[llvm] 3e4153c - [RISCV] Implement Builtins for XAndesBFHCvt extension. (#148804)
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Wed Jul 16 01:13:35 PDT 2025
Author: Jim Lin
Date: 2025-07-16T16:13:31+08:00
New Revision: 3e4153c97b54d456cfaf6ae21391122582b0ab28
URL: https://github.com/llvm/llvm-project/commit/3e4153c97b54d456cfaf6ae21391122582b0ab28
DIFF: https://github.com/llvm/llvm-project/commit/3e4153c97b54d456cfaf6ae21391122582b0ab28.diff
LOG: [RISCV] Implement Builtins for XAndesBFHCvt extension. (#148804)
XAndesBFHCvt provides two builtins functions for converting between
float and bf16. Users can use them to convert bf16 values loaded from
memory to float, perform arithmetic operations, then convert them back
to bf16 and store them to memory.
The load/store and move operations for bf16 will be handled in a later
patch.
Added:
clang/include/clang/Basic/BuiltinsRISCVXAndes.td
clang/lib/Headers/riscv_nds.h
clang/test/CodeGen/RISCV/riscv-xandesbfhcvt-c-api.c
clang/test/CodeGen/RISCV/riscv-xandesbfhcvt.c
llvm/test/CodeGen/RISCV/xandesbfhcvt.ll
Modified:
clang/include/clang/Basic/BuiltinsRISCV.td
clang/lib/CodeGen/TargetBuiltins/RISCV.cpp
clang/lib/Headers/CMakeLists.txt
llvm/lib/Target/RISCV/RISCVISelLowering.cpp
llvm/lib/Target/RISCV/RISCVInstrInfoXAndes.td
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/BuiltinsRISCV.td b/clang/include/clang/Basic/BuiltinsRISCV.td
index b2cd5648e008f..5927eaf80d57a 100644
--- a/clang/include/clang/Basic/BuiltinsRISCV.td
+++ b/clang/include/clang/Basic/BuiltinsRISCV.td
@@ -157,3 +157,8 @@ def pause : RISCVBuiltin<"void()">;
// XCV extensions.
//===----------------------------------------------------------------------===//
include "clang/Basic/BuiltinsRISCVXCV.td"
+
+//===----------------------------------------------------------------------===//
+// XAndes extensions.
+//===----------------------------------------------------------------------===//
+include "clang/Basic/BuiltinsRISCVXAndes.td"
diff --git a/clang/include/clang/Basic/BuiltinsRISCVXAndes.td b/clang/include/clang/Basic/BuiltinsRISCVXAndes.td
new file mode 100644
index 0000000000000..ea9a7166bc6e8
--- /dev/null
+++ b/clang/include/clang/Basic/BuiltinsRISCVXAndes.td
@@ -0,0 +1,27 @@
+//==- BuiltinsRISCVXAndes.td - RISC-V Andes Builtin database -----*- C++ -*-==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the Andes-specific builtin function database. Users of
+// this file must define the BUILTIN macro to make use of this information.
+//
+//===----------------------------------------------------------------------===//
+
+class RISCVXAndesBuiltin<string prototype, string features = ""> : TargetBuiltin {
+ let Spellings = ["__builtin_riscv_nds_" # NAME];
+ let Prototype = prototype;
+ let Features = features;
+}
+
+let Attributes = [NoThrow, Const] in {
+//===----------------------------------------------------------------------===//
+// XAndesBFHCvt extension.
+//===----------------------------------------------------------------------===//
+
+def fcvt_s_bf16 : RISCVXAndesBuiltin<"float(__bf16)", "xandesbfhcvt">;
+def fcvt_bf16_s : RISCVXAndesBuiltin<"__bf16(float)", "xandesbfhcvt">;
+} // Attributes = [NoThrow, Const]
diff --git a/clang/lib/CodeGen/TargetBuiltins/RISCV.cpp b/clang/lib/CodeGen/TargetBuiltins/RISCV.cpp
index 89e3f6f203df3..b08a0588c5ac1 100644
--- a/clang/lib/CodeGen/TargetBuiltins/RISCV.cpp
+++ b/clang/lib/CodeGen/TargetBuiltins/RISCV.cpp
@@ -413,6 +413,12 @@ Value *CodeGenFunction::EmitRISCVBuiltinExpr(unsigned BuiltinID,
ID = Intrinsic::riscv_cv_alu_subuRN;
break;
+ // XAndesBFHCvt
+ case RISCV::BI__builtin_riscv_nds_fcvt_s_bf16:
+ return Builder.CreateFPExt(Ops[0], FloatTy);
+ case RISCV::BI__builtin_riscv_nds_fcvt_bf16_s:
+ return Builder.CreateFPTrunc(Ops[0], BFloatTy);
+
// Vector builtins are handled from here.
