Unify read_initial_length implementations
There are two implementations of read_initial_length in gdb. This merges them and moves the resulting function to leb.c. 2020-02-08 Tom Tromey <tom@tromey.com> * dwarf2/read.c (read_initial_length): Move to leb.c. * dwarf2/leb.h (read_initial_length): Declare. * dwarf2/leb.c (read_initial_length): Move from read.c. Add handle_nonstd parameter. * dwarf2/frame.c (read_initial_length): Remove. (decode_frame_entry_1): Update. Change-Id: I34d37bad0f8a584bfa781432cba25e05e1bd5750
This commit is contained in:
Tom Tromey
parent
09ba997f32
commit
4075cb2668
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@ -1,3 +1,12 @@
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2020-02-08 Tom Tromey <tom@tromey.com>
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* dwarf2/read.c (read_initial_length): Move to leb.c.
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* dwarf2/leb.h (read_initial_length): Declare.
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* dwarf2/leb.c (read_initial_length): Move from read.c. Add
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handle_nonstd parameter.
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* dwarf2/frame.c (read_initial_length): Remove.
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(decode_frame_entry_1): Update.
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2020-02-08 Tom Tromey <tom@tromey.com>
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* dwarf2/loc.c (dwarf2_find_location_expression)
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@ -1475,24 +1475,6 @@ const struct objfile_key<dwarf2_fde_table,
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gdb::noop_deleter<dwarf2_fde_table>>
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dwarf2_frame_objfile_data;
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static ULONGEST
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read_initial_length (bfd *abfd, const gdb_byte *buf,
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unsigned int *bytes_read_ptr)
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{
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ULONGEST result;
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result = bfd_get_32 (abfd, buf);
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if (result == 0xffffffff)
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{
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result = bfd_get_64 (abfd, buf + 4);
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*bytes_read_ptr = 12;
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}
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else
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*bytes_read_ptr = 4;
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return result;
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}
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/* Pointer encoding helper functions. */
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@ -1744,7 +1726,7 @@ decode_frame_entry_1 (struct comp_unit *unit, const gdb_byte *start,
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uint64_t uleb128;
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buf = start;
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length = read_initial_length (unit->abfd, buf, &bytes_read);
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length = read_initial_length (unit->abfd, buf, &bytes_read, false);
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buf += bytes_read;
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end = buf + (size_t) length;
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@ -83,3 +83,30 @@ read_signed_leb128 (bfd *abfd, const gdb_byte *buf,
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*bytes_read_ptr = num_read;
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return result;
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}
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/* See leb.h. */
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LONGEST
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read_initial_length (bfd *abfd, const gdb_byte *buf, unsigned int *bytes_read,
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bool handle_nonstd)
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{
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LONGEST length = bfd_get_32 (abfd, buf);
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if (length == 0xffffffff)
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{
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length = bfd_get_64 (abfd, buf + 4);
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*bytes_read = 12;
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}
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else if (handle_nonstd && length == 0)
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{
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/* Handle the (non-standard) 64-bit DWARF2 format used by IRIX. */
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length = bfd_get_64 (abfd, buf);
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*bytes_read = 8;
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}
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else
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{
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*bytes_read = 4;
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}
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return length;
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}
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@ -89,4 +89,45 @@ extern LONGEST read_signed_leb128 (bfd *, const gdb_byte *, unsigned int *);
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extern ULONGEST read_unsigned_leb128 (bfd *, const gdb_byte *, unsigned int *);
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/* Read the initial length from a section. The (draft) DWARF 3
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specification allows the initial length to take up either 4 bytes
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or 12 bytes. If the first 4 bytes are 0xffffffff, then the next 8
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bytes describe the length and all offsets will be 8 bytes in length
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instead of 4.
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An older, non-standard 64-bit format is also handled by this
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function. The older format in question stores the initial length
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as an 8-byte quantity without an escape value. Lengths greater
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than 2^32 aren't very common which means that the initial 4 bytes
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is almost always zero. Since a length value of zero doesn't make
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sense for the 32-bit format, this initial zero can be considered to
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be an escape value which indicates the presence of the older 64-bit
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format. As written, the code can't detect (old format) lengths
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greater than 4GB. If it becomes necessary to handle lengths
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somewhat larger than 4GB, we could allow other small values (such
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as the non-sensical values of 1, 2, and 3) to also be used as
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escape values indicating the presence of the old format.
