extern ObjectCode *loaded_objects;
+
+// Mark bit for live objects
+extern uint8_t object_code_mark_bit;
+
+// Number of object code currently marked for unloading. See the definition in
+// CheckUnload.c for details.
+extern int n_unloaded_objects;
+
+void initUnloadCheck(void);
+void exitUnloadCheck(void);
+
+// Call before major GC to prepare section index table for marking
+bool prepareUnloadCheck(void);
+
+// Mark object code of a static closure address as 'live'
+void markObjectCode(const void *addr);
+
+// Call after major GC to unload unused and unmarked object code
+void checkUnload(void);
+
+// Call on loaded object code
+void insertOCSectionIndices(ObjectCode *oc);
#include "EndPrivate.h"
=====================================
rts/Hash.c
=====================================
@@ -400,6 +400,27 @@ mapHashTable(HashTable *table, void *data, MapHashFn fn)
}
}
+void
+iterHashTable(HashTable *table, void *data, IterHashFn fn)
+{
+ /* The last bucket with something in it is table->max + table->split - 1 */
+ long segment = (table->max + table->split - 1) / HSEGSIZE;
+ long index = (table->max + table->split - 1) % HSEGSIZE;
+
+ while (segment >= 0) {
+ while (index >= 0) {
+ for (HashList *hl = table->dir[segment][index]; hl != NULL; hl = hl->next) {
+ if (!fn(data, hl->key, hl->data)) {
+ return;
+ }
+ }
+ index--;
+ }
+ segment--;
+ index = HSEGSIZE - 1;
+ }
+}
+
/* -----------------------------------------------------------------------------
* When we initialize a hash table, we set up the first segment as well,
* initializing all of the first segment's hash buckets to NULL.
@@ -444,12 +465,6 @@ allocStrHashTable(void)
return allocHashTable_(hashStr, compareStr);
}
-void
-exitHashTable(void)
-{
- /* nothing to do */
-}
-
int keyCountHashTable (HashTable *table)
{
return table->kcount;
=====================================
rts/Hash.h
=====================================
@@ -33,8 +33,11 @@ int keyCountHashTable (HashTable *table);
int keysHashTable(HashTable *table, StgWord keys[], int szKeys);
typedef void (*MapHashFn)(void *data, StgWord key, const void *value);
+// Return true -> continue; false -> stop
+typedef bool (*IterHashFn)(void *data, StgWord key, const void *value);
void mapHashTable(HashTable *table, void *data, MapHashFn fn);
+void iterHashTable(HashTable *table, void *data, IterHashFn);
/* Hash table access where the keys are C strings (the strings are
* assumed to be allocated by the caller, and mustn't be deallocated
@@ -62,6 +65,32 @@ int hashStr(const HashTable *table, StgWord key);
*/
void freeHashTable ( HashTable *table, void (*freeDataFun)(void *) );
-void exitHashTable ( void );
+INLINE_HEADER void freeStrHashTable ( StrHashTable *table, void (*freeDataFun)(void *) )
+{
+ freeHashTable((HashTable*)table, freeDataFun);
+}
+
+/*
+ * Hash set API
+ *
+ * A hash set is bascially a hash table where values are NULL.
+ */
+
+typedef struct hashtable HashSet;
+
+INLINE_HEADER HashSet *allocHashSet ( void )
+{
+ return (HashSet*)allocHashTable();
+}
+
+INLINE_HEADER void freeHashSet ( HashSet *set )
+{
+ freeHashTable((HashTable*)set, NULL);
+}
+
+INLINE_HEADER void insertHashSet ( HashSet *set, StgWord key )
+{
+ insertHashTable((HashTable*)set, key, NULL);
+}
#include "EndPrivate.h"
=====================================
rts/Linker.c
=====================================
@@ -32,6 +32,7 @@
#include "linker/CacheFlush.h"
#include "linker/SymbolExtras.h"
#include "PathUtils.h"
+#include "CheckUnload.h" // createOCSectionIndices
#if !defined(mingw32_HOST_OS)
#include "posix/Signals.h"
@@ -161,23 +162,9 @@
*/
/*Str*/HashTable *symhash;
-/* List of currently loaded objects */
-ObjectCode *objects = NULL; /* initially empty */
-
-/* List of objects that have been unloaded via unloadObj(), but are waiting
- to be actually freed via checkUnload() */
-ObjectCode *unloaded_objects = NULL; /* initially empty */
-
#if defined(THREADED_RTS)
-/* This protects all the Linker's global state except unloaded_objects */
+/* This protects all the Linker's global state */
Mutex linker_mutex;
-/*
- * This protects unloaded_objects. We have a separate mutex for this, because
- * the GC needs to access unloaded_objects in checkUnload, while the linker only
- * needs to access unloaded_objects in unloadObj(), so this allows most linker
- * operations proceed concurrently with the GC.
