RE: [PATCH v1] RISC-V: Allow rounding mode control for RVV floating-point add

["Li, Pan2" <pan2.li@intel.com>]

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Ack, thanks Juzhe.

Pan

From: juzhe.zhong@rivai.ai <juzhe.zhong@rivai.ai>
Sent: Tuesday, June 27, 2023 3:00 PM
To: Li, Pan2 <pan2.li@intel.com>; gcc-patches <gcc-patches@gcc.gnu.org>
Cc: Kito.cheng <kito.cheng@sifive.com>; Li, Pan2 <pan2.li@intel.com>; Wang, Yanzhang <yanzhang.wang@intel.com>; jeffreyalaw <jeffreyalaw@gmail.com>
Subject: Re: [PATCH v1] RISC-V: Allow rounding mode control for RVV floating-point add

LGTM.
You can go ahead to implement rounding mode of floating-point by mode-switching:

Suggest you implement rounding mode for floating-poing as follows:

1st step: Implement mode-switching for floating-point rounding mode except DYNAMIC which should be totally same as fixed-point.
2nd step: Support DYNAMIC rounding mode on mode-switching which may need to modify the mode-switching PASS.

Thanks.
________________________________
juzhe.zhong@rivai.ai<mailto:juzhe.zhong@rivai.ai>

From: pan2.li<mailto:pan2.li@intel.com>
Date: 2023-06-27 14:06
To: gcc-patches<mailto:gcc-patches@gcc.gnu.org>
CC: juzhe.zhong<mailto:juzhe.zhong@rivai.ai>; kito.cheng<mailto:kito.cheng@sifive.com>; pan2.li<mailto:pan2.li@intel.com>; yanzhang.wang<mailto:yanzhang.wang@intel.com>; jeffreyalaw<mailto:jeffreyalaw@gmail.com>
Subject: [PATCH v1] RISC-V: Allow rounding mode control for RVV floating-point add
From: Pan Li <pan2.li@intel.com<mailto:pan2.li@intel.com>>

According to the doc as below, we need to support the rounding mode of
the RVV floating-point, both the static and dynamice frm.

https://github.com/riscv-non-isa/rvv-intrinsic-doc/pull/226

For tracking and development friendly, We will take some steps to support
all rounding modes for the RVV floating-point rounding modes.

1. Allow rounding mode control by one intrinsic (aka this patch), vfadd.
2. Support static rounding mode control by mode switch, like fixed-point.
3. Support dynamice round mode control by mode switch.
4. Support the rest floating-point instructions for frm.

Please *NOTE* this patch only allow the rounding mode control for the
vfadd intrinsic API, and the related frm will be coverred by step 2.

Signed-off-by: Pan Li <pan2.li@intel.com<mailto:pan2.li@intel.com>>
Co-Authored by: Juzhe-Zhong <juzhe.zhong@rivai.ai<mailto:juzhe.zhong@rivai.ai>>

gcc/ChangeLog:

* config/riscv/riscv-protos.h (enum floating_point_rounding_mode):
Add macro for static frm min and max.
* config/riscv/riscv-vector-builtins-bases.cc
(class binop_frm): New class for floating-point with frm.
(BASE): Add vfadd for frm.
* config/riscv/riscv-vector-builtins-bases.h: Likewise.
* config/riscv/riscv-vector-builtins-functions.def
(vfadd_frm): Likewise.
* config/riscv/riscv-vector-builtins-shapes.cc
(struct alu_frm_def): New struct for alu with frm.
(SHAPE): Add alu with frm.
* config/riscv/riscv-vector-builtins-shapes.h: Likewise.
* config/riscv/riscv-vector-builtins.cc
(function_checker::report_out_of_range_and_not): New function
for report out of range and not val.
(function_checker::require_immediate_range_or): New function
for checking in range or one val.
* config/riscv/riscv-vector-builtins.h: Add function decl.

gcc/testsuite/ChangeLog:

