[V2] aarch64: Implement the ACLE instruction/data prefetch functions.

Message ID 20231030145629.1022323-1-victor.donascimento@arm.com
State Accepted
Headers
Series [V2] aarch64: Implement the ACLE instruction/data prefetch functions. |

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Context Check Description
snail/gcc-patch-check success Github commit url

Commit Message

Victor Do Nascimento Oct. 30, 2023, 2:56 p.m. UTC
  Correct CV-qualification from being erroeously applied to the `addr'
pointer, applying it instead to its pointer target, as specified by
the ACLE standards.

---

Implement the ACLE data and instruction prefetch functions[1] with the
following signatures:

  1. Data prefetch intrinsics:
  ----------------------------
  void __pldx (/*constant*/ unsigned int /*access_kind*/,
               /*constant*/ unsigned int /*cache_level*/,
               /*constant*/ unsigned int /*retention_policy*/,
               void const volatile *addr);

  void __pld (void const volatile *addr);

  2. Instruction prefetch intrinsics:
  -----------------------------------
  void __plix (/*constant*/ unsigned int /*cache_level*/,
               /*constant*/ unsigned int /*retention_policy*/,
               void const volatile *addr);

  void __pli (void const volatile *addr);

`__pldx' affords the programmer more fine-grained control over the
data prefetch behaviour than the analogous GCC builtin
`__builtin_prefetch', and allows access to the "SLC" cache level.

While `__builtin_prefetch' chooses both cache-level and retention
policy automatically via the optional `locality' parameter, `__pldx'
expects 2 (mandatory) arguments to explicitly define the desired
cache-level and retention policies.

`__plix' on the other hand, generates a code prefetch instruction and
so extends functionality on aarch64 targets beyond that which is
exposed by `builtin_prefetch'.

`__pld' and `__pli' do prefetch of data and instructions,
respectively, using default values for both cache-level and retention
policies.

Bootstrapped and tested on aarch64-none-linux-gnu.

[1] https://arm-software.github.io/acle/main/acle.html#memory-prefetch-intrinsics

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.cc:
	(AARCH64_PLD): New enum aarch64_builtins entry.
	(AARCH64_PLDX): Likewise.
	(AARCH64_PLI): Likewise.
	(AARCH64_PLIX): Likewise.
	(aarch64_init_prefetch_builtin): New.
	(aarch64_general_init_builtins): Call prefetch init function.
	(aarch64_expand_prefetch_builtin): New.
	(aarch64_general_expand_builtin):  Add prefetch expansion.
	* config/aarch64/aarch64.md (UNSPEC_PLDX): New.
	(aarch64_pldx): New.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/builtin_pld_pli.c: New.
---
 gcc/config/aarch64/aarch64-builtins.cc        | 161 ++++++++++++++++++
 gcc/config/aarch64/aarch64.md                 |  12 ++
 gcc/config/aarch64/arm_acle.h                 |  30 ++++
 .../gcc.target/aarch64/builtin_pldx.c         |  90 ++++++++++
 4 files changed, 293 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/aarch64/builtin_pldx.c
  

Patch

diff --git a/gcc/config/aarch64/aarch64-builtins.cc b/gcc/config/aarch64/aarch64-builtins.cc
index 04f59fd9a54..27a4c87b300 100644
--- a/gcc/config/aarch64/aarch64-builtins.cc
+++ b/gcc/config/aarch64/aarch64-builtins.cc
@@ -808,6 +808,10 @@  enum aarch64_builtins
   AARCH64_RBIT,
   AARCH64_RBITL,
   AARCH64_RBITLL,
+  AARCH64_PLD,
+  AARCH64_PLDX,
+  AARCH64_PLI,
+  AARCH64_PLIX,
   AARCH64_BUILTIN_MAX
 };
 
@@ -1798,6 +1802,34 @@  aarch64_init_rng_builtins (void)
 				   AARCH64_BUILTIN_RNG_RNDRRS);
 }
 
