Add encode and decode methods to InlineInfo and document encoding format to the GSYM file format.

This patch adds the ability to encode and decode InlineInfo objects and adds test coverage. Error handling is introduced in the encoding and decoding which will be used from here on out for remaining patches.

Differential Revision: https://reviews.llvm.org/D66600

llvm-svn: 370936

2 files changed, 112 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/GSYM/InlineInfo.cpp b/llvm/lib/DebugInfo/GSYM/InlineInfo.cpp
index 781c1755241..a3e56bea529 100644
--- a/llvm/lib/DebugInfo/GSYM/InlineInfo.cpp
+++ b/llvm/lib/DebugInfo/GSYM/InlineInfo.cpp
@@ -8,7 +8,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/GSYM/FileEntry.h"
+#include "llvm/DebugInfo/GSYM/FileWriter.h"
 #include "llvm/DebugInfo/GSYM/InlineInfo.h"
+#include "llvm/Support/DataExtractor.h"
 #include <algorithm>
 #include <inttypes.h>
 
@@ -57,3 +59,102 @@ llvm::Optional<InlineInfo::InlineArray> InlineInfo::getInlineStack(uint64_t Addr
     return Result;
   return llvm::None;
 }
+
+/// Decode an InlineInfo in Data at the specified offset.
+///
+/// A local helper function to decode InlineInfo objects. This function is
+/// called recursively when parsing child InlineInfo objects.
+///
+/// \param Inline The InlineInfo object to decode into.
+/// \param Data The data extractor to decode from.
+/// \param Offset The offset within \a Data to decode from.
+/// \param BaseAddr The base address to use when decoding address ranges.
+/// \returns An InlineInfo or an error describing the issue that was
+/// encountered during decoding.
+static llvm::Expected<InlineInfo> decode(DataExtractor &Data, uint64_t &Offset,
+                                         uint64_t BaseAddr) {
+  InlineInfo Inline;
+  if (!Data.isValidOffset(Offset))
+    return createStringError(std::errc::io_error,
+        "0x%8.8" PRIx64 ": missing InlineInfo address ranges data", Offset);
+  Inline.Ranges.decode(Data, BaseAddr, Offset);
+  if (Inline.Ranges.empty())
+    return Inline;
+  if (!Data.isValidOffsetForDataOfSize(Offset, 1))
+    return createStringError(std::errc::io_error,
+        "0x%8.8" PRIx64 ": missing InlineInfo uint8_t indicating children",
+        Offset);
+  bool HasChildren = Data.getU8(&Offset) != 0;
+  if (!Data.isValidOffsetForDataOfSize(Offset, 4))
+    return createStringError(std::errc::io_error,
+        "0x%8.8" PRIx64 ": missing InlineInfo uint32_t for name", Offset);
+  Inline.Name = Data.getU32(&Offset);
+  if (!Data.isValidOffset(Offset))
+    return createStringError(std::errc::io_error,
+        "0x%8.8" PRIx64 ": missing ULEB128 for InlineInfo call file", Offset);
+  Inline.CallFile = (uint32_t)Data.getULEB128(&Offset);
+  if (!Data.isValidOffset(Offset))
+    return createStringError(std::errc::io_error,
+        "0x%8.8" PRIx64 ": missing ULEB128 for InlineInfo call line", Offset);
+  Inline.CallLine = (uint32_t)Data.getULEB128(&Offset);
+  if (HasChildren) {
+    // Child address ranges are encoded relative to the first address in the
+    // parent InlineInfo object.
+    const auto ChildBaseAddr = Inline.Ranges[0].Start;
+    while (true) {
+      llvm::Expected<InlineInfo> Child = decode(Data, Offset, ChildBaseAddr);
+      if (!Child)
+        return Child.takeError();
+      // InlineInfo with empty Ranges termintes a child sibling chain.
+      if (Child.get().Ranges.empty())
+        break;
+      Inline.Children.emplace_back(std::move(*Child));
+    }
+  }
+  return Inline;
+}
+
+llvm::Expected<InlineInfo> InlineInfo::decode(DataExtractor &Data,
+                                              uint64_t BaseAddr) {
+  uint64_t Offset = 0;
+  return ::decode(Data, Offset, BaseAddr);
+}
+
+llvm::Error InlineInfo::encode(FileWriter &O, uint64_t BaseAddr) const {
+  // Users must verify the InlineInfo is valid prior to calling this funtion.
+  // We don't want to emit any InlineInfo objects if they are not valid since
+  // it will waste space in the GSYM file.
+  if (!isValid())
+    return createStringError(std::errc::invalid_argument,
+                             "attempted to encode invalid InlineInfo object");
+  Ranges.encode(O, BaseAddr);
+  bool HasChildren = !Children.empty();
+  O.writeU8(HasChildren);
+  O.writeU32(Name);
+  O.writeULEB(CallFile);
+  O.writeULEB(CallLine);
+  if (HasChildren) {
+    // Child address ranges are encoded as relative to the first
+    // address in the Ranges for this object. This keeps the offsets
+    // small and allows for efficient encoding using ULEB offsets.
+    const uint64_t ChildBaseAddr = Ranges[0].Start;
+    for (const auto &Child : Children) {
+      // Make sure all child address ranges are contained in the parent address
+      // ranges.
+      for (const auto &ChildRange: Child.Ranges) {
+        if (!Ranges.contains(ChildRange))
+          return createStringError(std::errc::invalid_argument,
+                                   "child range not contained in parent");
+      }
+      llvm::Error Err = Child.encode(O, ChildBaseAddr);
+      if (Err)
+        return Err;
+    }
+
+    // Terminate child sibling chain by emitting a zero. This zero will cause
+    // the decodeAll() function above to return false and stop the decoding
+    // of child InlineInfo objects that are siblings.
+    O.writeULEB(0);
+  }
+  return Error::success();
+}
diff --git a/llvm/lib/DebugInfo/GSYM/Range.cpp b/llvm/lib/DebugInfo/GSYM/Range.cpp
index f4d31f328a2..19ab700fdd5 100644
--- a/llvm/lib/DebugInfo/GSYM/Range.cpp
+++ b/llvm/lib/DebugInfo/GSYM/Range.cpp
@@ -42,6 +42,17 @@ bool AddressRanges::contains(uint64_t Addr) const {
   return It != Ranges.begin() && Addr < It[-1].End;
 }
 
+bool AddressRanges::contains(AddressRange Range) const {
+  if (Range.size() == 0)
+    return false;
+  auto It = std::partition_point(
+      Ranges.begin(), Ranges.end(),
+      [=](const AddressRange &R) { return R.Start <= Range.Start; });
+  if (It == Ranges.begin())
+    return false;
+  return Range.End <= It[-1].End;
+}
+
 raw_ostream &llvm::gsym::operator<<(raw_ostream &OS, const AddressRange &R) {
   return OS << '[' << HEX64(R.Start) << " - " << HEX64(R.End) << ")";
 }