* config/rs6000/tm-rs6000.h (INIT_EXTRA_FRAME_INFO):

	Don't test for zero backchain pointer to recognize a signal
	handler frame, if read() gets interrupted by a signal, the
	backchain will be non zero.
	(SIG_FRAME_FP_OFFSET):  Move to here from rs6000-tdep.c,
	improve comment.
	(SIG_FRAME_PC_OFFSET):  New definition.
	(FRAME_SAVED_PC):  Return saved pc from sigcontext if this
	is a signal handler frame.
	* rs6000-tdep.c (function_frame_info):  Do not error out
	if we can't access the instructions.

	* config/rs6000/tm-rs6000.h (CONVERT_FROM_FUNC_PTR_ADDR):
	New definition to get the function address from a function pointer.
	* valops.c (find_function_addr):  Use it when calling a user
	function through a function pointer.

1 files changed, 31 insertions, 29 deletions

diff --git a/gdb/config/rs6000/tm-rs6000.h b/gdb/config/rs6000/tm-rs6000.h
index 08e5221..5e63f82 100644
--- a/gdb/config/rs6000/tm-rs6000.h
+++ b/gdb/config/rs6000/tm-rs6000.h
@@ -98,15 +98,6 @@ function_frame_info PARAMS ((CORE_ADDR, struct aix_framedata *));
 
 #define	SKIP_TRAMPOLINE_CODE(pc)	skip_trampoline_code (pc)
 
-/* When a child process is just starting, we sneak in and relocate
-   the symbol table (and other stuff) after the dynamic linker has
-   figured out where they go.  */
-
-#define	SOLIB_CREATE_INFERIOR_HOOK(PID)	\
-  do {					\
-    xcoff_relocate_symtab (PID);	\
-  } while (0)
-
 /* Number of trap signals we need to skip over, once the inferior process
    starts running. */
 
@@ -132,18 +123,6 @@ function_frame_info PARAMS ((CORE_ADDR, struct aix_framedata *));
 
 #define	PROCESS_LINENUMBER_HOOK()	aix_process_linenos ()
    
-/* When a target process or core-file has been attached, we sneak in
-   and figure out where the shared libraries have got to.  */
-
-#define	SOLIB_ADD(a, b, c)	\
-  if (inferior_pid)	\
-    /* Attach to process.  */  \
-    xcoff_relocate_symtab (inferior_pid); \
-  else		\
-    /* Core file.  */ \
-    xcoff_relocate_core ();
-extern void xcoff_relocate_core PARAMS ((void));
-
 /* Immediately after a function call, return the saved pc.
    Can't go through the frames for this because on some machines
    the new frame is not set up until the new function executes
@@ -189,10 +168,6 @@ extern void xcoff_relocate_core PARAMS ((void));
 #define ABOUT_TO_RETURN(pc)  \
    ((read_memory_integer (pc, 4) & 0xfe8007ff) == 0x4e800020)
 
-/* Return 1 if P points to an invalid floating point value.  */
-
-#define INVALID_FLOAT(p, len) 0   /* Just a first guess; not checked */
-
 /* Say how long (ordinary) registers are.  This is a piece of bogosity
    used in push_word and a few other places; REGISTER_RAW_SIZE is the
    real way to know how big a register is.  */
@@ -345,7 +320,7 @@ extern CORE_ADDR rs6000_struct_return_address;
 
 #define STORE_STRUCT_RETURN(ADDR, SP)	\
   { write_register (3, (ADDR));		\
-    rs6000_struct_return_address = (unsigned int)(ADDR); }
+    rs6000_struct_return_address = (ADDR); }
 
 /* Extract from an array REGBUF containing the (raw) register state
    a function return value of type TYPE, and copy that, in virtual format,
@@ -426,13 +401,23 @@ CORE_ADDR rs6000_frame_chain PARAMS ((struct frame_info *));
   fi->initial_sp = 0;		\
   fi->cache_fsr = 0; \
   if (fi->next != (CORE_ADDR)0 \
-      && read_memory_integer (fi->frame, 4) == 0 \
       && fi->pc < TEXT_SEGMENT_BASE) \
     /* We're in get_prev_frame_info */ \
     /* and this is a special signal frame.  */ \
-    /* (fi->pc will be something like 0x3f88 or 0x2790).  */ \
+    /* (fi->pc will be some low address in the kernel, */ \
+    /*  to which the signal handler returns).  */
     fi->signal_handler_caller = 1;
 
+/* If the kernel has to deliver a signal, it pushes a sigcontext
+   structure on the stack and then calls the signal handler, passing
+   the address of the sigcontext in an argument register. Usually
+   the signal handler doesn't save this register, so we have to
+   access the sigcontext structure via an offset from the signal handler
+   frame.
+   The following constants were determined by experimentation on AIX 3.2.  */
+#define SIG_FRAME_PC_OFFSET 96
+#define SIG_FRAME_FP_OFFSET 284
+
 /* Frameless function invocation in IBM RS/6000 is sometimes
    half-done. It perfectly sets up a new frame, e.g. a new frame (in
    fact stack) pointer, etc, but it doesn't save the %pc.  We call
@@ -441,7 +426,9 @@ CORE_ADDR rs6000_frame_chain PARAMS ((struct frame_info *));
 #define FRAME_SAVED_PC(FRAME)					\
 	(frameless_function_invocation (FRAME, 1)		\
 	 ? SAVED_PC_AFTER_CALL (FRAME)				\
-	 : read_memory_integer (rs6000_frame_chain (FRAME)+8, 4))
+	 : (FRAME)->signal_handler_caller			\
+	   ? read_memory_integer ((FRAME)->frame + SIG_FRAME_PC_OFFSET, 4) \
+	   : read_memory_integer (rs6000_frame_chain (FRAME) + 8, 4))
 
 #define FRAME_ARGS_ADDRESS(FI)	\
   (((struct frame_info*)(FI))->initial_sp ?		\
@@ -579,6 +566,21 @@ CORE_ADDR rs6000_frame_chain PARAMS ((struct frame_info *));
 #define FIX_CALL_DUMMY(dummyname, pc, fun, nargs, args, type, using_gcc) \
 	fix_call_dummy(dummyname, pc, fun, nargs, type)
 
+/* Usually a function pointer's representation is simply the address of
+   the function. On the RS/6000 however, a function pointer is represented
+   by a pointer to a TOC entry. This TOC entry contains three words,
+   the first word is the address of the function, the second word is the
+   TOC pointer (r2), and the third word is the static chain value.
+   Throughout GDB it is currently assumed that a function pointer contains
+   the address of the function, which is not easy to fix.
+   In addition, the conversion of a function address to a function
+   pointer would require allocation of a TOC entry in the inferior's
+   memory space, with all its drawbacks.
+   To be able to call C++ virtual methods in the inferior (which are called
+   via function pointers), find_function_addr uses this macro to
+   get the function address from a function pointer.  */
+#define CONVERT_FROM_FUNC_PTR_ADDR(ADDR) read_memory_integer (ADDR, 4)
+
 /* Flag for machine-specific stuff in shared files.  FIXME */
 #define IBM6000_TARGET