@@ -1,3 +1,11 @@
+2016-11-20 Jeff Law <law@redhat.com>
+
+ PR target/25128
+ * config/m68k/predicates.md (swap_peephole_relational_operator): New
+ predicate.
+ * config/m68k/m68k.md (relational tests against 65535/65536): New
+ peephole2.
+
2016-11-21 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
* tree-ssa-loop-prefetch.c: Delete FIXME after the includes.
@@ -7786,7 +7786,6 @@
operands[6] = GEN_INT (exact_log2 (INTVAL (operands[1]) + 1));
operands[7] = operands[2];
}")
-
(define_peephole2
[(set (cc0) (compare (match_operand:SI 0 "register_operand" "")
(match_operand:SI 1 "pow2_m1_operand" "")))
@@ -7804,3 +7803,23 @@
(match_dup 2) (match_dup 3)))]
"{ operands[4] = GEN_INT (exact_log2 (INTVAL (operands[1]) + 1)); }")
+;; When optimizing for size or for the original 68000 or 68010, we can
+;; improve some relational tests against 65536 (which get canonicalized
+;; internally against 65535).
+;; The rotate in the output pattern will turn into a swap.
+(define_peephole2
+ [(set (cc0) (compare (match_operand:SI 0 "register_operand" "")
+ (const_int 65535)))
+ (set (pc) (if_then_else (match_operator 1 "swap_peephole_relational_operator"
+ [(cc0) (const_int 0)])
+ (match_operand 2 "pc_or_label_operand")
+ (match_operand 3 "pc_or_label_operand")))]
+ "peep2_reg_dead_p (1, operands[0])
+ && (operands[2] == pc_rtx || operands[3] == pc_rtx)
+ && (optimize_size || TUNE_68000_10)
+ && DATA_REG_P (operands[0])"
+ [(set (match_dup 0) (rotate:SI (match_dup 0) (const_int 16)))
+ (set (cc0) (compare (subreg:HI (match_dup 0) 2) (const_int 0)))
+ (set (pc) (if_then_else (match_op_dup 1 [(cc0) (const_int 0)])
+ (match_dup 2) (match_dup 3)))]
+ "")
@@ -279,3 +279,6 @@
;; Used to detect (pc) or (label_ref) in some jumping patterns to cut down
(define_predicate "pc_or_label_operand"
(match_code "pc,label_ref"))
+
+(define_predicate "swap_peephole_relational_operator"
+ (match_code "gtu,leu,gt,le"))
@@ -1,3 +1,8 @@
+2016-11-20 Jeff Law <law@redhat.com>
+
+ PR target/25128
+ * gcc.target/m68k/pr25128.c: New test.
+
2016-11-21 Richard Sandiford <richard.sandiford@arm.com>
* gcc.dg/tree-ssa/tailcall-7.c: New test.
new file mode 100644
@@ -0,0 +1,48 @@
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+
+/* { dg-final { scan-assembler-times "swap" 4 } } */
+/* { dg-final { scan-assembler-times "tst.w" 4 } } */
+/* { dg-final { scan-assembler-not "cmp.l" } } */
+
+
+unsigned int bar (void);
+void
+foo1 (void)
+{
+ unsigned int a = bar ();
+ if (0x10000 <= a)
+ bar ();
+}
+
+
+void
+foo2 (void)
+{
+ unsigned int a = bar ();
+ if (0x10000 > a)
+ bar ();
+}
+
+
+void
+foo3 (void)
+{
+ int a = bar ();
+ if (0x10000 <= a)
+ bar ();
+}
+
+
+void
+foo4 (void)
+{
+ int a = bar ();
+ if (0x10000 > a)
+ bar ();
+}
+
+
+
+
+
One more gift to the retro-computing folks. GCC for the m68k generates poor code for some relational comparisons against 65536. Swapping the upper/lower halves of the register and doing a word sized tst is faster on the 68000/68010 and smaller on all variants. This doesn't work for all comparisons against 65536. Anyway, it's easy to implement, so here we go. Tested with m68k.md as well as by building newlib using a version which unconditionally made the transformation when it was valid (the committed version only fires with -Os or when tuning for a m68000/m68010. You might question if any of that testing is worthwhile -- it actually found a case where I thought I'd changed the in-progress peephole, but had instead changed something totally unrelated causing the compiler to hang! Installing on the trunk. I'm probably done with m68k hacking for 2016, barring problems with the yearly bootstrap. Jeff commit bdc7c1bb83d9baa342c0101049f7586330e406da Author: Jeff Law <law@redhat.com> Date: Mon Nov 21 11:18:34 2016 -0700 PR target/25128 * config/m68k/predicates.md (swap_peephole_relational_operator): New predicate. * config/m68k/m68k.md (relational tests against 65535/65536): New peephole2. PR target/25128 * gcc.target/m68k/pr25128.c: New test.