Index: config/pdp11/pdp11.md
===================================================================
--- config/pdp11/pdp11.md	(revision 165902)
+++ config/pdp11/pdp11.md	(working copy)
@@ -22,6 +22,22 @@
 (include "predicates.md")
 (include "constraints.md")
 
+(define_constants
+  [
+   ;; Register numbers
+   (FRAME_POINTER_REGNUM  5)
+   (STACK_POINTER_REGNUM  6)
+   (PC_REGNUM             7)
+   (AC0_REGNUM            8)
+   (AC3_REGNUM            11)
+   (AC4_REGNUM            12)
+   (AC5_REGNUM            13)
+   (FIRST_PSEUDO_REGISTER 14)
+   ;; Branch offset limits, as byte offsets from instruction address
+   (MIN_BRANCH            -254)
+   (MAX_BRANCH            256)
+   (MIN_SOB               -126)
+   (MAX_SOB               0)])
 
 ;; HI is 16 bit
 ;; QI is 8 bit 
@@ -165,12 +181,12 @@
 
  return \"\";
 }"
-  [(set (attr "length") (if_then_else (ior (le (minus (match_dup 0)
+  [(set (attr "length") (if_then_else (ior (lt (minus (match_dup 0)
 						       (pc))
-						(const_int -256))
-					   (ge (minus (match_dup 0)
+						(const_int MIN_SOB))
+					   (gt (minus (match_dup 0)
 						       (pc))
-						(const_int 0)))
+						(const_int MAX_SOB)))
 				      (const_int 8)
 				      (const_int 2)))])
 
@@ -228,12 +244,12 @@
 		      (pc)))]
   ""
   "* return output_jump(GET_CODE (operands[0]), 0, get_attr_length(insn));"
-  [(set (attr "length") (if_then_else (ior (le (minus (match_dup 1)
+  [(set (attr "length") (if_then_else (ior (lt (minus (match_dup 1)
 						      (pc))
-					       (const_int -256))
-					   (ge (minus (match_dup 1)
+					       (const_int MIN_BRANCH))
+					   (gt (minus (match_dup 1)
 						      (pc))
-					       (const_int 256)))
+					       (const_int MAX_BRANCH)))
 				      (const_int 6)
 				      (const_int 2)))])
 
@@ -248,12 +264,12 @@
 		      (label_ref (match_operand 1 "" ""))))]
   ""
   "* return output_jump(GET_CODE (operands[0]), 1, get_attr_length(insn));"
-  [(set (attr "length") (if_then_else (ior (le (minus (match_dup 1)
+  [(set (attr "length") (if_then_else (ior (lt (minus (match_dup 1)
 						      (pc))
-					       (const_int -256))
-					   (ge (minus (match_dup 1)
+					       (const_int MIN_BRANCH))
+					   (gt (minus (match_dup 1)
 						      (pc))
-					       (const_int 256)))
+					       (const_int MAX_BRANCH)))
 				      (const_int 6)
 				      (const_int 2)))])
 
@@ -1296,12 +1312,12 @@
     return \"br %l0\";
  return \"jmp %l0\";
 }"
-  [(set (attr "length") (if_then_else (ior (le (minus (match_dup 0)
+  [(set (attr "length") (if_then_else (ior (lt (minus (match_dup 0)
 						      (pc))
-					       (const_int -256))
-					   (ge (minus (match_dup 0)
+					       (const_int MIN_BRANCH))
+					   (gt (minus (match_dup 0)
 						      (pc))
-					       (const_int 256)))
+					       (const_int MAX_BRANCH)))
 				      (const_int 4)
 				      (const_int 2)))])
 
Index: config/pdp11/pdp11.c
===================================================================
--- config/pdp11/pdp11.c	(revision 165902)
+++ config/pdp11/pdp11.c	(working copy)
@@ -42,11 +42,6 @@
 #include "target-def.h"
 #include "df.h"
 
-/*
-#define FPU_REG_P(X)	((X)>=8 && (X)<14)
-#define CPU_REG_P(X)	((X)>=0 && (X)<8)
-*/
-
 /* this is the current value returned by the macro FIRST_PARM_OFFSET 
    defined in tm.h */
 int current_first_parm_offset;
@@ -295,7 +290,7 @@
 	asm_fprintf (stream, "\tsub $%#wo, sp\n", fsize);
 
     /* save CPU registers  */
-    for (regno = 0; regno < 8; regno++)				
+    for (regno = 0; regno <= PC_REGNUM; regno++)				
       if (df_regs_ever_live_p (regno) && ! call_used_regs[regno])	
 	    if (! ((regno == FRAME_POINTER_REGNUM)			
 		   && frame_pointer_needed))				
@@ -305,7 +300,7 @@
     /* via_ac specifies the ac to use for saving ac4, ac5 */
     via_ac = -1;
     
-    for (regno = 8; regno < FIRST_PSEUDO_REGISTER ; regno++) 
+    for (regno = AC0_REGNUM; regno <= AC5_REGNUM ; regno++) 
     {
 	/* ac0 - ac3 */						
 	if (LOAD_FPU_REG_P(regno)
@@ -366,7 +361,7 @@
 	/* hope this is safe - m68k does it also .... */		
         df_set_regs_ever_live (FRAME_POINTER_REGNUM, false);
 								