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The value returned via bytes_read should be used to increment the
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relevant pointer after calling read_initial_length().
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[ Note: read_initial_length() and read_offset() are based on the
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document entitled "DWARF Debugging Information Format", revision
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3, draft 8, dated November 19, 2001. This document was obtained
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from:
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http://reality.sgiweb.org/davea/dwarf3-draft8-011125.pdf
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This document is only a draft and is subject to change. (So beware.)
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Details regarding the older, non-standard 64-bit format were
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determined empirically by examining 64-bit ELF files produced by
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the SGI toolchain on an IRIX 6.5 machine.
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- Kevin, July 16, 2002
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] */
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extern LONGEST read_initial_length (bfd *abfd, const gdb_byte *buf,
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unsigned int *bytes_read,
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bool handle_nonstd = true);
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#endif /* GDB_DWARF2_LEB_H */
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@ -1277,8 +1277,6 @@ static CORE_ADDR read_addr_index (struct dwarf2_cu *cu, unsigned int addr_index)
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static CORE_ADDR read_address (bfd *, const gdb_byte *ptr, struct dwarf2_cu *,
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unsigned int *);
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static LONGEST read_initial_length (bfd *, const gdb_byte *, unsigned int *);
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static LONGEST read_checked_initial_length_and_offset
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(bfd *, const gdb_byte *, const struct comp_unit_head *,
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unsigned int *, unsigned int *);
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@ -19016,68 +19014,6 @@ read_address (bfd *abfd, const gdb_byte *buf, struct dwarf2_cu *cu,
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return retval;
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}
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/* Read the initial length from a section. The (draft) DWARF 3
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specification allows the initial length to take up either 4 bytes
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or 12 bytes. If the first 4 bytes are 0xffffffff, then the next 8
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bytes describe the length and all offsets will be 8 bytes in length
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instead of 4.
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An older, non-standard 64-bit format is also handled by this
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function. The older format in question stores the initial length
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as an 8-byte quantity without an escape value. Lengths greater
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than 2^32 aren't very common which means that the initial 4 bytes
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is almost always zero. Since a length value of zero doesn't make
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sense for the 32-bit format, this initial zero can be considered to
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be an escape value which indicates the presence of the older 64-bit
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format. As written, the code can't detect (old format) lengths
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greater than 4GB. If it becomes necessary to handle lengths
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somewhat larger than 4GB, we could allow other small values (such
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as the non-sensical values of 1, 2, and 3) to also be used as
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escape values indicating the presence of the old format.
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The value returned via bytes_read should be used to increment the
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relevant pointer after calling read_initial_length().
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[ Note: read_initial_length() and read_offset() are based on the
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document entitled "DWARF Debugging Information Format", revision
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3, draft 8, dated November 19, 2001. This document was obtained
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from:
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http://reality.sgiweb.org/davea/dwarf3-draft8-011125.pdf
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This document is only a draft and is subject to change. (So beware.)
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Details regarding the older, non-standard 64-bit format were
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determined empirically by examining 64-bit ELF files produced by
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the SGI toolchain on an IRIX 6.5 machine.
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- Kevin, July 16, 2002
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] */
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static LONGEST
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read_initial_length (bfd *abfd, const gdb_byte *buf, unsigned int *bytes_read)
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{
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LONGEST length = bfd_get_32 (abfd, buf);
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if (length == 0xffffffff)
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{
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length = bfd_get_64 (abfd, buf + 4);
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*bytes_read = 12;
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}
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else if (length == 0)
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{
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/* Handle the (non-standard) 64-bit DWARF2 format used by IRIX. */
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length = bfd_get_64 (abfd, buf);
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*bytes_read = 8;
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}
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else
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{
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*bytes_read = 4;
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}
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return length;
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}
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/* Cover function for read_initial_length.
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Returns the length of the object at BUF, and stores the size of the
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initial length in *BYTES_READ and stores the size that offsets will be in
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