- */
-Mutex linker_unloaded_mutex;
#endif
/* Generic wrapper function to try and Resolve and RunInit oc files */
@@ -447,12 +434,10 @@ initLinker_ (int retain_cafs)
linker_init_done = 1;
}
- objects = NULL;
- unloaded_objects = NULL;
+ initUnloadCheck();
#if defined(THREADED_RTS)
initMutex(&linker_mutex);
- initMutex(&linker_unloaded_mutex);
#if defined(OBJFORMAT_ELF) || defined(OBJFORMAT_MACHO)
initMutex(&dl_mutex);
#endif
@@ -538,6 +523,7 @@ exitLinker( void ) {
#endif
if (linker_init_done == 1) {
freeHashTable(symhash, free);
+ exitUnloadCheck();
}
#if defined(THREADED_RTS)
closeMutex(&linker_mutex);
@@ -864,18 +850,24 @@ HsInt insertSymbol(pathchar* obj_name, SymbolName* key, SymbolAddr* data)
}
/* -----------------------------------------------------------------------------
- * lookup a symbol in the hash table
+ * Lookup a symbol in the hash table
+ *
+ * When 'dependent' is not NULL, adds it as a dependent to the owner of the
+ * symbol.
*/
#if defined(OBJFORMAT_PEi386)
-SymbolAddr* lookupSymbol_ (SymbolName* lbl)
+SymbolAddr* lookupDependentSymbol (SymbolName* lbl, ObjectCode *dependent)
{
+ (void)dependent; // TODO
+ ASSERT_LOCK_HELD(&linker_mutex);
return lookupSymbol_PEi386(lbl);
}
#else
-SymbolAddr* lookupSymbol_ (SymbolName* lbl)
+SymbolAddr* lookupDependentSymbol (SymbolName* lbl, ObjectCode *dependent)
{
+ ASSERT_LOCK_HELD(&linker_mutex);
IF_DEBUG(linker, debugBelch("lookupSymbol: looking up '%s'\n", lbl));
ASSERT(symhash != NULL);
@@ -900,10 +892,18 @@ SymbolAddr* lookupSymbol_ (SymbolName* lbl)
return internal_dlsym(lbl + 1);
# else
- ASSERT(2+2 == 5);
+ ASSERT(false);
return NULL;
# endif
} else {
+ if (dependent) {
+ // Add dependent as symbol's owner's dependency
+ ObjectCode *owner = pinfo->owner;
+ if (owner) {
+ // TODO: what does it mean for a symbol to not have an owner?
+ insertHashSet(dependent->dependencies, (W_)owner);
+ }
+ }
return loadSymbol(lbl, pinfo);
}
}
@@ -1342,6 +1342,8 @@ void freeObjectCode (ObjectCode *oc)
stgFree(oc->fileName);
stgFree(oc->archiveMemberName);
+ freeHashSet(oc->dependencies);
+
stgFree(oc);
}
@@ -1403,6 +1405,10 @@ mkOc( pathchar *path, char *image, int imageSize,
/* chain it onto the list of objects */
oc->next = NULL;
+ oc->prev = NULL;
+ oc->next_loaded_object = NULL;
+ oc->mark = object_code_mark_bit;
+ oc->dependencies = allocHashSet();
#if RTS_LINKER_USE_MMAP
oc->rw_m32 = m32_allocator_new(false);
@@ -1421,9 +1427,9 @@ mkOc( pathchar *path, char *image, int imageSize,
HsInt
isAlreadyLoaded( pathchar *path )
{
- ObjectCode *o;
- for (o = objects; o; o = o->next) {
- if (0 == pathcmp(o->fileName, path)) {
+ for (ObjectCode *o = objects; o; o = o->next) {
+ if (0 == pathcmp(o->fileName, path)
+ && o->status != OBJECT_UNLOADED) {
return 1; /* already loaded */
}
}
@@ -1557,21 +1563,16 @@ preloadObjectFile (pathchar *path)
*/
static HsInt loadObj_ (pathchar *path)
{
- ObjectCode* oc;
- IF_DEBUG(linker, debugBelch("loadObj: %" PATH_FMT "\n", path));
-
- /* debugBelch("loadObj %s\n", path ); */
-
- /* Check that we haven't already loaded this object.
