[RISCV] Add Andes XAndesVBFHCvt (Andes Vector BFLOAT16 Conversion) extension (#144320)

The spec can be found at:
https://github.com/andestech/andes-v5-isa/releases/tag/ast-v5_4_0-release.

This patch only supports assembler. The instructions are similar to
`Zvfbfmin` and the only difference with `Zvfbfmin` is that
`XAndesVBFHCvt` doesn't have mask variant.

clang/test/Driver/print-supported-extensions-riscv.c

@@ -159,6 +159,7 @@
 // CHECK-NEXT:     svpbmt               1.0       'Svpbmt' (Page-Based Memory Types)
 // CHECK-NEXT:     svvptc               1.0       'Svvptc' (Obviating Memory-Management Instructions after Marking PTEs Valid)
 // CHECK-NEXT:     xandesperf           5.0       'XAndesPerf' (Andes Performance Extension)
+// CHECK-NEXT:     xandesvbfhcvt        5.0       'XAndesVBFHCvt' (Andes Vector BFLOAT16 Conversion Extension)
 // CHECK-NEXT:     xandesvdot           5.0       'XAndesVDot' (Andes Vector Dot Product Extension)
 // CHECK-NEXT:     xandesvpackfph       5.0       'XAndesVPackFPH' (Andes Vector Packed FP16 Extension)
 // CHECK-NEXT:     xcvalu               1.0       'XCValu' (CORE-V ALU Operations)

clang/test/Preprocessor/riscv-target-features-andes.c

@@ -15,6 +15,14 @@
 // RUN:   -o - | FileCheck --check-prefix=CHECK-XANDESPERF %s
 // CHECK-XANDESPERF: __riscv_xandesperf  5000000{{$}}
 
+// RUN: %clang --target=riscv32 \
+// RUN:   -march=rv32i_xandesvbfhcvt -E -dM %s \
+// RUN:   -o - | FileCheck --check-prefix=CHECK-XANDESVBFHCVT %s
+// RUN: %clang --target=riscv64 \
+// RUN:   -march=rv64i_xandesvbfhcvt -E -dM %s \
+// RUN:   -o - | FileCheck --check-prefix=CHECK-XANDESVBFHCVT %s
+// CHECK-XANDESVBFHCVT: __riscv_xandesvbfhcvt  5000000{{$}}
+
 // RUN: %clang --target=riscv32 \
 // RUN:   -march=rv32i_xandesvpackfph -E -dM %s \
 // RUN:   -o - | FileCheck --check-prefix=CHECK-XANDESVPACKFPH %s

llvm/docs/RISCVUsage.rst

@@ -513,6 +513,9 @@ The current vendor extensions supported are:
 ``XAndesPerf``
   LLVM implements `version 5.0.0 of the Andes Performance Extension specification <https://github.com/andestech/andes-v5-isa/releases/download/ast-v5_4_0-release/AndeStar_V5_ISA_Spec_UM165-v1.5.08-20250317.pdf>`__ by Andes Technology. All instructions are prefixed with `nds.` as described in the specification.
 
+``XAndesVBFHCvt``
+  LLVM implements `version 5.0.0 of the Andes Vector BFLOAT16 Conversion Extension specification <https://github.com/andestech/andes-v5-isa/releases/download/ast-v5_4_0-release/AndeStar_V5_ISA_Spec_UM165-v1.5.08-20250317.pdf>`__ by Andes Technology. All instructions are prefixed with `nds.` as described in the specification.
+
 ``XAndesVPackFPH``
   LLVM implements `version 5.0.0 of the Andes Vector Packed FP16 Extension specification <https://github.com/andestech/andes-v5-isa/releases/download/ast-v5_4_0-release/AndeStar_V5_ISA_Spec_UM165-v1.5.08-20250317.pdf>`__ by Andes Technology. All instructions are prefixed with `nds.` as described in the specification.
 

llvm/docs/ReleaseNotes.md

@@ -210,6 +210,7 @@ Changes to the RISC-V Backend
 * The `Shlcofideleg` extension was added.
 * `-mcpu=sifive-x390` was added.
 * `-mtune=andes-45-series` was added.
+* Adds assembler support for the Andes `XAndesvbfhcvt` (Andes Vector BFLOAT16 Conversion extension).
 
