[msf] Make FPM reader use MappedBlockStream.

MappedBlockSTream can work with any sequence of block data where
the ordering is specified by a list of block numbers.  So rather
than manually stitch them together in the case of the FPM, reuse
this functionality so that we can treat the FPM as if it were
contiguous.

Reviewed By: ruiu
Differential Revision: https://reviews.llvm.org/D23066

llvm-svn: 277609

1 files changed, 29 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp b/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
index 0a3b2b96ab4..bbcfbfca810 100644
--- a/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
+++ b/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
@@ -26,6 +26,19 @@ public:
 };
 }
 
+static void initializeFpmStreamLayout(const MSFLayout &Layout,
+                                      MSFStreamLayout &FpmLayout) {
+  uint32_t NumFpmIntervals = msf::getNumFpmIntervals(Layout);
+  support::ulittle32_t FpmBlock = Layout.SB->FreeBlockMapBlock;
+  assert(FpmBlock == 1 || FpmBlock == 2);
+  while (NumFpmIntervals > 0) {
+    FpmLayout.Blocks.push_back(FpmBlock);
+    FpmBlock += msf::getFpmIntervalLength(Layout);
+    --NumFpmIntervals;
+  }
+  FpmLayout.Length = msf::getFullFpmByteSize(Layout);
+}
+
 typedef std::pair<uint32_t, uint32_t> Interval;
 static Interval intersect(const Interval &I1, const Interval &I2) {
   return std::make_pair(std::max(I1.first, I2.first),
@@ -66,6 +79,14 @@ MappedBlockStream::createDirectoryStream(const MSFLayout &Layout,
   return createStream(Layout.SB->BlockSize, Layout.SB->NumBlocks, SL, MsfData);
 }
 
+std::unique_ptr<MappedBlockStream>
+MappedBlockStream::createFpmStream(const MSFLayout &Layout,
+                                   const ReadableStream &MsfData) {
+  MSFStreamLayout SL;
+  initializeFpmStreamLayout(Layout, SL);
+  return createStream(Layout.SB->BlockSize, Layout.SB->NumBlocks, SL, MsfData);
+}
+
 Error MappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
                                    ArrayRef<uint8_t> &Buffer) const {
   // Make sure we aren't trying to read beyond the end of the stream.
@@ -324,6 +345,14 @@ WritableMappedBlockStream::createDirectoryStream(
   return createStream(Layout.SB->BlockSize, Layout.SB->NumBlocks, SL, MsfData);
 }
 
+std::unique_ptr<WritableMappedBlockStream>
+WritableMappedBlockStream::createFpmStream(const MSFLayout &Layout,
+                                           const WritableStream &MsfData) {
+  MSFStreamLayout SL;
+  initializeFpmStreamLayout(Layout, SL);
+  return createStream(Layout.SB->BlockSize, Layout.SB->NumBlocks, SL, MsfData);
+}
+
 Error WritableMappedBlockStream::readBytes(uint32_t Offset, uint32_t Size,
                                            ArrayRef<uint8_t> &Buffer) const {
   return ReadInterface.readBytes(Offset, Size, Buffer);