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//===- PseudoProbe.h - Pseudo Probe IR Helpers ------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Pseudo probe IR intrinsic and dwarf discriminator manipulation routines.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_PSEUDOPROBE_H
#define LLVM_IR_PSEUDOPROBE_H
#include <cassert>
#include <cstdint>
#include <limits>
#include <optional>
namespace llvm {
class Instruction;
constexpr const char *PseudoProbeDescMetadataName = "llvm.pseudo_probe_desc";
enum class PseudoProbeReservedId { Invalid = 0, Last = Invalid };
enum class PseudoProbeType { Block = 0, IndirectCall, DirectCall };
enum class PseudoProbeAttributes {
Reserved = 0x1,
Sentinel = 0x2, // A place holder for split function entry address.
HasDiscriminator = 0x4, // for probes with a discriminator
};
// The saturated distrution factor representing 100% for block probes.
constexpr static uint64_t PseudoProbeFullDistributionFactor =
std::numeric_limits<uint64_t>::max();
struct PseudoProbeDwarfDiscriminator {
public:
// The following APIs encodes/decodes per-probe information to/from a
// 32-bit integer which is organized as:
// [2:0] - 0x7, this is reserved for regular discriminator,
// see DWARF discriminator encoding rule
// if the [28:28] bit is zero:
// [18:3] for probe id.
// else:
// [15:3] for probe id, [18:16] for dwarf base discriminator.
// [25:19] - probe distribution factor
// [27:26] - probe type, see PseudoProbeType
// [28:28] - indicates whether dwarf base discriminator is encoded.
// [30:29] - reserved for probe attributes
static uint32_t
packProbeData(uint32_t Index, uint32_t Type, uint32_t Flags, uint32_t Factor,
std::optional<uint32_t> DwarfBaseDiscriminator) {
assert(Index <= 0xFFFF && "Probe index too big to encode, exceeding 2^16");
assert(Type <= 0x3 && "Probe type too big to encode, exceeding 3");
assert(Flags <= 0x7);
assert(Factor <= 100 &&
"Probe distribution factor too big to encode, exceeding 100");
uint32_t V = (Index << 3) | (Factor << 19) | (Type << 26) | 0x7;
// If both the probe id and dwarf base discriminator is small, the probe id
// space is shared with the dwarf base discriminator, this is to make the
// probe-based build compatible with the dwarf-based profile.
// Pack the dwarf base discriminator into [18:16] and set the [28:28] bit.
if (Index <= 0x1FFF && DwarfBaseDiscriminator &&
*DwarfBaseDiscriminator <= 0x7)
V |= (1 << 28) | (*DwarfBaseDiscriminator << 16);
return V;
}
static uint32_t extractProbeIndex(uint32_t Value) {
if (isDwarfBaseDiscriminatorEncoded(Value))
return (Value >> 3) & 0x1FFF;
return (Value >> 3) & 0xFFFF;
}
static std::optional<uint32_t> extractDwarfBaseDiscriminator(uint32_t Value) {
if (isDwarfBaseDiscriminatorEncoded(Value))
return (Value >> 16) & 0x7;
return std::nullopt;
}
static bool isDwarfBaseDiscriminatorEncoded(uint32_t Value) {
return Value & 0x10000000;
}
static uint32_t extractProbeType(uint32_t Value) {
return (Value >> 26) & 0x3;
}
static uint32_t extractProbeAttributes(uint32_t Value) {
return (Value >> 29) & 0x7;
}
static uint32_t extractProbeFactor(uint32_t Value) {
return (Value >> 19) & 0x7F;
}
// The saturated distrution factor representing 100% for callsites.
constexpr static uint8_t FullDistributionFactor = 100;
};
class PseudoProbeDescriptor {
uint64_t FunctionGUID;
uint64_t FunctionHash;
public:
PseudoProbeDescriptor(uint64_t GUID, uint64_t Hash)
: FunctionGUID(GUID), FunctionHash(Hash) {}
uint64_t getFunctionGUID() const { return FunctionGUID; }
uint64_t getFunctionHash() const { return FunctionHash; }
};
struct PseudoProbe {
uint32_t Id;
uint32_t Type;
uint32_t Attr;
uint32_t Discriminator;
// Distribution factor that estimates the portion of the real execution count.
// A saturated distribution factor stands for 1.0 or 100%. A pesudo probe has
// a factor with the value ranged from 0.0 to 1.0.
float Factor;
};
static inline bool isSentinelProbe(uint32_t Flags) {
return Flags & (uint32_t)PseudoProbeAttributes::Sentinel;
}
static inline bool hasDiscriminator(uint32_t Flags) {
return Flags & (uint32_t)PseudoProbeAttributes::HasDiscriminator;
}
std::optional<PseudoProbe> extractProbe(const Instruction &Inst);
void setProbeDistributionFactor(Instruction &Inst, float Factor);
} // end namespace llvm
#endif // LLVM_IR_PSEUDOPROBE_H
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