[RISCV] Remove XSfcie extension.

This reverts 0d3eee3 and
4c37d30.

XSfcie is not an official SiFive extension name. It stands for
SiFive Custom Instruction Extension, which is mentioned in the S76
manual, but then elsewhere in the manual says it is not supported
for S76.

LLVM had various instructions and CSRs listed as part of this
extension, but as far as SiFive is concerned, none of them are part
of it. There are no documented extension names for these instructions
and CSRs either externally or internally.

If these are important to LLVM users, I can facilitate creating
extension names for them and have them documented. For now I'm
removing everything.

Unfortunately, these instructions and CSRs are in LLVM 17 so this
is an incompatible change.

clang/test/Driver/riscv-cpus.c

@@ -153,7 +153,6 @@
 // MCPU-SIFIVE-S76: "-target-feature" "+m" "-target-feature" "+a" "-target-feature" "+f" "-target-feature" "+d"
 // MCPU-SIFIVE-S76: "-target-feature" "+c"
 // MCPU-SIFIVE-S76: "-target-feature" "+zicsr" "-target-feature" "+zifencei" "-target-feature" "+zihintpause"
-// MCPU-SIFIVE-S76: "-target-feature" "+xsfcie"
 // MCPU-SIFIVE-S76: "-target-abi" "lp64d"
 
 // mcpu with default march

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

@@ -33,7 +33,6 @@
 // CHECK-NOT: __riscv_xcvmac {{.*$}}
 // CHECK-NOT: __riscv_xcvmem {{.*$}}
 // CHECK-NOT: __riscv_xcvsimd {{.*$}}
-// CHECK-NOT: __riscv_xsfcie {{.*$}}
 // CHECK-NOT: __riscv_xsfvcp {{.*$}}
 // CHECK-NOT: __riscv_xsfvfnrclipxfqf {{.*$}}
 // CHECK-NOT: __riscv_xsfvfwmaccqqq {{.*$}}
@@ -315,14 +314,6 @@
 // RUN: -o - | FileCheck --check-prefix=CHECK-XCVSIMD-EXT %s
 // CHECK-XCVSIMD-EXT: __riscv_xcvsimd 1000000{{$}}
 
-// RUN: %clang --target=riscv32-unknown-linux-gnu \
-// RUN: -march=rv32ixsfcie -x c -E -dM %s \
-// RUN: -o - | FileCheck --check-prefix=CHECK-XSFCIE-EXT %s
-// RUN: %clang --target=riscv64-unknown-linux-gnu \
-// RUN: -march=rv64ixsfcie -x c -E -dM %s \
-// RUN: -o - | FileCheck --check-prefix=CHECK-XSFCIE-EXT %s
-// CHECK-XSFCIE-EXT: __riscv_xsfcie 1000000{{$}}
-
 // RUN: %clang --target=riscv32-unknown-linux-gnu \
 // RUN: -march=rv32ixsfvcp -x c -E -dM %s \
 // RUN: -o - | FileCheck --check-prefix=CHECK-XSFVCP-EXT %s

llvm/docs/RISCVUsage.rst

@@ -300,9 +300,6 @@ The current vendor extensions supported are:
 ``XCVbi``
   LLVM implements `version 1.0.0 of the CORE-V immediate branching custom instructions specification <https://github.com/openhwgroup/cv32e40p/blob/cv32e40p_v1.3.2/docs/source/instruction_set_extensions.rst>`_ by OpenHW Group.  All instructions are prefixed with `cv.` as described in the specification. These instructions are only available for riscv32 at this time.
 
-``XSfcie``
-  LLVM implements `version 1.0.0 of the SiFive Custom Instruction Extension (CIE) Software Specification <https://sifive.cdn.prismic.io/sifive/767804da-53b2-4893-97d5-b7c030ae0a94_s76mc_core_complex_manual_21G3.pdf>`_ by SiFive.  All custom instruction are added as described in the specification, and the riscv-toolchain-convention document linked above. These instructions are only available for S76 processor at this time.
-
 Experimental C Intrinsics
 =========================
 

llvm/docs/ReleaseNotes.rst

@@ -146,6 +146,11 @@ Changes to the RISC-V Backend
   and is no longer experimental.  However, the C intrinsics for these extensions
   are still experimental.  To use the C intrinsics for these extensions,
   ``-menable-experimental-extensions`` needs to be passed to Clang.
+* XSfcie extension and SiFive CSRs and instructions that were associated with
+  it have been removed. None of these CSRs and instructions were part of
+  "SiFive Custom Instruction Extension" as SiFive defines it. The LLVM project
+  needs to work with SiFive to define and document real extension names for
+  individual CSRs and instructions.
 
