A location expression is stored in a block of contiguous bytes.
The bytes form a set of operations.
Each location operation has a 1-byte code
that identifies that operation. Operations can be followed
by one or more bytes of additional data. All operations in a
location expression are concatenated from left to right.
The encodings for the operations in a location expression
are described in Figures 22 and 23.
Operation Code No. of Operands Notes
DW_OP_addr 0x03 1 constant address (size target specific)
DW_OP_deref 0x06 0
DW_OP_const1u 0x08 1 1-byte constant
DW_OP_const1s 0x09 1 1-byte constant
DW_OP_const2u 0x0a 1 2-byte constant
DW_OP_const2s 0x0b 1 2-byte constant
DW_OP_const4u 0x0c 1 4-byte constant
DW_OP_const4s 0x0d 1 4-byte constant
DW_OP_const8u 0x0e 1 8-byte constant
DW_OP_const8s 0x0f 1 8-byte constant
DW_OP_constu 0x10 1 ULEB128 constant
DW_OP_consts 0x11 1 SLEB128 constant
DW_OP_dup 0x12 0
DW_OP_drop 0x13 0
DW_OP_over 0x14 0
DW_OP_pick 0x15 1 1-byte stack index
DW_OP_swap 0x16 0
DW_OP_rot 0x17 0
DW_OP_xderef 0x18 0
DW_OP_abs 0x19 0
DW_OP_and 0x1a 0
DW_OP_div 0x1b 0
DW_OP_minus 0x1c 0
DW_OP_mod 0x1d 0
DW_OP_mul 0x1e 0
DW_OP_neg 0x1f 0
DW_OP_not 0x20 0
DW_OP_or 0x21 0
DW_OP_plus 0x22 0
DW_OP_plus_uconst 0x23 1 ULEB128 addend
DW_OP_shl 0x24 0
DW_OP_shr 0x25 0
DW_OP_shra 0x26 0
Figure 22. Location operation encodings, part 1
Revision: 2.0.0 Page 103 July 27, 1993
Industry Review Draft
DWARF Debugging Information Format
Operation Code No. of Operands Notes
DW_OP_xor 0x27 0
DW_OP_skip 0x2f 1 signed 2-byte constant
DW_OP_bra 0x28 1 signed 2-byte constant
DW_OP_eq 0x29 0
DW_OP_ge 0x2a 0
DW_OP_gt 0x2b 0
DW_OP_le 0x2c 0
DW_OP_lt 0x2d 0
DW_OP_ne 0x2e 0
DW_OP_lit0 0x30 0 literals 0..31 = (DW_OP_LIT0|literal)
DW_OP_lit1 0x31 0
...
DW_OP_lit31 0x4f 0
DW_OP_reg0 0x50 0 reg 0..31 = (DW_OP_REG0|regnum)
DW_OP_reg1 0x51 0
...
DW_OP_reg31 0x6f 0
DW_OP_breg0 0x70 1 SLEB128 offset
DW_OP_breg1 0x71 1 base reg 0..31 = (DW_OP_BREG0|regnum)
...
DW_OP_breg31 0x8f 1
DW_OP_regx 0x90 1 ULEB128 register
DW_OP_fbreg 0x91 1 SLEB128 offset
DW_OP_bregx 0x92 2 ULEB128 register followed by SLEB128 offset
DW_OP_piece 0x93 1 ULEB128 size of piece addressed
DW_OP_deref_size 0x94 1 1-byte size of data retrieved
DW_OP_xderef_size 0x95 1 1-byte size of data retrieved
DW_OP_nop 0x96 0
DW_OP_lo_user 0xe0
DW_OP_hi_user 0xff
Figure 23. Location operation encodings, part 2
7.7.2 Location Lists
Each entry in a location list consists of two relative addresses
followed by a 2-byte length, followed by a block of contiguous
bytes. The length specifies the number of bytes in the block
that follows. The two addresses are the same size as used by
DW_FORM_addr
on the target machine.
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