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llvm-project/llvm/lib/Analysis/VFABIDemangling.cpp

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//===- VFABIDemangling.cpp - Vector Function ABI demangling utilities. ---===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Analysis/VectorUtils.h"
using namespace llvm;
namespace {
/// Utilities for the Vector Function ABI name parser.
/// Return types for the parser functions.
enum class ParseRet {
OK, // Found.
None, // Not found.
Error // Syntax error.
};
/// Extracts the `<isa>` information from the mangled string, and
/// sets the `ISA` accordingly.
ParseRet tryParseISA(StringRef &MangledName, VFISAKind &ISA) {
if (MangledName.empty())
return ParseRet::Error;
if (MangledName.startswith(VFABI::_LLVM_)) {
MangledName = MangledName.drop_front(strlen(VFABI::_LLVM_));
ISA = VFISAKind::LLVM;
} else {
ISA = StringSwitch<VFISAKind>(MangledName.take_front(1))
.Case("n", VFISAKind::AdvancedSIMD)
.Case("s", VFISAKind::SVE)
.Case("b", VFISAKind::SSE)
.Case("c", VFISAKind::AVX)
.Case("d", VFISAKind::AVX2)
.Case("e", VFISAKind::AVX512)
.Default(VFISAKind::Unknown);
MangledName = MangledName.drop_front(1);
}
return ParseRet::OK;
}
/// Extracts the `<mask>` information from the mangled string, and
/// sets `IsMasked` accordingly. The input string `MangledName` is
/// left unmodified.
ParseRet tryParseMask(StringRef &MangledName, bool &IsMasked) {
if (MangledName.consume_front("M")) {
IsMasked = true;
return ParseRet::OK;
}
if (MangledName.consume_front("N")) {
IsMasked = false;
return ParseRet::OK;
}
return ParseRet::Error;
}
/// Extract the `<vlen>` information from the mangled string, and
/// sets `VF` accordingly. A `<vlen> == "x"` token is interpreted as a scalable
/// vector length. On success, the `<vlen>` token is removed from
/// the input string `ParseString`.
///
ParseRet tryParseVLEN(StringRef &ParseString, unsigned &VF, bool &IsScalable) {
if (ParseString.consume_front("x")) {
// Set VF to 0, to be later adjusted to a value grater than zero
// by looking at the signature of the vector function with
// `getECFromSignature`.
VF = 0;
IsScalable = true;
return ParseRet::OK;
}
if (ParseString.consumeInteger(10, VF))
return ParseRet::Error;
// The token `0` is invalid for VLEN.
if (VF == 0)
return ParseRet::Error;
IsScalable = false;
return ParseRet::OK;
}
/// The function looks for the following strings at the beginning of
/// the input string `ParseString`:
///
/// <token> <number>
///
/// On success, it removes the parsed parameter from `ParseString`,
/// sets `PKind` to the correspondent enum value, sets `Pos` to
/// <number>, and return success. On a syntax error, it return a
/// parsing error. If nothing is parsed, it returns None.
///
/// The function expects <token> to be one of "ls", "Rs", "Us" or
/// "Ls".
ParseRet tryParseLinearTokenWithRuntimeStep(StringRef &ParseString,
VFParamKind &PKind, int &Pos,
const StringRef Token) {
if (ParseString.consume_front(Token)) {
PKind = VFABI::getVFParamKindFromString(Token);
if (ParseString.consumeInteger(10, Pos))
return ParseRet::Error;
return ParseRet::OK;
}
return ParseRet::None;
}
/// The function looks for the following stringt at the beginning of
/// the input string `ParseString`:
///
/// <token> <number>
///
/// <token> is one of "ls", "Rs", "Us" or "Ls".
///
/// On success, it removes the parsed parameter from `ParseString`,
/// sets `PKind` to the correspondent enum value, sets `StepOrPos` to
/// <number>, and return success. On a syntax error, it return a
/// parsing error. If nothing is parsed, it returns None.
