1999-05-20 Andrew Haley <aph@cygnus.com>

        * libjava/prims.cc (catch_fpe): Call to HANDLE_DIVIDE_OVERFLOW
        added.
        * include/i386-signal.h (HANDLE_DIVIDE_OVERFLOW): New macro.
        (INIT_FPE): Exception string made more informative.
        * include/sparc-signal.h (INIT_FPE): Exception string made more
        informative.
        * testsuite/libjava.lang/Divide_1.java: New file.
        * testsuite/libjava.lang/Divide_1.out: New file.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@27056 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 79 insertions, 7 deletions

diff --git a/libjava/include/i386-signal.h b/libjava/include/i386-signal.h
index 73d8bbbbfc0..12ffe2ada1f 100644
--- a/libjava/include/i386-signal.h
+++ b/libjava/include/i386-signal.h
@@ -25,16 +25,86 @@ details.  */
 static void _name (int _dummy)
 
 #define MAKE_THROW_FRAME						\
+do									\
 {									\
   void **_p = (void **)&_dummy;						\
   struct sigcontext_struct *_regs = (struct sigcontext_struct *)++_p;	\
 									\
   register unsigned long _ebp = _regs->ebp;				\
-  register unsigned long _eip = _regs->eip;				\
-  									\
+  register unsigned char *_eip = (unsigned char *)_regs->eip;		\
+									\
+  asm volatile ("mov %0, (%%ebp); mov %1, 4(%%ebp)"			\
+		: : "r"(_ebp), "r"(_eip));				\
+}									\
+while (0)
+
+#define HANDLE_DIVIDE_OVERFLOW						\
+do									\
+{									\
+  void **_p = (void **)&_dummy;						\
+  struct sigcontext_struct *_regs = (struct sigcontext_struct *)++_p;	\
+									\
+  register unsigned long *_ebp = (unsigned long *)_regs->ebp;		\
+  register unsigned char *_eip = (unsigned char *)_regs->eip;		\
+									\
+  /* According to the JVM spec, "if the dividend is the negative	\
+   * integer of the smallest magnitude and the divisor is -1, then	\
+   * overflow occurs and the result is equal to the dividend.  Despite	\
+   * the overflow, no exception occurs".				\
+									\
+   * We handle this by inspecting the instruction which generated the	\
+   * signal and advancing eip to point to the following instruction.	\
+   * As the instructions are variable length it is necessary to do a	\
+   * little calculation to figure out where the following instruction	\
+   * actually is.							\
+									\
+   */									\
+									\
+  if (_eip[0] == 0xf7)							\
+    {									\
+      unsigned char _modrm = _eip[1];					\
+									\
+      if (_regs->eax == 0x80000000					\
+	  && ((_modrm >> 3) & 7) == 7) /* Signed divide */		\
+	{								\
+	  _regs->edx = 0; /* the remainder is zero */			\
+	  switch (_modrm >> 6)						\
+	    {								\
+	    case 0:							\
+	      if ((_modrm & 7) == 5)					\
+		_eip += 4;						\
+	      break;							\
+	    case 1:							\
+	      _eip += 1;						\
+	      break;							\
+	    case 2:							\
+	      _eip += 4;						\
+	      break;							\
+	    case 3:							\
+	      break;							\
+	    }								\
+	  _eip += 2;							\
+	  _regs->eip = (unsigned long)_eip;				\
+	  return;							\
+	}								\
+      else if (((_modrm >> 3) & 7) == 6) /* Unsigned divide */		\
+	{								\
+	  /* We assume that unsigned divisions are in library code, so	\
+	   * we throw one level down the stack, which was hopefully	\
+	   * the place that called the library routine.  This will	\
+	   * break if the library is ever compiled with			\
+	   * -fomit-frame-pointer, but at least this way we've got a	\
+	   * good chance of finding the exception handler. */		\
+									\
+	  _eip = (unsigned char *)_ebp[1];				\
+	  _ebp = (unsigned long *)_ebp[0];				\
+	}								\
+    }									\
+									\
   asm volatile ("mov %0, (%%ebp); mov %1, 4(%%ebp)"			\
 		: : "r"(_ebp), "r"(_eip));				\
-}
+}									\
+while (0)
 
 #define INIT_SEGV						\
 do								\
@@ -48,10 +118,11 @@ do								\
   }								\
 while (0)  
 
-#define INIT_FPE						\
+#define INIT_FPE                                                \
 do								\
-  { 								\
-    arithexception = new java::lang::ArithmeticException ();	\
+  {								\
+    arithexception = new java::lang::ArithmeticException 	\
+      (JvNewStringLatin1 ("/ by zero"));			\
     struct sigaction act;					\
     act.sa_handler = catch_fpe;					\
     sigemptyset (&act.sa_mask);					\
diff --git a/libjava/include/sparc-signal.h b/libjava/include/sparc-signal.h
index dfe8635e3eb..03b5cdc4dc6 100644
--- a/libjava/include/sparc-signal.h
+++ b/libjava/include/sparc-signal.h
@@ -51,7 +51,8 @@ while (0)
 #define INIT_FPE						\
 do								\
   {								\
-    arithexception = new java::lang::ArithmeticException ();	\
+    arithexception = new java::lang::ArithmeticException 	\
+      (JvNewStringLatin1 ("/ by zero"));			\
     struct sigaction act;					\
     act.sa_flags = SA_SIGINFO;					\
     act.sa_sigaction = catch_fpe;				\