diff mbox

Commit: RX: Disable extender peepholes at -O3

Message ID m3sjpaan8l.fsf@redhat.com
State New
Headers show

Commit Message

Nick Clifton Aug. 9, 2011, 10:32 a.m. UTC 
Hi Guys,

  I am checking in the patch below to the mainline and 4.6 branch.  It
  disables the peephole optimizations in the rx.md file that combine a
  load followed by a zero- or sign- extend operation.  The disabling
  only happens at -O3 (or higher) as although the peepholes reduce the
  number of instructions they can introduce pipeline stalls that
  actually make the program slower.  (This is certainly true for the
  coremark test).

Cheers
  Nick

gcc/ChangeLog
2011-08-09  Nick Clifton  <nickc@redhat.com>

	* config/rx/rx.md: Disable extender peepholes at -O3.

Comments

Paul Koning Aug. 9, 2011, 10:51 a.m. UTC | #1 
>  I am checking in the patch below to the mainline and 4.6 branch.  It
>  disables the peephole optimizations in the rx.md file that combine a
>  load followed by a zero- or sign- extend operation.  The disabling
>  only happens at -O3 (or higher) as although the peepholes reduce the
>  number of instructions they can introduce pipeline stalls that
>  actually make the program slower.  (This is certainly true for the
>  coremark test).

Doesn't that mean it should be disabled for any optimization other than optimize_size?  It seems surprising to have a "size but not speed" optimization done at -O2.

	paul
Nick Clifton Aug. 9, 2011, 11:22 a.m. UTC | #2 
Hi Paul,

>>   It disables the peephole optimizations in the rx.md file that combine a
>>   load followed by a zero- or sign- extend operation.  The disabling
>>   only happens at -O3 (or higher) as although the peepholes reduce the
>>   number of instructions they can introduce pipeline stalls that
>>   actually make the program slower.
>
> Doesn't that mean it should be disabled for any optimization other than
> optimize_size?

That is what I thought as well.  But Renesas have specifically asked for 
this arrangement, so that is what I have done.