ParseRet tryParseLinearWithRuntimeStep(StringRef &ParseString,
VFParamKind &PKind, int &StepOrPos) {
ParseRet Ret;
// "ls" <RuntimeStepPos>
Ret = tryParseLinearTokenWithRuntimeStep(ParseString, PKind, StepOrPos, "ls");
if (Ret != ParseRet::None)
return Ret;
// "Rs" <RuntimeStepPos>
Ret = tryParseLinearTokenWithRuntimeStep(ParseString, PKind, StepOrPos, "Rs");
if (Ret != ParseRet::None)
return Ret;
// "Ls" <RuntimeStepPos>
Ret = tryParseLinearTokenWithRuntimeStep(ParseString, PKind, StepOrPos, "Ls");
if (Ret != ParseRet::None)
return Ret;
// "Us" <RuntimeStepPos>
Ret = tryParseLinearTokenWithRuntimeStep(ParseString, PKind, StepOrPos, "Us");
if (Ret != ParseRet::None)
return Ret;
return ParseRet::None;
}
/// The function looks for the following strings at the beginning of
/// the input string `ParseString`:
///
/// <token> {"n"} <number>
///
/// On success, it removes the parsed parameter from `ParseString`,
/// sets `PKind` to the correspondent enum value, sets `LinearStep` to
/// <number>, and return success. On a syntax error, it return a
/// parsing error. If nothing is parsed, it returns None.
///
/// The function expects <token> to be one of "l", "R", "U" or
/// "L".
ParseRet tryParseCompileTimeLinearToken(StringRef &ParseString,
VFParamKind &PKind, int &LinearStep,
const StringRef Token) {
if (ParseString.consume_front(Token)) {
PKind = VFABI::getVFParamKindFromString(Token);
const bool Negate = ParseString.consume_front("n");
if (ParseString.consumeInteger(10, LinearStep))
LinearStep = 1;
if (Negate)
LinearStep *= -1;
return ParseRet::OK;
}
return ParseRet::None;
}
/// The function looks for the following strings at the beginning of
/// the input string `ParseString`:
///
/// ["l" | "R" | "U" | "L"] {"n"} <number>
///
/// On success, it removes the parsed parameter from `ParseString`,
/// sets `PKind` to the correspondent enum value, sets `LinearStep` to
/// <number>, and return success. On a syntax error, it return a
/// parsing error. If nothing is parsed, it returns None.
ParseRet tryParseLinearWithCompileTimeStep(StringRef &ParseString,
VFParamKind &PKind, int &StepOrPos) {
// "l" {"n"} <CompileTimeStep>
if (tryParseCompileTimeLinearToken(ParseString, PKind, StepOrPos, "l") ==
ParseRet::OK)
return ParseRet::OK;
// "R" {"n"} <CompileTimeStep>
if (tryParseCompileTimeLinearToken(ParseString, PKind, StepOrPos, "R") ==
ParseRet::OK)
return ParseRet::OK;
// "L" {"n"} <CompileTimeStep>
if (tryParseCompileTimeLinearToken(ParseString, PKind, StepOrPos, "L") ==
ParseRet::OK)
return ParseRet::OK;
// "U" {"n"} <CompileTimeStep>
if (tryParseCompileTimeLinearToken(ParseString, PKind, StepOrPos, "U") ==
ParseRet::OK)
return ParseRet::OK;
return ParseRet::None;
}
/// Looks into the <parameters> part of the mangled name in search
/// for valid paramaters at the beginning of the string
/// `ParseString`.
///
/// On success, it removes the parsed parameter from `ParseString`,
/// sets `PKind` to the correspondent enum value, sets `StepOrPos`
/// accordingly, and return success. On a syntax error, it return a
/// parsing error. If nothing is parsed, it returns None.
ParseRet tryParseParameter(StringRef &ParseString, VFParamKind &PKind,
int &StepOrPos) {
if (ParseString.consume_front("v")) {
PKind = VFParamKind::Vector;
StepOrPos = 0;
return ParseRet::OK;
}
if (ParseString.consume_front("u")) {
PKind = VFParamKind::OMP_Uniform;
StepOrPos = 0;
return ParseRet::OK;
}
const ParseRet HasLinearRuntime =
tryParseLinearWithRuntimeStep(ParseString, PKind, StepOrPos);
if (HasLinearRuntime != ParseRet::None)
return HasLinearRuntime;
const ParseRet HasLinearCompileTime =
tryParseLinearWithCompileTimeStep(ParseString, PKind, StepOrPos);
if (HasLinearCompileTime != ParseRet::None)
return HasLinearCompileTime;
return ParseRet::None;
}
/// Looks into the <parameters> part of the mangled name in search
/// of a valid 'aligned' clause. The function should be invoked
/// after parsing a parameter via `tryParseParameter`.
