IA-64 ABI Exception Handling.

From-SVN: r40924

1 files changed, 492 insertions, 128 deletions

diff --git a/libjava/exception.cc b/libjava/exception.cc
index fdbfc42..41f7676 100644
--- a/libjava/exception.cc
+++ b/libjava/exception.cc
@@ -1,6 +1,6 @@
 // Functions for Exception Support for Java.
 
-/* Copyright (C) 1998, 1999  Free Software Foundation
+/* Copyright (C) 1998, 1999, 2001  Free Software Foundation
 
    This file is part of libgcj.
 
@@ -18,182 +18,546 @@ details.  */
 #include <gcj/cni.h>
 #include <jvm.h>
 
-// eh-common.h needs gansidecl.h.
-#include "gansidecl.h"
-#include "eh-common.h"
-
-typedef struct {
-  __eh_info eh_info;
-  jthrowable value;
-} java_eh_info;
+#include "unwind.h"
 
+
+// More nastiness: the GC wants to define TRUE and FALSE.  We don't
+// need the Java definitions (themselves a hack), so we undefine them.
+#undef TRUE
+#undef FALSE
 
-/* Language-specific EH info pointer, throw routine, and language/version
-   info routines. All defined in libgcc2. */
+extern "C"
+{
+#include <gc_priv.h>
+#include <gc_mark.h>
+#include <include/gc_gcj.h>
+};
 
-extern "C" java_eh_info **__get_eh_info (); 
-extern "C" void __throw () __attribute__ ((__noreturn__));
-extern "C" void __sjthrow () __attribute__ ((__noreturn__));
-extern "C" short __get_eh_table_version (void *table);
-extern "C" short __get_eh_table_language (void *table);
-extern "C" void *__get_eh_context ();
+
+struct alignment_test_struct
+{
+  char space;
+  char end[0] __attribute__((aligned));
+};
 
-extern "C" void *
-_Jv_type_matcher (java_eh_info *info, void* match_info, 
-		  void *exception_table)
+struct java_exception_header
 {
-#ifndef SJLJ_EXCEPTIONS
-  /* No exception table implies the old style mechanism, so don't check. */
-  if (exception_table != NULL
-      && __get_eh_table_language (exception_table) != EH_LANG_Java)
-    return NULL;
-#endif
+  /* Cache handler details between Phase 1 and Phase 2.  */
+  _Unwind_Ptr landingPad;
+  int handlerSwitchValue;
 
-  /* we don't worry about version info yet, there is only one version! */
-  
-  if (match_info != NULL)
-    {
-      // The match_info is either a (java::lang::Class*) or
-      // match_info is one more than a (Utf8Const*).
-      if (sizeof(void*) != sizeof(size_t))
-	abort();
-      size_t mi = (size_t) match_info;
-      if ((mi & 1) != 0)
-	match_info = _Jv_FindClass ((Utf8Const*) (mi - 1), NULL);
-      if (! _Jv_IsInstanceOf (info->value, (jclass) match_info))
-	return NULL;
-    }
+  /* The object being thrown.  Compiled code expects this to be immediately
+     before the generic exception header.  Which is complicated by the fact
+     that _Unwind_Exception is ((aligned)).  */
+
+  char pad[sizeof(jthrowable) < sizeof(alignment_test_struct)
+	   ? sizeof(alignment_test_struct) - sizeof(jthrowable) : 0]
+    __attribute__((aligned));
+
+  jthrowable value;
 
-  return info->value;
+  /* The generic exception header.  */
+  _Unwind_Exception unwindHeader;
+};
+
+// This is the exception class we report -- "GNUCJAVA".
+const _Unwind_Exception_Class __gcj_exception_class
+= ((((((((_Unwind_Exception_Class) 'G' 
+         << 8 | (_Unwind_Exception_Class) 'N')
+        << 8 | (_Unwind_Exception_Class) 'U')
+       << 8 | (_Unwind_Exception_Class) 'C')
+      << 8 | (_Unwind_Exception_Class) 'J')
+     << 8 | (_Unwind_Exception_Class) 'A')
+    << 8 | (_Unwind_Exception_Class) 'V')
+   << 8 | (_Unwind_Exception_Class) 'A');
+
+
+static inline java_exception_header *
+get_exception_header_from_ue (_Unwind_Exception *exc)
+{
+  return reinterpret_cast<java_exception_header *>(exc + 1) - 1;
 }
 