 Changes to the WebAssembly Backend
 ----------------------------------

llvm/lib/Support/RISCVISAInfo.cpp

@@ -75,7 +75,6 @@ static const RISCVSupportedExtension SupportedExtensions[] = {
     {"xcvmac", RISCVExtensionVersion{1, 0}},
     {"xcvmem", RISCVExtensionVersion{1, 0}},
     {"xcvsimd", RISCVExtensionVersion{1, 0}},
-    {"xsfcie", RISCVExtensionVersion{1, 0}},
     {"xsfvcp", RISCVExtensionVersion{1, 0}},
     {"xsfvfnrclipxfqf", RISCVExtensionVersion{1, 0}},
     {"xsfvfwmaccqqq", RISCVExtensionVersion{1, 0}},

llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp

@@ -1832,57 +1832,18 @@ ParseStatus RISCVAsmParser::parseCSRSystemRegister(OperandVector &Operands) {
     if (getParser().parseIdentifier(Identifier))
       return ParseStatus::Failure;
 
-    // Check for CSR names conflicts.
-    // Custom CSR names might conflict with CSR names in privileged spec.
-    // E.g. - SiFive mnscratch(0x350) and privileged spec mnscratch(0x740).
-    auto CheckCSRNameConflict = [&]() {
-      if (!(RISCVSysReg::lookupSysRegByName(Identifier))) {
-        Error(S, "system register use requires an option to be enabled");
-        return true;
-      }
-      return false;
-    };
-
-    // First check for vendor specific CSRs.
-    auto SiFiveReg = RISCVSysReg::lookupSiFiveRegByName(Identifier);
-    if (SiFiveReg) {
-      if (SiFiveReg->haveVendorRequiredFeatures(getSTI().getFeatureBits())) {
-        Operands.push_back(
-            RISCVOperand::createSysReg(Identifier, S, SiFiveReg->Encoding));
-        return ParseStatus::Success;
-      }
-      if (CheckCSRNameConflict())
-        return ParseStatus::Failure;
-    }
-
     auto SysReg = RISCVSysReg::lookupSysRegByName(Identifier);
+    if (!SysReg)
+      SysReg = RISCVSysReg::lookupSysRegByAltName(Identifier);
     if (!SysReg)
       if ((SysReg = RISCVSysReg::lookupSysRegByDeprecatedName(Identifier)))
         Warning(S, "'" + Identifier + "' is a deprecated alias for '" +
                        SysReg->Name + "'");
 
-    // Check for CSR encoding conflicts.
-    // Custom CSR encoding might conflict with CSR encoding in privileged spec.
-    // E.g. - SiFive mnscratch(0x350) and privileged spec miselect(0x350).
-    auto CheckCSREncodingConflict = [&]() {
-      auto Reg = RISCVSysReg::lookupSiFiveRegByEncoding(SysReg->Encoding);
-      if (Reg && Reg->haveVendorRequiredFeatures(getSTI().getFeatureBits())) {
-        Warning(S, "'" + Identifier + "' CSR is not available on the current " +
-                       "subtarget. Instead '" + Reg->Name +
-                       "' CSR will be used.");
-        Operands.push_back(
-            RISCVOperand::createSysReg(Reg->Name, S, Reg->Encoding));
-        return true;
-      }
-      return false;
-    };
-
-    // Accept a named SysReg if the required features are present.
+    // Accept a named Sys Reg if the required features are present.
     if (SysReg) {
       if (!SysReg->haveRequiredFeatures(getSTI().getFeatureBits()))
         return Error(S, "system register use requires an option to be enabled");
-      if (CheckCSREncodingConflict())
-        return ParseStatus::Success;
       Operands.push_back(
           RISCVOperand::createSysReg(Identifier, S, SysReg->Encoding));
       return ParseStatus::Success;