* gcc.target/riscv/rvv/base/float-point-frm-error.c: New test.
* gcc.target/riscv/rvv/base/float-point-frm.c: New test.
---
gcc/config/riscv/riscv-protos.h               |  2 +
.../riscv/riscv-vector-builtins-bases.cc      | 25 +++++++
.../riscv/riscv-vector-builtins-bases.h       |  1 +
.../riscv/riscv-vector-builtins-functions.def |  2 +
.../riscv/riscv-vector-builtins-shapes.cc     | 68 +++++++++++++++++++
.../riscv/riscv-vector-builtins-shapes.h      |  1 +
gcc/config/riscv/riscv-vector-builtins.cc     | 41 +++++++++++
gcc/config/riscv/riscv-vector-builtins.h      |  4 ++
.../riscv/rvv/base/float-point-frm-error.c    | 15 ++++
.../riscv/rvv/base/float-point-frm.c          | 30 ++++++++
10 files changed, 189 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm-error.c
create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm.c

diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index f686edab3d1..bee64eee504 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -278,6 +278,8 @@ enum floating_point_rounding_mode
   FRM_RUP = 3, /* Aka 0b011.  */
   FRM_RMM = 4, /* Aka 0b100.  */
   FRM_DYN = 7, /* Aka 0b111.  */
+  FRM_STATIC_MIN = FRM_RNE,
+  FRM_STATIC_MAX = FRM_RMM,
};
opt_machine_mode vectorize_related_mode (machine_mode, scalar_mode,
diff --git a/gcc/config/riscv/riscv-vector-builtins-bases.cc b/gcc/config/riscv/riscv-vector-builtins-bases.cc
index 5c8deda900d..1b4c2c6ad66 100644
--- a/gcc/config/riscv/riscv-vector-builtins-bases.cc
+++ b/gcc/config/riscv/riscv-vector-builtins-bases.cc
@@ -281,6 +281,29 @@ public:
   }
};
+/* Implements below instructions for now.
+   - vfadd
+*/
+template<rtx_code CODE>
+class binop_frm : public function_base
+{
+public:
+  bool has_rounding_mode_operand_p () const override { return true; }
+
+  rtx expand (function_expander &e) const override
+  {
+    switch (e.op_info->op)
+      {
+      case OP_TYPE_vf:
+ return e.use_exact_insn (code_for_pred_scalar (CODE, e.vector_mode ()));
+      case OP_TYPE_vv:
+ return e.use_exact_insn (code_for_pred (CODE, e.vector_mode ()));
+      default:
+ gcc_unreachable ();
+      }
+  }
+};
+
/* Implements vrsub.  */
class vrsub : public function_base
{
@@ -2006,6 +2029,7 @@ static CONSTEXPR const viota viota_obj;
static CONSTEXPR const vid vid_obj;
static CONSTEXPR const binop<PLUS> vfadd_obj;
static CONSTEXPR const binop<MINUS> vfsub_obj;
+static CONSTEXPR const binop_frm<PLUS> vfadd_frm_obj;
static CONSTEXPR const reverse_binop<MINUS> vfrsub_obj;
static CONSTEXPR const widen_binop<PLUS> vfwadd_obj;
static CONSTEXPR const widen_binop<MINUS> vfwsub_obj;
@@ -2231,6 +2255,7 @@ BASE (vmsof)
BASE (viota)
BASE (vid)
BASE (vfadd)
+BASE (vfadd_frm)
BASE (vfsub)
BASE (vfrsub)
BASE (vfwadd)
diff --git a/gcc/config/riscv/riscv-vector-builtins-bases.h b/gcc/config/riscv/riscv-vector-builtins-bases.h
index 62ff38a2811..54a81eab269 100644
--- a/gcc/config/riscv/riscv-vector-builtins-bases.h
+++ b/gcc/config/riscv/riscv-vector-builtins-bases.h
@@ -145,6 +145,7 @@ extern const function_base *const viota;
extern const function_base *const vid;
extern const function_base *const vfadd;
extern const function_base *const vfadd;