- Ignore requests to load multiple times */
+ // Check that we haven't already loaded this object.
+ // Ignore requests to load multiple times
if (isAlreadyLoaded(path)) {
IF_DEBUG(linker,
debugBelch("ignoring repeated load of %" PATH_FMT "\n", path));
- return 1; /* success */
+ return 1; // success
}
- oc = preloadObjectFile(path);
+ ObjectCode *oc = preloadObjectFile(path);
if (oc == NULL) return 0;
if (! loadOc(oc)) {
@@ -1582,8 +1583,10 @@ static HsInt loadObj_ (pathchar *path)
return 0;
}
- oc->next = objects;
- objects = oc;
+ insertOCSectionIndices(oc);
+
+ oc->next_loaded_object = loaded_objects;
+ loaded_objects = oc;
return 1;
}
@@ -1778,15 +1781,15 @@ int ocTryLoad (ObjectCode* oc) {
*/
static HsInt resolveObjs_ (void)
{
- ObjectCode *oc;
- int r;
-
IF_DEBUG(linker, debugBelch("resolveObjs: start\n"));
- for (oc = objects; oc; oc = oc->next) {
- r = ocTryLoad(oc);
+ for (ObjectCode *oc = objects; oc; oc = oc->next) {
+ int r = ocTryLoad(oc);
if (!r)
{
+ errorBelch("Could not load Object Code %" PATH_FMT ".\n", OC_INFORMATIVE_FILENAME(oc));
+ IF_DEBUG(linker, printLoadedObjects());
+ fflush(stderr);
return r;
}
}
@@ -1813,45 +1816,35 @@ HsInt resolveObjs (void)
*/
static HsInt unloadObj_ (pathchar *path, bool just_purge)
{
- ObjectCode *oc, *prev, *next;
- HsBool unloadedAnyObj = HS_BOOL_FALSE;
-
ASSERT(symhash != NULL);
ASSERT(objects != NULL);
IF_DEBUG(linker, debugBelch("unloadObj: %" PATH_FMT "\n", path));
- prev = NULL;
- for (oc = objects; oc; oc = next) {
- next = oc->next; // oc might be freed
-
- if (!pathcmp(oc->fileName,path)) {
+ bool unloadedAnyObj = false;
+ ObjectCode *prev = NULL;
+ // NOTE (osa): There may be more than one object with the same file name
+ // (happens when loading archive files) so we don't stop after unloading one
+ for (ObjectCode *oc = loaded_objects; oc; oc = oc->next_loaded_object) {
+ if (pathcmp(oc->fileName,path) == 0) {
+ oc->status = OBJECT_UNLOADED;
- // these are both idempotent, so in just_purge mode we can
- // later call unloadObj() to really unload the object.
+ // These are both idempotent, so in just_purge mode we can later
+ // call unloadObj() to really unload the object.
removeOcSymbols(oc);
freeOcStablePtrs(oc);
+ unloadedAnyObj = true;
+
if (!just_purge) {
+ n_unloaded_objects += 1;
+ // Remove object code from root set
if (prev == NULL) {
- objects = oc->next;
+ loaded_objects = oc->next_loaded_object;
} else {
- prev->next = oc->next;
+ prev->next_loaded_object = oc->next_loaded_object;
}
- ACQUIRE_LOCK(&linker_unloaded_mutex);
- oc->next = unloaded_objects;
- unloaded_objects = oc;
- oc->status = OBJECT_UNLOADED;
- RELEASE_LOCK(&linker_unloaded_mutex);
- // We do not own oc any more; it can be released at any time by
- // the GC in checkUnload().