-/* Compiler hook to return a pointer to java exception object. The value
-   is cleared, so if the exception needs to be rethrown, it should be set 
-   again */
+/* Perform a throw, Java style. Throw will unwind through this call,
+   so there better not be any handlers or exception thrown here. */
 
-extern "C" void *
-_Jv_exception_info (void)
+extern "C" void
+_Jv_Throw (jthrowable value)
 {
-  java_eh_info *info = *(__get_eh_info ());
-  void *ptr;
+  /* FIXME: Use the proper API to the collector.  */
+  java_exception_header *xh
+    = static_cast<java_exception_header *>(GC_malloc (sizeof (*xh)));
+
+  if (value == NULL)
+    value = new java::lang::NullPointerException ();
+  xh->value = value;
 
-  if (info == NULL)
-    abort ();
+  xh->unwindHeader.exception_class = __gcj_exception_class;
+  xh->unwindHeader.exception_cleanup = NULL;
 
-  ptr = info->value;
+  /* We're happy with setjmp/longjmp exceptions or region-based
+     exception handlers: entry points are provided here for both.  */
+  _Unwind_Reason_Code code;
+#ifdef SJLJ_EXCEPTIONS
+  code = _Unwind_SjLj_RaiseException (&xh->unwindHeader);
+#else
+  code = _Unwind_RaiseException (&xh->unwindHeader);
+#endif
 
-  /* clear the value so another throw is an error */
-  info->value = NULL;
+  /* FIXME: If code == _URC_END_OF_STACK, then we reached top of
+     stack without finding a handler for the exception.  I seem to
+     recall that Java has specific rules to handle this. 
 
-  return ptr;
+     If code is something else, we encountered some sort of heinous
+     lossage, from which we could not recover.  As is the way of such
+     things we'll almost certainly have crashed before now, rather
+     than actually being able to diagnose the problem.  */
+  abort ();
 }
 
+
+// ??? These ought to go somewhere else dwarf2 or dwarf2eh related.
+
+// Pointer encodings.
+#define DW_EH_PE_absptr         0x00
+#define DW_EH_PE_omit           0xff
+
+#define DW_EH_PE_uleb128        0x01
+#define DW_EH_PE_udata2         0x02
+#define DW_EH_PE_udata4         0x03
+#define DW_EH_PE_udata8         0x04
+#define DW_EH_PE_sleb128        0x09
+#define DW_EH_PE_sdata2         0x0A
+#define DW_EH_PE_sdata4         0x0B
+#define DW_EH_PE_sdata8         0x0C
+#define DW_EH_PE_signed         0x08
+
+#define DW_EH_PE_pcrel          0x10
+#define DW_EH_PE_textrel        0x20
+#define DW_EH_PE_datarel        0x30
+#define DW_EH_PE_funcrel        0x40
+
+static unsigned int
+size_of_encoded_value (unsigned char encoding)
+{
+  switch (encoding & 0x07)
+    {
+    case DW_EH_PE_absptr:
+      return sizeof (void *);
+    case DW_EH_PE_udata2:
+      return 2;
+    case DW_EH_PE_udata4:
+      return 4;
+    case DW_EH_PE_udata8:
+      return 8;
+    }
+  abort ();
+}
 