-	for (i =7, j = 0 ; i >= 0 ; i--)				
+	for (i = PC_REGNUM, j = 0 ; i >= 0 ; i--)				
 	  if (df_regs_ever_live_p (i) && ! call_used_regs[i])		
 		j++;
 	
@@ -374,22 +369,22 @@
 	k = 2*j;
 	
 	/* change fp -> r5 due to the compile error on libgcc2.c */
-	for (i =7 ; i >= 0 ; i--)					
+	for (i = PC_REGNUM ; i >= 0 ; i--)					
 	  if (df_regs_ever_live_p (i) && ! call_used_regs[i])		
 		fprintf(stream, "\tmov %#" HOST_WIDE_INT_PRINT "o(r5), %s\n",
 			(-fsize-2*j--)&0xffff, reg_names[i]);
 
 	/* get ACs */						
-	via_ac = FIRST_PSEUDO_REGISTER -1;
+	via_ac = AC5_REGNUM;
 	
-	for (i = FIRST_PSEUDO_REGISTER; i > 7; i--)
+	for (i = AC5_REGNUM; i >= AC0_REGNUM; i--)
 	  if (df_regs_ever_live_p (i) && ! call_used_regs[i])
 	    {
 		via_ac = i;
 		k += 8;
 	    }
 	
-	for (i = FIRST_PSEUDO_REGISTER; i > 7; i--)
+	for (i = AC5_REGNUM; i >= AC0_REGNUM; i--)
 	{
 	    if (LOAD_FPU_REG_P(i)
 		&& df_regs_ever_live_p (i)
@@ -418,14 +413,14 @@
     }								
     else								
     {		   
-	via_ac = FIRST_PSEUDO_REGISTER -1;
+      via_ac = AC5_REGNUM;
 	
 	/* get ACs */
-	for (i = FIRST_PSEUDO_REGISTER; i > 7; i--)
+	for (i = AC5_REGNUM; i >= AC0_REGNUM; i--)
 	  if (df_regs_ever_live_p (i) && call_used_regs[i])
 		via_ac = i;
 	
-	for (i = FIRST_PSEUDO_REGISTER; i > 7; i--)
+	for (i = AC5_REGNUM; i >= AC0_REGNUM; i--)
 	{
 	    if (LOAD_FPU_REG_P(i)
 		&& df_regs_ever_live_p (i)
@@ -443,7 +438,7 @@
 	    }
 	}
 
-	for (i=7; i >= 0; i--)					
+	for (i = PC_REGNUM; i >= 0; i--)					
 	  if (df_regs_ever_live_p (i) && !call_used_regs[i])		
 		fprintf(stream, "\tmov (sp)+, %s\n", reg_names[i]);	
 								
Index: config/pdp11/pdp11.h
===================================================================
--- config/pdp11/pdp11.h	(revision 165860)
+++ config/pdp11/pdp11.h	(working copy)
@@ -22,10 +22,10 @@
 #define CONSTANT_POOL_BEFORE_FUNCTION	0
 
 /* check whether load_fpu_reg or not */
-#define LOAD_FPU_REG_P(x) ((x)>=8 && (x)<=11)
-#define NO_LOAD_FPU_REG_P(x) ((x)==12 || (x)==13)
+#define LOAD_FPU_REG_P(x) ((x) >= AC0_REGNUM && (x) <= AC3_REGNUM)
+#define NO_LOAD_FPU_REG_P(x) ((x) == AC4_REGNUM || (x) == AC5_REGNUM)
 #define FPU_REG_P(x)	(LOAD_FPU_REG_P(x) || NO_LOAD_FPU_REG_P(x))
-#define CPU_REG_P(x)	((x)<8)
+#define CPU_REG_P(x)	((x) <= PC_REGNUM)
 
 /* Names to predefine in the preprocessor for this target machine.  */
 
@@ -140,8 +140,6 @@
    we have 8 integer registers, plus 6 float 
    (don't use scratch float !) */
 
-#define FIRST_PSEUDO_REGISTER 14
-
 /* 1 for registers that have pervasive standard uses
    and are not available for the register allocator.
 
@@ -191,7 +189,7 @@
     } 						\
 						\
   if (TARGET_AC0)				\
-      call_used_regs[8] = 1;			\
+      call_used_regs[AC0_REGNUM] = 1;		\
   if (TARGET_UNIX_ASM)				\
     {						\
       /* Change names of FPU registers for the UNIX assembler.  */ \
@@ -211,7 +209,7 @@
 */
 
 #define HARD_REGNO_NREGS(REGNO, MODE)   \
-((REGNO < 8)?								\
+((REGNO <= PC_REGNUM)?							\
     ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) / UNITS_PER_WORD)	\
     :1)
     
