From bf26413fc4081dfd18b915580b35bdb71481327e Mon Sep 17 00:00:00 2001
From: Monk Chiang <monk.chiang@sifive.com>
Date: Thu, 6 Jul 2023 14:05:17 +0800
Subject: [PATCH] RISC-V: Implement locality for __builtin_prefetch

The patch add the Zihintntl instructions in the prefetch pattern.
Zicbop has prefetch instructions. Zihintntl has NTL instructions.
Insert NTL instructions before prefetch instruction, if target
has Zihintntl extension.

gcc/ChangeLog:

	* config/riscv/riscv.cc (riscv_print_operand): Add 'L' letter
	to print zihintntl instructions string.
	* config/riscv/riscv.md (prefetch): Add zihintntl instructions.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/prefetch-zicbop.c: New test.
	* gcc.target/riscv/prefetch-zihintntl.c: New test.
---
 gcc/config/riscv/riscv.cc                     | 22 +++++++++++++++++++
 gcc/config/riscv/riscv.md                     | 10 ++++++---
 .../gcc.target/riscv/prefetch-zicbop.c        | 20 +++++++++++++++++
 .../gcc.target/riscv/prefetch-zihintntl.c     | 20 +++++++++++++++++
 4 files changed, 69 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/prefetch-zicbop.c
 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 53ab2f1a8814..084a592a313c 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -6488,6 +6488,7 @@ riscv_asm_output_opcode (FILE *asm_out_file, const char *p)
    '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.
+   'L'	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.
@@ -6682,6 +6683,27 @@ riscv_print_operand (FILE *file, rtx op, int letter)
       break;
     }
 
+    case 'L':
+      {
+	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 379015c60de8..46c46039c33a 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -4113,12 +4113,16 @@
 {
   switch (INTVAL (operands[1]))
   {
-    case 0: return "prefetch.r\t%a0";
-    case 1: return "prefetch.w\t%a0";
+    case 0: return TARGET_ZIHINTNTL ? "%L2prefetch.r\t%a0" : "prefetch.r\t%a0";
+    case 1: return TARGET_ZIHINTNTL ? "%L2prefetch.w\t%a0" : "prefetch.w\t%a0";
     default: gcc_unreachable ();
   }
 }
-  [(set_attr "type" "store")])
+  [(set_attr "type" "store")
+   (set (attr "length") (if_then_else (and (match_test "TARGET_ZIHINTNTL")
+					   (match_test "IN_RANGE (INTVAL (operands[2]), 0, 2)"))
+				      (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-zicbop.c b/gcc/testsuite/gcc.target/riscv/prefetch-zicbop.c
new file mode 100644
index 000000000000..0faa120f1f79
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/prefetch-zicbop.c
@@ -0,0 +1,20 @@
+/* { dg-do compile target { { rv64-*-*}}} */
+/* { dg-options "-march=rv64gc_zicbop -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-not "ntl.all\t" } } */
+/* { dg-final { scan-assembler-not "ntl.pall\t" } } */
+/* { dg-final { scan-assembler-not "ntl.p1\t" } } */
+/* { dg-final { scan-assembler-times "prefetch.r" 4 } } */
+/* { dg-final { scan-assembler-times "prefetch.w" 4 } } */
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 000000000000..78a3afe68333
--- /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 } } */
-- 
2.47.2