llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp

   1 //===- llvm/CodeGen/PseudoProbePrinter.cpp - Pseudo Probe Emission -------===//
   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 // This file contains support for writing pseudo probe info into asm files.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "PseudoProbePrinter.h"
  14 #include "llvm/CodeGen/AsmPrinter.h"
  15 #include "llvm/IR/DebugInfoMetadata.h"
  16 #include "llvm/IR/Function.h"
  17 #include "llvm/IR/PseudoProbe.h"
  18 #include "llvm/MC/MCPseudoProbe.h"
  19 #include "llvm/MC/MCStreamer.h"
  20
  21 using namespace llvm;
  22
  23 PseudoProbeHandler::~PseudoProbeHandler() = default;
  24
  25 void PseudoProbeHandler::emitPseudoProbe(uint64_t Guid, uint64_t Index,
  26                                          uint64_t Type, uint64_t Attr,
  27                                          const DILocation *DebugLoc) {
  28   // Gather all the inlined-at nodes.
  29   // When it's done ReversedInlineStack looks like ([66, B], [88, A])
  30   // which means, Function A inlines function B at calliste with a probe id 88,
  31   // and B inlines C at probe 66 where C is represented by Guid.
  32   SmallVector<InlineSite, 8> ReversedInlineStack;
  33   auto *InlinedAt = DebugLoc ? DebugLoc->getInlinedAt() : nullptr;
  34   while (InlinedAt) {
  35     auto Name = InlinedAt->getSubprogramLinkageName();
  36     // Use caching to avoid redundant md5 computation for build speed.
  37     uint64_t &CallerGuid = NameGuidMap[Name];
  38     if (!CallerGuid)
  39       CallerGuid = Function::getGUID(Name);
  40     uint64_t CallerProbeId = PseudoProbeDwarfDiscriminator::extractProbeIndex(
  41         InlinedAt->getDiscriminator());
  42     ReversedInlineStack.emplace_back(CallerGuid, CallerProbeId);
  43     InlinedAt = InlinedAt->getInlinedAt();
  44   }
  45   uint64_t Discriminator = 0;
  46   // For now only block probes have FS discriminators. See
  47   // MIRFSDiscriminator.cpp for more details.
  48   if (EnableFSDiscriminator && DebugLoc &&
  49       (Type == (uint64_t)PseudoProbeType::Block))
  50     Discriminator = DebugLoc->getDiscriminator();
  51   assert((EnableFSDiscriminator || Discriminator == 0) &&
  52          "Discriminator should not be set in non-FSAFDO mode");
  53   SmallVector<InlineSite, 8> InlineStack(llvm::reverse(ReversedInlineStack));
  54   Asm->OutStreamer->emitPseudoProbe(Guid, Index, Type, Attr, Discriminator,
  55                                     InlineStack, Asm->CurrentFnSym);
  56 }