[RFC] patch: Re: reg+reg addressing mode on SPARC

[Dan Nicolaescu]

Joe Buck <jbuck@synopsys.com> writes:

  > Dan Nicolaescu writes:
  > > Here is the result that I get for the code from the 2340 bug report
  > > using a version of gcc patched to have ADDRESS_COST 2 for the reg+reg
  > > addressing modes and 1 for all the other cases:
  > > 
  > > ./a.out
  > > test      absolute   additions      ratio with
  > > number    time       per second     test0
  > > 
  > >  0        0.31sec    161.29M         1.00
  > >  1        0.31sec    161.29M         1.00
  > [ all others are one as well ]
  > 
  > Cool.
  > 
  > Hmm.  Seems the next step is to try your patch on other benchmarks, such
  > as Spec-[year of your choice].  

I will try it on Spec95. 

Meanwhile let's see if my patch is correct...
(it bootstraps on sparc-sun-solaris2.8)

Can somebody that knows this stuff please look at the
sparc_address_cost function and see if it detects correctly the reg+reg
addressing mode?


2001-08-10  Dan Nicolaescu  <dann@ics.uci.edu>

	* config/sparc/sparc.c (sparc_address_cost): New function to
	compute the address mode cost.
	* config/sparc/sparc.h (ADDRESS_COST): Use it.
	* config/sparc/sparc-protos.h (sparc_address_cost): New prototype.
	


*** sparc.h~	Sun May 13 00:10:12 2001
--- sparc.h	Fri Aug 10 14:46:56 2001
***************
*** 2852,2858 ****
  	return 0;						\
      return 8;
  
! #define ADDRESS_COST(RTX)  1
  
  /* Compute extra cost of moving data between one register class
     and another.  */
--- 2852,2858 ----
  	return 0;						\
      return 8;
  
! #define ADDRESS_COST(RTX) sparc_address_cost(RTX)
  
  /* Compute extra cost of moving data between one register class
     and another.  */
*** sparc-protos.h~	Fri Aug 10 14:48:14 2001
--- sparc-protos.h	Fri Aug 10 18:13:12 2001
***************
*** 24,31 ****
  #ifndef __SPARC_PROTOS_H__
  #define __SPARC_PROTOS_H__
  
- extern int sparc_address_cost PARAMS ((rtx));
- 
  #ifdef TREE_CODE
  extern struct rtx_def *function_value PARAMS ((tree, enum machine_mode, int));
  extern void function_arg_advance PARAMS ((CUMULATIVE_ARGS *,
--- 24,29 ----
***************
*** 77,82 ****
--- 75,81 ----
  					     unsigned int, unsigned long,
  					     unsigned long, const char *,
  					     const char *, unsigned long));
+ extern int sparc_address_cost PARAMS ((rtx));
  
  #ifdef RTX_CODE
  extern enum machine_mode select_cc_mode PARAMS ((enum rtx_code, rtx, rtx));
*** sparc.c~	Sun May 13 00:10:12 2001
--- sparc.c	Fri Aug 10 18:07:56 2001
***************
*** 8606,8611 ****
--- 8606,8634 ----
      ggc_mark_rtx (ups->group[i]);
  }
  
+ /* Compute the cost of an addressing mode.
+    Just consider reg+reg more expensive. */
+ 
+ int
+ sparc_address_cost (addr)
+      rtx addr;
+ {
+   if (GET_CODE (addr) == REG)
+     return 1;
+ 
+   if (GET_CODE (addr) == PLUS)
+     {
+       rtx op0 = XEXP (addr, 0);
+       rtx op1 = XEXP (addr, 1);
+       enum rtx_code code0 = GET_CODE (op0);
+       enum rtx_code code1 = GET_CODE (op1);
+       if (code0 == REG || code1 == REG)
+         return 2;
+       return 1;
+     }
+   return 1;
+ }
+ 
  /* Called to register all of our global variables with the garbage
     collector.  */