Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 631 insertions, 0 deletions

diff --git a/tools/profiler/lul/LulMainInt.h b/tools/profiler/lul/LulMainInt.h
new file mode 100644
index 0000000000..001a4aecfb
--- /dev/null
+++ b/tools/profiler/lul/LulMainInt.h
@@ -0,0 +1,631 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef LulMainInt_h
+#define LulMainInt_h
+
+#include "PlatformMacros.h"
+#include "LulMain.h"  // for TaggedUWord
+
+#include <string>
+#include <vector>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/HashTable.h"
+#include "mozilla/Sprintf.h"
+
+// This file provides an internal interface inside LUL.  If you are an
+// end-user of LUL, do not include it in your code.  The end-user
+// interface is in LulMain.h.
+
+namespace lul {
+
+using std::vector;
+
+////////////////////////////////////////////////////////////////
+// DW_REG_ constants                                          //
+////////////////////////////////////////////////////////////////
+
+// These are the Dwarf CFI register numbers, as (presumably) defined
+// in the ELF ABI supplements for each architecture.
+
+enum DW_REG_NUMBER {
+  // No real register has this number.  It's convenient to be able to
+  // treat the CFA (Canonical Frame Address) as "just another
+  // register", though.
+  DW_REG_CFA = -1,
+#if defined(GP_ARCH_arm)
+  // ARM registers
+  DW_REG_ARM_R7 = 7,
+  DW_REG_ARM_R11 = 11,
+  DW_REG_ARM_R12 = 12,
+  DW_REG_ARM_R13 = 13,
+  DW_REG_ARM_R14 = 14,
+  DW_REG_ARM_R15 = 15,
+#elif defined(GP_ARCH_arm64)
+  // aarch64 registers
+  DW_REG_AARCH64_X29 = 29,
+  DW_REG_AARCH64_X30 = 30,
+  DW_REG_AARCH64_SP = 31,
+#elif defined(GP_ARCH_amd64)
+  // Because the X86 (32 bit) and AMD64 (64 bit) summarisers are
+  // combined, a merged set of register constants is needed.
+  DW_REG_INTEL_XBP = 6,
+  DW_REG_INTEL_XSP = 7,
+  DW_REG_INTEL_XIP = 16,
+#elif defined(GP_ARCH_x86)
+  DW_REG_INTEL_XBP = 5,
+  DW_REG_INTEL_XSP = 4,
+  DW_REG_INTEL_XIP = 8,
+#elif defined(GP_ARCH_mips64)
+  DW_REG_MIPS_SP = 29,
+  DW_REG_MIPS_FP = 30,
+  DW_REG_MIPS_PC = 34,
+#else
+#  error "Unknown arch"
+#endif
+};
+
+////////////////////////////////////////////////////////////////
+// PfxExpr                                                    //
+////////////////////////////////////////////////////////////////
+
+enum PfxExprOp {
+  //             meaning of mOperand     effect on stack
+  PX_Start,   // bool start-with-CFA?    start, with CFA on stack, or not
+  PX_End,     // none                    stop; result is at top of stack
+  PX_SImm32,  // int32                   push signed int32
+  PX_DwReg,   // DW_REG_NUMBER           push value of the specified reg
+  PX_Deref,   // none                    pop X ; push *X
+  PX_Add,     // none                    pop X ; pop Y ; push Y + X
+  PX_Sub,     // none                    pop X ; pop Y ; push Y - X
+  PX_And,     // none                    pop X ; pop Y ; push Y & X
+  PX_Or,      // none                    pop X ; pop Y ; push Y | X
+  PX_CmpGES,  // none                    pop X ; pop Y ; push (Y >=s X) ? 1 : 0
+  PX_Shl      // none                    pop X ; pop Y ; push Y << X
+};
+
+struct PfxInstr {
+  PfxInstr(PfxExprOp opcode, int32_t operand)
+      : mOpcode(opcode), mOperand(operand) {}
+  explicit PfxInstr(PfxExprOp opcode) : mOpcode(opcode), mOperand(0) {}
+  bool operator==(const PfxInstr& other) const {
+    return mOpcode == other.mOpcode && mOperand == other.mOperand;
+  }
+  PfxExprOp mOpcode;
+  int32_t mOperand;
+};
+
+static_assert(sizeof(PfxInstr) <= 8, "PfxInstr size changed unexpectedly");
+
+// Evaluate the prefix expression whose PfxInstrs start at aPfxInstrs[start].
