[PATCH][AArch64] Fix missing optimization for CMP+AND

During combine GCC tries to merge CMP (with zero) and AND into a TST. However,
in cases where an ANDS operand is not compatible, this was being missed. Adding
a define_split where this operand was moved to a register seems to help out. 

Committed on behalf of Sudi Das

---
gcc/

2017-07-27  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
	    Sudakshina Das  <sudi.das@arm.com>

	* config/aarch64/aarch64.md
	(define_split for and<mode>3nr_compare): Move
	non aarch64_logical_operand to a register.
	(define_split for and_<SHIFT:optab><mode>3nr_compare0): Move non
	register immediate operand to a register.
	* config/aarch64/predicates.md (aarch64_mov_imm_operand): New.

gcc/testsuite
    
2017-07-27  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
	    Sudakshina Das  <sudi.das@arm.com>

	* gcc.target/aarch64/tst_imm_split_1.c: New Test.


Co-Authored-By: Sudakshina Das <sudi.das@arm.com>

From-SVN: r250631

gcc/ChangeLog

+2017-07-27  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+	    Sudakshina Das  <sudi.das@arm.com>
+
+	* config/aarch64/aarch64.md
+	(define_split for and<mode>3nr_compare): Move
+	non aarch64_logical_operand to a register.
+	(define_split for and_<SHIFT:optab><mode>3nr_compare0): Move non
+	register immediate operand to a register.
+	* config/aarch64/predicates.md (aarch64_mov_imm_operand): New.
+
 2017-07-27  Peter Bergner  <bergner@vnet.ibm.com>
 
 	PR middle-end/81564

gcc/config/aarch64/aarch64.md

@@ -3835,6 +3835,22 @@
   [(set_attr "type" "logics_reg,logics_imm")]
 )
 
+(define_split
+  [(set (reg:CC_NZ CC_REGNUM)
+	(compare:CC_NZ
+	 (and:GPI (match_operand:GPI 0 "register_operand")
+		  (match_operand:GPI 1 "aarch64_mov_imm_operand"))
+	 (const_int 0)))
+   (clobber (match_operand:SI 2 "register_operand"))]
+  ""
+  [(set (match_dup 2) (match_dup 1))
+   (set (reg:CC_NZ CC_REGNUM)
+	(compare:CC_NZ
+	 (and:GPI (match_dup 0)
+		  (match_dup 2))
+	 (const_int 0)))]
+)
+
 (define_insn "*and<mode>3nr_compare0_zextract"
   [(set (reg:CC_NZ CC_REGNUM)
 	(compare:CC_NZ
@@ -3870,6 +3886,26 @@
   [(set_attr "type" "logics_shift_imm")]
 )
 
+(define_split
+  [(set (reg:CC_NZ CC_REGNUM)
+	(compare:CC_NZ
+	 (and:GPI (SHIFT:GPI
+		   (match_operand:GPI 0 "register_operand")
+		   (match_operand:QI 1 "aarch64_shift_imm_<mode>"))
+		  (match_operand:GPI 2 "aarch64_mov_imm_operand"))
+	(const_int 0)))
+    (clobber (match_operand:SI 3 "register_operand"))]
+  ""
+  [(set (match_dup 3) (match_dup 2))
+   (set (reg:CC_NZ CC_REGNUM)
+	(compare:CC_NZ
+	 (and:GPI (SHIFT:GPI
+		   (match_dup 0)
+		   (match_dup 1))
+		  (match_dup 3))
+	 (const_int 0)))]
+)
+
 ;; -------------------------------------------------------------------
 ;; Shifts
 ;; -------------------------------------------------------------------

gcc/config/aarch64/predicates.md

@@ -114,6 +114,10 @@
   (ior (match_operand 0 "register_operand")
        (match_operand 0 "aarch64_logical_immediate")))
 
+(define_predicate "aarch64_mov_imm_operand"
+  (and (match_code "const_int")
+       (match_test "aarch64_move_imm (INTVAL (op), mode)")))
+
 (define_predicate "aarch64_logical_and_immediate"
   (and (match_code "const_int")
        (match_test "aarch64_and_bitmask_imm (INTVAL (op), mode)")))

gcc/testsuite/ChangeLog

+2017-07-27  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+	    Sudakshina Das  <sudi.das@arm.com>
+
+	* gcc.target/aarch64/tst_imm_split_1.c: New Test.
+
 2017-07-27  Marek Polacek  <polacek@redhat.com>
 
 	PR c/81417

gcc/testsuite/gcc.target/aarch64/tst_imm_split_1.c

+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+int
+f (unsigned char *p)
+{
+  return p[0] == 50 || p[0] == 52;
+}
+
+int
+g (unsigned char *p)
+{
+  return (p[0] >> 4 & 0xfd) == 0;
+}
+
+/* { dg-final { scan-assembler-not "and\\t\[xw\]\[0-9\]+, \[xw\]\[0-9\]+.*" } } */
+/* { dg-final { scan-assembler "tst\\t\[xw\]\[0-9\]+, \[xw\]\[0-9\]+" } } */
+/* { dg-final { scan-assembler "tst\\t\[xw\]\[0-9\]+, \[xw\]\[0-9\]+, lsr 4" } } */