 Changes to the WebAssembly Backend
 ----------------------------------

llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp

@@ -774,8 +774,8 @@ static constexpr FeatureBitset XTHeadGroup = {
     RISCV::FeatureVendorXTHeadVdot};
 
 static constexpr FeatureBitset XAndesGroup = {
-    RISCV::FeatureVendorXAndesPerf, RISCV::FeatureVendorXAndesVPackFPH,
+    RISCV::FeatureVendorXAndesPerf, RISCV::FeatureVendorXAndesVBFHCvt,
-    RISCV::FeatureVendorXAndesVDot};
+    RISCV::FeatureVendorXAndesVPackFPH, RISCV::FeatureVendorXAndesVDot};
 
 static constexpr DecoderListEntry DecoderList32[]{
     // Vendor Extensions

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -1599,6 +1599,15 @@ def HasVendorXAndesPerf
       AssemblerPredicate<(all_of FeatureVendorXAndesPerf),
                          "'XAndesPerf' (Andes Performance Extension)">;
 
+def FeatureVendorXAndesVBFHCvt
+    : RISCVExtension<5, 0, "Andes Vector BFLOAT16 Conversion Extension",
+                     [FeatureStdExtZve32f]>;
+def HasVendorXAndesVBFHCvt
+    : Predicate<"Subtarget->hasVendorXAndesVBFHCvt()">,
+      AssemblerPredicate<(all_of FeatureVendorXAndesVBFHCvt),
+                         "'XAndesVBFHCvt' (Andes Vector BFLOAT16 Conversion Extension)">;
+
+
 def FeatureVendorXAndesVPackFPH
     : RISCVExtension<5, 0, "Andes Vector Packed FP16 Extension",
                      [FeatureStdExtZvfhmin]>;

llvm/lib/Target/RISCV/RISCVInstrInfoXAndes.td

@@ -361,6 +361,25 @@ class NDSRVInstVD4DOT<bits<6> funct6, string opcodestr>
   let RVVConstraint = VMConstraint;
 }
 
+class NDSRVInstVBFHCvt<bits<7> funct7, bits<5> vs1, string opcodestr>
+    : RVInst<(outs VR:$vd), (ins VR:$vs2, VMaskOp:$vm),
+             opcodestr, "$vd, $vs2", [], InstFormatR> {
+  bits<5> vs2;
+  bits<5> vd;
+
+  let Inst{31-25} = funct7;
+  let Inst{24-20} = vs2;
+  let Inst{19-15} = vs1;
+  let Inst{14-12} = 0b100;
+  let Inst{11-7} = vd;
+  let Inst{6-0} = OPC_CUSTOM_2.Value;
+  let hasSideEffects = 0;
+  let mayLoad = 0;
+  let mayStore = 0;
+
+  let Uses = [VL, VTYPE];
+}
+
 //===----------------------------------------------------------------------===//
 // Multiclass
 //===----------------------------------------------------------------------===//
@@ -460,6 +479,18 @@ def NDS_LDGP  : NDSRVInstLDGP<0b011, "nds.ldgp">;
 def NDS_SDGP  : NDSRVInstSDGP<0b111, "nds.sdgp">;
 } // Predicates = [HasVendorXAndesPerf, IsRV64]
 