+/* Add builtins for data and instrution prefetch.  */
+static void
+aarch64_init_prefetch_builtin (void)
+{
+#define AARCH64_INIT_PREFETCH_BUILTIN(INDEX, N)				\
+  aarch64_builtin_decls[INDEX] =					\
+    aarch64_general_add_builtin ("__builtin_aarch64_" N, ftype, INDEX)
+
+  tree ftype;
+  tree cv_argtype;
+  cv_argtype = build_qualified_type (void_type_node, TYPE_QUAL_CONST
+						     | TYPE_QUAL_VOLATILE);
+  cv_argtype = build_pointer_type (cv_argtype);
+
+  ftype = build_function_type_list (void_type_node, cv_argtype, NULL);
+  AARCH64_INIT_PREFETCH_BUILTIN (AARCH64_PLD, "pld");
+  AARCH64_INIT_PREFETCH_BUILTIN (AARCH64_PLI, "pli");
+
+  ftype = build_function_type_list (void_type_node, unsigned_type_node,
+				    unsigned_type_node, unsigned_type_node,
+				    cv_argtype, NULL);
+  AARCH64_INIT_PREFETCH_BUILTIN (AARCH64_PLDX, "pldx");
+
+  ftype = build_function_type_list (void_type_node, unsigned_type_node,
+				    unsigned_type_node, cv_argtype, NULL);
+  AARCH64_INIT_PREFETCH_BUILTIN (AARCH64_PLIX, "plix");
+}
+
 /* Initialize the memory tagging extension (MTE) builtins.  */
 struct
 {
@@ -2019,6 +2051,8 @@  aarch64_general_init_builtins (void)
   aarch64_init_rng_builtins ();
   aarch64_init_data_intrinsics ();
 
+  aarch64_init_prefetch_builtin ();
+
   tree ftype_jcvt
     = build_function_type_list (intSI_type_node, double_type_node, NULL);
   aarch64_builtin_decls[AARCH64_JSCVT]
@@ -2599,6 +2633,127 @@  aarch64_expand_rng_builtin (tree exp, rtx target, int fcode, int ignore)
   return target;
 }
 
+/* Expand a prefetch builtin EXP.  */
+void
+aarch64_expand_prefetch_builtin (tree exp, int fcode)
+{
+
+#define EXPAND_CONST_INT(IN_IDX, OUT_IDX, ERRMSG)	\
+  if (TREE_CODE (args[IN_IDX]) != INTEGER_CST)		\
+    {							\
+      error_at (EXPR_LOCATION (exp), ERRMSG);		\
+      args[IN_IDX] = integer_zero_node;			\
+    }							\
+    ops[OUT_IDX] = expand_normal (args[IN_IDX])
+
+#define WARN_INVALID(VAR, ERRMSG)			\
+  do {							\
+    warning_at (EXPR_LOCATION (exp), 0, ERRMSG);	\
+    VAR = 0;						\
+  } while (0)
+
+  unsigned narg;
+
+  tree args[4];
+  rtx ops[4];
+  int kind_id, level_id, rettn_id;
+  char prfop[11];
+
+  char kind_s[3][4] = {"PLD", "PST", "PLI"};
+  char level_s[4][4] = {"L1", "L2", "L3", "SLC"};
+  char rettn_s[2][5] = {"KEEP", "STRM"};
+
+  /* Each of the four prefetch builtins takes a different number of
+     arguments, but proceeds to call the PRFM insn which requires 4
+     pieces of information to be fully defined.
+
+     Specify the total number of arguments for each builtin and, where
+     one of these takes less than 4 arguments, set sensible defaults.  */
+  switch (fcode)
+    {
+    case AARCH64_PLDX:
+      kind_id = -1;
+      narg = 4;
+      break;
+    case AARCH64_PLIX:
+      kind_id = 2;
+      narg = 3;
+      break;
+    case AARCH64_PLI:
+    case AARCH64_PLD:
+    default:
+      kind_id  = (fcode == AARCH64_PLD) ? 0 : 2;
+      level_id = 0;
+      rettn_id = 0;
+      narg = 1;
+      break;
+    }
+
+  int addr_arg_index  = narg - 1;
+
+  /* Extract the correct number of arguments from our function call.  */
+  for (unsigned i = 0; i < narg; i++)
+    args[i] = CALL_EXPR_ARG (exp, i);
+
+  /* Check address argument.  */
+  if (!(POINTER_TYPE_P (TREE_TYPE (args[addr_arg_index])))
+      || (TREE_CODE (TREE_TYPE (TREE_TYPE (args[addr_arg_index])))
+	  != VOID_TYPE))
+    error_at (EXPR_LOCATION (exp), "invalid address type specified;"
+				   " void const volatile * required");
+
+  ops[3] = expand_expr (args[addr_arg_index], NULL_RTX, Pmode, EXPAND_NORMAL);
+
+  /* Check arguments common to both pldx and plix.  */
+  if (fcode == AARCH64_PLDX || fcode == AARCH64_PLIX)
+    {
+      int cache_index = (fcode == AARCH64_PLIX) ? 0 : 1;
+      int policy_index = cache_index + 1;
+
+      /* Cache level must be 0, 1, 2 or 3.  */
+      EXPAND_CONST_INT (cache_index, 1,
+			"Cache-level argument must be a constant");
+      level_id = INTVAL (ops[1]);
+      if (level_id < 0 || level_id > 3)
+	WARN_INVALID (level_id, "invalid cache level selected; using zero");
+
+      /* Retention policy must be either zero or one.  */
+      EXPAND_CONST_INT (policy_index, 2,
+			"Retention policy argument must be a constant");
+      rettn_id = INTVAL (ops[2]);
+      if (rettn_id != 0 && rettn_id != 1)
+	WARN_INVALID (rettn_id, "invalid retention policy selected; "
+				"using zero");
+    }
+
+  /* For PLDX, validate the access kind argument.  */
+  if (fcode == AARCH64_PLDX)
+    {
+      /* Argument 0 must be either zero or one.  */
+      EXPAND_CONST_INT (0, 0, "Access kind argument must be a constant");
+      kind_id = INTVAL (ops[0]);
+      if (kind_id != 0 && kind_id != 1)
+	WARN_INVALID (kind_id, "invalid access kind argument; using zero");
+    }
+
+  sprintf (prfop, "%s%s%s", kind_s[kind_id],
+			    level_s[level_id],
+			    rettn_s[rettn_id]);
+
+  rtx const_str = rtx_alloc (CONST_STRING);
+  PUT_CODE (const_str, CONST_STRING);
+  XSTR (const_str, 0) = xstrdup (prfop);
+
+  class expand_operand exp_ops[2];
+
+  create_fixed_operand (&exp_ops[0], const_str);
+  create_address_operand (&exp_ops[1], ops[3]);
+  maybe_expand_insn (CODE_FOR_aarch64_pldx, 2, exp_ops);
+
+  #undef EXPAND_CONST_INT
+  #undef WARN_INVALID
+}
+
 /* Expand an expression EXP that calls a MEMTAG built-in FCODE
    with result going to TARGET.  */
 static rtx
@@ -2832,6 +2987,12 @@  aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
     case AARCH64_BUILTIN_RNG_RNDR:
     case AARCH64_BUILTIN_RNG_RNDRRS:
       return aarch64_expand_rng_builtin (exp, target, fcode, ignore);
+    case AARCH64_PLD:
+    case AARCH64_PLDX:
+    case AARCH64_PLI:
+    case AARCH64_PLIX:
+      aarch64_expand_prefetch_builtin (exp, fcode);
+      return target;
     }
 
