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/Module.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     const DISubprogram *SP = InlinedAt->getScope()->getSubprogram();
36     // Use linkage name for C++ if possible.
37     auto Name = SP->getLinkageName();
38     if (Name.empty())
39       Name = SP->getName();
40     // Use caching to avoid redundant md5 computation for build speed.
41     uint64_t &CallerGuid = NameGuidMap[Name];
42     if (!CallerGuid)
43       CallerGuid = Function::getGUID(Name);
44     uint64_t CallerProbeId = PseudoProbeDwarfDiscriminator::extractProbeIndex(
45         InlinedAt->getDiscriminator());
46     ReversedInlineStack.emplace_back(CallerGuid, CallerProbeId);
47     InlinedAt = InlinedAt->getInlinedAt();
48   }
49 
50   SmallVector<InlineSite, 8> InlineStack(llvm::reverse(ReversedInlineStack));
51   Asm->OutStreamer->emitPseudoProbe(Guid, Index, Type, Attr, InlineStack);
52 }
53