+// In the case of any mishap (stack over/underflow, running off the end of
+// the instruction vector, obviously malformed sequences),
+// return an invalid TaggedUWord.
+// RUNS IN NO-MALLOC CONTEXT
+TaggedUWord EvaluatePfxExpr(int32_t start, const UnwindRegs* aOldRegs,
+                            TaggedUWord aCFA, const StackImage* aStackImg,
+                            const vector<PfxInstr>& aPfxInstrs);
+
+////////////////////////////////////////////////////////////////
+// LExpr                                                      //
+////////////////////////////////////////////////////////////////
+
+// An expression -- very primitive.  Denotes either "register +
+// offset", a dereferenced version of the same, or a reference to a
+// prefix expression stored elsewhere.  So as to allow convenient
+// handling of Dwarf-derived unwind info, the register may also denote
+// the CFA.  A large number of these need to be stored, so we ensure
+// it fits into 8 bytes.  See comment below on RuleSet to see how
+// expressions fit into the bigger picture.
+
+enum LExprHow {
+  UNKNOWN = 0,  // This LExpr denotes no value.
+  NODEREF,      // Value is  (mReg + mOffset).
+  DEREF,        // Value is *(mReg + mOffset).
+  PFXEXPR       // Value is EvaluatePfxExpr(secMap->mPfxInstrs[mOffset])
+};
+
+inline static const char* NameOf_LExprHow(LExprHow how) {
+  switch (how) {
+    case UNKNOWN:
+      return "UNKNOWN";
+    case NODEREF:
+      return "NODEREF";
+    case DEREF:
+      return "DEREF";
+    case PFXEXPR:
+      return "PFXEXPR";
+    default:
+      return "LExpr-??";
+  }
+}
+
+struct LExpr {
+  // Denotes an expression with no value.
+  LExpr() : mHow(UNKNOWN), mReg(0), mOffset(0) {}
+
+  // Denotes any expressible expression.
+  LExpr(LExprHow how, int16_t reg, int32_t offset)
+      : mHow(how), mReg(reg), mOffset(offset) {
+    switch (how) {
+      case UNKNOWN:
+        MOZ_ASSERT(reg == 0 && offset == 0);
+        break;
+      case NODEREF:
+        break;
+      case DEREF:
+        break;
+      case PFXEXPR:
+        MOZ_ASSERT(reg == 0 && offset >= 0);
+        break;
+      default:
+        MOZ_RELEASE_ASSERT(0, "LExpr::LExpr: invalid how");
+    }
+  }
+
+  // Hash it, carefully looking only at defined parts.
+  mozilla::HashNumber hash() const {
+    mozilla::HashNumber h = mHow;
+    switch (mHow) {
+      case UNKNOWN:
+        break;
+      case NODEREF:
+      case DEREF:
+        h = mozilla::AddToHash(h, mReg);
+        h = mozilla::AddToHash(h, mOffset);
+        break;
+      case PFXEXPR:
+        h = mozilla::AddToHash(h, mOffset);
+        break;
+      default:
+        MOZ_RELEASE_ASSERT(0, "LExpr::hash: invalid how");
+    }
+    return h;
+  }
+
+  // And structural equality.
+  bool equals(const LExpr& other) const {
+    if (mHow != other.mHow) {
+      return false;
+    }
+    switch (mHow) {
+      case UNKNOWN:
+        return true;
+      case NODEREF:
+      case DEREF:
+        return mReg == other.mReg && mOffset == other.mOffset;
+      case PFXEXPR:
+        return mOffset == other.mOffset;
+      default:
+        MOZ_RELEASE_ASSERT(0, "LExpr::equals: invalid how");
+    }
+  }
+
+  // Change the offset for an expression that references memory.
