WIP: Making HPC-GAP work with Julia

Makefile.rules

@@ -64,9 +64,7 @@ SOURCES += src/intfuncs.c
 SOURCES += src/intrprtr.c
 SOURCES += src/io.c
 SOURCES += src/iostream.c
-ifeq ($(HPCGAP),no)             # we don't support a kernel API in HPC-GAP atm
 SOURCES += src/libgap-api.c
-endif
 SOURCES += src/listfunc.c
 SOURCES += src/listoper.c
 SOURCES += src/lists.c

configure.ac

@@ -204,6 +204,29 @@ AS_CASE([$with_gc],
     )
 AC_MSG_RESULT([$with_gc])
 
+dnl
+dnl User setting: disable guards (race protection)
+dnl
+
+AC_ARG_ENABLE([guards],
+    [AS_HELP_STRING([--enable-guards],
+        [enable guards for race protection in HPC-GAP])],
+    [enable_guards=$enableval],
+    [enable_guards=no])
+
+AS_IF([[test "x$enable_guards" == "xyes"]], [
+    AC_DEFINE([USE_HPC_GUARDS], [1], [define as 1 if guards should be checked])
+])
+AC_MSG_CHECKING([whether to use guards for race protection in HPC-GAP])
+AC_MSG_RESULT([$enable_guards])
+
+dnl
+dnl Check: --enable-guards requires --enable-hpcgap
+dnl
+
+AS_IF([[test "x$enable_guards" == "xyes" && test "x$enable_hpcgap" == "xno"]],
+  [AC_MSG_ERROR([Option --enable-guards requires --enable-hpcgap])])
+
 dnl
 dnl User setting: native thread-local storage (off by default)
 dnl See src/hpc/tls.h for more details on thread-local storage options.
@@ -915,6 +938,9 @@ AS_IF([test "x$enable_hpcgap" = xyes],[
   AS_BOX([WARNING: Experimental HPC-GAP mode enabled])
   dnl also enable backtrace, to help debug spurious crashes
   AC_DEFINE([GAP_PRINT_BACKTRACE], [1], [to enable backtraces upon crashes])
+  AS_IF([test "x$enable_guards" = xno], [
+    AS_BOX([WARNING: HPC-GAP guards (race condition protection) are disabled.])
+    ])
   ])
 
 AS_IF([test "x$enable_macos_tls_asm" = xno],[

etc/ci-prepare.sh

@@ -23,7 +23,7 @@ BUILDDIR=$PWD
 
 if [[ $HPCGAP = yes ]]
 then
-  CONFIGFLAGS="--enable-hpcgap $CONFIGFLAGS"
+  CONFIGFLAGS="--enable-hpcgap --enable-guards $CONFIGFLAGS"
 fi
 
 
@@ -40,8 +40,22 @@ then
 fi
 
 
-# configure and make GAP
+# configure
 time "$SRCDIR/configure" --enable-Werror $CONFIGFLAGS
+
+if [[ $HPCGAP = yes ]]
+then
+  git clone https://github.com/rbehrends/unward
+  cd unward
+  ./configure CC=gcc CXX=g++ CFLAGS=-O2 CXXFLAGS=-O2
+  make
+  cd ..
+  unward/bin/unward --inplace src
+  # commit the result to prevent the docomp test from triggering
+  git commit -m "Unward" src
+fi
+
+# build GAP
 time make V=1 -j4
 
 # download packages; instruct wget to retry several times if the

lib/oper.g

@@ -1983,8 +1983,6 @@ BIND_GLOBAL( "InstallGlobalFunction", function( arg )
     od;
 end );
 
-if not IsHPCGAP then
-
 BIND_GLOBAL( "FLUSH_ALL_METHOD_CACHES", function()
     local oper,j;
     for oper in OPERATIONS do
@@ -1994,8 +1992,6 @@ BIND_GLOBAL( "FLUSH_ALL_METHOD_CACHES", function()
     od;
 end);
 
-fi;
-
 if BASE_SIZE_METHODS_OPER_ENTRY <> 6 then
     Error("MethodsOperation must be updated for new BASE_SIZE_METHODS_OPER_ENTRY");
 fi;

src/boehm_gc.c

@@ -334,6 +334,9 @@ void RetypeBagIntern(Bag bag, UInt new_type)
     if (old_type == new_type)
         return;
 
+#if defined(HPCGAP) && defined(USE_HPC_GUARDS)
+    WriteGuard(bag);
+#endif
     /* change the size-type word                                           */
     header->type = new_type;
     {
@@ -456,6 +459,9 @@ UInt ResizeBag(Bag bag, UInt new_size)
     CollectBags(0, 0);
 #endif
 
+#if defined(HPCGAP) && defined(USE_HPC_GUARDS)
+    WriteGuard(bag);
+#endif
     BagHeader * header = BAG_HEADER(bag);
 
     /* get type and old size of the bag                                    */

src/gasman.h

@@ -38,6 +38,11 @@
 
 #include "common.h"
 