+static const unsigned char *
+read_encoded_value (_Unwind_Context *context, unsigned char encoding,
+		    const unsigned char *p, _Unwind_Ptr *val)
+{
+  union unaligned
+    {
+      void *ptr;
+      unsigned u2 __attribute__ ((mode (HI)));
+      unsigned u4 __attribute__ ((mode (SI)));
+      unsigned u8 __attribute__ ((mode (DI)));
+      signed s2 __attribute__ ((mode (HI)));
+      signed s4 __attribute__ ((mode (SI)));
+      signed s8 __attribute__ ((mode (DI)));
+    } __attribute__((__packed__));
+
+  union unaligned *u = (union unaligned *) p;
+  _Unwind_Ptr result;
+
+  switch (encoding & 0x0f)
+    {
+    case DW_EH_PE_absptr:
+      result = (_Unwind_Ptr) u->ptr;
+      p += sizeof (void *);
+      break;
+
+    case DW_EH_PE_uleb128:
+      {
+	unsigned int shift = 0;
+	unsigned char byte;
+
+	result = 0;
+	do
+	  {
+	    byte = *p++;
+	    result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
+	    shift += 7;
+	  }
+	while (byte & 0x80);
+      }
+      break;
+
+    case DW_EH_PE_sleb128:
+      {
+	unsigned int shift = 0;
+	unsigned char byte;
+
+	result = 0;
+	do
+	  {
+	    byte = *p++;
+	    result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
+	    shift += 7;
+	  }
+	while (byte & 0x80);
+
+	if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)
+	  result |= -(1L << shift);
+      }
+      break;
+
+    case DW_EH_PE_udata2:
+      result = u->u2;
+      p += 2;
+      break;
+    case DW_EH_PE_udata4:
+      result = u->u4;
+      p += 4;
+      break;
+    case DW_EH_PE_udata8:
+      result = u->u8;
+      p += 8;
+      break;
+
+    case DW_EH_PE_sdata2:
+      result = u->s2;
+      p += 2;
+      break;
+    case DW_EH_PE_sdata4:
+      result = u->s4;
+      p += 4;
+      break;
+    case DW_EH_PE_sdata8:
+      result = u->s8;
+      p += 8;
+      break;
+
+    default:
+      abort ();
+    }
 
-/* Allocate an exception info structure for java. Called the first time
-   an exception is thrown. */
+  if (result != 0)
+    switch (encoding & 0xf0)
+      {
+      case DW_EH_PE_absptr:
+	break;
 
-extern "C" void
-_Jv_eh_alloc ()
-{
-  /* FIXME: we should use _Jv_AllocBytes here.  However, libgcc2
-     apparently can sometimes free() this value itself.  */
-  java_eh_info *p = (java_eh_info *) malloc (sizeof (java_eh_info));
-  if (p == 0)
-    abort ();
+      case DW_EH_PE_pcrel:
+	// Define as relative to the beginning of the pointer.
+	result += (_Unwind_Ptr) u;
+	break;
+
+      case DW_EH_PE_textrel:
+      case DW_EH_PE_datarel:
+	// FIXME.
+	abort ();
 
-  p->value = 0;
-  java_eh_info ** info_ptr = __get_eh_info ();
+      case DW_EH_PE_funcrel:
+	result += _Unwind_GetRegionStart (context);
+	break;
 
-  /* There should NOT be an exception info pointer already. */
-  if (*info_ptr != NULL)
-    abort ();
+      default:
+	abort ();
+      }
 
-  *info_ptr = p;
+  *val = result;
+  return p;
 }
 
-/* Deallocate the current exception info structure. Called at shutdown time. */
+static inline const unsigned char *
+read_uleb128 (const unsigned char *p, _Unwind_Ptr *val)
+{
+  return read_encoded_value (0, DW_EH_PE_uleb128, p, val);
+}
 
-extern "C" void
-_Jv_eh_free ()
+static inline const unsigned char *
+read_sleb128 (const unsigned char *p, _Unwind_Ptr *val)
 {
-  java_eh_info ** info_ptr = __get_eh_info ();
-  if (*info_ptr == NULL)
-    abort ();
-  
-  /* FIXME: ideally we should just let the GC handle this.  */
-  free (*info_ptr);
-  *info_ptr = NULL;
+  return read_encoded_value (0, DW_EH_PE_sleb128, p, val);
 }
 