+extern const function_base *const vfadd_frm;
extern const function_base *const vfsub;
extern const function_base *const vfsub;
extern const function_base *const vfrsub;
diff --git a/gcc/config/riscv/riscv-vector-builtins-functions.def b/gcc/config/riscv/riscv-vector-builtins-functions.def
index 89aff27bf26..035c9e4252f 100644
--- a/gcc/config/riscv/riscv-vector-builtins-functions.def
+++ b/gcc/config/riscv/riscv-vector-builtins-functions.def
@@ -289,6 +289,8 @@ DEF_RVV_FUNCTION (vfadd, alu, full_preds, f_vvf_ops)
DEF_RVV_FUNCTION (vfsub, alu, full_preds, f_vvv_ops)
DEF_RVV_FUNCTION (vfsub, alu, full_preds, f_vvf_ops)
DEF_RVV_FUNCTION (vfrsub, alu, full_preds, f_vvf_ops)
+DEF_RVV_FUNCTION (vfadd_frm, alu_frm, full_preds, f_vvv_ops)
+DEF_RVV_FUNCTION (vfadd_frm, alu_frm, full_preds, f_vvf_ops)
// 13.3. Vector Widening Floating-Point Add/Subtract Instructions
DEF_RVV_FUNCTION (vfwadd, widen_alu, full_preds, f_wvv_ops)
diff --git a/gcc/config/riscv/riscv-vector-builtins-shapes.cc b/gcc/config/riscv/riscv-vector-builtins-shapes.cc
index c8daae01f91..69a67106418 100644
--- a/gcc/config/riscv/riscv-vector-builtins-shapes.cc
+++ b/gcc/config/riscv/riscv-vector-builtins-shapes.cc
@@ -226,6 +226,73 @@ struct alu_def : public build_base
   }
};
+/* alu_frm_def class.  */
+struct alu_frm_def : public build_base
+{
+  /* Normalize vf<op>_frm to vf<op>.  */
+  static void normalize_base_name (char *to, const char *from, int limit)
+  {
+    strncpy (to, from, limit - 1);
+    char *suffix = strstr (to, "_frm");
+
+    if (suffix)
+      *suffix = '\0';
+
+    to[limit - 1] = '\0';
+  }
+
+  char *get_name (function_builder &b, const function_instance &instance,
+   bool overloaded_p) const override
+  {
+    char base_name[16] = {};
+
+    /* Return nullptr if it can not be overloaded.  */
+    if (overloaded_p && !instance.base->can_be_overloaded_p (instance.pred))
+      return nullptr;
+
+    normalize_base_name (base_name, instance.base_name, sizeof (base_name));
+
+    b.append_base_name (base_name);
+
+    /* vop<sew>_<op> --> vop<sew>_<op>_<type>.  */
+    if (!overloaded_p)
+      {
+ b.append_name (operand_suffixes[instance.op_info->op]);
+ b.append_name (type_suffixes[instance.type.index].vector);
+      }
+
+    /* According to rvv-intrinsic-doc, it does not add "_m" suffix
+       for vop_m C++ overloaded API.  */
+    if (overloaded_p && instance.pred == PRED_TYPE_m)
+      return b.finish_name ();
+
+    b.append_name (predication_suffixes[instance.pred]);
+
+    /* According to rvv-intrinsic-doc, it does not add "_rm" suffix
+       for vop_rm C++ overloaded API.  */
+    if (!overloaded_p)
+      b.append_name ("_rm");
+
+    return b.finish_name ();
+  }
+
+  bool check (function_checker &c) const override
+  {
+    gcc_assert (c.any_type_float_p ());
+
+    /* Check whether rounding mode argument is a valid immediate.  */
+    if (c.base->has_rounding_mode_operand_p ())
+      {
+ unsigned int frm_num = c.arg_num () - 2;
+
+ return c.require_immediate_range_or (frm_num, FRM_STATIC_MIN,
+      FRM_STATIC_MAX, FRM_DYN);
+      }
+
+    return true;
+  }
+};