- } else {
- prev = oc;
}
-
- /* This could be a member of an archive so continue
- * unloading other members. */
- unloadedAnyObj = HS_BOOL_TRUE;
} else {
prev = oc;
}
@@ -1859,8 +1852,7 @@ static HsInt unloadObj_ (pathchar *path, bool just_purge)
if (unloadedAnyObj) {
return 1;
- }
- else {
+ } else {
errorBelch("unloadObj: can't find `%" PATH_FMT "' to unload", path);
return 0;
}
@@ -1884,13 +1876,7 @@ HsInt purgeObj (pathchar *path)
static OStatus getObjectLoadStatus_ (pathchar *path)
{
- ObjectCode *o;
- for (o = objects; o; o = o->next) {
- if (0 == pathcmp(o->fileName, path)) {
- return o->status;
- }
- }
- for (o = unloaded_objects; o; o = o->next) {
+ for (ObjectCode *o = objects; o; o = o->next) {
if (0 == pathcmp(o->fileName, path)) {
return o->status;
}
=====================================
rts/LinkerInternals.h
=====================================
@@ -191,9 +191,6 @@ typedef struct _ObjectCode {
/* non-zero if the object file was mmap'd, otherwise malloc'd */
int imageMapped;
- /* flag used when deciding whether to unload an object file */
- int referenced;
-
/* record by how much image has been deliberately misaligned
after allocation, so that we can use realloc */
int misalignment;
@@ -205,8 +202,37 @@ typedef struct _ObjectCode {
int n_segments;
Segment *segments;
- /* Allow a chain of these things */
- struct _ObjectCode * next;
+ //
+ // Garbage collection fields
+ //
+
+ // Next object in `objects` list
+ struct _ObjectCode *next;
+
+ // Previous object in `objects` list
+ struct _ObjectCode *prev;
+
+ // Next object in `loaded_objects` list
+ struct _ObjectCode *next_loaded_object;
+
+ // Mark bit
+ uint8_t mark;
+
+ // Set of dependencies (ObjectCode*) of the object file. Traverse
+ // dependencies using `iterHashTable`.
+ //
+ // New entries are added as we resolve symbols in an object file, in
+ // `lookupDependentSymbol`. When an object file uses multiple symbols from
+ // another object file we add the dependent multiple times, so we use a
+ // `HashTable` here rather than a list/array to avoid copies.
+ //
+ // Used when unloading object files. See Note [Object unloading] in
+ // CheckUnload.c.
+ HashSet *dependencies;
+
+ //
+ // End of garbage collection fields
+ //
/* SANITY CHECK ONLY: a list of the only memory regions which may
safely be prodded during relocation. Any attempt to prod
@@ -250,12 +276,8 @@ typedef struct _ObjectCode {
(OC)->fileName \
)
-extern ObjectCode *objects;
-extern ObjectCode *unloaded_objects;
-
#if defined(THREADED_RTS)
extern Mutex linker_mutex;
-extern Mutex linker_unloaded_mutex;
#endif
/* Type of the initializer */
@@ -306,8 +328,9 @@ int ghciInsertSymbolTable(
HsBool weak,
ObjectCode *owner);
-/* lock-free version of lookupSymbol */
-SymbolAddr* lookupSymbol_ (SymbolName* lbl);
+/* Lock-free version of lookupSymbol. When 'dependent' is not NULL, adds it as a
+ * dependent to the owner of the symbol. */
+SymbolAddr* lookupDependentSymbol (SymbolName* lbl, ObjectCode *dependent);
extern /*Str*/HashTable *symhash;
=====================================
rts/PrimOps.cmm
=====================================
@@ -1816,9 +1816,16 @@ loop:
// There are readMVar/takeMVar(s) waiting: wake up the first one
tso = StgMVarTSOQueue_tso(q);
- StgMVar_head(mvar) = StgMVarTSOQueue_link(q);
- if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
+ q = StgMVarTSOQueue_link(q);
+ StgMVar_head(mvar) = q;
+ if (q == stg_END_TSO_QUEUE_closure) {
StgMVar_tail(mvar) = stg_END_TSO_QUEUE_closure;
+ } else {
+ if (info == stg_MVAR_CLEAN_info) {
+ // Resolve #18919.
+ ccall dirty_MVAR(BaseReg "ptr", mvar "ptr",
+ StgMVar_value(mvar) "ptr");
+ }
}
ASSERT(StgTSO_block_info(tso) == mvar);
@@ -1843,10 +1850,8 @@ loop:
// If it was a readMVar, then we can still do work,
// so loop back. (XXX: This could take a while)
- if (why_blocked == BlockedOnMVarRead) {
- q = StgMVarTSOQueue_link(q);
+ if (why_blocked == BlockedOnMVarRead)
goto loop;
- }
ASSERT(why_blocked == BlockedOnMVar);
@@ -1901,9 +1906,16 @@ loop:
// There are takeMVar(s) waiting: wake up the first one
tso = StgMVarTSOQueue_tso(q);
- StgMVar_head(mvar) = StgMVarTSOQueue_link(q);
- if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
+ q = StgMVarTSOQueue_link(q);
+ StgMVar_head(mvar) = q;
+ if (q == stg_END_TSO_QUEUE_closure) {
StgMVar_tail(mvar) = stg_END_TSO_QUEUE_closure;
+ } else {
+ if (info == stg_MVAR_CLEAN_info) {
+ // Resolve #18919.
