arc/nps400: New peephole2 pattern allow more cmem loads

In the case where we access a single bit from a value and use this in a
EQ/NE comparison, GCC will convert this into a sign-extend and GE/LT
comparison.

Normally this would be fine, however, if the value is in CMEM memory,
then we don't have a sign-extending load available (using the special
short CMEM load instructions), and instead we end up using a long form
load with LIMM, which is less efficient.

This peephole optimisation looks for the sign-extend followed by GE/LT
pattern and converts this back into a load and EQ/NE comparison.

gcc/ChangeLog:

	* config/arc/arc.md (cmem bit/sign-extend peephole2): New peephole
	to make better use of cmem loads in the case where a single bit is
	being accessed.
	* config/arc/predicates.md (ge_lt_comparison_operator): New
	predicate.

gcc/testsuite/ChangeLog:

	* gcc.target/arc/cmem-bit-1.c: New file.
	* gcc.target/arc/cmem-bit-2.c: New file.
	* gcc.target/arc/cmem-bit-3.c: New file.
	* gcc.target/arc/cmem-bit-4.c: New file.

From-SVN: r242572

gcc/ChangeLog

+2016-11-17  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* config/arc/arc.md (cmem bit/sign-extend peephole2): New peephole
+	to make better use of cmem loads in the case where a single bit is
+	being accessed.
+	* config/arc/predicates.md (ge_lt_comparison_operator): New
+	predicate.
+
 2016-11-17  Andrew Senkevich <andrew.senkevich@intel.com>
 
 	* config/i386/i386.c (processor_features): Add F_AVX5124VNNIW,

gcc/config/arc/arc.md

@@ -1465,6 +1465,49 @@
   [(set_attr "type" "cmove,cmove")
    (set_attr "length" "4,8")])
 
+;; When there's a mask of a single bit, and then a compare to 0 or 1,
+;; if the single bit is the sign bit, then GCC likes to convert this
+;; into a sign extend and a compare less than, or greater to zero.
+;; This is usually fine, except for the NXP400 where we have access to
+;; a bit test instruction, along with a special short load instruction
+;; (from CMEM), that doesn't support sign-extension on load.
+;;
+;; This peephole optimisation attempts to restore the use of bit-test
+;; in those cases where it is useful to do so.
+(define_peephole2
+  [(set (match_operand:SI 0 "register_operand" "")
+		(sign_extend:SI
+		(match_operand:QI 1 "any_mem_operand" "")))
+   (set (reg:CC_ZN CC_REG)
+	(compare:CC_ZN (match_dup 0)
+		       (const_int 0)))
+   (set (pc)
+	(if_then_else (match_operator 2 "ge_lt_comparison_operator"
+		       [(reg:CC_ZN CC_REG) (const_int 0)])
+		      (match_operand 3 "" "")
+		      (match_operand 4 "" "")))]
+  "TARGET_NPS_CMEM
+   && cmem_address (XEXP (operands[1], 0), SImode)
+   && peep2_reg_dead_p (2, operands[0])
+   && peep2_regno_dead_p (3, CC_REG)"
+  [(set (match_dup 0)
+	(zero_extend:SI
+	(match_dup 1)))
+   (set (reg:CC_ZN CC_REG)
+	(compare:CC_ZN (zero_extract:SI
+			 (match_dup 0)
+			 (const_int 1)
+			 (const_int 7))
+		       (const_int 0)))
+   (set (pc)
+	(if_then_else (match_dup 2)
+		      (match_dup 3)
+		      (match_dup 4)))]
+  "if (GET_CODE (operands[2]) == GE)
+     operands[2] = gen_rtx_EQ (VOIDmode, gen_rtx_REG (CC_ZNmode, 61), const0_rtx);
+   else
+     operands[2] = gen_rtx_NE (VOIDmode, gen_rtx_REG (CC_ZNmode, 61), const0_rtx);")
+
 ; Try to generate more short moves, and/or less limms, by substituting a
 ; conditional move with a conditional sub.
 (define_peephole2

gcc/config/arc/predicates.md

@@ -452,6 +452,9 @@
 (define_predicate "equality_comparison_operator"
   (match_code "eq, ne"))
 