+
/* widen_alu_def class. Handle vwadd/vwsub. Unlike
    vadd.vx/vadd.vv/vwmul.vv/vwmul.vx, vwadd.vv/vwadd.vx/vwadd.wv/vwadd.wx has
    'OP' suffix in overloaded API.  */
@@ -743,6 +810,7 @@ SHAPE(vsetvl, vsetvlmax)
SHAPE(loadstore, loadstore)
SHAPE(indexed_loadstore, indexed_loadstore)
SHAPE(alu, alu)
+SHAPE(alu_frm, alu_frm)
SHAPE(widen_alu, widen_alu)
SHAPE(no_mask_policy, no_mask_policy)
SHAPE(return_mask, return_mask)
diff --git a/gcc/config/riscv/riscv-vector-builtins-shapes.h b/gcc/config/riscv/riscv-vector-builtins-shapes.h
index 6a51713c12c..15fef8342ec 100644
--- a/gcc/config/riscv/riscv-vector-builtins-shapes.h
+++ b/gcc/config/riscv/riscv-vector-builtins-shapes.h
@@ -29,6 +29,7 @@ extern const function_shape *const vsetvlmax;
extern const function_shape *const loadstore;
extern const function_shape *const indexed_loadstore;
extern const function_shape *const alu;
+extern const function_shape *const alu_frm;
extern const function_shape *const widen_alu;
extern const function_shape *const no_mask_policy;
extern const function_shape *const return_mask;
diff --git a/gcc/config/riscv/riscv-vector-builtins.cc b/gcc/config/riscv/riscv-vector-builtins.cc
index 466e36d50b7..648c765a5d1 100644
--- a/gcc/config/riscv/riscv-vector-builtins.cc
+++ b/gcc/config/riscv/riscv-vector-builtins.cc
@@ -3852,6 +3852,23 @@ function_checker::report_out_of_range (unsigned int argno, HOST_WIDE_INT actual,
    actual, argno + 1, fndecl, min, max);
}
+/* Report that LOCATION has a call to FNDECL in which argument ARGNO has
+   the value ACTUAL, whereas the function requires a value in the range
+   [MIN, MAX] or OR_VAL.  ARGNO counts from zero.  */
+void
+function_checker::report_out_of_range_and_not (unsigned int argno,
+        HOST_WIDE_INT actual,
+        HOST_WIDE_INT min,
+        HOST_WIDE_INT max,
+        HOST_WIDE_INT or_val) const
+{
+  error_at (location,
+     "passing %wd to argument %d of %qE, which expects"
+     " a value in the range [%wd, %wd] or %wd",
+     actual, argno + 1, fndecl, min, max, or_val);
+}
+
+
/* Check that argument ARGNO is an integer constant expression and
    store its value in VALUE_OUT if so.  The caller should first
    check that argument ARGNO exists.  */
@@ -3893,6 +3910,30 @@ function_checker::require_immediate_range (unsigned int argno,
   return true;
}
+/* Check that argument REL_ARGNO is an integer constant expression in the
+   range [MIN, MAX] or OR_VAL.  REL_ARGNO counts from the end of the
+   predication arguments.  */
+bool
+function_checker::require_immediate_range_or (unsigned int argno,
+       HOST_WIDE_INT min,
+       HOST_WIDE_INT max,
+       HOST_WIDE_INT or_val) const
+{
+  gcc_assert (min >= 0 && min <= max);
+  gcc_assert (argno < m_nargs);
+
+  tree arg = m_args[argno];
+  HOST_WIDE_INT actual = tree_to_uhwi (arg);
+
+  if (!IN_RANGE (actual, min, max) && actual != or_val)
+    {
+      report_out_of_range_and_not (argno, actual, min, max, or_val);
+      return false;
+    }
+
+  return true;
+}
+
/* Perform semantic checks on the call.  Return true if the call is valid,
    otherwise report a suitable error.  */
bool