+ ccall dirty_MVAR(BaseReg "ptr", mvar "ptr",
+ StgMVar_value(mvar) "ptr");
+ }
}
ASSERT(StgTSO_block_info(tso) == mvar);
@@ -1928,10 +1940,8 @@ loop:
// If it was a readMVar, then we can still do work,
// so loop back. (XXX: This could take a while)
- if (why_blocked == BlockedOnMVarRead) {
- q = StgMVarTSOQueue_link(q);
+ if (why_blocked == BlockedOnMVarRead)
goto loop;
- }
ASSERT(why_blocked == BlockedOnMVar);
=====================================
rts/RtsStartup.c
=====================================
@@ -512,9 +512,6 @@ hs_exit_(bool wait_foreign)
shutdownAsyncIO(wait_foreign);
#endif
- /* free hash table storage */
- exitHashTable();
-
// Finally, free all our storage. However, we only free the heap
// memory if we have waited for foreign calls to complete;
// otherwise a foreign call in progress may still be referencing
=====================================
rts/Threads.c
=====================================
@@ -790,9 +790,14 @@ loop:
// There are takeMVar(s) waiting: wake up the first one
tso = q->tso;
- mvar->head = q->link;
- if (mvar->head == (StgMVarTSOQueue*)&stg_END_TSO_QUEUE_closure) {
+ mvar->head = q = q->link;
+ if (q == (StgMVarTSOQueue*)&stg_END_TSO_QUEUE_closure) {
mvar->tail = (StgMVarTSOQueue*)&stg_END_TSO_QUEUE_closure;
+ } else {
+ if (info == &stg_MVAR_CLEAN_info) {
+ // Resolve #18919.
+ dirty_MVAR(&cap->r, (StgClosure*)mvar, mvar->value);
+ }
}
ASSERT(tso->block_info.closure == (StgClosure*)mvar);
@@ -816,10 +821,8 @@ loop:
// If it was a readMVar, then we can still do work,
// so loop back. (XXX: This could take a while)
- if (why_blocked == BlockedOnMVarRead) {
- q = ((StgMVarTSOQueue*)q)->link;
+ if (why_blocked == BlockedOnMVarRead)
goto loop;
- }
ASSERT(why_blocked == BlockedOnMVar);
=====================================
rts/linker/Elf.c
=====================================
@@ -1099,7 +1099,7 @@ do_Elf_Rel_relocations ( ObjectCode* oc, char* ehdrC,
if (ELF_ST_BIND(symbol->elf_sym->st_info) == STB_LOCAL || strncmp(symbol->name, "_GLOBAL_OFFSET_TABLE_", 21) == 0) {
S = (Elf_Addr)symbol->addr;
} else {
- S_tmp = lookupSymbol_( symbol->name );
+ S_tmp = lookupDependentSymbol( symbol->name, oc );
S = (Elf_Addr)S_tmp;
}
if (!S) {
@@ -1519,7 +1519,7 @@ do_Elf_Rela_relocations ( ObjectCode* oc, char* ehdrC,
} else {
/* No, so look up the name in our global table. */
symbol = strtab + sym.st_name;
- S_tmp = lookupSymbol_( symbol );
+ S_tmp = lookupDependentSymbol( symbol, oc );
S = (Elf_Addr)S_tmp;
}
if (!S) {
=====================================
rts/linker/LoadArchive.c
=====================================
@@ -5,6 +5,7 @@
#include "sm/OSMem.h"
#include "RtsUtils.h"
#include "LinkerInternals.h"
+#include "CheckUnload.h" // loaded_objects, insertOCSectionIndices
#include "linker/M32Alloc.h"
/* Platform specific headers */
@@ -241,7 +242,6 @@ lookupGNUArchiveIndex(int gnuFileIndexSize, char **fileName_,
static HsInt loadArchive_ (pathchar *path)
{
- ObjectCode* oc = NULL;
char *image = NULL;
HsInt retcode = 0;
int memberSize;
@@ -520,8 +520,8 @@ static HsInt loadArchive_ (pathchar *path)