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

@@ -566,8 +566,6 @@ DecodeStatus RISCVDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
     TRY_TO_DECODE_FEATURE(
         RISCV::FeatureVendorXSfvfnrclipxfqf, DecoderTableXSfvfnrclipxfqf32,
         "SiFive FP32-to-int8 Ranged Clip Instructions opcode table");
-    TRY_TO_DECODE_FEATURE(RISCV::FeatureVendorXSfcie, DecoderTableXSfcie32,
-                          "Sifive CIE custom opcode table");
     TRY_TO_DECODE_FEATURE(RISCV::FeatureVendorXCVbitmanip,
                           DecoderTableXCVbitmanip32,
                           "CORE-V Bit Manipulation custom opcode table");

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.cpp

@@ -27,7 +27,6 @@ extern const SubtargetFeatureKV RISCVFeatureKV[RISCV::NumSubtargetFeatures];
 
 namespace RISCVSysReg {
 #define GET_SysRegsList_IMPL
-#define GET_SiFiveRegsList_IMPL
 #include "RISCVGenSearchableTables.inc"
 } // namespace RISCVSysReg
 

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.h

@@ -401,6 +401,7 @@ int getLoadFPImm(APFloat FPImm);
 namespace RISCVSysReg {
 struct SysReg {
   const char *Name;
+  const char *AltName;
   const char *DeprecatedName;
   unsigned Encoding;
   // FIXME: add these additional fields when needed.
@@ -424,22 +425,9 @@ struct SysReg {
       return true;
     return (FeaturesRequired & ActiveFeatures) == FeaturesRequired;
   }
-
-  bool haveVendorRequiredFeatures(const FeatureBitset &ActiveFeatures) const {
-    // Not in 32-bit mode.
-    if (isRV32Only && ActiveFeatures[RISCV::Feature64Bit])
-      return false;
-    // No required feature associated with the system register.
-    if (FeaturesRequired.none())
-      return false;
-    return (FeaturesRequired & ActiveFeatures) == FeaturesRequired;
-  }
 };
 
-struct SiFiveReg : SysReg {};
-
 #define GET_SysRegsList_DECL
-#define GET_SiFiveRegsList_DECL
 #include "RISCVGenSearchableTables.inc"
 } // end namespace RISCVSysReg
 

llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.cpp

@@ -121,11 +121,8 @@ void RISCVInstPrinter::printCSRSystemRegister(const MCInst *MI, unsigned OpNo,
                                               const MCSubtargetInfo &STI,
                                               raw_ostream &O) {
   unsigned Imm = MI->getOperand(OpNo).getImm();
-  auto SiFiveReg = RISCVSysReg::lookupSiFiveRegByEncoding(Imm);
   auto SysReg = RISCVSysReg::lookupSysRegByEncoding(Imm);
-  if (SiFiveReg && SiFiveReg->haveVendorRequiredFeatures(STI.getFeatureBits()))
-    markup(O, Markup::Register) << SiFiveReg->Name;
-  else if (SysReg && SysReg->haveRequiredFeatures(STI.getFeatureBits()))
+  if (SysReg && SysReg->haveRequiredFeatures(STI.getFeatureBits()))
     markup(O, Markup::Register) << SysReg->Name;
   else
     markup(O, Markup::Register) << formatImm(Imm);

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -826,13 +826,6 @@ def HasVendorXSfvcp : Predicate<"Subtarget->hasVendorXSfvcp()">,
                                 AssemblerPredicate<(all_of FeatureVendorXSfvcp),
                                 "'XSfvcp' (SiFive Custom Vector Coprocessor Interface Instructions)">;
 
-def FeatureVendorXSfcie
-    : SubtargetFeature<"xsfcie", "HasVendorXSfcie", "true",
-                       "'XSfcie' (SiFive Custom Instruction Extension SCIE.)">;
-def HasVendorXSfcie : Predicate<"Subtarget->hasVendorXSfcie()">,
-                        AssemblerPredicate<(all_of FeatureVendorXSfcie),
-                        "'XSfcie' (SiFive Custom Instruction Extension SCIE.)">;
-
 def FeatureVendorXSfvqmaccdod
     : SubtargetFeature<"xsfvqmaccdod", "HasVendorXSfvqmaccdod", "true",
                        "'XSfvqmaccdod' (SiFive Int8 Matrix Multiplication Instructions (2-by-8 and 8-by-2))",