   if (fcode >= AARCH64_SIMD_BUILTIN_BASE && fcode <= AARCH64_SIMD_BUILTIN_MAX)
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 5bb8c772be8..7b1cc4c137b 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -281,6 +281,7 @@ 
     UNSPEC_UPDATE_FFRT
     UNSPEC_RDFFR
     UNSPEC_WRFFR
+    UNSPEC_PLDX
     ;; Represents an SVE-style lane index, in which the indexing applies
     ;; within the containing 128-bit block.
     UNSPEC_SVE_LANE_SELECT
@@ -844,6 +845,17 @@ 
   [(set_attr "type" "load_4")]
 )
 
+(define_insn "aarch64_pldx"
+  [(unspec [(match_operand 0 "" "")
+	    (match_operand:DI 1 "aarch64_prefetch_operand" "Dp")] UNSPEC_PLDX)]
+  ""
+  {
+    operands[1] = gen_rtx_MEM (DImode, operands[1]);
+    return "prfm\\t%0, %1";
+  }
+  [(set_attr "type" "load_4")]
+)
+
 (define_insn "trap"
   [(trap_if (const_int 1) (const_int 8))]
   ""
diff --git a/gcc/config/aarch64/arm_acle.h b/gcc/config/aarch64/arm_acle.h
index 7599a32301d..40e5aa61be2 100644
--- a/gcc/config/aarch64/arm_acle.h
+++ b/gcc/config/aarch64/arm_acle.h
@@ -78,6 +78,36 @@  _GCC_ARM_ACLE_DATA_FN (revll, bswap64, uint64_t, uint64_t)
 