+  LExpr add_delta(long delta) {
+    MOZ_ASSERT(mHow == NODEREF);
+    // If this is a non-debug build and the above assertion would have
+    // failed, at least return LExpr() so that the machinery that uses
+    // the resulting expression fails in a repeatable way.
+    return (mHow == NODEREF) ? LExpr(mHow, mReg, mOffset + delta)
+                             : LExpr();  // Gone bad
+  }
+
+  // Dereference an expression that denotes a memory address.
+  LExpr deref() {
+    MOZ_ASSERT(mHow == NODEREF);
+    // Same rationale as for add_delta().
+    return (mHow == NODEREF) ? LExpr(DEREF, mReg, mOffset)
+                             : LExpr();  // Gone bad
+  }
+
+  // Print a rule for recovery of |aNewReg| whose recovered value
+  // is this LExpr.
+  std::string ShowRule(const char* aNewReg) const;
+
+  // Evaluate this expression, producing a TaggedUWord.  |aOldRegs|
+  // holds register values that may be referred to by the expression.
+  // |aCFA| holds the CFA value, if any, that applies.  |aStackImg|
+  // contains a chuck of stack that will be consulted if the expression
+  // references memory.  |aPfxInstrs| holds the vector of PfxInstrs
+  // that will be consulted if this is a PFXEXPR.
+  // RUNS IN NO-MALLOC CONTEXT
+  TaggedUWord EvaluateExpr(const UnwindRegs* aOldRegs, TaggedUWord aCFA,
+                           const StackImage* aStackImg,
+                           const vector<PfxInstr>* aPfxInstrs) const;
+
+  // Representation of expressions.  If |mReg| is DW_REG_CFA (-1) then
+  // it denotes the CFA.  All other allowed values for |mReg| are
+  // nonnegative and are DW_REG_ values.
+  LExprHow mHow : 8;
+  int16_t mReg;     // A DW_REG_ value
+  int32_t mOffset;  // 32-bit signed offset should be more than enough.
+};
+
+static_assert(sizeof(LExpr) <= 8, "LExpr size changed unexpectedly");
+
+////////////////////////////////////////////////////////////////
+// RuleSet                                                    //
+////////////////////////////////////////////////////////////////
+
+// This is platform-dependent.  It describes how to recover the CFA and then
+// how to recover the registers for the previous frame.  Such "recipes" are
+// specific to particular ranges of machine code, but the associated range
+// is not stored in RuleSet, because in general each RuleSet may be used
+// for many such range fragments ("extents").  See the comments below for
+// Extent and SecMap.
+//
+// The set of LExprs contained in a given RuleSet describe a DAG which
+// says how to compute the caller's registers ("new registers") from
+// the callee's registers ("old registers").  The DAG can contain a
+// single internal node, which is the value of the CFA for the callee.
+// It would be possible to construct a DAG that omits the CFA, but
+// including it makes the summarisers simpler, and the Dwarf CFI spec
+// has the CFA as a central concept.
+//
+// For this to make sense, |mCfaExpr| can't have
+// |mReg| == DW_REG_CFA since we have no previous value for the CFA.
+// All of the other |Expr| fields can -- and usually do -- specify
+// |mReg| == DW_REG_CFA.
+//
+// With that in place, the unwind algorithm proceeds as follows.
+//
+// (0) Initially: we have values for the old registers, and a memory
+//     image.
+//
+// (1) Compute the CFA by evaluating |mCfaExpr|.  Add the computed
+//     value to the set of "old registers".
+//
+// (2) Compute values for the registers by evaluating all of the other
+//     |Expr| fields in the RuleSet.  These can depend on both the old
+//     register values and the just-computed CFA.
+//
+// If we are unwinding without computing a CFA, perhaps because the
+// RuleSets are derived from EXIDX instead of Dwarf, then
+// |mCfaExpr.mHow| will be LExpr::UNKNOWN, so the computed value will
+// be invalid -- that is, TaggedUWord() -- and so any attempt to use
+// that will result in the same value.  But that's OK because the
+// RuleSet would make no sense if depended on the CFA but specified no
+// way to compute it.