sprintf(archiveMemberName, "%" PATH_FMT "(%.*s)",
path, (int)thisFileNameSize, fileName);
- oc = mkOc(path, image, memberSize, false, archiveMemberName
- , misalignment);
+ ObjectCode *oc = mkOc(path, image, memberSize, false, archiveMemberName,
+ misalignment);
#if defined(OBJFORMAT_MACHO)
ocInit_MachO( oc );
#endif
@@ -536,8 +536,9 @@ static HsInt loadArchive_ (pathchar *path)
fclose(f);
return 0;
} else {
- oc->next = objects;
- objects = oc;
+ insertOCSectionIndices(oc); // also adds the object to `objects` list
+ oc->next_loaded_object = loaded_objects;
+ loaded_objects = oc;
}
}
else if (isGnuIndex) {
=====================================
rts/linker/MachO.c
=====================================
@@ -242,7 +242,7 @@ resolveImports(
addr = (SymbolAddr*) (symbol->nlist->n_value);
IF_DEBUG(linker, debugBelch("resolveImports: undefined external %s has value %p\n", symbol->name, addr));
} else {
- addr = lookupSymbol_(symbol->name);
+ addr = lookupDependentSymbol(symbol->name, oc);
IF_DEBUG(linker, debugBelch("resolveImports: looking up %s, %p\n", symbol->name, addr));
}
@@ -564,12 +564,12 @@ relocateSectionAarch64(ObjectCode * oc, Section * section)
uint64_t value = 0;
if(symbol->nlist->n_type & N_EXT) {
/* external symbols should be able to be
- * looked up via the lookupSymbol_ function.
+ * looked up via the lookupDependentSymbol function.
* Either through the global symbol hashmap
* or asking the system, if not found
* in the symbol hashmap
*/
- value = (uint64_t)lookupSymbol_((char*)symbol->name);
+ value = (uint64_t)lookupDependentSymbol((char*)symbol->name, oc);
if(!value)
barf("Could not lookup symbol: %s!", symbol->name);
} else {
@@ -609,7 +609,7 @@ relocateSectionAarch64(ObjectCode * oc, Section * section)
uint64_t pc = (uint64_t)section->start + ri->r_address;
uint64_t value = 0;
if(symbol->nlist->n_type & N_EXT) {
- value = (uint64_t)lookupSymbol_((char*)symbol->name);
+ value = (uint64_t)lookupDependentSymbol((char*)symbol->name, oc);
if(!value)
barf("Could not lookup symbol: %s!", symbol->name);
} else {
@@ -784,7 +784,7 @@ relocateSection(ObjectCode* oc, int curSection)
// symtab, or it is undefined, meaning dlsym must be used
// to resolve it.
- addr = lookupSymbol_(nm);
+ addr = lookupDependentSymbol(nm, oc);
IF_DEBUG(linker, debugBelch("relocateSection: looked up %s, "
"external X86_64_RELOC_GOT or X86_64_RELOC_GOT_LOAD\n"
" : addr = %p\n", nm, addr));
@@ -845,7 +845,7 @@ relocateSection(ObjectCode* oc, int curSection)
nm, (void *)value));
}
else {
- addr = lookupSymbol_(nm);
+ addr = lookupDependentSymbol(nm, oc);
if (addr == NULL)
{
errorBelch("\nlookupSymbol failed in relocateSection (relocate external)\n"
@@ -1345,7 +1345,7 @@ ocGetNames_MachO(ObjectCode* oc)
if (oc->info->nlist[i].n_type & N_EXT)
{
if ( (oc->info->nlist[i].n_desc & N_WEAK_DEF)
- && lookupSymbol_(nm)) {
+ && lookupDependentSymbol(nm, oc)) {
// weak definition, and we already have a definition
IF_DEBUG(linker, debugBelch(" weak: %s\n", nm));
}
@@ -1497,7 +1497,7 @@ ocResolve_MachO(ObjectCode* oc)
* have the address.
