[PATCH 4/5][Arm] New pattern for CSNEG instructions

This patch adds a new pattern, *thumb2_csneg, for generating CSNEG
instructions. It also restricts *if_neg_move and *thumb2_negscc to only match
if !TARGET_COND_ARITH which prevents undesirable matches during ifcvt.

gcc/ChangeLog:

	* config/arm/thumb2.md (*thumb2_csneg): New.
	(*thumb2_negscc): Don't match if TARGET_COND_ARITH.
	* config/arm/arm.md (*if_neg_move): Don't match if TARGET_COND_ARITH.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/csneg.c: New test.

Co-authored-by: Omar Tahir <omar.tahir@arm.com>

3 files changed, 49 insertions, 2 deletions

diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index dd13c77..bffdb0b 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -11213,7 +11213,7 @@
 	  [(match_operand 3 "cc_register" "") (const_int 0)])
 	 (neg:SI (match_operand:SI 2 "s_register_operand" "l,r"))
 	 (match_operand:SI 1 "s_register_operand" "0,0")))]
-  "TARGET_32BIT"
+  "TARGET_32BIT && !TARGET_COND_ARITH"
   "#"
   "&& reload_completed"
   [(cond_exec (match_op_dup 4 [(match_dup 3) (const_int 0)])
diff --git a/gcc/config/arm/thumb2.md b/gcc/config/arm/thumb2.md
index 0ff5a53..2a8fdf2 100644
--- a/gcc/config/arm/thumb2.md
+++ b/gcc/config/arm/thumb2.md
@@ -881,7 +881,7 @@
 		 [(match_operand:SI 1 "s_register_operand" "r")
 		  (match_operand:SI 2 "arm_rhs_operand" "rI")])))
    (clobber (reg:CC CC_REGNUM))]
-  "TARGET_THUMB2"
+  "TARGET_THUMB2 && !TARGET_COND_ARITH"
   "#"
   "&& reload_completed"
   [(const_int 0)]
@@ -971,6 +971,20 @@
    (set_attr "predicable" "no")]
 )
 
+(define_insn "*thumb2_csneg"
+  [(set (match_operand:SI 0 "arm_general_register_operand" "=r, r")
+        (if_then_else:SI
+         (match_operand 1 "arm_comparison_operation" "")
+         (neg:SI (match_operand:SI 2 "arm_general_register_operand" "r, r"))
+         (match_operand:SI 3 "reg_or_zero_operand" "r, Pz")))]
+  "TARGET_COND_ARITH"
+  "@
+   csneg\\t%0, %3, %2, %D1
+   csneg\\t%0, zr, %2, %D1"
+  [(set_attr "type" "csel")
+   (set_attr "predicable" "no")]
+)
+
 (define_insn "*thumb2_movcond"
   [(set (match_operand:SI 0 "s_register_operand" "=Ts,Ts,Ts")
 	(if_then_else:SI
diff --git a/gcc/testsuite/gcc.target/arm/csneg.c b/gcc/testsuite/gcc.target/arm/csneg.c
new file mode 100644
index 0000000..e486062
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/csneg.c
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_arch_v8_1m_main_ok } */
+/* { dg-options "-O2 -march=armv8.1-m.main" } */
+
+int
+test_csneg32_condasn1(int w0, int w1, int w2, int w3)
+{
+  int w4;
+
+  /* { dg-final { scan-assembler "csneg\tr\[0-9\]*.*ne" } } */
+  w4 = (w0 == w1) ? -w2 : w3;
+  return w4;
+}
+
+int
+test_csneg32_condasn2(int w0, int w1, int w2, int w3)
+{
+  int w4;
+
+  /* { dg-final { scan-assembler "csneg\tr\[0-9\]*.*eq" } } */
+  w4 = (w0 == w1) ? w3 : -w2;
+  return w4;
+}
+
+unsigned long long
+test_csneg_uxtw (unsigned int a, unsigned int b, unsigned int c)
+{
+  unsigned int val;
+
+  /* { dg-final { scan-assembler "csneg\tr\[0-9\]*.*ne" } } */
+  val = a ? b : -c;
+  return val;
+}