[PATCH 2/2] RISC-V: Implement locality for __builtin_prefetch

[Monk Chiang via Gcc-patches]

    gcc/ChangeLog:

            * config/riscv/riscv.cc (riscv_print_operand):
              Add 'N' for print a non-temporal locality hints instruction.
            * config/riscv/riscv.md (prefetch):
              Add NTLH instruction for prefetch.r and prefetch.w.
    gcc/testsuite/ChangeLog:

            * gcc.target/riscv/prefetch-zihintntl.c: New test.
---
 gcc/config/riscv/riscv.cc                     | 22 +++++++++++++++++++
 gcc/config/riscv/riscv.md                     | 10 ++++++---
 .../gcc.target/riscv/prefetch-zihintntl.c     | 20 +++++++++++++++++
 3 files changed, 49 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/prefetch-zihintntl.c

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 706c18416db..42f80088bab 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -4532,6 +4532,7 @@ riscv_memmodel_needs_amo_release (enum memmodel model)
    'A' Print the atomic operation suffix for memory model OP.
    'I' Print the LR suffix for memory model OP.
    'J' Print the SC suffix for memory model OP.
+   'N' Print a non-temporal locality hints instruction.
    'z' Print x0 if OP is zero, otherwise print OP normally.
    'i' Print i if the operand is not a register.
    'S' Print shift-index of single-bit mask OP.
@@ -4718,6 +4719,27 @@ riscv_print_operand (FILE *file, rtx op, int letter)
       break;
     }
 
+    case 'N':
+      {
+       const char *ntl_hint = NULL;
+       switch (INTVAL (op))
+         {
+         case 0:
+           ntl_hint = "ntl.all";
+           break;
+         case 1:
+           ntl_hint = "ntl.pall";
+           break;
+         case 2:
+           ntl_hint = "ntl.p1";
+           break;
+         }
+
+      if (ntl_hint)
+       asm_fprintf (file, "%s\n\t", ntl_hint);
+      break;
+      }
+
     case 'i':
       if (code != REG)
         fputs ("i", file);
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 7988026d129..3357c981b5d 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -3256,11 +3256,15 @@
 {
   switch (INTVAL (operands[1]))
   {
-    case 0: return "prefetch.r\t%a0";
-    case 1: return "prefetch.w\t%a0";
+    case 0: return TARGET_ZIHINTNTL ? "%N2prefetch.r\t%a0" : "prefetch.r\t%a0";
+    case 1: return TARGET_ZIHINTNTL ? "%N2prefetch.w\t%a0" : "prefetch.w\t%a0";
     default: gcc_unreachable ();
   }
-})
+}
+  [(set (attr "length") (if_then_else (and (match_test "TARGET_ZIHINTNTL")
+                                          (match_test "INTVAL (operands[2]) != 
3"))
+                                     (const_string "8")
+                                     (const_string "4")))])
 
 (define_insn "riscv_prefetchi_<mode>"
   [(unspec_volatile:X [(match_operand:X 0 "address_operand" "r")
diff --git a/gcc/testsuite/gcc.target/riscv/prefetch-zihintntl.c 
b/gcc/testsuite/gcc.target/riscv/prefetch-zihintntl.c
new file mode 100644
index 00000000000..78a3afe6833
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/prefetch-zihintntl.c
@@ -0,0 +1,20 @@
+/* { dg-do compile target { { rv64-*-*}}} */
+/* { dg-options "-march=rv64gc_zicbop_zihintntl -mabi=lp64" } */
+
+void foo (char *p)
+{
+  __builtin_prefetch (p, 0, 0);
+  __builtin_prefetch (p, 0, 1);
+  __builtin_prefetch (p, 0, 2);
+  __builtin_prefetch (p, 0, 3);
+  __builtin_prefetch (p, 1, 0);
+  __builtin_prefetch (p, 1, 1);
+  __builtin_prefetch (p, 1, 2);
+  __builtin_prefetch (p, 1, 3);
+}
+
+/* { dg-final { scan-assembler-times "ntl.all" 2 } } */
+/* { dg-final { scan-assembler-times "ntl.pall" 2 } } */
+/* { dg-final { scan-assembler-times "ntl.p1" 2 } } */
+/* { dg-final { scan-assembler-times "prefetch.r" 4 } } */
+/* { dg-final { scan-assembler-times "prefetch.w" 4 } } */
-- 
2.40.1