From 4666953ce229cd7a8b042e5f80ecc97b4eae3636 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka@google.com>
Date: Sun, 31 May 2020 23:49:57 -0700
Subject: [StackSafety] Add info into function summary

Summary:
This patch adds optional field into function summary,
implements asm and bitcode serialization. YAML
serialization is omitted and can be added later if
needed.

This patch includes this information into summary only
if module contains at least one sanitize_memtag function.
In a near future MTE is the user of the analysis.
Later if needed we can provede more direct control
on when information is included into summary.

Reviewers: eugenis

Subscribers: hiraditya, steven_wu, dexonsmith, arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80908
---
 llvm/lib/Bitcode/Reader/BitcodeReader.cpp | 48 +++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

(limited to 'llvm/lib/Bitcode/Reader/BitcodeReader.cpp')

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 615b646..2f9331e 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5804,6 +5804,41 @@ static void parseTypeIdSummaryRecord(ArrayRef<uint64_t> Record,
     parseWholeProgramDevirtResolution(Record, Strtab, Slot, TypeId);
 }
 
+static std::vector<FunctionSummary::ParamAccess>
+parseParamAccesses(ArrayRef<uint64_t> Record) {
+  auto ReadRange = [&]() {
+    APInt Lower(FunctionSummary::ParamAccess::RangeWidth,
+                BitcodeReader::decodeSignRotatedValue(Record.front()));
+    Record = Record.drop_front();
+    APInt Upper(FunctionSummary::ParamAccess::RangeWidth,
+                BitcodeReader::decodeSignRotatedValue(Record.front()));
+    Record = Record.drop_front();
+    ConstantRange Range{Lower, Upper};
+    assert(!Range.isFullSet());
+    assert(!Range.isUpperSignWrapped());
+    return Range;
+  };
+
+  std::vector<FunctionSummary::ParamAccess> PendingParamAccesses;
+  while (!Record.empty()) {
+    PendingParamAccesses.emplace_back();
+    FunctionSummary::ParamAccess &ParamAccess = PendingParamAccesses.back();
+    ParamAccess.ParamNo = Record.front();
+    Record = Record.drop_front();
+    ParamAccess.Use = ReadRange();
+    ParamAccess.Calls.resize(Record.front());
+    Record = Record.drop_front();
+    for (auto &Call : ParamAccess.Calls) {
+      Call.ParamNo = Record.front();
+      Record = Record.drop_front();
+      Call.Callee = Record.front();
+      Record = Record.drop_front();
+      Call.Offsets = ReadRange();
+    }
+  }
+  return PendingParamAccesses;
+}
+
 void ModuleSummaryIndexBitcodeReader::parseTypeIdCompatibleVtableInfo(
     ArrayRef<uint64_t> Record, size_t &Slot,
     TypeIdCompatibleVtableInfo &TypeId) {
@@ -5881,6 +5916,7 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
       PendingTypeCheckedLoadVCalls;
   std::vector<FunctionSummary::ConstVCall> PendingTypeTestAssumeConstVCalls,
       PendingTypeCheckedLoadConstVCalls;
+  std::vector<FunctionSummary::ParamAccess> PendingParamAccesses;
 
   while (true) {
     Expected<BitstreamEntry> MaybeEntry = Stream.advanceSkippingSubblocks();
@@ -5979,7 +6015,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
           std::move(PendingTypeTestAssumeVCalls),
           std::move(PendingTypeCheckedLoadVCalls),
           std::move(PendingTypeTestAssumeConstVCalls),
-          std::move(PendingTypeCheckedLoadConstVCalls));
+          std::move(PendingTypeCheckedLoadConstVCalls),
+          std::move(PendingParamAccesses));
       auto VIAndOriginalGUID = getValueInfoFromValueId(ValueID);
       FS->setModulePath(getThisModule()->first());
       FS->setOriginalName(VIAndOriginalGUID.second);
@@ -6121,7 +6158,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
           std::move(PendingTypeTestAssumeVCalls),
           std::move(PendingTypeCheckedLoadVCalls),
           std::move(PendingTypeTestAssumeConstVCalls),
-          std::move(PendingTypeCheckedLoadConstVCalls));
+          std::move(PendingTypeCheckedLoadConstVCalls),
+          std::move(PendingParamAccesses));
       LastSeenSummary = FS.get();
       LastSeenGUID = VI.getGUID();
       FS->setModulePath(ModuleIdMap[ModuleId]);
@@ -6242,6 +6280,12 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
 
     case bitc::FS_BLOCK_COUNT:
       TheIndex.addBlockCount(Record[0]);
+      break;
+
+    case bitc::FS_PARAM_ACCESS: {
+      PendingParamAccesses = parseParamAccesses(Record);
+      break;
+    }
     }
   }
   llvm_unreachable("Exit infinite loop");
-- 
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