*/
if(NULL == symbol->addr) {
- symbol->addr = lookupSymbol_((char*)symbol->name);
+ symbol->addr = lookupDependentSymbol((char*)symbol->name, oc);
if(NULL == symbol->addr)
barf("Failed to lookup symbol: %s", symbol->name);
} else {
=====================================
rts/linker/PEi386.c
=====================================
@@ -185,6 +185,7 @@
#include "RtsUtils.h"
#include "RtsSymbolInfo.h"
#include "GetEnv.h"
+#include "CheckUnload.h"
#include "linker/PEi386.h"
#include "linker/PEi386Types.h"
#include "linker/SymbolExtras.h"
@@ -1894,7 +1895,7 @@ ocResolve_PEi386 ( ObjectCode* oc )
} else {
copyName ( getSymShortName (info, sym), oc, symbol,
sizeof(symbol)-1 );
- S = (size_t) lookupSymbol_( (char*)symbol );
+ S = (size_t) lookupDependentSymbol( (char*)symbol, oc );
if ((void*)S == NULL) {
errorBelch(" | %" PATH_FMT ": unknown symbol `%s'", oc->fileName, symbol);
releaseOcInfo (oc);
=====================================
rts/linker/elf_got.c
=====================================
@@ -88,7 +88,7 @@ fillGot(ObjectCode * oc) {
if( STT_NOTYPE == ELF_ST_TYPE(symbol->elf_sym->st_info)
|| STB_WEAK == ELF_ST_BIND(symbol->elf_sym->st_info)) {
if(0x0 == symbol->addr) {
- symbol->addr = lookupSymbol_(symbol->name);
+ symbol->addr = lookupDependentSymbol(symbol->name, oc);
if(0x0 == symbol->addr) {
if(0 == strncmp(symbol->name,"_GLOBAL_OFFSET_TABLE_",21)) {
symbol->addr = oc->info->got_start;
=====================================
rts/sm/Evac.c
=====================================
@@ -28,6 +28,7 @@
#include "CNF.h"
#include "Scav.h"
#include "NonMoving.h"
+#include "CheckUnload.h" // n_unloaded_objects and markObjectCode
#if defined(THREADED_RTS) && !defined(PARALLEL_GC)
#define evacuate(p) evacuate1(p)
@@ -593,6 +594,11 @@ loop:
if (!HEAP_ALLOCED_GC(q)) {
if (!major_gc) return;
+ // Note [Object unloading] in CheckUnload.c
+ if (RTS_UNLIKELY(unload_mark_needed)) {
+ markObjectCode(q);
+ }
+
info = get_itbl(q);
switch (info->type) {
=====================================
rts/sm/GC.c
=====================================
@@ -97,6 +97,13 @@
* See also: Note [STATIC_LINK fields] in Storage.h.
*/
+/* Hot GC globals
+ * ~~~~~~~~~~~~~~
+ * The globals below are quite hot during GC but read-only, initialized during
+ * the beginning of collection. It is important that they reside in the same
+ * cache-line to minimize unnecessary cache misses.
+ */
+
/* N is the oldest generation being collected, where the generations
* are numbered starting at 0. A major GC (indicated by the major_gc
* flag) is when we're collecting all generations. We only attempt to
@@ -105,6 +112,7 @@
uint32_t N;
bool major_gc;
bool deadlock_detect_gc;
+bool unload_mark_needed;
/* Data used for allocation area sizing.
*/
@@ -297,6 +305,12 @@ GarbageCollect (uint32_t collect_gen,
static_flag == STATIC_FLAG_A ? STATIC_FLAG_B : STATIC_FLAG_A;
}
+ if (major_gc) {
+ unload_mark_needed = prepareUnloadCheck();
+ } else {
+ unload_mark_needed = false;
+ }
+
#if defined(THREADED_RTS)
work_stealing = RtsFlags.ParFlags.parGcLoadBalancingEnabled &&
N >= RtsFlags.ParFlags.parGcLoadBalancingGen;
@@ -810,9 +824,12 @@ GarbageCollect (uint32_t collect_gen,
resetNurseries();
- // mark the garbage collected CAFs as dead
#if defined(DEBUG)
- if (major_gc && !RtsFlags.GcFlags.useNonmoving) { gcCAFs(); }
+ // Mark the garbage collected CAFs as dead. Done in `nonmovingGcCafs()` when
+ // non-moving GC is enabled.
+ if (major_gc && !RtsFlags.GcFlags.useNonmoving) {
+ gcCAFs();
+ }
#endif
// Update the stable name hash table
@@ -823,9 +840,14 @@ GarbageCollect (uint32_t collect_gen,
// hs_free_stable_ptr(), both of which access the StablePtr table.
stablePtrUnlock();
- // Must be after stablePtrUnlock(), because it might free stable ptrs.
