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  1. //===- PseudoProbe.h - Pseudo Probe IR Helpers ------------------*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. //
  9. // Pseudo probe IR intrinsic and dwarf discriminator manipulation routines.
  10. //
  11. //===----------------------------------------------------------------------===//
  12.  
  13. #ifndef LLVM_IR_PSEUDOPROBE_H
  14. #define LLVM_IR_PSEUDOPROBE_H
  15.  
  16. #include <cassert>
  17. #include <cstdint>
  18. #include <limits>
  19. #include <optional>
  20.  
  21. namespace llvm {
  22.  
  23. class Instruction;
  24.  
  25. constexpr const char *PseudoProbeDescMetadataName = "llvm.pseudo_probe_desc";
  26.  
  27. enum class PseudoProbeReservedId { Invalid = 0, Last = Invalid };
  28.  
  29. enum class PseudoProbeType { Block = 0, IndirectCall, DirectCall };
  30.  
  31. enum class PseudoProbeAttributes {
  32.   Reserved = 0x1,
  33.   Sentinel = 0x2, // A place holder for split function entry address.
  34. };
  35.  
  36. // The saturated distrution factor representing 100% for block probes.
  37. constexpr static uint64_t PseudoProbeFullDistributionFactor =
  38.     std::numeric_limits<uint64_t>::max();
  39.  
  40. struct PseudoProbeDwarfDiscriminator {
  41. public:
  42.   // The following APIs encodes/decodes per-probe information to/from a
  43.   // 32-bit integer which is organized as:
  44.   //  [2:0] - 0x7, this is reserved for regular discriminator,
  45.   //          see DWARF discriminator encoding rule
  46.   //  [18:3] - probe id
  47.   //  [25:19] - probe distribution factor
  48.   //  [28:26] - probe type, see PseudoProbeType
  49.   //  [31:29] - reserved for probe attributes
  50.   static uint32_t packProbeData(uint32_t Index, uint32_t Type, uint32_t Flags,
  51.                                 uint32_t Factor) {
  52.     assert(Index <= 0xFFFF && "Probe index too big to encode, exceeding 2^16");
  53.     assert(Type <= 0x7 && "Probe type too big to encode, exceeding 7");
  54.     assert(Flags <= 0x7);
  55.     assert(Factor <= 100 &&
  56.            "Probe distribution factor too big to encode, exceeding 100");
  57.     return (Index << 3) | (Factor << 19) | (Type << 26) | 0x7;
  58.   }
  59.  
  60.   static uint32_t extractProbeIndex(uint32_t Value) {
  61.     return (Value >> 3) & 0xFFFF;
  62.   }
  63.  
  64.   static uint32_t extractProbeType(uint32_t Value) {
  65.     return (Value >> 26) & 0x7;
  66.   }
  67.  
  68.   static uint32_t extractProbeAttributes(uint32_t Value) {
  69.     return (Value >> 29) & 0x7;
  70.   }
  71.  
  72.   static uint32_t extractProbeFactor(uint32_t Value) {
  73.     return (Value >> 19) & 0x7F;
  74.   }
  75.  
  76.   // The saturated distrution factor representing 100% for callsites.
  77.   constexpr static uint8_t FullDistributionFactor = 100;
  78. };
  79.  
  80. struct PseudoProbe {
  81.   uint32_t Id;
  82.   uint32_t Type;
  83.   uint32_t Attr;
  84.   // Distribution factor that estimates the portion of the real execution count.
  85.   // A saturated distribution factor stands for 1.0 or 100%. A pesudo probe has
  86.   // a factor with the value ranged from 0.0 to 1.0.
  87.   float Factor;
  88. };
  89.  
  90. static inline bool isSentinelProbe(uint32_t Flags) {
  91.   return Flags & (uint32_t)PseudoProbeAttributes::Sentinel;
  92. }
  93.  
  94. std::optional<PseudoProbe> extractProbe(const Instruction &Inst);
  95.  
  96. void setProbeDistributionFactor(Instruction &Inst, float Factor);
  97. } // end namespace llvm
  98.  
  99. #endif // LLVM_IR_PSEUDOPROBE_H
  100.