#include "clang/Basic/riscv_vector_builtin_cg.inc"
diff --git a/clang/lib/Headers/CMakeLists.txt b/clang/lib/Headers/CMakeLists.txt
index b4618fe4a46da..dd52498bbef4c 100644
--- a/clang/lib/Headers/CMakeLists.txt
+++ b/clang/lib/Headers/CMakeLists.txt
@@ -127,6 +127,7 @@ set(riscv_files
riscv_bitmanip.h
riscv_corev_alu.h
riscv_crypto.h
+ riscv_nds.h
riscv_ntlh.h
sifive_vector.h
andes_vector.h
diff --git a/clang/lib/Headers/riscv_nds.h b/clang/lib/Headers/riscv_nds.h
new file mode 100644
index 0000000000000..5ccef00e332ed
--- /dev/null
+++ b/clang/lib/Headers/riscv_nds.h
@@ -0,0 +1,35 @@
+/*===---- riscv_nds.h - Andes intrinsics -----------------------------------===
+ *
+ * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+ * See https://llvm.org/LICENSE.txt for license information.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#ifndef __RISCV_NDS_H
+#define __RISCV_NDS_H
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#if defined(__riscv_xandesbfhcvt)
+
+#define __DEFAULT_FN_ATTRS __attribute__((__always_inline__, __nodebug__))
+
+static __inline__ float __DEFAULT_FN_ATTRS __riscv_nds_fcvt_s_bf16(__bf16 bf) {
+ return __builtin_riscv_nds_fcvt_s_bf16(bf);
+}
+
+static __inline__ __bf16 __DEFAULT_FN_ATTRS __riscv_nds_fcvt_bf16_s(float sf) {
+ return __builtin_riscv_nds_fcvt_bf16_s(sf);
+}
+
+#endif // defined(__riscv_xandesbfhcvt)
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif // define __RISCV_NDS_H
diff --git a/clang/test/CodeGen/RISCV/riscv-xandesbfhcvt-c-api.c b/clang/test/CodeGen/RISCV/riscv-xandesbfhcvt-c-api.c
new file mode 100644
index 0000000000000..9feeafe42c79f
--- /dev/null
+++ b/clang/test/CodeGen/RISCV/riscv-xandesbfhcvt-c-api.c
@@ -0,0 +1,25 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
+// RUN: %clang_cc1 -triple riscv32 -target-feature +xandesbfhcvt -emit-llvm %s -o - \
+// RUN: -disable-O0-optnone | opt -S -passes=mem2reg | FileCheck %s
+// RUN: %clang_cc1 -triple riscv64 -target-feature +xandesbfhcvt -emit-llvm %s -o - \
+// RUN: -disable-O0-optnone | opt -S -passes=mem2reg | FileCheck %s
+
+#include <riscv_nds.h>
+
+// CHECK-LABEL: @test_fcvt_s_bf16(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[TMP0:%.*]] = fpext bfloat [[BF:%.*]] to float
+// CHECK-NEXT: ret float [[TMP0]]
+//
+float test_fcvt_s_bf16(__bf16 bf) {
+ return __riscv_nds_fcvt_s_bf16(bf);
+}
+
+// CHECK-LABEL: @test_fcvt_bf16_s(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[TMP0:%.*]] = fptrunc float [[SF:%.*]] to bfloat
+// CHECK-NEXT: ret bfloat [[TMP0]]
+//
+__bf16 test_fcvt_bf16_s(float sf) {
+ return __riscv_nds_fcvt_bf16_s(sf);
+}
diff --git a/clang/test/CodeGen/RISCV/riscv-xandesbfhcvt.c b/clang/test/CodeGen/RISCV/riscv-xandesbfhcvt.c
new file mode 100644
index 0000000000000..2f5e754d38704
--- /dev/null
+++ b/clang/test/CodeGen/RISCV/riscv-xandesbfhcvt.c
@@ -0,0 +1,23 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
+// RUN: %clang_cc1 -triple riscv32 -target-feature +xandesbfhcvt -emit-llvm %s -o - \
+// RUN: -disable-O0-optnone | opt -S -passes=mem2reg | FileCheck %s
