Re: [Lldb-commits] [PATCH] D18982: Handle bit fields on big-endian systems correctly
This revision was automatically updated to reflect the committed changes.
Closed by commit rL266312: Handle bit fields on big-endian systems correctly
(authored by uweigand).
Changed prior to commit:
http://reviews.llvm.org/D18982?vs=53605&id=53711#toc
Repository:
rL LLVM
http://reviews.llvm.org/D18982
Files:
lldb/trunk/include/lldb/Core/DataExtractor.h
lldb/trunk/source/Core/DataExtractor.cpp
lldb/trunk/source/Core/ValueObject.cpp
lldb/trunk/unittests/Core/CMakeLists.txt
lldb/trunk/unittests/Core/DataExtractorTest.cpp
Index: lldb/trunk/include/lldb/Core/DataExtractor.h
===
--- lldb/trunk/include/lldb/Core/DataExtractor.h
+++ lldb/trunk/include/lldb/Core/DataExtractor.h
@@ -763,8 +763,10 @@
///
/// @param[in] bitfield_bit_offset
/// The bit offset of the bitfield value in the extracted
-/// integer (the number of bits to shift the integer to the
-/// right).
+/// integer. For little-endian data, this is the offset of
+/// the LSB of the bitfield from the LSB of the integer.
+/// For big-endian data, this is the offset of the MSB of the
+/// bitfield from the MSB of the integer.
///
/// @return
/// The unsigned bitfield integer value that was extracted, or
@@ -805,8 +807,10 @@
///
/// @param[in] bitfield_bit_offset
/// The bit offset of the bitfield value in the extracted
-/// integer (the number of bits to shift the integer to the
-/// right).
+/// integer. For little-endian data, this is the offset of
+/// the LSB of the bitfield from the LSB of the integer.
+/// For big-endian data, this is the offset of the MSB of the
+/// bitfield from the MSB of the integer.
///
/// @return
/// The signed bitfield integer value that was extracted, or
Index: lldb/trunk/unittests/Core/DataExtractorTest.cpp
===
--- lldb/trunk/unittests/Core/DataExtractorTest.cpp
+++ lldb/trunk/unittests/Core/DataExtractorTest.cpp
@@ -0,0 +1,39 @@
+//===-- DataExtractorTest.cpp ---*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===--===//
+
+#if defined(_MSC_VER) && (_HAS_EXCEPTIONS == 0)
+// Workaround for MSVC standard library bug, which fails to include when
+// exceptions are disabled.
+#include
+#endif
+
+#include "gtest/gtest.h"
+
+#include "lldb/Core/DataExtractor.h"
+
+using namespace lldb_private;
+
+TEST(DataExtractorTest, GetBitfield)
+{
+char buffer[] = { 0x01, 0x23, 0x45, 0x67 };
+DataExtractor LE(buffer, sizeof(buffer), lldb::eByteOrderLittle, sizeof(void *));
+DataExtractor BE(buffer, sizeof(buffer), lldb::eByteOrderBig, sizeof(void *));
+
+lldb::offset_t offset;
+
+offset = 0;
+ASSERT_EQ(buffer[1], LE.GetMaxU64Bitfield(&offset, sizeof(buffer), 8, 8));
+offset = 0;
+ASSERT_EQ(buffer[1], BE.GetMaxU64Bitfield(&offset, sizeof(buffer), 8, 8));
+
+offset = 0;
+ASSERT_EQ(buffer[1], LE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8));
+offset = 0;
+ASSERT_EQ(buffer[1], BE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8));
+}
Index: lldb/trunk/unittests/Core/CMakeLists.txt
===
--- lldb/trunk/unittests/Core/CMakeLists.txt
+++ lldb/trunk/unittests/Core/CMakeLists.txt
@@ -1,3 +1,4 @@
add_lldb_unittest(LLDBCoreTests
+ DataExtractorTest.cpp
ScalarTest.cpp
)
Index: lldb/trunk/source/Core/ValueObject.cpp
===
--- lldb/trunk/source/Core/ValueObject.cpp
+++ lldb/trunk/source/Core/ValueObject.cpp
@@ -2146,15 +2146,19 @@
synthetic_child_sp = GetSyntheticChild (index_const_str);
if (!synthetic_child_sp)
{
+uint32_t bit_field_size = to - from + 1;
+uint32_t bit_field_offset = from;
+if (GetDataExtractor().GetByteOrder() == eByteOrderBig)
+bit_field_offset = GetByteSize() * 8 - bit_field_size - bit_field_offset;
// We haven't made a synthetic array member for INDEX yet, so
// lets make one and cache it for any future reference.