llvm/lib/Target/RISCV/RISCVInstrInfoXSf.td

@@ -673,27 +673,3 @@ let Predicates = [HasVendorXSfvfnrclipxfqf] in {
   defm : VPatVFNRCLIP<"vfnrclip_xu_f_qf", "VFNRCLIP_XU_F_QF">;
   defm : VPatVFNRCLIP<"vfnrclip_x_f_qf", "VFNRCLIP_X_F_QF">;
 }
-
-let Predicates = [HasVendorXSfcie] in {
-let hasSideEffects = 1, mayLoad = 0, mayStore = 0, DecoderNamespace = "XSfcie" in {
-def SF_CFLUSH_D_L1 : RVInstI<0b000, OPC_SYSTEM, (outs), (ins GPR:$rs1), "cflush.d.l1","$rs1">,
-                             Sched<[]> {
-  let rd = 0;
-  let imm12 = {0b1111,0b1100,0b0000};
-}
-
-def SF_CDISCARD_D_L1 : RVInstI<0b000, OPC_SYSTEM, (outs), (ins GPR:$rs1), "cdiscard.d.l1","$rs1">,
-                               Sched<[]> {
-  let rd = 0;
-  let imm12 = {0b1111,0b1100,0b0010};
-}
-
-def SF_CEASE : RVInstI<0b000, OPC_SYSTEM, (outs), (ins), "cease","">,  Sched<[]> {
-  let rs1 = 0;
-  let rd = 0;
-  let imm12 = {0b0011,0b0000,0b0101};
-}
-}
-def : InstAlias<"cflush.d.l1", (SF_CFLUSH_D_L1 X0)>;
-def : InstAlias<"cdiscard.d.l1", (SF_CDISCARD_D_L1 X0)>;
-} // Predicates = [HasVendorXScie]

llvm/lib/Target/RISCV/RISCVProcessors.td

@@ -174,8 +174,7 @@ def SIFIVE_S76 : RISCVProcessorModel<"sifive-s76",
                                       FeatureStdExtF,
                                       FeatureStdExtD,
                                       FeatureStdExtC,
-                                      FeatureStdExtZihintpause,
-                                      FeatureVendorXSfcie],
+                                      FeatureStdExtZihintpause],
                                      [TuneSiFive7]>;
 
 def SIFIVE_U54 : RISCVProcessorModel<"sifive-u54",

llvm/lib/Target/RISCV/RISCVSystemOperands.td

@@ -19,9 +19,11 @@ include "llvm/TableGen/SearchableTable.td"
 
 class SysReg<string name, bits<12> op> {
   string Name = name;
-  // A maximum of one deprecated name is supported right now. It generates a
-  // diagnostic when the name is used to encourage software to migrate away from
-  // the name.
+  // A maximum of one alias is supported right now.
+  string AltName = name;
+  // A maximum of one deprecated name is supported right now.  Unlike the
+  // `AltName` alias, a `DeprecatedName` generates a diagnostic when the name is
+  // used to encourage software to migrate away from the name.
   string DeprecatedName = "";
   bits<12> Encoding = op;
   // FIXME: add these additional fields when needed.
@@ -41,7 +43,7 @@ def SysRegsList : GenericTable {
   let FilterClass = "SysReg";
   // FIXME: add "ReadWrite", "Mode", "Extra", "Number" fields when needed.
   let Fields = [
-    "Name", "DeprecatedName", "Encoding", "FeaturesRequired",
+    "Name", "AltName", "DeprecatedName", "Encoding", "FeaturesRequired",
     "isRV32Only",
   ];
 
@@ -54,32 +56,13 @@ def lookupSysRegByName : SearchIndex {
   let Key = [ "Name" ];
 }
 
-def lookupSysRegByDeprecatedName : SearchIndex {
+def lookupSysRegByAltName : SearchIndex {
   let Table = SysRegsList;
-  let Key = [ "DeprecatedName" ];
-}
-
-class SiFiveReg<string name, bits<12> op> : SysReg<name, op>;
-
-def SiFiveRegsList : GenericTable {
-  let FilterClass = "SiFiveReg";
-  // FIXME: add "ReadWrite", "Mode", "Extra", "Number" fields when needed.
-  let Fields = [
-    "Name", "DeprecatedName", "Encoding", "FeaturesRequired",
-    "isRV32Only",
-  ];
-
-  let PrimaryKey = [ "Encoding" ];
-  let PrimaryKeyName = "lookupSiFiveRegByEncoding";
+  let Key = [ "AltName" ];
 }
 