+//
+// A RuleSet is not allowed to cover zero address range.  Having zero
+// length would break binary searching in SecMaps and PriMaps.
+
+class RuleSet {
+ public:
+  RuleSet();
+  void Print(uintptr_t avma, uintptr_t len, void (*aLog)(const char*)) const;
+
+  // Find the LExpr* for a given DW_REG_ value in this class.
+  LExpr* ExprForRegno(DW_REG_NUMBER aRegno);
+
+  // How to compute the CFA.
+  LExpr mCfaExpr;
+  // How to compute caller register values.  These may reference the
+  // value defined by |mCfaExpr|.
+#if defined(GP_ARCH_amd64) || defined(GP_ARCH_x86)
+  LExpr mXipExpr;  // return address
+  LExpr mXspExpr;
+  LExpr mXbpExpr;
+#elif defined(GP_ARCH_arm)
+  LExpr mR15expr;  // return address
+  LExpr mR14expr;
+  LExpr mR13expr;
+  LExpr mR12expr;
+  LExpr mR11expr;
+  LExpr mR7expr;
+#elif defined(GP_ARCH_arm64)
+  LExpr mX29expr;  // frame pointer register
+  LExpr mX30expr;  // link register
+  LExpr mSPexpr;
+#elif defined(GP_ARCH_mips64)
+  LExpr mPCexpr;
+  LExpr mFPexpr;
+  LExpr mSPexpr;
+#else
+#  error "Unknown arch"
+#endif
+
+  // Machinery in support of hashing.
+  typedef RuleSet Lookup;
+
+  static mozilla::HashNumber hash(RuleSet rs) {
+    mozilla::HashNumber h = rs.mCfaExpr.hash();
+#if defined(GP_ARCH_amd64) || defined(GP_ARCH_x86)
+    h = mozilla::AddToHash(h, rs.mXipExpr.hash());
+    h = mozilla::AddToHash(h, rs.mXspExpr.hash());
+    h = mozilla::AddToHash(h, rs.mXbpExpr.hash());
+#elif defined(GP_ARCH_arm)
+    h = mozilla::AddToHash(h, rs.mR15expr.hash());
+    h = mozilla::AddToHash(h, rs.mR14expr.hash());
+    h = mozilla::AddToHash(h, rs.mR13expr.hash());
+    h = mozilla::AddToHash(h, rs.mR12expr.hash());
+    h = mozilla::AddToHash(h, rs.mR11expr.hash());
+    h = mozilla::AddToHash(h, rs.mR7expr.hash());
+#elif defined(GP_ARCH_arm64)
+    h = mozilla::AddToHash(h, rs.mX29expr.hash());
+    h = mozilla::AddToHash(h, rs.mX30expr.hash());
+    h = mozilla::AddToHash(h, rs.mSPexpr.hash());
+#elif defined(GP_ARCH_mips64)
+    h = mozilla::AddToHash(h, rs.mPCexpr.hash());
+    h = mozilla::AddToHash(h, rs.mFPexpr.hash());
+    h = mozilla::AddToHash(h, rs.mSPexpr.hash());
+#else
+#  error "Unknown arch"
+#endif
+    return h;
+  }
+
+  static bool match(const RuleSet& rs1, const RuleSet& rs2) {
+    return rs1.mCfaExpr.equals(rs2.mCfaExpr) &&
+#if defined(GP_ARCH_amd64) || defined(GP_ARCH_x86)
+           rs1.mXipExpr.equals(rs2.mXipExpr) &&
+           rs1.mXspExpr.equals(rs2.mXspExpr) &&
+           rs1.mXbpExpr.equals(rs2.mXbpExpr);
+#elif defined(GP_ARCH_arm)
+           rs1.mR15expr.equals(rs2.mR15expr) &&
+           rs1.mR14expr.equals(rs2.mR14expr) &&
+           rs1.mR13expr.equals(rs2.mR13expr) &&
+           rs1.mR12expr.equals(rs2.mR12expr) &&
+           rs1.mR11expr.equals(rs2.mR11expr) && rs1.mR7expr.equals(rs2.mR7expr);
+#elif defined(GP_ARCH_arm64)
+           rs1.mX29expr.equals(rs2.mX29expr) &&
+           rs1.mX30expr.equals(rs2.mX30expr) && rs1.mSPexpr.equals(rs2.mSPexpr);
+#elif defined(GP_ARCH_mips64)
+           rs1.mPCexpr.equals(rs2.mPCexpr) && rs1.mFPexpr.equals(rs2.mFPexpr) &&
+           rs1.mSPexpr.equals(rs2.mSPexpr);
+#else
+#  error "Unknown arch"
+#endif
+  }
+};
+
+// Returns |true| for Dwarf register numbers which are members
+// of the set of registers that LUL unwinds on this target.
