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[VFABI] Move the Vector ABI demangling utility to LLVMCore. #77513

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Jan 17, 2024
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[VFABI] Move the Vector ABI demangling utility to LLVMCore. #77513

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187 changes: 1 addition & 186 deletions llvm/include/llvm/Analysis/VectorUtils.h
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Expand Up @@ -16,197 +16,12 @@
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/LoopAccessAnalysis.h"
#include "llvm/IR/VFABIDemangler.h"
#include "llvm/Support/CheckedArithmetic.h"

namespace llvm {
class TargetLibraryInfo;

/// Describes the type of Parameters
enum class VFParamKind {
Vector, // No semantic information.
OMP_Linear, // declare simd linear(i)
OMP_LinearRef, // declare simd linear(ref(i))
OMP_LinearVal, // declare simd linear(val(i))
OMP_LinearUVal, // declare simd linear(uval(i))
OMP_LinearPos, // declare simd linear(i:c) uniform(c)
OMP_LinearValPos, // declare simd linear(val(i:c)) uniform(c)
OMP_LinearRefPos, // declare simd linear(ref(i:c)) uniform(c)
OMP_LinearUValPos, // declare simd linear(uval(i:c)) uniform(c)
OMP_Uniform, // declare simd uniform(i)
GlobalPredicate, // Global logical predicate that acts on all lanes
// of the input and output mask concurrently. For
// example, it is implied by the `M` token in the
// Vector Function ABI mangled name.
Unknown
};

/// Describes the type of Instruction Set Architecture
enum class VFISAKind {
AdvancedSIMD, // AArch64 Advanced SIMD (NEON)
SVE, // AArch64 Scalable Vector Extension
SSE, // x86 SSE
AVX, // x86 AVX
AVX2, // x86 AVX2
AVX512, // x86 AVX512
LLVM, // LLVM internal ISA for functions that are not
// attached to an existing ABI via name mangling.
Unknown // Unknown ISA
};

/// Encapsulates information needed to describe a parameter.
///
/// The description of the parameter is not linked directly to
/// OpenMP or any other vector function description. This structure
/// is extendible to handle other paradigms that describe vector
/// functions and their parameters.
struct VFParameter {
unsigned ParamPos; // Parameter Position in Scalar Function.
VFParamKind ParamKind; // Kind of Parameter.
int LinearStepOrPos = 0; // Step or Position of the Parameter.
Align Alignment = Align(); // Optional alignment in bytes, defaulted to 1.

// Comparison operator.
bool operator==(const VFParameter &Other) const {
return std::tie(ParamPos, ParamKind, LinearStepOrPos, Alignment) ==
std::tie(Other.ParamPos, Other.ParamKind, Other.LinearStepOrPos,
Other.Alignment);
}
};

/// Contains the information about the kind of vectorization
/// available.
///
/// This object in independent on the paradigm used to
/// represent vector functions. in particular, it is not attached to
/// any target-specific ABI.
struct VFShape {
ElementCount VF; // Vectorization factor.
SmallVector<VFParameter, 8> Parameters; // List of parameter information.
// Comparison operator.
bool operator==(const VFShape &Other) const {
return std::tie(VF, Parameters) == std::tie(Other.VF, Other.Parameters);
}

/// Update the parameter in position P.ParamPos to P.
void updateParam(VFParameter P) {
assert(P.ParamPos < Parameters.size() && "Invalid parameter position.");
Parameters[P.ParamPos] = P;
assert(hasValidParameterList() && "Invalid parameter list");
}

/// Retrieve the VFShape that can be used to map a scalar function to itself,
/// with VF = 1.
static VFShape getScalarShape(const FunctionType *FTy) {
return VFShape::get(FTy, ElementCount::getFixed(1),
/*HasGlobalPredicate*/ false);
}

/// Retrieve the basic vectorization shape of the function, where all
/// parameters are mapped to VFParamKind::Vector with \p EC lanes. Specifies
/// whether the function has a Global Predicate argument via \p HasGlobalPred.
static VFShape get(const FunctionType *FTy, ElementCount EC,
bool HasGlobalPred) {
SmallVector<VFParameter, 8> Parameters;
for (unsigned I = 0; I < FTy->getNumParams(); ++I)
Parameters.push_back(VFParameter({I, VFParamKind::Vector}));
if (HasGlobalPred)
Parameters.push_back(
VFParameter({FTy->getNumParams(), VFParamKind::GlobalPredicate}));

return {EC, Parameters};
}
/// Validation check on the Parameters in the VFShape.
bool hasValidParameterList() const;
};

/// Holds the VFShape for a specific scalar to vector function mapping.
struct VFInfo {
VFShape Shape; /// Classification of the vector function.
std::string ScalarName; /// Scalar Function Name.
std::string VectorName; /// Vector Function Name associated to this VFInfo.
VFISAKind ISA; /// Instruction Set Architecture.