-def lookupSiFiveRegByName : SearchIndex {
-  let Table = SiFiveRegsList;
-  let Key = [ "Name" ];
-}
-
-def lookupSiFiveRegByDeprecatedName : SearchIndex {
-  let Table = SiFiveRegsList;
+def lookupSysRegByDeprecatedName : SearchIndex {
+  let Table = SysRegsList;
   let Key = [ "DeprecatedName" ];
 }
 
@@ -309,7 +292,7 @@ foreach i = 3...31 in
 //===----------------------------------------------------------------------===//
 // Machine Counter Setup
 //===----------------------------------------------------------------------===//
-let DeprecatedName = "mucounteren" in // Privileged spec v1.9.1 Name
+let AltName = "mucounteren" in // Privileged spec v1.9.1 Name
 def : SysReg<"mcountinhibit", 0x320>;
 
 // mhpmevent3-mhpmevent31 at 0x323-0x33F.
@@ -322,20 +305,6 @@ foreach i = 3...31 in {
   def : SysReg<"mhpmevent"#i#"h", !add(0x723, !sub(i, 3))>;
 }
 
-//===----------------------------------------------------------------------===//
-// SiFive Custom Machine Mode Registers
-//===----------------------------------------------------------------------===//
-
-let FeaturesRequired = [{ {RISCV::FeatureVendorXSfcie} }] in {
-def : SiFiveReg<"mnscratch", 0x350>;
-def : SiFiveReg<"mnepc", 0x351>;
-def : SiFiveReg<"mncause", 0x352>;
-def : SiFiveReg<"mnstatus", 0x353>;
-def : SiFiveReg<"mbpm", 0x7C0>;
-def : SiFiveReg<"mfd", 0x7C1>;
-def : SiFiveReg<"mpd", 0x7C8>;
-}
-
 //===----------------------------------------------------------------------===//
 // Debug/ Trace Registers (shared with Debug Mode)
 //===----------------------------------------------------------------------===//
@@ -353,7 +322,7 @@ def : SysReg<"dpc", 0x7B1>;
 
 // "dscratch" is an alternative name for "dscratch0" which appeared in earlier
 // drafts of the RISC-V debug spec
-let DeprecatedName = "dscratch" in
+let AltName = "dscratch" in
 def : SysReg<"dscratch0", 0x7B2>;
 def : SysReg<"dscratch1", 0x7B3>;
 

llvm/test/MC/RISCV/attribute-arch.s

@@ -282,9 +282,6 @@
 .attribute arch, "rv32i_zvfbfwma0p8"
 # CHECK: .attribute     5, "rv32i2p1_f2p2_zicsr2p0_zfbfmin0p8_zve32f1p0_zve32x1p0_zvfbfmin0p8_zvfbfwma0p8_zvl32b1p0"
 
-.attribute arch, "rv64i_xsfcie"
-# CHECK: attribute      5, "rv64i2p1_xsfcie1p0"
-
 .attribute arch, "rv32izacas1p0"
 # CHECK: attribute      5, "rv32i2p1_a2p1_zacas1p0"
 

llvm/test/MC/RISCV/machine-csr-names.s

@@ -9,9 +9,6 @@
 # RUN: llvm-mc -filetype=obj -triple riscv64 < %s \
 # RUN:     | llvm-objdump -d - \
 # RUN:     | FileCheck -check-prefix=CHECK-INST-ALIAS %s
-#
-# RUN: llvm-mc -triple riscv32 %s 2>&1 | FileCheck -check-prefix CHECK-WARN %s
-# RUN: llvm-mc -triple riscv64 %s 2>&1 | FileCheck -check-prefix CHECK-WARN %s
 
 ##################################
 # Machine Information Registers
@@ -1495,8 +1492,6 @@ csrrs t1, dscratch, zero
 # uimm12
 csrrs t2, 0x7B2, zero
 
-# CHECK-WARN: warning: 'dscratch' is a deprecated alias for 'dscratch0'
-
 # dscratch1
 # name
 # CHECK-INST: csrrs t1, dscratch1, zero
@@ -1949,8 +1944,6 @@ csrrs t1, mucounteren, zero
 # uimm12
 csrrs t2, 0x320, zero
 
-# CHECK-WARN: warning: 'mucounteren' is a deprecated alias for 'mcountinhibit'
-
 # mhpmevent3
 # name
 # CHECK-INST: csrrs t1, mhpmevent3, zero