 #undef _GCC_ARM_ACLE_DATA_FN
 
+__extension__ extern __inline void
+__attribute__ ((__always_inline__, __gnu_inline__, __artificial__))
+__pld (void const volatile *__addr)
+{
+  return __builtin_aarch64_pld (__addr);
+}
+
+__extension__ extern __inline void
+__attribute__ ((__always_inline__, __gnu_inline__, __artificial__))
+__pli (void const volatile *__addr)
+{
+  return __builtin_aarch64_pli (__addr);
+}
+
+__extension__ extern __inline void
+__attribute__ ((__always_inline__, __gnu_inline__, __artificial__))
+__plix (unsigned int __cache, unsigned int __rettn,
+	void const volatile *__addr)
+{
+  return __builtin_aarch64_plix (__cache, __rettn, __addr);
+}
+
+__extension__ extern __inline void
+__attribute__ ((__always_inline__, __gnu_inline__, __artificial__))
+__pldx (unsigned int __access, unsigned int __cache, unsigned int __rettn,
+	void const volatile *__addr)
+{
+  return __builtin_aarch64_pldx (__access, __cache, __rettn, __addr);
+}
+
 __extension__ extern __inline unsigned long
 __attribute__ ((__always_inline__, __gnu_inline__, __artificial__))
 __revl (unsigned long __value)
diff --git a/gcc/testsuite/gcc.target/aarch64/builtin_pldx.c b/gcc/testsuite/gcc.target/aarch64/builtin_pldx.c
new file mode 100644
index 00000000000..8cbaa97c00c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/builtin_pldx.c
@@ -0,0 +1,90 @@ 
+/* { dg-do compile } */
+/* { dg-options "-march=armv8-a -O2" } */
+
+#include <arm_acle.h>
+
+/* Check that we can generate the immediate-offset addressing
+   mode for PRFM.  */
+
+/* Access kind specifiers.  */
+#define PLD 0
+#define PST 1
+/* Cache levels.  */
+#define L1  0
+#define L2  1
+#define L3  2
+#define SLC 3
+/* Retention policies.  */
+#define KEEP 0
+#define STRM 1
+
+void
+prefetch_for_read_write (void *a)
+{
+  __pldx (PLD, L1, KEEP, a);
+  __pldx (PLD, L1, STRM, a);
+  __pldx (PLD, L2, KEEP, a);
+  __pldx (PLD, L2, STRM, a);
+  __pldx (PLD, L3, KEEP, a);
+  __pldx (PLD, L3, STRM, a);
+  __pldx (PLD, SLC, KEEP, a);
+  __pldx (PLD, SLC, STRM, a);
+  __pldx (PST, L1, KEEP, a);
+  __pldx (PST, L1, STRM, a);
+  __pldx (PST, L2, KEEP, a);
+  __pldx (PST, L2, STRM, a);
+  __pldx (PST, L3, KEEP, a);
+  __pldx (PST, L3, STRM, a);
+  __pldx (PST, SLC, KEEP, a);
+  __pldx (PST, SLC, STRM, a);
+}
+
+/* { dg-final { scan-assembler "prfm\tPLDL1KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLDL1STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLDL2KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLDL2STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLDL3KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLDL3STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLDSLCKEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLDSLCSTRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTL1KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTL1STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTL2KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTL2STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTL3KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTL3STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTSLCKEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPSTSLCSTRM, \\\[x\[0-9\]+\\\]" } } */
+
+void
+prefetch_simple (void *a)
+{
+  __pld (a);
+  __pli (a);
+}
+
+/* { dg-final { scan-assembler "prfm\tPLDL1KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLIL1KEEP, \\\[x\[0-9\]+\\\]" } } */
+
+void
+prefetch_instructions (void *a)
+{
+  __plix (L1, KEEP, a);
+  __plix (L1, STRM, a);
+  __plix (L2, KEEP, a);
+  __plix (L2, STRM, a);
+  __plix (L3, KEEP, a);
+  __plix (L3, STRM, a);
+  __plix (SLC, KEEP, a);
+  __plix (SLC, STRM, a);
+}
+
+/* { dg-final { scan-assembler "prfm\tPLIL1KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLIL1STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLIL2KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLIL2STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLIL3KEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLIL3STRM, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLISLCKEEP, \\\[x\[0-9\]+\\\]" } } */
+/* { dg-final { scan-assembler "prfm\tPLISLCSTRM, \\\[x\[0-9\]+\\\]" } } */
+