re PR target/82981 (unnecessary __multi3 call for mips64r6 linux kernel)

	PR target/82981
        * config/mips/mips.md (<u>mulditi3): Generate patterns for high
        doubleword and low doubleword result of multiplication on
        MIPS64R6.

        * gcc.target/mips/mips64r6-ti-mult.c: New test.

From-SVN: r277537

gcc/ChangeLog

 2019-10-28  Mihailo Stojanovic  <mistojanovic@wavecomp.com>
 
+	PR target/82981
+	* config/mips/mips.md (<u>mulditi3): Generate patterns for high
+	doubleword and low doubleword result of multiplication on
+	MIPS64R6.
+
 	* config/mips/mips.c (DIRECT_BUILTIN_PURE): New macro. Add a
 	pure qualifier to the built-in.
 	(MSA_BUILTIN_PURE): New macro. Add a pure qualifier to the MSA

gcc/config/mips/mips.md

@@ -2464,9 +2464,11 @@
   [(set (match_operand:TI 0 "register_operand")
 	(mult:TI (any_extend:TI (match_operand:DI 1 "register_operand"))
 		 (any_extend:TI (match_operand:DI 2 "register_operand"))))]
-  "ISA_HAS_DMULT && !(<CODE> == ZERO_EXTEND && TARGET_FIX_VR4120)"
+  "ISA_HAS_R6DMUL
+   || (ISA_HAS_DMULT
+       && !(<CODE> == ZERO_EXTEND && TARGET_FIX_VR4120))"
 {
-  rtx hilo;
+  rtx hilo, hi, lo;
 
   if (TARGET_MIPS16)
     {
@@ -2476,9 +2478,16 @@
     }
   else if (TARGET_FIX_R4000)
     emit_insn (gen_<u>mulditi3_r4000 (operands[0], operands[1], operands[2]));
-  else
+  else if (ISA_HAS_DMULT)
     emit_insn (gen_<u>mulditi3_internal (operands[0], operands[1],
 					 operands[2]));
+  else
+    {
+      hi = mips_subword (operands[0], 1);
+      lo = mips_subword (operands[0], 0);
+      emit_insn (gen_muldi3_mul3_nohilo (lo, operands[1], operands[2]));
+      emit_insn (gen_<su>muldi3_highpart_r6 (hi, operands[1], operands[2]));
+    }
   DONE;
 })
 

gcc/testsuite/ChangeLog

 2019-10-28  Mihailo Stojanovic  <mistojanovic@wavecomp.com>
 
+	PR target/82981
+	* gcc.target/mips/mips64r6-ti-mult.c: New test.
+
 	* gcc.target/mips/mips-builtins-pure.c: New test.
 
 	* gcc.target/mips/msa-insert-split.c: New test.

gcc/testsuite/gcc.target/mips/mips64r6-ti-mult.c

+/* { dg-do compile } */
+/* { dg-options "-mabi=64 -march=mips64r6" } */
+/* { dg-skip-if "code quality test" { *-*-* } { "-O0" } } */
+
+typedef unsigned __int128 u128;
+typedef unsigned long long u64;
+
+u128
+test (u64 a, u64 b)
+{
+  return (u128)a * (u128)b;
+}
+
+/* { dg-final { scan-assembler-not "__multi3" } } */
+/* { dg-final { scan-assembler "dmul" } } */
+/* { dg-final { scan-assembler "dmuhu" } } */