LoongArch: Adjust insn patterns for better combine

For some instruction patterns with commutative operands,
the order of operands needs to be adjusted to match the rules.

gcc/ChangeLog:

	* config/loongarch/loongarch.md
	(bytepick_d_<bytepick_imm>_rev): New combiner.
	(bstrpick_alsl_paired): Reorder input operands.

gcc/testsuite/ChangeLog:

	* gcc.target/loongarch/bstrpick_alsl_paired.c: New test.
	* gcc.target/loongarch/bytepick_combine.c: New test.

3 files changed, 49 insertions, 6 deletions

diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
index 7a110ca..1c294d8 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -3111,13 +3111,14 @@
 
 (define_insn "bstrpick_alsl_paired"
   [(set (match_operand:DI 0 "register_operand" "=&r")
-	(plus:DI (match_operand:DI 1 "register_operand" "r")
-		 (and:DI (ashift:DI (match_operand:DI 2 "register_operand" "r")
-				    (match_operand 3 "const_immalsl_operand" ""))
-			 (match_operand 4 "immediate_operand" ""))))]
+	(plus:DI
+	  (and:DI (ashift:DI (match_operand:DI 1 "register_operand" "r")
+			     (match_operand 2 "const_immalsl_operand" ""))
+		  (match_operand 3 "immediate_operand" ""))
+	  (match_operand:DI 4 "register_operand" "r")))]
   "TARGET_64BIT
-   && ((INTVAL (operands[4]) >> INTVAL (operands[3])) == 0xffffffff)"
-  "bstrpick.d\t%0,%2,31,0\n\talsl.d\t%0,%0,%1,%3"
+   && ((INTVAL (operands[3]) >> INTVAL (operands[2])) == 0xffffffff)"
+  "bstrpick.d\t%0,%1,31,0\n\talsl.d\t%0,%0,%4,%2"
   [(set_attr "type" "arith")
    (set_attr "mode" "DI")
    (set_attr "insn_count" "2")])
@@ -4221,6 +4222,16 @@
   "bytepick.d\t%0,%1,%2,<bytepick_imm>"
   [(set_attr "mode" "DI")])
 
+(define_insn "bytepick_d_<bytepick_imm>_rev"
+  [(set (match_operand:DI 0 "register_operand" "=r")
+	(ior:DI (ashift (match_operand:DI 1 "register_operand" "r")
+			(const_int bytepick_d_ashift_amount))
+		(lshiftrt (match_operand:DI 2 "register_operand" "r")
+			  (const_int <bytepick_d_lshiftrt_amount>))))]
+  "TARGET_64BIT"
+  "bytepick.d\t%0,%2,%1,<bytepick_imm>"
+  [(set_attr "mode" "DI")])
+
 (define_insn "bitrev_4b"
   [(set (match_operand:SI 0 "register_operand" "=r")
 	(unspec:SI [(match_operand:SI 1 "register_operand" "r")]
diff --git a/gcc/testsuite/gcc.target/loongarch/bstrpick_alsl_paired.c b/gcc/testsuite/gcc.target/loongarch/bstrpick_alsl_paired.c
new file mode 100644
index 0000000..0bca388
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/bstrpick_alsl_paired.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+/* { dg-options "-mabi=lp64d -O2 -fdump-rtl-combine" } */
+/* { dg-final { scan-rtl-dump "{bstrpick_alsl_paired}" "combine" } } */
+/* { dg-final { scan-assembler-not "alsl.d\t\\\$r\[0-9\]+,\\\$r\[0-9\]+,\\\$r0" } } */
+
+struct SA
+{
+  const char *a;
+  unsigned int b : 16;
+  unsigned int c : 16;
+};
+
+extern struct SA SAs[];
+
+void
+test ()
+{
+  unsigned int i;
+  for (i = 0; i < 100; i++)
+    SAs[i].c = i;
+}
diff --git a/gcc/testsuite/gcc.target/loongarch/bytepick_combine.c b/gcc/testsuite/gcc.target/loongarch/bytepick_combine.c
new file mode 100644
index 0000000..2a88082
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/bytepick_combine.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-not "slli\\.d" } } */
+/* { dg-final { scan-assembler-not "srli\\.d" } } */
+/* { dg-final { scan-assembler-times "bytepick\\.d" 1 } } */
+
+unsigned long
+bytepick_d_n (unsigned long a, unsigned long b)
+{
+  return a >> 56 | b << 8;
+}