///
/// On success, it removes the parsed parameter from `ParseString`,
/// sets `PKind` to the correspondent enum value, sets `StepOrPos`
/// accordingly, and return success. On a syntax error, it return a
/// parsing error. If nothing is parsed, it returns None.
ParseRet tryParseAlign(StringRef &ParseString, Align &Alignment) {
uint64_t Val;
// "a" <number>
if (ParseString.consume_front("a")) {
if (ParseString.consumeInteger(10, Val))
return ParseRet::Error;
if (!isPowerOf2_64(Val))
return ParseRet::Error;
Alignment = Align(Val);
return ParseRet::OK;
}
return ParseRet::None;
}
#ifndef NDEBUG
// Verify the assumtion that all vectors in the signature of a vector
// function have the same number of elements.
bool verifyAllVectorsHaveSameWidth(FunctionType *Signature) {
SmallVector<VectorType *, 2> VecTys;
if (auto *RetTy = dyn_cast<VectorType>(Signature->getReturnType()))
VecTys.push_back(RetTy);
for (auto *Ty : Signature->params())
if (auto *VTy = dyn_cast<VectorType>(Ty))
VecTys.push_back(VTy);
if (VecTys.size() <= 1)
return true;
assert(VecTys.size() > 1 && "Invalid number of elements.");
const ElementCount EC = VecTys[0]->getElementCount();
return llvm::all_of(llvm::drop_begin(VecTys), [&EC](VectorType *VTy) {
return (EC == VTy->getElementCount());
});
}
#endif // NDEBUG
// Extract the VectorizationFactor from a given function signature,
// under the assumtion that all vectors have the same number of
// elements, i.e. same ElementCount.Min.
ElementCount getECFromSignature(FunctionType *Signature) {
assert(verifyAllVectorsHaveSameWidth(Signature) &&
"Invalid vector signature.");
if (auto *RetTy = dyn_cast<VectorType>(Signature->getReturnType()))
return RetTy->getElementCount();
for (auto *Ty : Signature->params())
if (auto *VTy = dyn_cast<VectorType>(Ty))
return VTy->getElementCount();
return ElementCount::getFixed(/*Min=*/1);
}
} // namespace
// Format of the ABI name:
// _ZGV<isa><mask><vlen><parameters>_<scalarname>[(<redirection>)]
Optional<VFInfo> VFABI::tryDemangleForVFABI(StringRef MangledName,
const Module &M) {
const StringRef OriginalName = MangledName;
// Assume there is no custom name <redirection>, and therefore the
// vector name consists of
// _ZGV<isa><mask><vlen><parameters>_<scalarname>.
StringRef VectorName = MangledName;
// Parse the fixed size part of the manled name
if (!MangledName.consume_front("_ZGV"))
return None;
// Extract ISA. An unknow ISA is also supported, so we accept all
// values.
VFISAKind ISA;
if (tryParseISA(MangledName, ISA) != ParseRet::OK)
return None;
// Extract <mask>.
bool IsMasked;
if (tryParseMask(MangledName, IsMasked) != ParseRet::OK)
return None;
// Parse the variable size, starting from <vlen>.
unsigned VF;
bool IsScalable;
if (tryParseVLEN(MangledName, VF, IsScalable) != ParseRet::OK)
return None;
// Parse the <parameters>.
ParseRet ParamFound;
SmallVector<VFParameter, 8> Parameters;
do {
const unsigned ParameterPos = Parameters.size();
VFParamKind PKind;
int StepOrPos;
ParamFound = tryParseParameter(MangledName, PKind, StepOrPos);
// Bail off if there is a parsing error in the parsing of the parameter.
if (ParamFound == ParseRet::Error)
return None;
if (ParamFound == ParseRet::OK) {
Align Alignment;
// Look for the alignment token "a <number>".
const ParseRet AlignFound = tryParseAlign(MangledName, Alignment);
// Bail off if there is a syntax error in the align token.
if (AlignFound == ParseRet::Error)
return None;
// Add the parameter.