/// Returns the index of the first parameter with the kind 'GlobalPredicate',
/// if any exist.
std::optional<unsigned> getParamIndexForOptionalMask() const {
unsigned ParamCount = Shape.Parameters.size();
for (unsigned i = 0; i < ParamCount; ++i)
if (Shape.Parameters[i].ParamKind == VFParamKind::GlobalPredicate)
return i;

return std::nullopt;
}

/// Returns true if at least one of the operands to the vectorized function
/// has the kind 'GlobalPredicate'.
bool isMasked() const { return getParamIndexForOptionalMask().has_value(); }
};

namespace VFABI {
/// LLVM Internal VFABI ISA token for vector functions.
static constexpr char const *_LLVM_ = "_LLVM_";
/// Prefix for internal name redirection for vector function that
/// tells the compiler to scalarize the call using the scalar name
/// of the function. For example, a mangled name like
/// `_ZGV_LLVM_N2v_foo(_LLVM_Scalarize_foo)` would tell the
/// vectorizer to vectorize the scalar call `foo`, and to scalarize
/// it once vectorization is done.
static constexpr char const *_LLVM_Scalarize_ = "_LLVM_Scalarize_";

/// Function to construct a VFInfo out of a mangled names in the
/// following format:
///
/// <VFABI_name>{(<redirection>)}
///
/// where <VFABI_name> is the name of the vector function, mangled according
/// to the rules described in the Vector Function ABI of the target vector
/// extension (or <isa> from now on). The <VFABI_name> is in the following
/// format:
///
/// _ZGV<isa><mask><vlen><parameters>_<scalarname>[(<redirection>)]
///
/// This methods support demangling rules for the following <isa>:
///
/// * AArch64: https://developer.arm.com/docs/101129/latest
///
/// * x86 (libmvec): https://sourceware.org/glibc/wiki/libmvec and
/// https://sourceware.org/glibc/wiki/libmvec?action=AttachFile&do=view&target=VectorABI.txt
///
/// \param MangledName -> input string in the format
/// _ZGV<isa><mask><vlen><parameters>_<scalarname>[(<redirection>)].
/// \param FTy -> FunctionType of the scalar function which we're trying to find
/// a vectorized variant for. This is required to determine the vectorization
/// factor for scalable vectors, since the mangled name doesn't encode that;
/// it needs to be derived from the widest element types of vector arguments
/// or return values.
std::optional<VFInfo> tryDemangleForVFABI(StringRef MangledName,
const FunctionType *FTy);

/// Retrieve the `VFParamKind` from a string token.
VFParamKind getVFParamKindFromString(const StringRef Token);

// Name of the attribute where the variant mappings are stored.
static constexpr char const *MappingsAttrName = "vector-function-abi-variant";

/// Populates a set of strings representing the Vector Function ABI variants
/// associated to the CallInst CI. If the CI does not contain the
/// vector-function-abi-variant attribute, we return without populating
/// VariantMappings, i.e. callers of getVectorVariantNames need not check for
/// the presence of the attribute (see InjectTLIMappings).
void getVectorVariantNames(const CallInst &CI,
SmallVectorImpl<std::string> &VariantMappings);

/// Constructs a FunctionType by applying vector function information to the
/// type of a matching scalar function.
/// \param Info gets the vectorization factor (VF) and the VFParamKind of the
/// parameters.
/// \param ScalarFTy gets the Type information of parameters, as it is not
/// stored in \p Info.
/// \returns a pointer to a newly created vector FunctionType
FunctionType *createFunctionType(const VFInfo &Info,
const FunctionType *ScalarFTy);
} // end namespace VFABI

/// The Vector Function Database.
///
/// Helper class used to find the vector functions associated to a
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