+// RUN: %clang_cc1 -triple riscv64 -target-feature +xandesbfhcvt -emit-llvm %s -o - \
+// RUN: -disable-O0-optnone | opt -S -passes=mem2reg | FileCheck %s
+
+// CHECK-LABEL: @test_fcvt_s_bf16(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[TMP0:%.*]] = fpext bfloat [[BF:%.*]] to float
+// CHECK-NEXT: ret float [[TMP0]]
+//
+float test_fcvt_s_bf16(__bf16 bf) {
+ return __builtin_riscv_nds_fcvt_s_bf16(bf);
+}
+
+// CHECK-LABEL: @test_fcvt_bf16_s(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[TMP0:%.*]] = fptrunc float [[SF:%.*]] to bfloat
+// CHECK-NEXT: ret bfloat [[TMP0]]
+//
+__bf16 test_fcvt_bf16_s(float sf) {
+ return __builtin_riscv_nds_fcvt_bf16_s(sf);
+}
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 583e9f5ab26f1..2754f6c3f8252 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -128,7 +128,7 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
if (Subtarget.hasStdExtZfhmin())
addRegisterClass(MVT::f16, &RISCV::FPR16RegClass);
- if (Subtarget.hasStdExtZfbfmin())
+ if (Subtarget.hasStdExtZfbfmin() || Subtarget.hasVendorXAndesBFHCvt())
addRegisterClass(MVT::bf16, &RISCV::FPR16RegClass);
if (Subtarget.hasStdExtF())
addRegisterClass(MVT::f32, &RISCV::FPR32RegClass);
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoXAndes.td b/llvm/lib/Target/RISCV/RISCVInstrInfoXAndes.td
index a20348e02da47..5220815336441 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoXAndes.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoXAndes.td
@@ -767,6 +767,13 @@ def : Sh2AddPat<NDS_LEA_W_ZE>;
def : Sh3AddPat<NDS_LEA_D_ZE>;
} // Predicates = [HasVendorXAndesPerf, IsRV64]
+let Predicates = [HasVendorXAndesBFHCvt] in {
+def : Pat<(fpextend (bf16 FPR16:$rs)),
+ (NDS_FCVT_S_BF16 (bf16 FPR16:$rs))>;
+def : Pat<(bf16 (fpround FPR32:$rs)),
+ (NDS_FCVT_BF16_S FPR32:$rs)>;
+} // Predicates = [HasVendorXAndesBFHCvt]
+
let Predicates = [HasVendorXAndesVBFHCvt] in {
defm PseudoNDS_VFWCVT_S_BF16 : VPseudoVWCVT_S_BF16;
defm PseudoNDS_VFNCVT_BF16_S : VPseudoVNCVT_BF16_S;
diff --git a/llvm/test/CodeGen/RISCV/xandesbfhcvt.ll b/llvm/test/CodeGen/RISCV/xandesbfhcvt.ll
new file mode 100644
index 0000000000000..e4524394b9991
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/xandesbfhcvt.ll
@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -mattr=+xandesbfhcvt -target-abi ilp32f \
+; RUN: -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=riscv64 -mattr=+xandesbfhcvt -target-abi lp64f \
+; RUN: -verify-machineinstrs < %s | FileCheck %s
+
+declare bfloat @llvm.riscv.nds.fcvt.bf16.s(float)
+
+define float @fcvt_s_bf16(bfloat %a) nounwind {
+; CHECK-LABEL: fcvt_s_bf16:
+; CHECK: # %bb.0:
+; CHECK-NEXT: nds.fcvt.s.bf16 fa0, fa0
+; CHECK-NEXT: ret
+ %1 = fpext bfloat %a to float
+ ret float %1
+}
+
+declare float @llvm.riscv.nds.fcvt.s.bf16(bfloat)
+
+define bfloat @fcvt_bf16_s(float %a) nounwind {
+; CHECK-LABEL: fcvt_bf16_s:
+; CHECK: # %bb.0:
+; CHECK-NEXT: nds.fcvt.bf16.s fa0, fa0
+; CHECK-NEXT: ret
+ %1 = fptrunc float %a to bfloat
+ ret bfloat %1
+}
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