Parameters.push_back({ParameterPos, PKind, StepOrPos, Alignment});
}
} while (ParamFound == ParseRet::OK);
// A valid MangledName must have at least one valid entry in the
// <parameters>.
if (Parameters.empty())
return None;
// Check for the <scalarname> and the optional <redirection>, which
// are separated from the prefix with "_"
if (!MangledName.consume_front("_"))
return None;
// The rest of the string must be in the format:
// <scalarname>[(<redirection>)]
const StringRef ScalarName =
MangledName.take_while([](char In) { return In != '('; });
if (ScalarName.empty())
return None;
// Reduce MangledName to [(<redirection>)].
MangledName = MangledName.ltrim(ScalarName);
// Find the optional custom name redirection.
if (MangledName.consume_front("(")) {
if (!MangledName.consume_back(")"))
return None;
// Update the vector variant with the one specified by the user.
VectorName = MangledName;
// If the vector name is missing, bail out.
if (VectorName.empty())
return None;
}
// LLVM internal mapping via the TargetLibraryInfo (TLI) must be
// redirected to an existing name.
if (ISA == VFISAKind::LLVM && VectorName == OriginalName)
return None;
// When <mask> is "M", we need to add a parameter that is used as
// global predicate for the function.
if (IsMasked) {
const unsigned Pos = Parameters.size();
Parameters.push_back({Pos, VFParamKind::GlobalPredicate});
}
// Asserts for parameters of type `VFParamKind::GlobalPredicate`, as
// prescribed by the Vector Function ABI specifications supported by
// this parser:
// 1. Uniqueness.
// 2. Must be the last in the parameter list.
const auto NGlobalPreds = std::count_if(
Parameters.begin(), Parameters.end(), [](const VFParameter PK) {
return PK.ParamKind == VFParamKind::GlobalPredicate;
});
assert(NGlobalPreds < 2 && "Cannot have more than one global predicate.");
if (NGlobalPreds)
assert(Parameters.back().ParamKind == VFParamKind::GlobalPredicate &&
"The global predicate must be the last parameter");
// Adjust the VF for scalable signatures. The EC.Min is not encoded
// in the name of the function, but it is encoded in the IR
// signature of the function. We need to extract this information
// because it is needed by the loop vectorizer, which reasons in
// terms of VectorizationFactor or ElementCount. In particular, we
// need to make sure that the VF field of the VFShape class is never
// set to 0.
if (IsScalable) {
const Function *F = M.getFunction(VectorName);
// The declaration of the function must be present in the module
// to be able to retrieve its signature.
if (!F)
return None;
const ElementCount EC = getECFromSignature(F->getFunctionType());
VF = EC.getKnownMinValue();
}
// Sanity checks.
// 1. We don't accept a zero lanes vectorization factor.
// 2. We don't accept the demangling if the vector function is not
// present in the module.
if (VF == 0)
return None;
if (!M.getFunction(VectorName))
return None;
const VFShape Shape({VF, IsScalable, Parameters});
return VFInfo({Shape, std::string(ScalarName), std::string(VectorName), ISA});
}
VFParamKind VFABI::getVFParamKindFromString(const StringRef Token) {
const VFParamKind ParamKind = StringSwitch<VFParamKind>(Token)
.Case("v", VFParamKind::Vector)
.Case("l", VFParamKind::OMP_Linear)
.Case("R", VFParamKind::OMP_LinearRef)
.Case("L", VFParamKind::OMP_LinearVal)
.Case("U", VFParamKind::OMP_LinearUVal)
.Case("ls", VFParamKind::OMP_LinearPos)
.Case("Ls", VFParamKind::OMP_LinearValPos)
.Case("Rs", VFParamKind::OMP_LinearRefPos)
.Case("Us", VFParamKind::OMP_LinearUValPos)
.Case("u", VFParamKind::OMP_Uniform)
.Default(VFParamKind::Unknown);
if (ParamKind != VFParamKind::Unknown)
return ParamKind;
// This function should never be invoked with an invalid input.
llvm_unreachable("This fuction should be invoken only on parameters"
" that have a textual representation in the mangled name"
" of the Vector Function ABI");
}
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