+//===----------------------------------------------------------------------===//
+// XAndesVBFHCvt
+//===----------------------------------------------------------------------===//
+
+let Predicates = [HasVendorXAndesVBFHCvt], Constraints = "@earlyclobber $vd",
+    mayRaiseFPException = true in {
+let RVVConstraint = VS2Constraint, DestEEW = EEWSEWx2 in
+def NDS_VFWCVT_S_BF16 : NDSRVInstVBFHCvt<0b0000000, 0b00000, "nds.vfwcvt.s.bf16">;
+let Uses = [FRM, VL, VTYPE] in
+def NDS_VFNCVT_BF16_S : NDSRVInstVBFHCvt<0b0000000, 0b00001, "nds.vfncvt.bf16.s">;
+}
+
 //===----------------------------------------------------------------------===//
 // XAndesVPackFPH
 //===----------------------------------------------------------------------===//

llvm/test/CodeGen/RISCV/attributes.ll

@@ -106,6 +106,7 @@
 ; RUN: llc -mtriple=riscv32 -mattr=+experimental-xqcisls %s -o - | FileCheck --check-prefix=RV32XQCISLS %s
 ; RUN: llc -mtriple=riscv32 -mattr=+experimental-xqcisync %s -o - | FileCheck --check-prefix=RV32XQCISYNC %s
 ; RUN: llc -mtriple=riscv32 -mattr=+xandesperf %s -o - | FileCheck --check-prefix=RV32XANDESPERF %s
+; RUN: llc -mtriple=riscv32 -mattr=+xandesvbfhcvt %s -o - | FileCheck --check-prefix=RV32XANDESVBFHCVT %s
 ; RUN: llc -mtriple=riscv32 -mattr=+xandesvdot %s -o - | FileCheck --check-prefix=RV32XANDESVDOT %s
 ; RUN: llc -mtriple=riscv32 -mattr=+xandesvpackfph %s -o - | FileCheck --check-prefix=RV32XANDESVPACKFPH %s
 ; RUN: llc -mtriple=riscv32 -mattr=+zaamo %s -o - | FileCheck --check-prefix=RV32ZAAMO %s
@@ -260,6 +261,7 @@
 ; RUN: llc -mtriple=riscv64 -mattr=+xtheadsync %s -o - | FileCheck --check-prefix=RV64XTHEADSYNC %s
 ; RUN: llc -mtriple=riscv64 -mattr=+xtheadvdot %s -o - | FileCheck --check-prefixes=CHECK,RV64XTHEADVDOT %s
 ; RUN: llc -mtriple=riscv64 -mattr=+xandesperf %s -o - | FileCheck --check-prefix=RV64XANDESPERF %s
+; RUN: llc -mtriple=riscv64 -mattr=+xandesvbfhcvt %s -o - | FileCheck --check-prefix=RV64XANDESVBFHCVT %s
 ; RUN: llc -mtriple=riscv64 -mattr=+xandesvdot %s -o - | FileCheck --check-prefix=RV64XANDESVDOT %s
 ; RUN: llc -mtriple=riscv64 -mattr=+xandesvpackfph %s -o - | FileCheck --check-prefix=RV64XANDESVPACKFPH %s
 ; RUN: llc -mtriple=riscv64 -mattr=+za64rs %s -o - | FileCheck --check-prefixes=CHECK,RV64ZA64RS %s
@@ -457,6 +459,7 @@
 ; RV32XQCISLS: .attribute 5, "rv32i2p1_xqcisls0p2"
 ; RV32XQCISYNC: attribute 5, "rv32i2p1_zca1p0_xqcisync0p3"
 ; RV32XANDESPERF: .attribute 5, "rv32i2p1_xandesperf5p0"
+; RV32XANDESVBFHCVT: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvl32b1p0_xandesvbfhcvt5p0"
 ; RV32XANDESVDOT: .attribute 5, "rv32i2p1_zicsr2p0_zve32x1p0_zvl32b1p0_xandesvdot5p0"
 ; RV32XANDESVPACKFPH: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvfhmin1p0_zvl32b1p0_xandesvpackfph5p0"
 ; RV32ZAAMO: .attribute 5, "rv32i2p1_zaamo1p0"
@@ -612,6 +615,7 @@
 ; RV64XTHEADSYNC: .attribute 5, "rv64i2p1_xtheadsync1p0"
 ; RV64XTHEADVDOT: .attribute 5, "rv64i2p1_f2p2_d2p2_v1p0_zicsr2p0_zve32f1p0_zve32x1p0_zve64d1p0_zve64f1p0_zve64x1p0_zvl128b1p0_zvl32b1p0_zvl64b1p0_xtheadvdot1p0"
 ; RV64XANDESPERF: .attribute 5, "rv64i2p1_xandesperf5p0"
+; RV64XANDESVBFHCVT: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvl32b1p0_xandesvbfhcvt5p0"
 ; RV64XANDESVDOT: .attribute 5, "rv64i2p1_zicsr2p0_zve32x1p0_zvl32b1p0_xandesvdot5p0"
 ; RV64XANDESVPACKFPH: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvfhmin1p0_zvl32b1p0_xandesvpackfph5p0"
 ; RV64ZTSO: .attribute 5, "rv64i2p1_ztso1p0"

