vendor/llvm/llvm-trunk-r366426

1 files changed, 78 insertions, 61 deletions

diff --git a/lib/DebugInfo/PDB/Native/PDBStringTableBuilder.cpp b/lib/DebugInfo/PDB/Native/PDBStringTableBuilder.cpp
index d9dcabf3d958..f7f36901e4d4 100644
--- a/lib/DebugInfo/PDB/Native/PDBStringTableBuilder.cpp
+++ b/lib/DebugInfo/PDB/Native/PDBStringTableBuilder.cpp
@@ -1,9 +1,8 @@
 //===- PDBStringTableBuilder.cpp - PDB String Table -------------*- C++ -*-===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
@@ -27,7 +26,13 @@ StringTableHashTraits::StringTableHashTraits(PDBStringTableBuilder &Table)
     : Table(&Table) {}
 
 uint32_t StringTableHashTraits::hashLookupKey(StringRef S) const {
-  return Table->getIdForString(S);
+  // The reference implementation doesn't include code for /src/headerblock
+  // handling, but it can only read natvis entries lld's PDB files if
+  // this hash function truncates the hash to 16 bit.
+  // PDB/include/misc.h in the reference implementation has a hashSz() function
+  // that returns an unsigned short, that seems what's being used for
+  // /src/headerblock.
+  return static_cast<uint16_t>(Table->getIdForString(S));
 }
 
 StringRef StringTableHashTraits::storageKeyToLookupKey(uint32_t Offset) const {
@@ -50,63 +55,75 @@ StringRef PDBStringTableBuilder::getStringForId(uint32_t Id) const {
   return Strings.getStringForId(Id);
 }
 
-// This is a precomputed list of Buckets given the specified number of
-// strings.  Matching the reference algorithm exactly is not strictly
-// necessary for correctness, but it helps when comparing LLD's PDBs with
-// Microsoft's PDBs so as to eliminate superfluous differences.
-static std::map<uint32_t, uint32_t> StringsToBuckets = {
-    {1, 2},
-    {2, 4},
-    {4, 7},
-    {6, 11},
-    {9, 17},
-    {13, 26},
-    {20, 40},
-    {31, 61},
-    {46, 92},
-    {70, 139},
-    {105, 209},
-    {157, 314},
-    {236, 472},
-    {355, 709},
-    {532, 1064},
-    {799, 1597},
-    {1198, 2396},
-    {1798, 3595},
-    {2697, 5393},
-    {4045, 8090},
-    {6068, 12136},
-    {9103, 18205},
-    {13654, 27308},
-    {20482, 40963},
-    {30723, 61445},
-    {46084, 92168},
-    {69127, 138253},
-    {103690, 207380},
-    {155536, 311071},
-    {233304, 466607},
-    {349956, 699911},
-    {524934, 1049867},
-    {787401, 1574801},
-    {1181101, 2362202},
-    {1771652, 3543304},
-    {2657479, 5314957},
-    {3986218, 7972436},
-    {5979328, 11958655},
-    {8968992, 17937983},
-    {13453488, 26906975},
-    {20180232, 40360463},
-    {30270348, 60540695},
-    {45405522, 90811043},
-    {68108283, 136216565},
-    {102162424, 204324848},
-    {153243637, 306487273},
-    {229865455, 459730910},
-    {344798183, 689596366},
-    {517197275, 1034394550},
-    {775795913, 1551591826}};
-
 static uint32_t computeBucketCount(uint32_t NumStrings) {
+  // This is a precomputed list of Buckets given the specified number of
+  // strings.  Matching the reference algorithm exactly is not strictly
+  // necessary for correctness, but it helps when comparing LLD's PDBs with
+  // Microsoft's PDBs so as to eliminate superfluous differences.
+  // The reference implementation does (in nmt.h, NMT::grow()):
+  //   unsigned StringCount = 0;
+  //   unsigned BucketCount = 1;
+  //   fn insert() {
+  //     ++StringCount;
+  //     if (BucketCount * 3 / 4 < StringCount)
+  //       BucketCount = BucketCount * 3 / 2 + 1;
+  //   }
+  // This list contains all StringCount, BucketCount pairs where BucketCount was
+  // just incremented.  It ends before the first BucketCount entry where
+  // BucketCount * 3 would overflow a 32-bit unsigned int.
+  static std::map<uint32_t, uint32_t> StringsToBuckets = {
+      {0, 1},
+      {1, 2},
+      {2, 4},
+      {4, 7},
+      {6, 11},
+      {9, 17},
+      {13, 26},
+      {20, 40},
+      {31, 61},
+      {46, 92},
+      {70, 139},
+      {105, 209},
+      {157, 314},
+      {236, 472},
+      {355, 709},
+      {532, 1064},
+      {799, 1597},
+      {1198, 2396},
+      {1798, 3595},
+      {2697, 5393},
+      {4045, 8090},
+      {6068, 12136},
+      {9103, 18205},
+      {13654, 27308},
+      {20482, 40963},
+      {30723, 61445},
+      {46084, 92168},
+      {69127, 138253},
+      {103690, 207380},
+      {155536, 311071},
+      {233304, 466607},
+      {349956, 699911},
+      {524934, 1049867},
+      {787401, 1574801},
+      {1181101, 2362202},
+      {1771652, 3543304},
+      {2657479, 5314957},
+      {3986218, 7972436},
+      {5979328, 11958655},
+      {8968992, 17937983},
+      {13453488, 26906975},
+      {20180232, 40360463},
+      {30270348, 60540695},
+      {45405522, 90811043},
+      {68108283, 136216565},
+      {102162424, 204324848},
+      {153243637, 306487273},
+      {229865455, 459730910},
+      {344798183, 689596366},
+      {517197275, 1034394550},
+      {775795913, 1551591826},
+      {1163693870, 2327387740}};
   auto Entry = StringsToBuckets.lower_bound(NumStrings);
   assert(Entry != StringsToBuckets.end());
   return Entry->second;