+#ifdef HPCGAP
+#include "hpc/region.h"
+#include "hpc/tls.h"
+#endif
+
 
 /****************************************************************************
 **
@@ -139,6 +144,46 @@ EXPORT_INLINE UInt TNUM_BAG(Bag bag)
     return BAG_HEADER(bag)->type;
 }
 
+/****************************************************************************
+**
+*F  ReadCheck(<bag>) . . . . . . . . . . . . . is the bag readable in HPCGAP?
+*F  WriteCheck(<bag>)  . . . . . . . . . . . . is the bag writable in HPCGAP?
+*F  HandleReadGuardError(<bag>)  . . . . . . . . . . signal read access error
+*F  HandleWriteGuardError(<bag>) . . . . . . . . .  signal write access error
+**
+**  These funtion handle access checks in HPCGAP, i.e. whether a bag can
+**  safely be read or modified without causing race conditions. These are
+**  called in functions such as PTR_BAG() and CONST_PTR_BAG(), which should
+**  implicitly or explicitly guard all object accesses. In order to access
+**  objects without triggering checks, alternative functions UNSAFE_PTR_BAG()
+**  and UNSAFE_CONST_PTR_BAG() are provided.
+*/
+#ifdef HPCGAP
+extern int ExtendedGuardCheck(Bag) PURE_FUNC;
+
+EXPORT_INLINE int ReadCheck(Bag bag)
+{
+    Region *region;
+    region = REGION(bag);
+    if (!region)
+        return 1;
+    if (region->owner == GetTLS())
+        return 1;
+    if (region->readers[TLS(threadID)])
+        return 1;
+    return ExtendedGuardCheck(bag);
+}
+
+EXPORT_INLINE int WriteCheck(Bag bag)
+{
+    Region * region;
+    region = REGION(bag);
+    return !region || region->owner == GetTLS() || ExtendedGuardCheck(bag);
+}
+
+extern void HandleReadGuardError(Bag) NORETURN;
+extern void HandleWriteGuardError(Bag) NORETURN;
+#endif // HPCGAP
 
 /****************************************************************************
 **
@@ -296,15 +341,43 @@ EXPORT_INLINE UInt SIZE_BAG_CONTENTS(const void *ptr) {
 EXPORT_INLINE Bag *PTR_BAG(Bag bag)
 {
     GAP_ASSERT(bag != 0);
+#ifdef USE_HPC_GUARDS
+    if (!WriteCheck(bag))
+      HandleWriteGuardError(bag);
+#endif
     return *(Bag**)bag;
 }
 
+#ifdef USE_HPC_GUARDS
+EXPORT_INLINE Bag *UNSAFE_PTR_BAG(Bag bag)
+{
+    GAP_ASSERT(bag != 0);
+    return *(Bag**)bag;
+}
+#else
+#define UNSAFE_PTR_BAG PTR_BAG
+#endif
+
 EXPORT_INLINE const Bag *CONST_PTR_BAG(Bag bag)
 {
     GAP_ASSERT(bag != 0);
+#ifdef USE_HPC_GUARDS
+    if (!ReadCheck(bag))
+      HandleReadGuardError(bag);
+#endif
     return *(const Bag * const *)bag;
 }
 
+#ifdef USE_HPC_GUARDS
+EXPORT_INLINE const Bag *UNSAFE_CONST_PTR_BAG(Bag bag)
+{
+    GAP_ASSERT(bag != 0);
+    return *(const Bag * const *)bag;
+}
+#else
+#define UNSAFE_CONST_PTR_BAG CONST_PTR_BAG
+#endif
+
 EXPORT_INLINE void SET_PTR_BAG(Bag bag, Bag *val)
 {
     GAP_ASSERT(bag != 0);

src/gvars.c

@@ -1485,7 +1485,6 @@ Obj GVarFunction(GVarDescriptor *gvar)
     ErrorQuit("Global variable '%s' not initialized", (UInt)(gvar->name), 0);
   if (REGION(result))
     ErrorQuit("Global variable '%s' is not a function", (UInt)(gvar->name), 0);
-  ImpliedWriteGuard(result);
   if (TNUM_OBJ(result) != T_FUNCTION)
     ErrorQuit("Global variable '%s' is not a function", (UInt)(gvar->name), 0);
   MEMBAR_READ();
@@ -1499,7 +1498,6 @@ Obj GVarOptFunction(GVarDescriptor *gvar)
     return (Obj) 0;
   if (REGION(result))
     return (Obj) 0;
-  ImpliedWriteGuard(result);
   if (TNUM_OBJ(result) != T_FUNCTION)
     return (Obj) 0;
   MEMBAR_READ();

src/hpc/guards.h

@@ -11,108 +11,78 @@
 #ifndef GAP_HPC_GUARD_H
 #define GAP_HPC_GUARD_H
 
+#include "gasman.h"
 #include "hpc/region.h"
 #include "hpc/tls.h"
 