llvm/test/CodeGen/RISCV/features-info.ll

@@ -174,6 +174,7 @@
 ; CHECK-NEXT:   ventana-veyron                   - Ventana Veyron-Series processors.
 ; CHECK-NEXT:   vxrm-pipeline-flush              - VXRM writes causes pipeline flush.
 ; CHECK-NEXT:   xandesperf                       - 'XAndesPerf' (Andes Performance Extension).
+; CHECK-NEXT:   xandesvbfhcvt                    - 'XAndesVBFHCvt' (Andes Vector BFLOAT16 Conversion Extension).
 ; CHECK-NEXT:   xandesvdot                       - 'XAndesVDot' (Andes Vector Dot Product Extension).
 ; CHECK-NEXT:   xandesvpackfph                   - 'XAndesVPackFPH' (Andes Vector Packed FP16 Extension).
 ; CHECK-NEXT:   xcvalu                           - 'XCValu' (CORE-V ALU Operations).

llvm/test/MC/RISCV/xandesvbfhcvt-valid.s

@@ -0,0 +1,27 @@
+# XAndesVBFHCvt - Andes Vector BFLOAT16 Conversion Extension
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+xandesvbfhcvt -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK-ASM %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+xandesvbfhcvt < %s \
+# RUN:     | llvm-objdump --mattr=+xandesvbfhcvt -M no-aliases -d -r - \
+# RUN:     | FileCheck -check-prefixes=CHECK-OBJ %s
+# RUN: not llvm-mc -triple=riscv32 -show-encoding %s 2>&1 \
+# RUN:        | FileCheck %s --check-prefix=CHECK-ERROR
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+xandesvbfhcvt -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK-ASM %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+xandesvbfhcvt < %s \
+# RUN:     | llvm-objdump --mattr=+xandesvbfhcvt -M no-aliases -d -r - \
+# RUN:     | FileCheck -check-prefixes=CHECK-OBJ %s
+# RUN: not llvm-mc -triple=riscv64 -show-encoding %s 2>&1 \
+# RUN:        | FileCheck %s --check-prefix=CHECK-ERROR
+
+# CHECK-OBJ: nds.vfwcvt.s.bf16 v8, v10
+# CHECK-ASM: nds.vfwcvt.s.bf16 v8, v10
+# CHECK-ASM: encoding: [0x5b,0x44,0xa0,0x00]
+# CHECK-ERROR: instruction requires the following: 'XAndesVBFHCvt' (Andes Vector BFLOAT16 Conversion Extension){{$}}
+nds.vfwcvt.s.bf16 v8, v10
+
+# CHECK-OBJ: nds.vfncvt.bf16.s v8, v10
+# CHECK-ASM: nds.vfncvt.bf16.s v8, v10
+# CHECK-ASM: encoding: [0x5b,0xc4,0xa0,0x00]
+# CHECK-ERROR: instruction requires the following: 'XAndesVBFHCvt' (Andes Vector BFLOAT16 Conversion Extension){{$}}
+nds.vfncvt.bf16.s v8, v10

llvm/unittests/TargetParser/RISCVISAInfoTest.cpp

@@ -1130,6 +1130,7 @@ R"(All available -march extensions for RISC-V
     svpbmt               1.0
     svvptc               1.0
     xandesperf           5.0
+    xandesvbfhcvt        5.0
     xandesvdot           5.0
     xandesvpackfph       5.0
     xcvalu               1.0