+(define_predicate "ge_lt_comparison_operator"
+  (match_code "ge, lt"))
+
 (define_predicate "brcc_nolimm_operator"
   (ior (match_test "REG_P (XEXP (op, 1))")
        (and (match_code "eq, ne, lt, ge, ltu, geu")

gcc/testsuite/ChangeLog

+2016-11-17  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* gcc.target/arc/cmem-bit-1.c: New file.
+	* gcc.target/arc/cmem-bit-2.c: New file.
+	* gcc.target/arc/cmem-bit-3.c: New file.
+	* gcc.target/arc/cmem-bit-4.c: New file.
+
 2016-11-17  Andrew Senkevich <andrew.senkevich@intel.com>
 
 	* gcc.target/i386/builtin_target.c: Handle new "avx5124vnniw",

gcc/testsuite/gcc.target/arc/cmem-bit-1.c

+/* { dg-do compile } */
+/* { dg-options "-mcpu=nps400 -mcmem -O2" } */
+
+struct strange_bool
+{
+  unsigned char bool_bit   :1;
+  unsigned char other_bits :7;
+};
+
+struct strange_bool a_strange_bool __attribute__((section(".cmem")));
+
+extern void bar();
+
+void foo() {
+  if (a_strange_bool.bool_bit)
+    bar();
+}
+
+/* { dg-final { scan-assembler "xldb r\[0-9\]+,\\\[@a_strange_bool\\\]" } } */
+/* { dg-final { scan-assembler "btst_s r\[0-9\]+,7" { target arceb-*-* } } } */

gcc/testsuite/gcc.target/arc/cmem-bit-2.c

+/* { dg-do compile } */
+/* { dg-options "-mcpu=nps400 -mcmem -O2" } */
+
+struct strange_bool
+{
+  unsigned short bool_bit   :1;
+  unsigned short other_bits :15;
+};
+
+struct strange_bool a_strange_bool __attribute__((section(".cmem")));
+
+extern void bar();
+
+void foo() {
+  if (a_strange_bool.bool_bit)
+    bar();
+}
+
+/* { dg-final { scan-assembler "xldb r\[0-9\]+,\\\[@a_strange_bool\\\]" } } */
+/* { dg-final { scan-assembler "btst_s r\[0-9\]+,7" { target arceb-*-* } } } */

gcc/testsuite/gcc.target/arc/cmem-bit-3.c

+/* { dg-do compile } */
+/* { dg-options "-mcpu=nps400 -mcmem -O2" } */
+
+struct strange_bool
+{
+  unsigned int bool_bit   :1;
+  unsigned int other_bits :31;
+};
+
+struct strange_bool a_strange_bool __attribute__((section(".cmem")));
+
+extern void bar();
+
+void foo() {
+  if (a_strange_bool.bool_bit)
+    bar();
+}
+
+/* { dg-final { scan-assembler "xldb r\[0-9\]+,\\\[@a_strange_bool\\\]" } } */
+/* { dg-final { scan-assembler "btst_s r\[0-9\]+,7" { target arceb-*-* } } } */

gcc/testsuite/gcc.target/arc/cmem-bit-4.c

+/* { dg-do compile } */
+/* { dg-options "-mcpu=nps400 -mcmem -O2" } */
+
+struct strange_bool
+{
+  unsigned long long bool_bit   :1;
+  unsigned long long other_bits :61;
+};
+
+struct strange_bool a_strange_bool __attribute__((section(".cmem")));
+
+extern void bar();
+
+void foo() {
+  if (a_strange_bool.bool_bit)
+    bar();
+}
+
+/* { dg-final { scan-assembler "xldb r\[0-9\]+,\\\[@a_strange_bool\\\]" } } */
+/* { dg-final { scan-assembler "btst_s r\[0-9\]+,7" { target arceb-*-* } } } */