1 files changed, 148 insertions, 1 deletions

diff --git a/include/llvm/CodeGen/FaultMaps.h b/include/llvm/CodeGen/FaultMaps.h
index d5c2feefaa67..f4b646322143 100644
--- a/include/llvm/CodeGen/FaultMaps.h
+++ b/include/llvm/CodeGen/FaultMaps.h
@@ -1,4 +1,4 @@
-//===------------------- FaultMaps.h - StackMaps ----------------*- C++ -*-===//
+//===------------------- FaultMaps.h - The "FaultMaps" section --*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -12,6 +12,8 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Format.h"
 
 #include <vector>
 #include <map>
@@ -68,6 +70,151 @@ private:
 
   void emitFunctionInfo(const MCSymbol *FnLabel, const FunctionFaultInfos &FFI);
 };
+
+/// A parser for the __llvm_faultmaps section generated by the FaultMaps class
+/// above.  This parser is version locked with with the __llvm_faultmaps section
+/// generated by the version of LLVM that includes it.  No guarantees are made
+/// with respect to forward or backward compatibility.
+class FaultMapParser {
+  typedef uint8_t FaultMapVersionType;
+  static const size_t FaultMapVersionOffset = 0;
+
+  typedef uint8_t Reserved0Type;
+  static const size_t Reserved0Offset =
+      FaultMapVersionOffset + sizeof(FaultMapVersionType);
+
+  typedef uint16_t Reserved1Type;
+  static const size_t Reserved1Offset = Reserved0Offset + sizeof(Reserved0Type);
+
+  typedef uint32_t NumFunctionsType;
+  static const size_t NumFunctionsOffset =
+      Reserved1Offset + sizeof(Reserved1Type);
+
+  static const size_t FunctionInfosOffset =
+      NumFunctionsOffset + sizeof(NumFunctionsType);
+
+  const uint8_t *P;
+  const uint8_t *E;
+
+  template <typename T> static T read(const uint8_t *P, const uint8_t *E) {
+    assert(P + sizeof(T) <= E && "out of bounds read!");
+    return support::endian::read<T, support::little, 1>(P);
+  }
+
+public:
+  class FunctionFaultInfoAccessor {
+    typedef uint32_t FaultKindType;
+    static const size_t FaultKindOffset = 0;
+
+    typedef uint32_t FaultingPCOffsetType;
+    static const size_t FaultingPCOffsetOffset =
+        FaultKindOffset + sizeof(FaultKindType);
+
+    typedef uint32_t HandlerPCOffsetType;
+    static const size_t HandlerPCOffsetOffset =
+        FaultingPCOffsetOffset + sizeof(FaultingPCOffsetType);
+
+    const uint8_t *P;
+    const uint8_t *E;
+
+  public:
+    static const size_t Size =
+        HandlerPCOffsetOffset + sizeof(HandlerPCOffsetType);
+
+    explicit FunctionFaultInfoAccessor(const uint8_t *P, const uint8_t *E)
+        : P(P), E(E) {}
+
+    FaultKindType getFaultKind() const {
+      return read<FaultKindType>(P + FaultKindOffset, E);
+    }
+
+    FaultingPCOffsetType getFaultingPCOffset() const {
+      return read<FaultingPCOffsetType>(P + FaultingPCOffsetOffset, E);
+    }
+
+    HandlerPCOffsetType getHandlerPCOffset() const {
+      return read<HandlerPCOffsetType>(P + HandlerPCOffsetOffset, E);
+    }
+  };
+
+  class FunctionInfoAccessor {
+    typedef uint64_t FunctionAddrType;
+    static const size_t FunctionAddrOffset = 0;
+
+    typedef uint32_t NumFaultingPCsType;
+    static const size_t NumFaultingPCsOffset =
+        FunctionAddrOffset + sizeof(FunctionAddrType);
+
+    typedef uint32_t ReservedType;
+    static const size_t ReservedOffset =
+        NumFaultingPCsOffset + sizeof(NumFaultingPCsType);
+
+    static const size_t FunctionFaultInfosOffset =
+        ReservedOffset + sizeof(ReservedType);
+
+    static const size_t FunctionInfoHeaderSize = FunctionFaultInfosOffset;
+
+    const uint8_t *P;
+    const uint8_t *E;
+
+  public:
+    FunctionInfoAccessor() : P(nullptr), E(nullptr) {}
+
+    explicit FunctionInfoAccessor(const uint8_t *P, const uint8_t *E)
+        : P(P), E(E) {}
+
+    FunctionAddrType getFunctionAddr() const {
+      return read<FunctionAddrType>(P + FunctionAddrOffset, E);
+    }
+
+    NumFaultingPCsType getNumFaultingPCs() const {
+      return read<NumFaultingPCsType>(P + NumFaultingPCsOffset, E);
+    }
+
+    FunctionFaultInfoAccessor getFunctionFaultInfoAt(uint32_t Index) const {
+      assert(Index < getNumFaultingPCs() && "index out of bounds!");
+      const uint8_t *Begin = P + FunctionFaultInfosOffset +
+                             FunctionFaultInfoAccessor::Size * Index;
+      return FunctionFaultInfoAccessor(Begin, E);
+    }
+
+    FunctionInfoAccessor getNextFunctionInfo() const {
+      size_t MySize = FunctionInfoHeaderSize +
+                      getNumFaultingPCs() * FunctionFaultInfoAccessor::Size;
+
+      const uint8_t *Begin = P + MySize;
+      assert(Begin < E && "out of bounds!");
+      return FunctionInfoAccessor(Begin, E);
+    }
+  };
+
+  explicit FaultMapParser(const uint8_t *Begin, const uint8_t *End)
+      : P(Begin), E(End) {}
+
+  FaultMapVersionType getFaultMapVersion() const {
+    auto Version = read<FaultMapVersionType>(P + FaultMapVersionOffset, E);
+    assert(Version == 1 && "only version 1 supported!");
+    return Version;
+  }
+
+  NumFunctionsType getNumFunctions() const {
+    return read<NumFunctionsType>(P + NumFunctionsOffset, E);
+  }
+
+  FunctionInfoAccessor getFirstFunctionInfo() const {
+    const uint8_t *Begin = P + FunctionInfosOffset;
+    return FunctionInfoAccessor(Begin, E);
+  }
+};
+
+raw_ostream &
+operator<<(raw_ostream &OS, const FaultMapParser::FunctionFaultInfoAccessor &);
+
+raw_ostream &operator<<(raw_ostream &OS,
+                        const FaultMapParser::FunctionInfoAccessor &);
+
+raw_ostream &operator<<(raw_ostream &OS, const FaultMapParser &);
+
 } // namespace llvm
 
 #endif