+static inline bool registerIsTracked(DW_REG_NUMBER reg) {
+  switch (reg) {
+#if defined(GP_ARCH_amd64) || defined(GP_ARCH_x86)
+    case DW_REG_INTEL_XBP:
+    case DW_REG_INTEL_XSP:
+    case DW_REG_INTEL_XIP:
+      return true;
+#elif defined(GP_ARCH_arm)
+    case DW_REG_ARM_R7:
+    case DW_REG_ARM_R11:
+    case DW_REG_ARM_R12:
+    case DW_REG_ARM_R13:
+    case DW_REG_ARM_R14:
+    case DW_REG_ARM_R15:
+      return true;
+#elif defined(GP_ARCH_arm64)
+    case DW_REG_AARCH64_X29:
+    case DW_REG_AARCH64_X30:
+    case DW_REG_AARCH64_SP:
+      return true;
+#elif defined(GP_ARCH_mips64)
+    case DW_REG_MIPS_FP:
+    case DW_REG_MIPS_SP:
+    case DW_REG_MIPS_PC:
+      return true;
+#else
+#  error "Unknown arch"
+#endif
+    default:
+      return false;
+  }
+}
+
+////////////////////////////////////////////////////////////////
+// Extent                                                     //
+////////////////////////////////////////////////////////////////
+
+struct Extent {
+  // Three fields, which together take 8 bytes.
+  uint32_t mOffset;
+  uint16_t mLen;
+  uint16_t mDictIx;
+
+  // What this means is: suppose we are looking for the unwind rules for some
+  // code address (AVMA) `avma`.  If we can find some SecMap `secmap` such
+  // that `avma` falls in the range
+  //
+  //   `[secmap.mMapMinAVMA, secmap.mMapMaxAVMA]`
+  //
+  // then the RuleSet to use is `secmap.mDictionary[dictIx]` iff we can find
+  // an `extent` in `secmap.mExtents` such that `avma` falls into the range
+  //
+  //   `[secmap.mMapMinAVMA + extent.offset(),
+  //     secmap.mMapMinAVMA + extent.offset() + extent.len())`.
+  //
+  // Packing Extent into the minimum space is important, since there will be
+  // huge numbers of Extents -- around 3 million for libxul.so as of Sept
+  // 2020.  Here, we aim for an 8-byte size, with the field sizes chosen
+  // carefully, as follows:
+  //
+  // `offset` denotes a byte offset inside the text section for some shared
+  // object.  libxul.so is by far the largest.  As of Sept 2020 it has a text
+  // size of up to around 120MB, that is, close to 2^27 bytes.  Hence a 32-bit
+  // `offset` field gives a safety margin of around a factor of 32
+  // (== 2 ^(32 - 27)).
+  //
+  // `dictIx` indicates a unique `RuleSet` for some code address range.
+  // Experimentation on x86_64-linux indicates that only around 300 different
+  // `RuleSet`s exist, for libxul.so.  A 16-bit bit field allows up to 65536
+  // to be recorded, hence leaving us a generous safety margin.
+  //
+  // `len` indicates the length of the associated address range.