 #ifndef HPCGAP
 #error This header is only meant to be used with HPC-GAP
 #endif
 
-#ifdef VERBOSE_GUARDS
-void WriteGuardError(Bag bag,
-    const char *file, unsigned line, const char *func, const char *expr);
-void ReadGuardError(Bag bag,
-    const char *file, unsigned line, const char *func, const char *expr);
-#else
-void WriteGuardError(Bag bag);
-void ReadGuardError(Bag bag);
-#endif
-
-#ifdef VERBOSE_GUARDS
-#define WriteGuard(bag) WriteGuardFull(bag, __FILE__, __LINE__, __FUNCTION__, #bag)
-static ALWAYS_INLINE Bag WriteGuardFull(Bag bag,
-  const char *file, unsigned line, const char *func, const char *expr)
-#else
 static ALWAYS_INLINE Bag WriteGuard(Bag bag)
-#endif
 {
-  Region *region;
-  if (!IS_BAG_REF(bag))
-    return bag;
-  region = REGION(bag);
-  if (region && region->owner != GetTLS() && region->alt_owner != GetTLS())
-    WriteGuardError(bag
-#ifdef VERBOSE_GUARDS
-    , file, line, func, expr
+#ifdef USE_HPC_GUARDS
+    if (!WriteCheck(bag))
+        HandleWriteGuardError(bag);
 #endif
-    );
-  return bag;
+    return bag;
 }
 
-EXPORT_INLINE Bag ImpliedWriteGuard(Bag bag)
-{
-  return bag;
-}
 
 EXPORT_INLINE int CheckWriteAccess(Bag bag)
 {
-  Region *region;
-  if (!IS_BAG_REF(bag))
+#ifdef USE_HPC_GUARDS
+    Region * region;
+    if (!IS_BAG_REF(bag))
+        return 1;
+    region = REGION(bag);
+    return !(region && region->owner != GetTLS() &&
+             region->alt_owner != GetTLS()) ||
+           TLS(DisableGuards) >= 2;
+#else
     return 1;
-  region = REGION(bag);
-  return !(region && region->owner != GetTLS() && region->alt_owner != GetTLS())
-    || TLS(DisableGuards) >= 2;
+#endif
 }
 
 EXPORT_INLINE int CheckExclusiveWriteAccess(Bag bag)
 {
-  Region *region;
-  if (!IS_BAG_REF(bag))
+#ifdef USE_HPC_GUARDS
+    Region * region;
+    if (!IS_BAG_REF(bag))
+        return 1;
+    region = REGION(bag);
+    if (!region)
+        return 0;
+    return region->owner == GetTLS() || region->alt_owner == GetTLS() ||
+           TLS(DisableGuards) >= 2;
+#else
     return 1;
-  region = REGION(bag);
-  if (!region)
-    return 0;
-  return region->owner == GetTLS() || region->alt_owner == GetTLS()
-    || TLS(DisableGuards) >= 2;
+#endif
 }
 
-#ifdef VERBOSE_GUARDS
-#define ReadGuard(bag) ReadGuardFull(bag, __FILE__, __LINE__, __FUNCTION__, #bag)
-static ALWAYS_INLINE Bag ReadGuardFull(Bag bag,
-  const char *file, unsigned line, const char *func, const char *expr)
-#else
 static ALWAYS_INLINE Bag ReadGuard(Bag bag)
-#endif
 {
-  Region *region;
-  if (!IS_BAG_REF(bag))
-    return bag;
-  region = REGION(bag);
-  if (region && region->owner != GetTLS() &&
-      !region->readers[TLS(threadID)] && region->alt_owner != GetTLS())
-    ReadGuardError(bag
-#ifdef VERBOSE_GUARDS
-    , file, line, func, expr
+#ifdef USE_HPC_GUARDS
+    if (!ReadCheck(bag))
+        HandleReadGuardError(bag);
 #endif
-    );
-  return bag;
-}
-
-
-static ALWAYS_INLINE Bag ImpliedReadGuard(Bag bag)
-{
-  return bag;
+    return bag;
 }
 
 static ALWAYS_INLINE int CheckReadAccess(Bag bag)
 {
-  Region *region;
-  if (!IS_BAG_REF(bag))
+#ifdef USE_HPC_GUARDS
+    Region * region;
+    if (!IS_BAG_REF(bag))
+        return 1;
+    region = REGION(bag);
+    return !(region && region->owner != GetTLS() &&
+             !region->readers[TLS(threadID)] &&
+             region->alt_owner != GetTLS()) ||
+           TLS(DisableGuards) >= 2;
+#else
     return 1;
-  region = REGION(bag);
-  return !(region && region->owner != GetTLS() &&
-    !region->readers[TLS(threadID)] && region->alt_owner != GetTLS())
-    || TLS(DisableGuards) >= 2;
+#endif
 }
 
-#endif // GAP_HPC_GUARD_H
+#endif    // GAP_HPC_GUARD_H

src/hpc/misc.c

@@ -50,7 +50,7 @@ UInt SyNumGCThreads = 0;
 *V  SingleThreadStartup . . . . . . . . .  start HPC-GAP with just one thread
 **
 */
-UInt SingleThreadStartup = 0;
+UInt SingleThreadStartup = 1;
 
 /****************************************************************************
 **