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2006-04-10 Andrew Haley <aph@redhat.com>
authoraph <aph@138bc75d-0d04-0410-961f-82ee72b054a4>
Mon, 10 Apr 2006 16:01:23 +0000 (16:01 +0000)
committeraph <aph@138bc75d-0d04-0410-961f-82ee72b054a4>
Mon, 10 Apr 2006 16:01:23 +0000 (16:01 +0000)
        * include/x86_64-signal.h (HANDLE_DIVIDE_OVERFLOW): New.
        (SIGNAL_HANDLER): Mark arg as unused.
        * configure.host (x86_64-* DIVIDESPEC): Use
        fno-use-divide-subroutine.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@112827 138bc75d-0d04-0410-961f-82ee72b054a4

libjava/ChangeLog
libjava/configure.host
libjava/include/x86_64-signal.h

index d52d8ab..2117abf 100644 (file)
@@ -1,3 +1,10 @@
+2006-04-10  Andrew Haley  <aph@redhat.com>
+
+       * include/x86_64-signal.h (HANDLE_DIVIDE_OVERFLOW): New.
+       (SIGNAL_HANDLER): Mark arg as unused.
+       * configure.host (x86_64-* DIVIDESPEC): Use
+       fno-use-divide-subroutine.
+
 2006-04-07  Andrew Haley  <aph@redhat.com>
 
        * java/net/InetAddress.java: Throw an UnknownHostException if
index 108f3a2..e213072 100644 (file)
@@ -115,7 +115,7 @@ case "${host}" in
        libgcj_flags="${libgcj_flags} -fomit-frame-pointer"
        libgcj_cxxflags=
        libgcj_cflags=
-       DIVIDESPEC=-f%{m32:no-}use-divide-subroutine
+       DIVIDESPEC=-fno-use-divide-subroutine
        enable_hash_synchronization_default=yes
        slow_pthread_self=yes
        libgcj_interpreter=yes
index b4b4c2b..479be3f 100644 (file)
@@ -19,9 +19,88 @@ details.  */
 #include <sys/syscall.h>
 
 #define HANDLE_SEGV 1
-
-#define SIGNAL_HANDLER(_name)  \
-static void _Jv_##_name (int, siginfo_t *, void *_p)
+#define HANDLE_FPE 1
+
+#define SIGNAL_HANDLER(_name)                                  \
+static void _Jv_##_name (int, siginfo_t *,                     \
+                        void *_p __attribute__ ((__unused__)))
+
+#define HANDLE_DIVIDE_OVERFLOW                                         \
+do                                                                     \
+{                                                                      \
+  struct ucontext *_uc = (struct ucontext *)_p;                                \
+  volatile struct sigcontext *_sc = (struct sigcontext *) &_uc->uc_mcontext; \
+                                                                       \
+  register unsigned char *_rip = (unsigned char *)_sc->rip;            \
+                                                                       \
+  /* According to the JVM spec, "if the dividend is the negative       \
+   * integer of largest possible magnitude for the type 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 ip 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.                                                      \
+                                                                       \
+   */                                                                  \
+                                                                       \
+  bool _is_64_bit = false;                                             \
+                                                                       \
+  if ((_rip[0] & 0xf0) == 0x40)  /* REX byte present.  */              \
+    {                                                                  \
+      unsigned char _rex = _rip[0] & 0x0f;                             \
+      _is_64_bit = (_rex & 0x08) != 0;                                 \
+      _rip++;                                                          \
+    }                                                                  \
+                                                                       \
+  /* Detect a signed division of Integer.MIN_VALUE or Long.MIN_VALUE.  */ \
+  if (_rip[0] == 0xf7)                                                 \
+    {                                                                  \
+      bool _min_value_dividend = false;                                        \
+      unsigned char _modrm = _rip[1];                                  \
+                                                                       \
+      if (((_modrm >> 3) & 7) == 7)                                    \
+       {                                                               \
+         if (_is_64_bit)                                               \
+           _min_value_dividend = (_sc->rax == 0x8000000000000000L);    \
+         else                                                          \
+           _min_value_dividend = ((_sc->rax & 0xffffffff) == 0x80000000); \
+       }                                                               \
+                                                                       \
+      if (_min_value_dividend)                                         \
+       {                                                               \
+         unsigned char _rm = _modrm & 7;                               \
+         _sc->rdx = 0; /* the remainder is zero */                     \
+         switch (_modrm >> 6)                                          \
+           {                                                           \
+           case 0:  /* register indirect */                            \
+             if (_rm == 5)   /* 32-bit displacement */                 \
+               _rip += 4;                                              \
+             if (_rm == 4)  /* A SIB byte follows the ModR/M byte */   \
+               _rip += 1;                                              \
+             break;                                                    \
+           case 1:  /* register indirect + 8-bit displacement */       \
+             _rip += 1;                                                \
+             if (_rm == 4)  /* A SIB byte follows the ModR/M byte */   \
+               _rip += 1;                                              \
+             break;                                                    \
+           case 2:  /* register indirect + 32-bit displacement */      \
+             _rip += 4;                                                \
+             if (_rm == 4)  /* A SIB byte follows the ModR/M byte */   \
+               _rip += 1;                                              \
+             break;                                                    \
+           case 3:                                                     \
+             break;                                                    \
+           }                                                           \
+         _rip += 2;                                                    \
+         _sc->rip = (unsigned long)_rip;                               \
+         return;                                                       \
+       }                                                               \
+    }                                                                  \
+}                                                                      \
+while (0)
 
 extern "C" 
 {
@@ -65,12 +144,29 @@ do                                                         \
   }                                                            \
 while (0)  
 
-/* We use syscall(SYS_rt_sigaction) in INIT_SEGV instead of
- * sigaction() because on some systems the pthreads wrappers for
- * signal handlers are not compiled with unwind information, so it's
- * not possible to unwind through them.  This is a problem that will
- * go away if all systems ever have pthreads libraries that are
- * compiled with unwind info.  */
+#define INIT_FPE                                               \
+do                                                             \
+  {                                                            \
+    struct kernel_sigaction act;                               \
+    act.k_sa_sigaction = _Jv_catch_fpe;                                \
+    sigemptyset (&act.k_sa_mask);                              \
+    act.k_sa_flags = SA_SIGINFO|0x4000000;                     \
+    act.k_sa_restorer = restore_rt;                            \
+    syscall (SYS_rt_sigaction, SIGFPE, &act, NULL, _NSIG / 8); \
+  }                                                            \
+while (0)  
+
+/* You might wonder why we use syscall(SYS_sigaction) in INIT_FPE
+ * instead of the standard sigaction().  This is necessary because of
+ * the shenanigans above where we increment the PC saved in the
+ * context and then return.  This trick will only work when we are
+ * called _directly_ by the kernel, because linuxthreads wraps signal
+ * handlers and its wrappers do not copy the sigcontext struct back
+ * when returning from a signal handler.  If we return from our divide
+ * handler to a linuxthreads wrapper, we will lose the PC adjustment
+ * we made and return to the faulting instruction again.  Using
+ * syscall(SYS_sigaction) causes our handler to be called directly
+ * by the kernel, bypassing any wrappers.  */
 
 #endif /* JAVA_SIGNAL_H */