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[RISCV] Reduce size of CSR lookup tables. NFC #121606

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Merged
merged 1 commit into from
Jan 4, 2025
Merged

[RISCV] Reduce size of CSR lookup tables. NFC #121606

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25 changes: 16 additions & 9 deletions llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1915,6 +1915,8 @@ ParseStatus RISCVAsmParser::parseCSRSystemRegister(OperandVector &Operands) {
// Accept an immediate representing a named Sys Reg if it satisfies the
// the required features.
for (auto &Reg : Range) {
if (Reg.IsAltName || Reg.IsDeprecatedName)
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This isn't strictly needed, but ensures we use the required features from the primary name and not the alternate or deprecated names.

continue;
if (Reg.haveRequiredFeatures(STI->getFeatureBits()))
return RISCVOperand::createSysReg(Reg.Name, S, Imm);
}
Expand Down Expand Up @@ -1952,22 +1954,27 @@ ParseStatus RISCVAsmParser::parseCSRSystemRegister(OperandVector &Operands) {
return ParseStatus::Failure;

const 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 + "'");

// Accept a named Sys Reg if the required features are present.

if (SysReg) {
if (SysReg->IsDeprecatedName) {
// Lookup the undeprecated name.
auto Range = RISCVSysReg::lookupSysRegByEncoding(SysReg->Encoding);
for (auto &Reg : Range) {
if (Reg.IsAltName || Reg.IsDeprecatedName)
continue;
Warning(S, "'" + Identifier + "' is a deprecated alias for '" +
Reg.Name + "'");
}
}

// Accept a named Sys Reg if the required features are present.
const auto &FeatureBits = getSTI().getFeatureBits();
if (!SysReg->haveRequiredFeatures(FeatureBits)) {
const auto *Feature = llvm::find_if(RISCVFeatureKV, [&](auto Feature) {
return SysReg->FeaturesRequired[Feature.Value];
});
auto ErrorMsg = std::string("system register '") + SysReg->Name + "' ";
if (SysReg->isRV32Only && FeatureBits[RISCV::Feature64Bit]) {
if (SysReg->IsRV32Only && FeatureBits[RISCV::Feature64Bit]) {
ErrorMsg += "is RV32 only";
if (Feature != std::end(RISCVFeatureKV))
ErrorMsg += " and ";
Expand Down
8 changes: 4 additions & 4 deletions llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.h
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Expand Up @@ -454,8 +454,6 @@ int getLoadFPImm(APFloat FPImm);
namespace RISCVSysReg {
struct SysReg {
const char Name[32];
const char AltName[32];
const char DeprecatedName[32];
unsigned Encoding;
// FIXME: add these additional fields when needed.
// Privilege Access: Read, Write, Read-Only.
Expand All @@ -467,11 +465,13 @@ struct SysReg {
// Register number without the privilege bits.
// unsigned Number;
FeatureBitset FeaturesRequired;
bool isRV32Only;
bool IsRV32Only;
bool IsAltName;
bool IsDeprecatedName;

bool haveRequiredFeatures(const FeatureBitset &ActiveFeatures) const {
// Not in 32-bit mode.
if (isRV32Only && ActiveFeatures[RISCV::Feature64Bit])
if (IsRV32Only && ActiveFeatures[RISCV::Feature64Bit])
return false;
// No required feature associated with the system register.
if (FeaturesRequired.none())
Expand Down
2 changes: 2 additions & 0 deletions llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -121,6 +121,8 @@ void RISCVInstPrinter::printCSRSystemRegister(const MCInst *MI, unsigned OpNo,
unsigned Imm = MI->getOperand(OpNo).getImm();
auto Range = RISCVSysReg::lookupSysRegByEncoding(Imm);
for (auto &Reg : Range) {
if (Reg.IsAltName || Reg.IsDeprecatedName)
continue;
if (Reg.haveRequiredFeatures(STI.getFeatureBits())) {
markup(O, Markup::Register) << Reg.Name;
return;
Expand Down
37 changes: 14 additions & 23 deletions llvm/lib/Target/RISCV/RISCVSystemOperands.td
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Expand Up @@ -19,12 +19,6 @@ include "llvm/TableGen/SearchableTable.td"