+  //
+  // Note the representation becomes unusable if either `offset` overflows 32
+  // bits or `dictIx` overflows 16 bits.  On the other hand, it does not
+  // matter (although is undesirable) if `len` overflows 16 bits, because in
+  // that case we can add multiple size-65535 entries to `secmap.mExtents` to
+  // cover the entire range.  Hence the field sizes are biased so as to give a
+  // good safety margin for `offset` and `dictIx` at the cost of stealing bits
+  // from `len`.  Almost all `len` values we will ever see in practice are
+  // 65535 or less, so stealing those bits does not matter much.
+  //
+  // If further compression is required, it would be feasible to implement
+  // Extent using 29 bits for the offset, 8 bits for the length and 11 bits
+  // for the dictionary index, giving a total of 6 bytes, provided that the
+  // data is packed into 3 uint16_t's.  That would be a bit slower, though,
+  // due to the bit packing, and it would be more fragile, in the sense that
+  // it would fail for any object with more than 512MB of text segment, or
+  // with more than 2048 different `RuleSet`s.  For the current (Sept 2020)
+  // libxul.so situation, though, it would work fine.
+
+  Extent(uint32_t offset, uint32_t len, uint32_t dictIx) {
+    MOZ_RELEASE_ASSERT(len < (1 << 16));
+    MOZ_RELEASE_ASSERT(dictIx < (1 << 16));
+    mOffset = offset;
+    mLen = len;
+    mDictIx = dictIx;
+  }
+  inline uint32_t offset() const { return mOffset; }
+  inline uint32_t len() const { return mLen; }
+  inline uint32_t dictIx() const { return mDictIx; }
+  void setLen(uint32_t len) {
+    MOZ_RELEASE_ASSERT(len < (1 << 16));
+    mLen = len;
+  }
+  void Print(void (*aLog)(const char*)) const {
+    char buf[64];
+    SprintfLiteral(buf, "Extent(offs=0x%x, len=%u, dictIx=%u)", this->offset(),
+                   this->len(), this->dictIx());
+    aLog(buf);
+  }
+};
+
+static_assert(sizeof(Extent) == 8);
+
+////////////////////////////////////////////////////////////////
+// SecMap                                                     //
+////////////////////////////////////////////////////////////////
+
+// A SecMap may have zero address range, temporarily, whilst RuleSets
+// are being added to it.  But adding a zero-range SecMap to a PriMap
+// will make it impossible to maintain the total order of the PriMap
+// entries, and so that can't be allowed to happen.
+
+class SecMap {
+ public:
+  // In the constructor, `mapStartAVMA` and `mapLen` define the actual
+  // (in-process) virtual addresses covered by the SecMap.  All RuleSets
+  // subsequently added to it by calling `AddRuleSet` must fall into this
+  // address range, and attempts to add ones outside the range will be
+  // ignored.  This restriction exists because the type Extent (see below)
+  // indicates an address range for a RuleSet, but for reasons of compactness,
+  // it does not contain the start address of the range.  Instead, it contains
+  // a 32-bit offset from the base address of the SecMap.  This is also the
+  // reason why the map's size is a `uint32_t` and not a `uintptr_t`.
+  //
+  // The effect is to limit this mechanism to shared objects / executables
+  // whose text section size does not exceed 4GB (2^32 bytes).  Given that, as
+  // of Sept 2020, libxul.so's text section size is around 120MB, this does
+  // not seem like much of a limitation.
+  //
+  // From the supplied `mapStartAVMA` and `mapLen`, fields `mMapMinAVMA` and
+  // `mMapMaxAVMA` are calculated.  It is intended that no two SecMaps owned
+  // by the same PriMap contain overlapping address ranges, and the PriMap
+  // logic enforces that.
+  //
+  // Some invariants:
+  //
+  // mExtents is nonempty
+  //    <=> mMapMinAVMA <= mMapMaxAVMA
+  //        && mMapMinAVMA <= apply_delta(mExtents[0].offset())
+  //        && apply_delta(mExtents[#rulesets-1].offset()
+  //             + mExtents[#rulesets-1].len() - 1) <= mMapMaxAVMA
+  //        where
+  //           apply_delta(off) = off + mMapMinAVMA
+  //
+  //        This requires that no RuleSet has zero length.