ValueObjectChild *synthetic_child = new ValueObjectChild (*this,
GetCompilerType(),
index_const_str,
GetByteSize(),
0,
-
Re: [Lldb-commits] [PATCH] D18982: Handle bit fields on big-endian systems correctly
uweigand updated this revision to Diff 53605.
uweigand added a comment.
Updated interface documentation in DataExtractor.h.
Added unit test case for the DataExtractor::GetMaxU64Bitfield and
GetMaxS64Bitfield routines.
Retested on System z and Intel.
http://reviews.llvm.org/D18982
Files:
include/lldb/Core/DataExtractor.h
source/Core/DataExtractor.cpp
source/Core/ValueObject.cpp
unittests/Core/CMakeLists.txt
unittests/Core/DataExtractorTest.cpp
Index: unittests/Core/DataExtractorTest.cpp
===
--- unittests/Core/DataExtractorTest.cpp
+++ unittests/Core/DataExtractorTest.cpp
@@ -0,0 +1,39 @@
+//===-- DataExtractorTest.cpp ---*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===--===//
+
+#if defined(_MSC_VER) && (_HAS_EXCEPTIONS == 0)
+// Workaround for MSVC standard library bug, which fails to include when
+// exceptions are disabled.
+#include
+#endif
+
+#include "gtest/gtest.h"
+
+#include "lldb/Core/DataExtractor.h"
+
+using namespace lldb_private;
+
+TEST(DataExtractorTest, GetBitfield)
+{
+char buffer[] = { 0x01, 0x23, 0x45, 0x67 };
+DataExtractor LE(buffer, sizeof(buffer), lldb::eByteOrderLittle, sizeof(void *));
+DataExtractor BE(buffer, sizeof(buffer), lldb::eByteOrderBig, sizeof(void *));
+
+lldb::offset_t offset;
+
+offset = 0;
+ASSERT_EQ(buffer[1], LE.GetMaxU64Bitfield(&offset, sizeof(buffer), 8, 8));
+offset = 0;
+ASSERT_EQ(buffer[1], BE.GetMaxU64Bitfield(&offset, sizeof(buffer), 8, 8));
+
+offset = 0;
+ASSERT_EQ(buffer[1], LE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8));
+offset = 0;
+ASSERT_EQ(buffer[1], BE.GetMaxS64Bitfield(&offset, sizeof(buffer), 8, 8));
+}
Index: unittests/Core/CMakeLists.txt
===
--- unittests/Core/CMakeLists.txt
+++ unittests/Core/CMakeLists.txt
@@ -1,3 +1,4 @@
add_lldb_unittest(LLDBCoreTests
+ DataExtractorTest.cpp
ScalarTest.cpp
)
Index: source/Core/ValueObject.cpp
===
--- source/Core/ValueObject.cpp
+++ source/Core/ValueObject.cpp
@@ -2146,15 +2146,19 @@
synthetic_child_sp = GetSyntheticChild (index_const_str);
if (!synthetic_child_sp)
{
+uint32_t bit_field_size = to - from + 1;
+uint32_t bit_field_offset = from;
+if (GetDataExtractor().GetByteOrder() == eByteOrderBig)
+bit_field_offset = GetByteSize() * 8 - bit_field_size - bit_field_offset;
// We haven't made a synthetic array member for INDEX yet, so
// lets make one and cache it for any future reference.
ValueObjectChild *synthetic_child = new ValueObjectChild (*this,
GetCompilerType(),
index_const_str,
GetByteSize(),
0,
- to-from+1,
- from,
+ bit_field_size,
+ bit_field_offset,
false,
false,
eAddressTypeInvalid,
Index: source/Core/DataExtractor.cpp
===
--- source/Core/DataExtractor.cpp
+++ source/Core/DataExtractor.cpp
@@ -733,8 +733,11 @@
uint64_t uval64 = GetMaxU64 (offset_ptr, size);
if (bitfield_bit_size > 0)
{
-if (bitfield_bit_offset > 0)
-uval64 >>= bitfield_bit_offset;
+int32_t lsbcount = bitfield_bit_offset;
+if (m_byte_order == eByteOrderBig)
+lsbcount = size * 8 - bitfield_bit_offset - bitfield_bit_size;
+if (lsbcount > 0)
+uval64 >>= lsbcount;
uint64_t bitfield_mask = ((1ul << bitfield_bit_size) - 1);
if (!bitfield_mask && bitfield_bit_offset == 0 && bitfield_bit_size == 64)
return uval64;
@@ -749,8 +752,11 @@
int64_t sval64 = GetMaxS64 (offset_ptr, size);
if (bitfield_bit_size > 0)
{
-if (bitfield_bit_offset > 0)
-sval64 >>= bitfield_bit_offset;
+int32_t lsbcount = bitfield_bit_offset;
+if
Re: [Lldb-commits] [PATCH] D18982: Handle bit fields on big-endian systems correctly
labath added a subscriber: labath. labath added a comment. It would be worthwhile to add a unit test for the DataExtractor fix (we don't have many of those, but we're trying to build them up). http://reviews.llvm.org/D18982 ___ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
Re: [Lldb-commits] [PATCH] D18982: Handle bit fields on big-endian systems correctly
clayborg accepted this revision. clayborg added a comment. This revision is now accepted and ready to land. Looks good as long as all tests still pass on all other systems. http://reviews.llvm.org/D18982 ___ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
[Lldb-commits] [PATCH] D18982: Handle bit fields on big-endian systems correctly
uweigand created this revision.
