llvm/lib/CodeGen/FaultMaps.cpp

   1 //===- FaultMaps.cpp ------------------------------------------------------===//
   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 #include "llvm/CodeGen/FaultMaps.h"
  10 #include "llvm/ADT/Twine.h"
  11 #include "llvm/CodeGen/AsmPrinter.h"
  12 #include "llvm/MC/MCContext.h"
  13 #include "llvm/MC/MCExpr.h"
  14 #include "llvm/MC/MCObjectFileInfo.h"
  15 #include "llvm/MC/MCStreamer.h"
  16 #include "llvm/Support/Debug.h"
  17 #include "llvm/Support/ErrorHandling.h"
  18
  19 using namespace llvm;
  20
  21 #define DEBUG_TYPE "faultmaps"
  22
  23 static const int FaultMapVersion = 1;
  24 const char *FaultMaps::WFMP = "Fault Maps: ";
  25
  26 FaultMaps::FaultMaps(AsmPrinter &AP) : AP(AP) {}
  27
  28 void FaultMaps::recordFaultingOp(FaultKind FaultTy,
  29                                  const MCSymbol *FaultingLabel,
  30                                  const MCSymbol *HandlerLabel) {
  31   MCContext &OutContext = AP.OutStreamer->getContext();
  32
  33   const MCExpr *FaultingOffset = MCBinaryExpr::createSub(
  34       MCSymbolRefExpr::create(FaultingLabel, OutContext),
  35       MCSymbolRefExpr::create(AP.CurrentFnSymForSize, OutContext), OutContext);
  36
  37   const MCExpr *HandlerOffset = MCBinaryExpr::createSub(
  38       MCSymbolRefExpr::create(HandlerLabel, OutContext),
  39       MCSymbolRefExpr::create(AP.CurrentFnSymForSize, OutContext), OutContext);
  40
  41   FunctionInfos[AP.CurrentFnSym].emplace_back(FaultTy, FaultingOffset,
  42                                               HandlerOffset);
  43 }
  44
  45 void FaultMaps::serializeToFaultMapSection() {
  46   if (FunctionInfos.empty())
  47     return;
  48
  49   MCContext &OutContext = AP.OutStreamer->getContext();
  50   MCStreamer &OS = *AP.OutStreamer;
  51
  52   // Create the section.
  53   MCSection *FaultMapSection =
  54       OutContext.getObjectFileInfo()->getFaultMapSection();
  55   OS.switchSection(FaultMapSection);
  56
  57   // Emit a dummy symbol to force section inclusion.
  58   OS.emitLabel(OutContext.getOrCreateSymbol(Twine("__LLVM_FaultMaps")));
  59
  60   LLVM_DEBUG(dbgs() << "********** Fault Map Output **********\n");
  61
  62   // Header
  63   OS.emitIntValue(FaultMapVersion, 1); // Version.
  64   OS.emitIntValue(0, 1);               // Reserved.
  65   OS.emitInt16(0);                     // Reserved.
  66
  67   LLVM_DEBUG(dbgs() << WFMP << "#functions = " << FunctionInfos.size() << "\n");
  68   OS.emitInt32(FunctionInfos.size());
  69
  70   LLVM_DEBUG(dbgs() << WFMP << "functions:\n");
  71
  72   for (const auto &FFI : FunctionInfos)
  73     emitFunctionInfo(FFI.first, FFI.second);
  74 }
  75
  76 void FaultMaps::emitFunctionInfo(const MCSymbol *FnLabel,
  77                                  const FunctionFaultInfos &FFI) {
  78   MCStreamer &OS = *AP.OutStreamer;
  79
  80   LLVM_DEBUG(dbgs() << WFMP << "  function addr: " << *FnLabel << "\n");
  81   OS.emitSymbolValue(FnLabel, 8);
  82
  83   LLVM_DEBUG(dbgs() << WFMP << "  #faulting PCs: " << FFI.size() << "\n");
  84   OS.emitInt32(FFI.size());
  85
  86   OS.emitInt32(0); // Reserved
  87
  88   for (const auto &Fault : FFI) {
  89     LLVM_DEBUG(dbgs() << WFMP << "    fault type: "
  90                       << faultTypeToString(Fault.Kind) << "\n");
  91     OS.emitInt32(Fault.Kind);
  92
  93     LLVM_DEBUG(dbgs() << WFMP << "    faulting PC offset: "
  94                       << *Fault.FaultingOffsetExpr << "\n");
  95     OS.emitValue(Fault.FaultingOffsetExpr, 4);
  96
  97     LLVM_DEBUG(dbgs() << WFMP << "    fault handler PC offset: "
  98                       << *Fault.HandlerOffsetExpr << "\n");
  99     OS.emitValue(Fault.HandlerOffsetExpr, 4);
 100   }
 101 }
 102
 103 const char *FaultMaps::faultTypeToString(FaultMaps::FaultKind FT) {
 104   switch (FT) {
 105   default:
 106     llvm_unreachable("unhandled fault type!");
 107   case FaultMaps::FaultingLoad:
 108     return "FaultingLoad";
 109   case FaultMaps::FaultingLoadStore:
 110     return "FaultingLoadStore";
 111   case FaultMaps::FaultingStore:
 112     return "FaultingStore";
 113   }
 114 }