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ARM: new peephole to turn {add,sub}+cmp into {add,sub}s
- To: gcc-patches at gcc dot gnu dot org
- Subject: ARM: new peephole to turn {add,sub}+cmp into {add,sub}s
- From: Alexandre Oliva <aoliva at redhat dot com>
- Date: 06 Jul 2000 17:08:26 -0300
- Organization: GCC Team, Red Hat
Even though combine attempts to merge add and sub with cmp, it won't
do that if there are other insns between them. When the intervening
insn is a store, it will typically be re-scheduled for execution after
the cmp. Then, these new peepholes will match the sequence of add/sub
and cmp and arrange for us to use adds/subs instead.
Ok to install?
Index: gcc/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>
* config/arm/arm.md (adds, subs): Define peepholes.
Index: gcc/config/arm/arm.md
===================================================================
RCS file: /cvs/gcc/egcs/gcc/config/arm/arm.md,v
retrieving revision 1.52
diff -u -r1.52 arm.md
--- gcc/config/arm/arm.md 2000/07/03 18:02:13 1.52
+++ gcc/config/arm/arm.md 2000/07/06 20:03:58
@@ -7793,6 +7793,28 @@
"sub%?s\\t%0, %1, #0"
[(set_attr "conds" "set")])
+;; Combine may miss these because of intervening insns before sched.
+
+(define_peephole
+ [(set (match_operand:SI 0 "s_register_operand" "=r,r")
+ (plus:SI (match_operand:SI 1 "s_register_operand" "r,r")
+ (match_operand:SI 2 "arm_add_operand" "rI,L")))
+ (set (reg:CC 24)
+ (compare:CC (match_dup 0) (const_int 0)))]
+ ""
+ "add%?s\\t%0, %1, %2"
+[(set_attr "conds" "set")])
+
+(define_peephole
+ [(set (match_operand:SI 0 "s_register_operand" "=r,r")
+ (minus:SI (match_operand:SI 1 "s_register_operand" "r,r")
+ (match_operand:SI 2 "arm_add_operand" "rI,L")))
+ (set (reg:CC 24)
+ (compare:CC (match_dup 0) (const_int 0)))]
+ ""
+ "sub%?s\\t%0, %1, %2"
+[(set_attr "conds" "set")])
+
; Peepholes to spot possible load- and store-multiples, if the ordering is
; reversed, check that the memory references aren't volatile.
--
Alexandre Oliva Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer aoliva@{cygnus.com, redhat.com}
CS PhD student at IC-Unicamp oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist *Please* write to mailing lists, not to me