DWARF2 unwind support

gcc/ChangeLog.or1k

@@ -1,3 +1,34 @@
+2013-01-22  Christian Svensson  <blue@cmd.nu>
+
+	* common/config/or1k/or1k-common.c:
+	(TARGET_EXCEPT_UNWIND_INFO) define.
+	(or1k_except_unwind_info) use DWARF2 unwind info as default
+	but support SJLJ if forced with --enable-sjlj-exceptions.
+	* config/or1k/or1k-protos.h: 
+	(or1k_expand_pic_symbol_ref) removed unneeded ATTRIBUTE_UNUSED.
+	(or1k_eh_return_handler_rtx) defined prototype (body in or1k.c).
+	(or1k_return_addr_rtx) defined prototype (body in or1k.c).
+	* config/or1k/or1k.c:
+	(or1k_save_reg_p) save stack pointer when frame pointer is not saved.
+	(or1k_save_reg_p) save registers used with eh_return.
+	(or1k_expand_epilogue) do not restore link register if we are 
+	returning from eh_return.
+	(or1k_expand_epilogue) apply EH stack adjustment to stack pointer.
+	(or1k_eh_return_handler_rtx) eh_return should write to the link register.
+	(or1k_return_addr_rtx) in the case of GOT the link register cannot be read
+	after the prologue. in this case, use the stored link register from the
+	stack frame.
+	(or1k_frame_pointer_required) require FP in eh_return and 
+	when alloca is used.
+	(TARGET_FRAME_POINTER_REQUIRED) define.
+	* config/or1k/or1k.h:
+	(INITIAL_FRAME_POINTER_OFFSET) not used, removed.
+	(RETURN_ADDR_RTX) define.
+	(EH_RETURN_REGNUM) define. use reg 23.
+	(EH_RETURN_DATA_REGNO) define. use reg 25, 27, 29 and 31.
+	(EH_RETURN_STACKADJ_RTX) define.
+	(EH_RETURN_HANDLER_RTX) define.
+
 2012-12-29  Christian Svensson  <blue@cmd.nu>
 
 	* config.gcc: Use GNU userspace link options when compiling for Linux.

gcc/common/config/or1k/or1k-common.c

@@ -33,8 +33,24 @@ static const struct default_options or1k_option_optimization_table[] =
     { OPT_LEVELS_NONE, 0, NULL, 0 }
   };
 
-#undef TARGET_EXCEPT_UNWIND_INFO
-#define TARGET_EXCEPT_UNWIND_INFO sjlj_except_unwind_info
+/* Implement TARGET_EXCEPT_UNWIND_INFO.  */
+static enum unwind_info_type
+or1k_except_unwind_info (struct gcc_options *opts)
+{
+    /* Honor the --enable-sjlj-exceptions configure switch.  */
+#ifdef CONFIG_SJLJ_EXCEPTIONS
+    if (CONFIG_SJLJ_EXCEPTIONS)
+          return UI_SJLJ;
+#endif
+
+    if (DWARF2_UNWIND_INFO)
+      return UI_DWARF2;
+
+    return UI_SJLJ;
+}
+
+#undef  TARGET_EXCEPT_UNWIND_INFO
+#define TARGET_EXCEPT_UNWIND_INFO  or1k_except_unwind_info
 
 #undef TARGET_OPTION_OPTIMIZATION_TABLE
 #define TARGET_OPTION_OPTIMIZATION_TABLE or1k_option_optimization_table

gcc/config/or1k/or1k-protos.h

@@ -41,7 +41,7 @@ extern const char *or1k_output_bf (rtx * operands);
 extern const char *or1k_output_cmov (rtx * operands);
 extern void        or1k_emit_set_const32 (rtx  op0,
 					  rtx  op1);
-extern bool        or1k_expand_pic_symbol_ref (enum machine_mode mode ATTRIBUTE_UNUSED,
+extern bool        or1k_expand_pic_symbol_ref (enum machine_mode mode,
                                                rtx operands[]);
 #endif
 
@@ -52,6 +52,8 @@ extern int or1k_data_alignment (tree, int);
 extern int or1k_initial_elimination_offset (int, int);
 extern bool or1k_save_reg_p_cached (int regno);
 extern void or1k_print_jump_restore (rtx jump_address);
+extern rtx or1k_eh_return_handler_rtx (void);
+extern rtx or1k_return_addr_rtx (int, rtx);
 
 extern int or1k_legitimate_pic_operand_p (rtx x);
 

gcc/config/or1k/or1k.c

@@ -125,12 +125,28 @@ or1k_save_reg_p (int regno)
   if (regno == HARD_FRAME_POINTER_REGNUM && frame_pointer_needed)
     return true;
 
+  /* Save the stack pointer for DWARF2 for now.
+   * AFAIK, DWARF should be able to unwind using only the current stack
+   * register and the CFA offset, but I never got that to work. */
+  if (regno == STACK_POINTER_REGNUM && !frame_pointer_needed)
+    return true;
+
   /* We need to save the incoming return address if it is ever clobbered
      within the function.  */
   if (regno == LINK_REGNUM
       && (df_regs_ever_live_p(regno) || crtl->uses_pic_offset_table))
     return true;
 
+  if(crtl->calls_eh_return)
+    {
+      unsigned int i;
+      for (i = 0; EH_RETURN_DATA_REGNO (i) != INVALID_REGNUM; i++)
+        {
+          if ((unsigned int)regno == EH_RETURN_DATA_REGNO (i))
+            return true;
+        }
+    }
+
   return false;
 