- if (major_gc) {
- checkUnload (gct->scavenged_static_objects);
+ // Unload dynamically-loaded object code after a major GC.
+ // See Note [Object unloading] in CheckUnload.c for details.
+ //
+ // TODO: Similar to `nonmovingGcCafs` non-moving GC should have its own
+ // collector for these objects, but that's currently not implemented, so we
+ // simply don't unload object code when non-moving GC is enabled.
+ if (major_gc && !RtsFlags.GcFlags.useNonmoving) {
+ checkUnload();
}
#if defined(PROFILING)
=====================================
rts/sm/GC.h
=====================================
@@ -35,6 +35,7 @@ extern uint32_t N;
extern bool major_gc;
/* See Note [Deadlock detection under nonmoving collector]. */
extern bool deadlock_detect_gc;
+extern bool unload_mark_needed;
extern bdescr *mark_stack_bd;
extern bdescr *mark_stack_top_bd;
=====================================
testsuite/tests/ghci/T16525a/T16525a.script
=====================================
@@ -1,6 +1,10 @@
:set -fobject-code
:load A
import Control.Concurrent
-_ <- forkIO $ threadDelay 1000000 >> (print (map v1 value))
+_ <- forkIO $ threadDelay 500000 >> print (map v1 value)
:l []
System.Mem.performGC
+threadDelay 500000
+System.Mem.performGC
+threadDelay 500000
+System.Mem.performGC
=====================================
testsuite/tests/ghci/T16525a/T16525a.stdout
=====================================
@@ -0,0 +1 @@
+["a;lskdfa;lszkfsd;alkfjas"]
=====================================
testsuite/tests/ghci/T16525a/all.T
=====================================
@@ -1,6 +1,3 @@
test('T16525a',
- [extra_files(['A.hs', 'B.hs', ]),
- when(compiler_debugged(), extra_run_opts('+RTS -DS -RTS')),
- # We don't support unloading with the dynamic linker
- when(ghc_dynamic(), skip), ],
+ [extra_files(['A.hs', 'B.hs'])],
ghci_script, ['T16525a.script'])
=====================================
testsuite/tests/ghci/T16525b/A.hs
=====================================
@@ -0,0 +1,6 @@
+module A (a) where
+
+import B
+
+a :: () -> IO Int
+a x = b x
=====================================
testsuite/tests/ghci/T16525b/B.hs
=====================================
@@ -0,0 +1,5 @@
+module B (b) where
+
+{-# NOINLINE b #-}
+b :: () -> IO Int
+b () = return 999999999
=====================================
testsuite/tests/ghci/T16525b/T16525b.script
=====================================
@@ -0,0 +1,22 @@
+:set -fobject-code
+:load A
+import Control.Concurrent
+import Control.Monad
+:{
+_ <- forkIO $ do
+ replicateM_ 3 (a () >>= print >> threadDelay 500000)
+ putStrLn "===== THREAD DONE ====="
+:}
+:l []
+System.Mem.performGC
+threadDelay 500000
+System.Mem.performGC
+threadDelay 500000
+System.Mem.performGC
+threadDelay 500000
+System.Mem.performGC
+threadDelay 500000
+System.Mem.performGC
+threadDelay 500000
+System.Mem.performGC
+threadDelay 500000
=====================================
testsuite/tests/ghci/T16525b/T16525b.stdout
=====================================
@@ -0,0 +1,4 @@
+999999999
+999999999
+999999999
+===== THREAD DONE =====
=====================================
testsuite/tests/ghci/T16525b/all.T
=====================================
@@ -0,0 +1,2 @@
+# Tests unloading an object file which is in use in a thread
+test('T16525b', [extra_files(['A.hs', 'B.hs'])], ghci_script, ['T16525b.script'])
=====================================
testsuite/tests/rts/linker/linker_error.c
=====================================
@@ -57,7 +57,10 @@ int main (int argc, char *argv[])
r = resolveObjs();
if (!r) {
debugBelch("resolveObjs failed\n");
+ // Mark the object as unloadable:
unloadObj(obj);
+ // Actually unload it:
+ performMajorGC();
continue;
}
errorBelch("loading succeeded");
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/a4153029347c48be38bace114438b72475e2c40f...180f58cf281e00bf5c9b7a514a799706535dc5b9
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/a4153029347c48be38bace114438b72475e2c40f...180f58cf281e00bf5c9b7a514a799706535dc5b9
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