Cheers
   Nick
diff mbox

Patch

Index: gcc/config/rx/rx.md
===================================================================
--- gcc/config/rx/rx.md	(revision 177584)
+++ gcc/config/rx/rx.md	(working copy)
@@ -1598,7 +1598,7 @@ 
 		   (memex_commutative:SI (match_dup 0)
 					 (match_dup 2)))
 	      (clobber (reg:CC CC_REG))])]
-  "peep2_regno_dead_p (2, REGNO (operands[0]))"
+  "peep2_regno_dead_p (2, REGNO (operands[0])) && (optimize < 3 || optimize_size)"
   [(parallel [(set:SI (match_dup 2)
 		      (memex_commutative:SI (match_dup 2)
 					    (extend_types:SI (match_dup 1))))
@@ -1612,7 +1612,7 @@ 
 		   (memex_commutative:SI (match_dup 2)
 					 (match_dup 0)))
 	      (clobber (reg:CC CC_REG))])]
-  "peep2_regno_dead_p (2, REGNO (operands[0]))"
+  "peep2_regno_dead_p (2, REGNO (operands[0])) && (optimize < 3 || optimize_size)"
   [(parallel [(set:SI (match_dup 2)
 		      (memex_commutative:SI (match_dup 2)
 					    (extend_types:SI (match_dup 1))))
@@ -1626,7 +1626,7 @@ 
 		   (memex_noncomm:SI (match_dup 2)
 				     (match_dup 0)))
 	      (clobber (reg:CC CC_REG))])]
-  "peep2_regno_dead_p (2, REGNO (operands[0]))"
+  "peep2_regno_dead_p (2, REGNO (operands[0])) && (optimize < 3 || optimize_size)"
   [(parallel [(set:SI (match_dup 2)
 		      (memex_noncomm:SI (match_dup 2)
 					(extend_types:SI (match_dup 1))))
@@ -1639,7 +1639,7 @@ 
    (set (match_operand:SI                               2 "register_operand")
 	(memex_nocc:SI (match_dup 0)
 		       (match_dup 2)))]
-  "peep2_regno_dead_p (2, REGNO (operands[0]))"
+  "peep2_regno_dead_p (2, REGNO (operands[0])) && (optimize < 3 || optimize_size)"
   [(set:SI (match_dup 2)
 	   (memex_nocc:SI (match_dup 2)
 			  (extend_types:SI (match_dup 1))))]
@@ -1651,7 +1651,7 @@ 
    (set (match_operand:SI                               2 "register_operand")
 	(memex_nocc:SI (match_dup 2)
 		       (match_dup 0)))]
-  "peep2_regno_dead_p (2, REGNO (operands[0]))"
+  "peep2_regno_dead_p (2, REGNO (operands[0])) && (optimize < 3 || optimize_size)"
   [(set:SI (match_dup 2)
 	   (memex_nocc:SI (match_dup 2)
 			  (extend_types:SI (match_dup 1))))]
@@ -1662,7 +1662,7 @@ 
 	(memex_commutative:SI (match_operand:SI                               1 "register_operand" "%0")
  		              (extend_types:SI (match_operand:small_int_modes 2 "rx_restricted_mem_operand" "Q"))))
    (clobber (reg:CC CC_REG))]
-  ""
+  "(optimize < 3 || optimize_size)"
   "<memex_commutative:op>\t%<extend_types:letter>2, %0"
   [(set_attr "timings" "33")
    (set_attr "length"  "5")] ;; This length is corrected in rx_adjust_insn_length
@@ -1673,7 +1673,7 @@ 
 	(memex_noncomm:SI (match_operand:SI                               1 "register_operand" "0")
                           (extend_types:SI (match_operand:small_int_modes 2 "rx_restricted_mem_operand" "Q"))))
    (clobber (reg:CC CC_REG))]
-  ""
+  "(optimize < 3 || optimize_size)"
   "<memex_noncomm:op>\t%<extend_types:letter>2, %0"
   [(set_attr "timings" "33")
    (set_attr "length"  "5")] ;; This length is corrected in rx_adjust_insn_length
@@ -1683,7 +1683,7 @@ 
   [(set (match_operand:SI                                              0 "register_operand" "=r")
 	(memex_nocc:SI (match_operand:SI                               1 "register_operand" "%0")
 		       (extend_types:SI (match_operand:small_int_modes 2 "rx_restricted_mem_operand" "Q"))))]
-  ""
+  "(optimize < 3 || optimize_size)"
   "<memex_nocc:op>\t%<extend_types:letter>2, %0"
   [(set_attr "timings" "33")
    (set_attr "length"  "5")] ;; This length is corrected in rx_adjust_insn_length
@@ -1695,7 +1695,7 @@ 
    (set (reg:CC CC_REG)
 	(compare:CC (match_operand:SI                   2 "register_operand")
 		    (match_dup 0)))]
-  "peep2_regno_dead_p (2, REGNO (operands[0]))"
+  "peep2_regno_dead_p (2, REGNO (operands[0])) && (optimize < 3 || optimize_size)"
   [(set (reg:CC CC_REG)
 	(compare:CC (match_dup 2)
 		    (extend_types:SI (match_dup 1))))]
@@ -1734,7 +1734,7 @@ 
   [(set (reg:CC CC_REG)
 	(compare:CC (match_operand:SI                               0 "register_operand" "=r")
 		    (extend_types:SI (match_operand:small_int_modes 1 "rx_restricted_mem_operand" "Q"))))]
-  ""
+  "(optimize < 3 || optimize_size)"
   "cmp\t%<extend_types:letter>1, %0"
   [(set_attr "timings" "33")
    (set_attr "length"  "5")] ;; This length is corrected in rx_adjust_insn_length