-/* Initialize an __eh_info structure with this libraries matching info. */
+
+struct lsda_header_info
+{
+  _Unwind_Ptr Start;
+  _Unwind_Ptr LPStart;
+  const unsigned char *TType;
+  const unsigned char *action_table;
+  unsigned char ttype_encoding;
+  unsigned char call_site_encoding;
+};
+
+static const unsigned char *
+parse_lsda_header (_Unwind_Context *context, const unsigned char *p,
+		   lsda_header_info *info)
+{
+  _Unwind_Ptr tmp;
+  unsigned char lpstart_encoding;
+
+  info->Start = (context ? _Unwind_GetRegionStart (context) : 0);
 
-extern "C" void
-_Jv_setup_eh_info (__eh_info *)
+  // Find @LPStart, the base to which landing pad offsets are relative.
+  lpstart_encoding = *p++;
+  if (lpstart_encoding != DW_EH_PE_omit)
+    p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);
+  else
+    info->LPStart = info->Start;
+
+  // Find @TType, the base of the handler and exception spec type data.
+  info->ttype_encoding = *p++;
+  if (info->ttype_encoding != DW_EH_PE_omit)
+    {
+      p = read_uleb128 (p, &tmp);
+      info->TType = p + tmp;
+    }
+  else
+    info->TType = 0;
+
+  // The encoding and length of the call-site table; the action table
+  // immediately follows.
+  info->call_site_encoding = *p++;
+  p = read_uleb128 (p, &tmp);
+  info->action_table = p + tmp;
+
+  return p;
+}
+
+static jclass
+get_ttype_entry (_Unwind_Context *context, lsda_header_info *info, long i)
 {
+  _Unwind_Ptr ptr;
+
+  i *= size_of_encoded_value (info->ttype_encoding);
+  read_encoded_value (context, info->ttype_encoding, info->TType - i, &ptr);
+
+  return reinterpret_cast<jclass>(ptr);
 }
 
-/* Perform a throw, Java style. Throw will unwind through this call,
-   so there better not be any handlers or exception thrown here. */
 
+// Using a different personality function name causes link failures
+// when trying to mix code using different exception handling models.
 #ifdef SJLJ_EXCEPTIONS
-#define _Jv_Throw _Jv_Sjlj_Throw
+#define PERSONALITY_FUNCTION	__gcj_personality_sj0
+#define __builtin_eh_return_data_regno(x) x
+#else
+#define PERSONALITY_FUNCTION	__gcj_personality_v0
 #endif
 
-extern "C" void
-_Jv_Throw (jthrowable value)
+extern "C" _Unwind_Reason_Code
+PERSONALITY_FUNCTION (int version,
+		      _Unwind_Action actions,
+		      _Unwind_Exception_Class exception_class,
+		      struct _Unwind_Exception *ue_header,
+		      struct _Unwind_Context *context)
 {
-  if (value == NULL)
-    value = new java::lang::NullPointerException;
-  java_eh_info *ehinfo = *(__get_eh_info ());
-  if (ehinfo == NULL)
+  java_exception_header *xh = get_exception_header_from_ue (ue_header);
+
+  lsda_header_info info;
+  const unsigned char *language_specific_data;
+  const unsigned char *action_record;
+  const unsigned char *p;
+  _Unwind_Ptr landing_pad, ip;
+  int handler_switch_value;
+  bool saw_cleanup;
+  bool saw_handler;
+
+
+  // Interface version check.
+  if (version != 1)
+    return _URC_FATAL_PHASE1_ERROR;
+
+  // Shortcut for phase 2 found handler for domestic exception.
+  if (actions == (_UA_CLEANUP_PHASE | _UA_HANDLER_FRAME)
+      && exception_class == __gcj_exception_class)
     {
-      _Jv_eh_alloc ();
-      ehinfo = *(__get_eh_info ());
+      handler_switch_value = xh->handlerSwitchValue;
+      landing_pad = xh->landingPad;
+      goto install_context;
     }
-  ehinfo->eh_info.match_function = (__eh_matcher) _Jv_type_matcher;
-  ehinfo->eh_info.language = EH_LANG_Java;
-  ehinfo->eh_info.version = 1;
-  ehinfo->value = value;
 