uweigand added reviewers: granata.enrico, clayborg.
uweigand added a subscriber: lldb-commits.
Currently, the DataExtractor::GetMaxU64Bitfield and GetMaxS64Bitfield
routines assume the incoming "bitfield_bit_offset" parameter uses
little-endian bit numbering, i.e. a bitfield_bit_offset 0 refers to
a bitfield whose least-significant bit coincides with the least-
significant bit of the surrounding integer.
On many big-endian systems, however, the big-endian bit numbering
is used for bit fields. Here, a bitfield_bit_offset 0 refers to
a bitfield whose most-significant bit conincides with the most-
significant bit of the surrounding integer.
Now, in principle LLDB could arbitrarily choose which semantics of
bitfield_bit_offset to use. However, there are two problems with
the current approach:
- When parsing DWARF, LLDB decodes bit offsets in little-endian
bit numbering on LE systems, but in big-endian bit numbering
on BE systems. Passing those offsets later on into the
DataExtractor routines gives incorrect results on BE.
- In the interim, LLDB's type layer combines byte and bit offsets
into a single number. I.e. instead of recording bitfields by
specifying the byte offset and byte size of the surrounding
integer *plus* the bit offset of the bit field within that field,
it simply records a single bit offset number.
Now, note that converting from byte offset + bit offset to a
single offset value and back is well-defined if we either use
little-endian byte order *and* little-endian bit numbering,
or use big-endian byte order *and* big-endian bit numbering.
Any other combination will yield incorrect results.
Therefore, the simplest approach would seem to be to always use
the bit numbering that matches the system byte order. This makes
storing a single bit offset valid, and makes the existing DWARF
code correct. The only place to fix is to teach DataExtractor
to use big-endian bit numbering on big endian systems.
However, there is only additional caveat: we also get bit offsets
from LLDB synthetic bitfields. While the exact semantics of those
doesn't seem to be well-defined, from test cases it appears that
the intent was for the user-provided synthetic bitfield offset to
always use little-endian bit numbering. Therefore, on a big-endian
system we now have to convert those to big-endian bit numbering
to remain consistent.
http://reviews.llvm.org/D18982
Files:
source/Core/DataExtractor.cpp
source/Core/ValueObject.cpp
Index: source/Core/ValueObject.cpp
===
--- source/Core/ValueObject.cpp
+++ source/Core/ValueObject.cpp
@@ -2146,15 +2146,19 @@
synthetic_child_sp = GetSyntheticChild (index_const_str);
if (!synthetic_child_sp)
{
+uint32_t bit_field_size = to - from + 1;
+uint32_t bit_field_offset = from;
+if (GetDataExtractor().GetByteOrder() == eByteOrderBig)
+bit_field_offset = GetByteSize() * 8 - bit_field_size -
bit_field_offset;
// We haven't made a synthetic array member for INDEX yet, so
// lets make one and cache it for any future reference.
ValueObjectChild *synthetic_child = new ValueObjectChild (*this,
GetCompilerType(),
index_const_str,
GetByteSize(),
0,
-
to-from+1,
- from,
+
bit_field_size,
+
bit_field_offset,
false,
false,
eAddressTypeInvalid,
Index: source/Core/DataExtractor.cpp
===
--- source/Core/DataExtractor.cpp
+++ source/Core/DataExtractor.cpp
@@ -733,8 +733,11 @@
uint64_t uval64 = GetMaxU64 (offset_ptr, size);
if (bitfield_bit_size > 0)
{
-if (bitfield_bit_offset > 0)
-uval64 >>= bitfield_bit_offset;
+int32_t lsbcount = bitfield_bit_offset;
+if (m_byte_order == eByteOrderBig)
+lsbcount = size * 8 - bitfield_bit_offset - bitfield_bit_size;
+if (lsbcount > 0)
+uval64 >>= lsbcount;
uint64_t bitfield_mask = ((1ul << bitfield_bit_size) - 1);
if (!bitfield_mask && bitfield_bit_offset == 0 && bitfield_bit_size ==
64)