class SysReg<string name, bits<12> op> {
string Name = 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.
// Privilege Access: Read and Write = 0, 1, 2; Read-Only = 3.
Expand All @@ -37,14 +31,16 @@ class SysReg<string name, bits<12> op> {
// bits<6> Number = op{5 - 0};
code FeaturesRequired = [{ {} }];
bit isRV32Only = 0;
bit isAltName = 0;
bit isDeprecatedName = 0;
}

def SysRegsList : GenericTable {
let FilterClass = "SysReg";
// FIXME: add "ReadWrite", "Mode", "Extra", "Number" fields when needed.
let Fields = [
"Name", "AltName", "DeprecatedName", "Encoding", "FeaturesRequired",
"isRV32Only",
"Name", "Encoding", "FeaturesRequired",
"isRV32Only", "isAltName", "isDeprecatedName"
];

let PrimaryKey = [ "Encoding" ];
Expand All @@ -57,16 +53,6 @@ def lookupSysRegByName : SearchIndex {
let Key = [ "Name" ];
}

def lookupSysRegByAltName : SearchIndex {
let Table = SysRegsList;
let Key = [ "AltName" ];
}

def lookupSysRegByDeprecatedName : SearchIndex {
let Table = SysRegsList;
let Key = [ "DeprecatedName" ];
}

// The following CSR encodings match those given in Tables 2.2,
// 2.3, 2.4, 2.5 and 2.6 in the RISC-V Instruction Set Manual
// Volume II: Privileged Architecture.
Expand Down Expand Up @@ -123,15 +109,17 @@ def : SysReg<"senvcfg", 0x10A>;
def : SysReg<"sscratch", 0x140>;
def : SysReg<"sepc", 0x141>;
def : SysReg<"scause", 0x142>;
let DeprecatedName = "sbadaddr" in
def : SysReg<"stval", 0x143>;
let isDeprecatedName = 1 in
def : SysReg<"sbadaddr", 0x143>;
def : SysReg<"sip", 0x144>;

//===----------------------------------------------------------------------===//
// Supervisor Protection and Translation
//===----------------------------------------------------------------------===//
let DeprecatedName = "sptbr" in
def : SysReg<"satp", 0x180>;
let isDeprecatedName = 1 in
def : SysReg<"sptbr", 0x180>;

//===----------------------------------------------------------------------===//
// Quality-of-Service(QoS) Identifiers (Ssqosid)
Expand Down Expand Up @@ -245,8 +233,9 @@ def : SysReg<"mstatush", 0x310>;
def : SysReg<"mscratch", 0x340>;
def : SysReg<"mepc", 0x341>;
def : SysReg<"mcause", 0x342>;
let DeprecatedName = "mbadaddr" in
def : SysReg<"mtval", 0x343>;
let isDeprecatedName = 1 in
def : SysReg<"mbadaddr", 0x343>;
def : SysReg<"mip", 0x344>;
def : SysReg<"mtinst", 0x34A>;
def : SysReg<"mtval2", 0x34B>;
Expand Down Expand Up @@ -298,8 +287,9 @@ foreach i = 3...31 in
//===----------------------------------------------------------------------===//
// Machine Counter Setup
//===----------------------------------------------------------------------===//
let AltName = "mucounteren" in // Privileged spec v1.9.1 Name
def : SysReg<"mcountinhibit", 0x320>;
let isAltName = 1 in
def : SysReg<"mucounteren", 0x320>;

// mhpmevent3-mhpmevent31 at 0x323-0x33F.
foreach i = 3...31 in
Expand Down Expand Up @@ -336,8 +326,9 @@ def : SysReg<"dpc", 0x7B1>;

// "dscratch" is an alternative name for "dscratch0" which appeared in earlier
// drafts of the RISC-V debug spec
let AltName = "dscratch" in
def : SysReg<"dscratch0", 0x7B2>;
let isAltName = 1 in
def : SysReg<"dscratch", 0x7B2>;
def : SysReg<"dscratch1", 0x7B3>;

//===----------------------------------------------------------------------===//
Expand Down
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