-/* We're happy with setjmp/longjmp exceptions or region-based
-   exception handlers: entry points are provided here for both.  */
+  // FIXME: In Phase 1, record _Unwind_GetIP in xh->obj as a part of
+  // the stack trace for this exception.  This will only collect Java
+  // frames, but perhaps that is acceptable.
+  // FIXME2: _Unwind_GetIP is nonsensical for SJLJ, being a call-site
+  // index instead of a PC value.  We could perhaps arrange for
+  // _Unwind_GetRegionStart to return context->fc->jbuf[1], which
+  // is the address of the handler label for __builtin_longjmp, but
+  // there is no solution for DONT_USE_BUILTIN_SETJMP.
+
+  language_specific_data = (const unsigned char *)
+    _Unwind_GetLanguageSpecificData (context);
+
+  // If no LSDA, then there are no handlers or cleanups.
+  if (! language_specific_data)
+    return _URC_CONTINUE_UNWIND;
+
+  // Parse the LSDA header.
+  p = parse_lsda_header (context, language_specific_data, &info);
+  ip = _Unwind_GetIP (context) - 1;
+  landing_pad = 0;
+  action_record = 0;
+  handler_switch_value = 0;
+
 #ifdef SJLJ_EXCEPTIONS
-  __sjthrow ();
+  // The given "IP" is an index into the call-site table, with two
+  // exceptions -- -1 means no-action, and 0 means terminate.  But
+  // since we're using uleb128 values, we've not got random access
+  // to the array.
+  if ((int) ip <= 0)
+    return _URC_CONTINUE_UNWIND;
+  else
+    {
+      _Unwind_Ptr cs_lp, cs_action;
+      do
+	{
+	  p = read_uleb128 (p, &cs_lp);
+	  p = read_uleb128 (p, &cs_action);
+	}
+      while (--ip);
+
+      // Can never have null landing pad for sjlj -- that would have
+      // been indicated by a -1 call site index.
+      landing_pad = cs_lp + 1;
+      if (cs_action)
+	action_record = info.action_table + cs_action - 1;
+      goto found_something;
+    }
 #else
-  __throw ();
-#endif
-}
+  // Search the call-site table for the action associated with this IP.
+  while (p < info.action_table)
+    {
+      _Unwind_Ptr cs_start, cs_len, cs_lp, cs_action;
+
+      // Note that all call-site encodings are "absolute" displacements.
+      p = read_encoded_value (0, info.call_site_encoding, p, &cs_start);
+      p = read_encoded_value (0, info.call_site_encoding, p, &cs_len);
+      p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp);
+      p = read_uleb128 (p, &cs_action);
+
+      // The table is sorted, so if we've passed the ip, stop.
+      if (ip < info.Start + cs_start)
+	p = info.action_table;
+      else if (ip < info.Start + cs_start + cs_len)
+	{
+	  if (cs_lp)
+	    landing_pad = info.LPStart + cs_lp;
+	  if (cs_action)
+	    action_record = info.action_table + cs_action - 1;
+	  goto found_something;
+	}
+    }
+#endif // SJLJ_EXCEPTIONS
 
-#ifdef USE_WIN32_SIGNALLING
+  // If ip is not present in the table, C++ would call terminate.
+  // ??? It is perhaps better to tweek the LSDA so that no-action
+  // is mapped to no-entry for Java.
+  return _URC_CONTINUE_UNWIND;
 
-// This is a mangled version of _Jv_Throw and __sjthrow except
-// rather than calling longjmp, it returns a pointer to the jmp buffer
+ found_something:
+  saw_cleanup = false;
+  saw_handler = false;
 