@@ -222,7 +220,7 @@
    FPU can only hold DF - simplifies life!
 */
 #define HARD_REGNO_MODE_OK(REGNO, MODE) \
-(((REGNO) < 8)?						\
+(((REGNO) <= PC_REGNUM)?				\
   ((GET_MODE_BITSIZE(MODE) <= 16) 			\
    || (GET_MODE_BITSIZE(MODE) >= 32 && !((REGNO) & 1)))	\
   :(MODE) == DFmode)
@@ -237,17 +235,8 @@
 /* Specify the registers used for certain standard purposes.
    The values of these macros are register numbers.  */
 
-/* the pdp11 pc overloaded on a register that the compiler knows about.  */
-#define PC_REGNUM  7
-
-/* Register to use for pushing function arguments.  */
-#define STACK_POINTER_REGNUM 6
-
-/* Base register for access to local variables of the function.  */
-#define FRAME_POINTER_REGNUM 5
-
 /* Base register for access to arguments of the function.  */
-#define ARG_POINTER_REGNUM 5
+#define ARG_POINTER_REGNUM FRAME_POINTER_REGNUM
 
 /* Register in which static-chain is passed to a function.  */
 /* ??? - i don't want to give up a reg for this! */
@@ -313,7 +302,10 @@
    or could index an array.  */
 
 #define REGNO_REG_CLASS(REGNO) 		\
-((REGNO)>=8?((REGNO)<=11?LOAD_FPU_REGS:NO_LOAD_FPU_REGS):(((REGNO)&1)?MUL_REGS:GENERAL_REGS))
+((REGNO) >= AC0_REGNUM ? \
+ ((REGNO) <= AC3_REGNUM ? LOAD_FPU_REGS : \
+  NO_LOAD_FPU_REGS) :                     \
+ (((REGNO) & 1) ? MUL_REGS : GENERAL_REGS))
 
 
 /* The class value for index registers, and the one for base regs.  */
@@ -441,10 +433,10 @@
 {								\
   int offset, regno;		      				\
   offset = get_frame_size();					\
-  for (regno = 0; regno < 8; regno++)				\
+  for (regno = 0; regno <= PC_REGNUM; regno++)			\
     if (df_regs_ever_live_p (regno) && ! call_used_regs[regno])	\
       offset += 2;						\
-  for (regno = 8; regno < 14; regno++)				\
+  for (regno = AC0_REGNUM; regno <= AC5_REGNUM; regno++)	\
     if (df_regs_ever_live_p (regno) && ! call_used_regs[regno])	\
       offset += 8;						\
   /* offset -= 2;   no fp on stack frame */			\
@@ -467,9 +459,9 @@
    has been allocated, which happens in local-alloc.c.  */
 
 #define REGNO_OK_FOR_INDEX_P(REGNO) \
-  ((REGNO) < 8 || (unsigned) reg_renumber[REGNO] < 8)
+  ((REGNO) <= PC_REGNUM || (unsigned) reg_renumber[REGNO] <= PC_REGNUM)
 #define REGNO_OK_FOR_BASE_P(REGNO)  \
-  ((REGNO) < 8 || (unsigned) reg_renumber[REGNO] < 8)
+  ((REGNO) <= PC_REGNUM || (unsigned) reg_renumber[REGNO] <= PC_REGNUM)
 
 /* Now macros that check whether X is a register and also,
    strictly, whether it is in a specified class.
@@ -560,10 +552,10 @@
     /* accept -(SP) -- which uses PRE_MODIFY for byte mode */		\
     if (GET_CODE (operand) == PRE_MODIFY				\
 	&& GET_CODE (XEXP (operand, 0)) == REG				\
-	&& REGNO (XEXP (operand, 0)) == 6        	        	\
+	&& REGNO (XEXP (operand, 0)) == STACK_POINTER_REGNUM       	\
 	&& GET_CODE ((xfoob = XEXP (operand, 1))) == PLUS		\
 	&& GET_CODE (XEXP (xfoob, 0)) == REG				\
-	&& REGNO (XEXP (xfoob, 0)) == 6	        	        	\
+	&& REGNO (XEXP (xfoob, 0)) == STACK_POINTER_REGNUM       	\
 	&& CONSTANT_P (XEXP (xfoob, 1))                                 \
 	&& INTVAL (XEXP (xfoob,1)) == -2)      	               		\
       goto ADDR;							\
@@ -571,10 +563,10 @@
     /* accept (SP)+ -- which uses POST_MODIFY for byte mode */		\
     if (GET_CODE (operand) == POST_MODIFY				\
 	&& GET_CODE (XEXP (operand, 0)) == REG				\
-	&& REGNO (XEXP (operand, 0)) == 6        	        	\
+	&& REGNO (XEXP (operand, 0)) == STACK_POINTER_REGNUM       	\
 	&& GET_CODE ((xfoob = XEXP (operand, 1))) == PLUS		\
 	&& GET_CODE (XEXP (xfoob, 0)) == REG				\
-	&& REGNO (XEXP (xfoob, 0)) == 6	        	        	\
+	&& REGNO (XEXP (xfoob, 0)) == STACK_POINTER_REGNUM		\
 	&& CONSTANT_P (XEXP (xfoob, 1))                                 \
 	&& INTVAL (XEXP (xfoob,1)) == 2)      	               		\
       goto ADDR;							\