 }	/* or1k_save_reg_p () */
@@ -931,7 +947,8 @@ or1k_expand_epilogue (void)
 	emit_insn (gen_frame_dealloc_sp (value_rtx));
     }
 
-  if (frame_info.save_lr_p)
+  /* eh_return sets the LR, do not overwrite it */
+  if (frame_info.save_lr_p && !crtl->calls_eh_return)
     {
       emit_insn
         (gen_rtx_SET (Pmode, gen_rtx_REG (Pmode, LINK_REGNUM),
@@ -956,6 +973,9 @@ or1k_expand_epilogue (void)
 	}
     }
 
+  if (crtl->calls_eh_return)
+    emit_insn (gen_add2_insn (stack_pointer_rtx, EH_RETURN_STACKADJ_RTX));
+
   if (frame_info.gpr_frame)
     emit_insn (gen_add2_insn (stack_pointer_rtx,
 			      GEN_INT (frame_info.gpr_frame)));
@@ -2086,5 +2106,44 @@ or1k_asm_file_start(void)
   }
 }
 
+/* Implement EH_RETURN_HANDLER_RTX. 
+ * Make eh_return use the link register. Epilogue LR restore
+ * is suppressed for eh_return. */
+rtx
+or1k_eh_return_handler_rtx (void)
+{
+  return INCOMING_RETURN_ADDR_RTX;
+}
+
+/* Implement RETURN_ADDR_RTX.
+ * We do not support moving back to a previous frame. */
+rtx
+or1k_return_addr_rtx (int count, rtx frame ATTRIBUTE_UNUSED)
+{
+  if (count != 0)
+    return const0_rtx;
+
+  or1k_compute_frame_size (get_frame_size ());
+
+  /* If we clobber the LR register, we should have saved it.
+   * If we didn't save it - assume it's still in LR */
+  if (frame_info.save_lr_p)
+    return gen_rtx_MEM (Pmode, plus_constant (Pmode, arg_pointer_rtx,
+                                              frame_info.lr_save_offset));
+  else
+    return get_hard_reg_initial_val (Pmode, LINK_REGNUM);
+}
+
+/* Implement TARGET_FRAME_POINTER_REQUIRED.
+ * We want frame pointer in eh_return and when alloca is used */
+static bool
+or1k_frame_pointer_required (void)
+{
+  return crtl->calls_eh_return || cfun->calls_alloca;
+}
+
+#undef  TARGET_FRAME_POINTER_REQUIRED
+#define TARGET_FRAME_POINTER_REQUIRED or1k_frame_pointer_required
+
 /* Initialize the GCC target structure.  */
 struct gcc_target targetm = TARGET_INITIALIZER;

gcc/config/or1k/or1k.h

@@ -350,29 +350,6 @@ Boston, MA 02111-1307, USA.  */
 /* Link register. */
 #define LINK_REGNUM 9
 
-/* This function computes the initial size of the frame (difference between SP
-   and FP) after the function prologue. */
-#define INITIAL_FRAME_POINTER_OFFSET(depth)				\
-  {									\
-    int regno;								\
-    int offset = 0;							\
-  									\
-    for (regno=0; regno < FIRST_PSEUDO_REGISTER;  regno++)		\
-      {									\
-	if (df_regs_ever_live_p (regno) && !call_used_regs[regno])	\
-	  {								\
-	    offset += 4;						\
-	  }								\
-      }									\
-									\
-    (depth) = ((!current_function_is_leaf				\
-		|| df_regs_ever_live_p (LINK_REGNUM)) ? 4 : 0)		\
-      + (frame_pointer_needed ? 4 : 0)					\
-      + offset								\
-      + OR1K_ALIGN (crtl->outgoing_args_size, 4)			\
-      + OR1K_ALIGN (get_frame_size(), 4);				\
-  }
-
 /* Register in which static-chain is passed to a function.  */
 
 #define STATIC_CHAIN_REGNUM 11
@@ -708,8 +685,7 @@ enum reg_class
    the stack.  */
 #define INCOMING_RETURN_ADDR_RTX gen_rtx_REG (Pmode, LINK_REGNUM)
 
-#define RETURN_ADDR_RTX(COUNT, FP) \
-  ((COUNT) ? NULL_RTX : get_hard_reg_initial_val (Pmode, LINK_REGNUM))
+#define RETURN_ADDR_RTX or1k_return_addr_rtx
 
 /* Addressing modes, and classification of registers for them.  */
 
@@ -1206,4 +1182,11 @@ enum reg_class
    For the OR1K, there is no need for anything other than word alignment. */
 #define TRAMPOLINE_ALIGNMENT  32
 
+/* Describe how we implement __builtin_eh_return.  */
+#define EH_RETURN_REGNUM 23
+/* Use r25, r27, r29 and r31 (clobber regs) for exception data */
+#define EH_RETURN_DATA_REGNO(N) ((N) < 4 ? (25 + ((N)<<1)) : INVALID_REGNUM)
+#define EH_RETURN_STACKADJ_RTX  gen_rtx_REG (Pmode, EH_RETURN_REGNUM)
+#define EH_RETURN_HANDLER_RTX   or1k_eh_return_handler_rtx ()
+
 #endif /* _OR1K_H_ */