+  //
+  // mExtents is empty
+  //    <=> mMapMinAVMA > mMapMaxAVMA
+  //
+  // This doesn't constrain mMapMinAVMA and mMapMaxAVMA uniquely, so let's use
+  // mMapMinAVMA == 1 and mMapMaxAVMA == 0 to denote this case.
+
+  SecMap(uintptr_t mapStartAVMA, uint32_t mapLen, void (*aLog)(const char*));
+  ~SecMap();
+
+  // Binary search mRuleSets to find one that brackets |ia|, or nullptr
+  // if none is found.  It's not allowable to do this until PrepareRuleSets
+  // has been called first.
+  RuleSet* FindRuleSet(uintptr_t ia);
+
+  // Add a RuleSet to the collection.  The rule is copied in.  Calling
+  // this makes the map non-searchable.
+  void AddRuleSet(const RuleSet* rs, uintptr_t avma, uintptr_t len);
+
+  // Add a PfxInstr to the vector of such instrs, and return the index
+  // in the vector.  Calling this makes the map non-searchable.
+  uint32_t AddPfxInstr(PfxInstr pfxi);
+
+  // Returns the entire vector of PfxInstrs.
+  const vector<PfxInstr>* GetPfxInstrs() { return &mPfxInstrs; }
+
+  // Prepare the map for searching, by sorting it, de-overlapping entries and
+  // removing any resulting zero-length entries.  At the start of this
+  // routine, all Extents should fall within [mMapMinAVMA, mMapMaxAVMA] and
+  // not have zero length, as a result of the checks in AddRuleSet().
+  void PrepareRuleSets();
+
+  bool IsEmpty();
+
+  size_t Size() { return mExtents.size() + mDictionary.size(); }
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+  // The extent of this SecMap as a whole.  The extents of all contained
+  // RuleSets must fall inside this.  See comment above for details.
+  uintptr_t mMapMinAVMA;
+  uintptr_t mMapMaxAVMA;
+
+ private:
+  // False whilst adding entries; true once it is safe to call FindRuleSet.
+  // Transition (false->true) is caused by calling PrepareRuleSets().
+  bool mUsable;
+
+  // This is used to find and remove duplicate RuleSets while we are adding
+  // them to the SecMap.  Almost all RuleSets are duplicates, so de-duping
+  // them is a huge space win.  This is non-null while `mUsable` is false, and
+  // becomes null (is discarded) after the call to PrepareRuleSets, which
+  // copies all the entries into `mDictionary`.
+  mozilla::UniquePtr<
+      mozilla::HashMap<RuleSet, uint32_t, RuleSet, InfallibleAllocPolicy>>
+      mUniqifier;
+
+  // This will contain final contents of `mUniqifier`, but ordered
+  // (implicitly) by the `uint32_t` value fields, for fast access.
+  vector<RuleSet> mDictionary;
+
+  // A vector of Extents, sorted by offset value, nonoverlapping (post
+  // PrepareRuleSets()).
+  vector<Extent> mExtents;
+
+  // A vector of PfxInstrs, which are referred to by the RuleSets.
+  // These are provided as a representation of Dwarf expressions
+  // (DW_CFA_val_expression, DW_CFA_expression, DW_CFA_def_cfa_expression),
+  // are relatively expensive to evaluate, and and are therefore
+  // expected to be used only occasionally.
+  //
+  // The vector holds a bunch of separate PfxInstr programs, each one
+  // starting with a PX_Start and terminated by a PX_End, all
+  // concatenated together.  When a RuleSet can't recover a value
+  // using a self-contained LExpr, it uses a PFXEXPR whose mOffset is
+  // the index in this vector of start of the necessary PfxInstr program.
+  vector<PfxInstr> mPfxInstrs;
+
+  // A logging sink, for debugging.
+  void (*mLog)(const char*);
+};
+
+}  // namespace lul
+
+#endif  // ndef LulMainInt_h