-extern "C" int *
-win32_get_restart_frame (void *value)
-{
-  struct eh_context *eh = (struct eh_context *)__get_eh_context ();
-  void ***dhc = &eh->dynamic_handler_chain;
- 
-  java_eh_info *ehinfo = *(__get_eh_info ());
-  if (ehinfo == NULL)
+  if (landing_pad == 0)
     {
-      _Jv_eh_alloc ();
-      ehinfo = *(__get_eh_info ());
+      // If ip is present, and has a null landing pad, there are
+      // no cleanups or handlers to be run.
+    }
+  else if (action_record == 0)
+    {
+      // If ip is present, has a non-null landing pad, and a null
+      // action table offset, then there are only cleanups present.
+      // Cleanups use a zero switch value, as set above.
+      saw_cleanup = true;
+    }
+  else
+    {
+      // Otherwise we have a catch handler.
+      signed long ar_filter, ar_disp;
+
+      while (1)
+	{
+	  _Unwind_Ptr tmp;
+
+	  p = action_record;
+	  p = read_sleb128 (p, &tmp); ar_filter = tmp;
+	  read_sleb128 (p, &tmp); ar_disp = tmp;
+
+	  if (ar_filter == 0)
+	    {
+	      // Zero filter values are cleanups.
+	      saw_cleanup = true;
+	    }
+
+	  // During forced unwinding, we only run cleanups.  With a
+	  // foreign exception class, we have no class info to match.
+	  else if ((actions & _UA_FORCE_UNWIND)
+	      || exception_class != __gcj_exception_class)
+	    ;
+
+	  else if (ar_filter > 0)
+	    {
+	      // Positive filter values are handlers.
+
+	      jclass catch_type = get_ttype_entry (context, &info, ar_filter);
+
+	      // The catch_type is either a (java::lang::Class*) or
+	      // is one more than a (Utf8Const*).
+	      if ((size_t)catch_type & 1)
+		catch_type = _Jv_FindClass ((Utf8Const*)catch_type - 1, NULL);
+
+	      if (_Jv_IsInstanceOf (xh->value, catch_type))
+		{
+		  handler_switch_value = ar_filter;
+		  saw_handler = true;
+		  break;
+		}
+	    }
+	  else
+	    {
+	      // Negative filter values are exception specifications,
+	      // which Java does not use.
+	      // ??? Perhaps better to make them an index into a table
+	      // of null-terminated strings instead of playing games
+	      // with Utf8Const+1 as above.
+	      abort ();
+	    }
+
+	  if (ar_disp == 0)
+	    break;
+	  action_record = p + ar_disp;
+	}
     }
-  ehinfo->eh_info.match_function = (__eh_matcher) _Jv_type_matcher;
-  ehinfo->eh_info.language = EH_LANG_Java;
-  ehinfo->eh_info.version = 1;
-  ehinfo->value = value;
-
-  // FIXME: Run clean ups?
 
-  int *jmpbuf = (int*)&(*dhc)[2];
+  if (! saw_handler && ! saw_cleanup)
+    return _URC_CONTINUE_UNWIND;
 
-  *dhc = (void**)(*dhc)[0];
+  if (actions & _UA_SEARCH_PHASE)
+    {
+      if (! saw_handler)
+	return _URC_CONTINUE_UNWIND;
+
+      // For domestic exceptions, we cache data from phase 1 for phase 2.
+      if (exception_class == __gcj_exception_class)
+        {
+          xh->handlerSwitchValue = handler_switch_value;
+          xh->landingPad = landing_pad;
+	}
+      return _URC_HANDLER_FOUND;
+    }
 
-  return  jmpbuf;
+ install_context:
+  _Unwind_SetGR (context, __builtin_eh_return_data_regno (0),
+		 (_Unwind_Ptr) &xh->unwindHeader);
+  _Unwind_SetGR (context, __builtin_eh_return_data_regno (1),
+		 handler_switch_value);
+  _Unwind_SetIP (context, landing_pad);
+  return _URC_INSTALL_CONTEXT;
 }
-
-#endif /* USE_WIN32_SIGNALLING */