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authorDimitry Andric <dim@FreeBSD.org>2019-01-19 10:01:25 +0000
committerDimitry Andric <dim@FreeBSD.org>2019-01-19 10:01:25 +0000
commitd8e91e46262bc44006913e6796843909f1ac7bcd (patch)
tree7d0c143d9b38190e0fa0180805389da22cd834c5 /lib/XRay/FileHeaderReader.cpp
parentb7eb8e35e481a74962664b63dfb09483b200209a (diff)
Notes
Diffstat (limited to 'lib/XRay/FileHeaderReader.cpp')
-rw-r--r--lib/XRay/FileHeaderReader.cpp70
1 files changed, 70 insertions, 0 deletions
diff --git a/lib/XRay/FileHeaderReader.cpp b/lib/XRay/FileHeaderReader.cpp
new file mode 100644
index 000000000000..0b3fb8b6f692
--- /dev/null
+++ b/lib/XRay/FileHeaderReader.cpp
@@ -0,0 +1,70 @@
+//===- FileHeaderReader.cpp - XRay File Header Reader --------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm/XRay/FileHeaderReader.h"
+
+namespace llvm {
+namespace xray {
+
+// Populates the FileHeader reference by reading the first 32 bytes of the file.
+Expected<XRayFileHeader> readBinaryFormatHeader(DataExtractor &HeaderExtractor,
+ uint32_t &OffsetPtr) {
+ // FIXME: Maybe deduce whether the data is little or big-endian using some
+ // magic bytes in the beginning of the file?
+
+ // First 32 bytes of the file will always be the header. We assume a certain
+ // format here:
+ //
+ // (2) uint16 : version
+ // (2) uint16 : type
+ // (4) uint32 : bitfield
+ // (8) uint64 : cycle frequency
+ // (16) - : padding
+ XRayFileHeader FileHeader;
+ auto PreReadOffset = OffsetPtr;
+ FileHeader.Version = HeaderExtractor.getU16(&OffsetPtr);
+ if (OffsetPtr == PreReadOffset)
+ return createStringError(
+ std::make_error_code(std::errc::invalid_argument),
+ "Failed reading version from file header at offset %d.", OffsetPtr);
+
+ PreReadOffset = OffsetPtr;
+ FileHeader.Type = HeaderExtractor.getU16(&OffsetPtr);
+ if (OffsetPtr == PreReadOffset)
+ return createStringError(
+ std::make_error_code(std::errc::invalid_argument),
+ "Failed reading file type from file header at offset %d.", OffsetPtr);
+
+ PreReadOffset = OffsetPtr;
+ uint32_t Bitfield = HeaderExtractor.getU32(&OffsetPtr);
+ if (OffsetPtr == PreReadOffset)
+ return createStringError(
+ std::make_error_code(std::errc::invalid_argument),
+ "Failed reading flag bits from file header at offset %d.", OffsetPtr);
+
+ FileHeader.ConstantTSC = Bitfield & 1uL;
+ FileHeader.NonstopTSC = Bitfield & 1uL << 1;
+ PreReadOffset = OffsetPtr;
+ FileHeader.CycleFrequency = HeaderExtractor.getU64(&OffsetPtr);
+ if (OffsetPtr == PreReadOffset)
+ return createStringError(
+ std::make_error_code(std::errc::invalid_argument),
+ "Failed reading cycle frequency from file header at offset %d.",
+ OffsetPtr);
+
+ std::memcpy(&FileHeader.FreeFormData,
+ HeaderExtractor.getData().bytes_begin() + OffsetPtr, 16);
+
+ // Manually advance the offset pointer 16 bytes, after getting a raw memcpy
+ // from the underlying data.
+ OffsetPtr += 16;
+ return std::move(FileHeader);
+}
+
+} // namespace xray
+} // namespace llvm