diff --git a/gcc/config/riscv/riscv-vector-builtins.h b/gcc/config/riscv/riscv-vector-builtins.h
index b0c3a42d820..e358a8e4d91 100644
--- a/gcc/config/riscv/riscv-vector-builtins.h
+++ b/gcc/config/riscv/riscv-vector-builtins.h
@@ -442,6 +442,8 @@ public:
   bool check (void);
   bool require_immediate (unsigned int, HOST_WIDE_INT, HOST_WIDE_INT) const;
+  bool require_immediate_range_or (unsigned int, HOST_WIDE_INT,
+    HOST_WIDE_INT, HOST_WIDE_INT) const;
private:
   bool require_immediate_range (unsigned int, HOST_WIDE_INT,
@@ -449,6 +451,8 @@ private:
   void report_non_ice (unsigned int) const;
   void report_out_of_range (unsigned int, HOST_WIDE_INT, HOST_WIDE_INT,
    HOST_WIDE_INT) const;
+  void report_out_of_range_and_not (unsigned int, HOST_WIDE_INT, HOST_WIDE_INT,
+     HOST_WIDE_INT, HOST_WIDE_INT) const;
   /* The type of the resolved function.  */
   tree m_fntype;
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm-error.c b/gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm-error.c
new file mode 100644
index 00000000000..4ebaa15ab0b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm-error.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv -mabi=lp64 -O3 -Wno-psabi" } */
+
+#include "riscv_vector.h"
+
+typedef float float32_t;
+
+void test_float_point_frm_error (float32_t *out, vfloat32m1_t op1, vfloat32m1_t op2, size_t vl)
+{
+  vfloat32m1_t v1 = __riscv_vfadd_vv_f32m1_rm (op1, op2, 5, vl); /* { dg-error {passing 5 to argument 3 of '__riscv_vfadd_vv_f32m1_rm', which expects a value in the range \[0, 4\] or 7} } */
+  vfloat32m1_t v2 = __riscv_vfadd_vv_f32m1_rm (v1, v1, 6, vl);   /* { dg-error {passing 6 to argument 3 of '__riscv_vfadd_vv_f32m1_rm', which expects a value in the range \[0, 4\] or 7} } */
+  vfloat32m1_t v3 = __riscv_vfadd_vv_f32m1_rm (v2, v2, 8, vl);   /* { dg-error {passing 8 to argument 3 of '__riscv_vfadd_vv_f32m1_rm', which expects a value in the range \[0, 4\] or 7} } */
+
+  __riscv_vse32_v_f32m1 (out, v3, vl);
+}
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm.c b/gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm.c
new file mode 100644
index 00000000000..95271b2c822
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/float-point-frm.c
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv -mabi=lp64 -O3 -Wno-psabi" } */
+
+#include "riscv_vector.h"
+
+typedef float float32_t;
+
+vfloat32m1_t
+test_riscv_vfadd_vv_f32m1_rm (vfloat32m1_t op1, vfloat32m1_t op2, size_t vl) {
+  return __riscv_vfadd_vv_f32m1_rm (op1, op2, 0, vl);
+}
+
+vfloat32m1_t
+test_vfadd_vv_f32m1_m_rm(vbool32_t mask, vfloat32m1_t op1, vfloat32m1_t op2,
+ size_t vl) {
+  return __riscv_vfadd_vv_f32m1_m_rm(mask, op1, op2, 0, vl);
+}
+
+vfloat32m1_t
+test_vfadd_vf_f32m1_rm(vfloat32m1_t op1, float32_t op2, size_t vl) {
+  return __riscv_vfadd_vf_f32m1_rm(op1, op2, 0, vl);
+}
+
+vfloat32m1_t
+test_vfadd_vf_f32m1_m_rm(vbool32_t mask, vfloat32m1_t op1, float32_t op2,
+ size_t vl) {
+  return __riscv_vfadd_vf_f32m1_m_rm(mask, op1, op2, 0, vl);
+}
+
+/* { dg-final { scan-assembler-times {vfadd\.v[vf]\s+v[0-9]+,\s*v[0-9]+,\s*[fav]+[0-9]+} 4 } } */
--
2.34.1