diff options
Diffstat (limited to 'gdb/ax-general.c')
| -rw-r--r-- | gdb/ax-general.c | 552 |
1 files changed, 552 insertions, 0 deletions
diff --git a/gdb/ax-general.c b/gdb/ax-general.c new file mode 100644 index 0000000..76e9bb4 --- /dev/null +++ b/gdb/ax-general.c @@ -0,0 +1,552 @@ +/* Functions for manipulating expressions designed to be executed on the agent + Copyright 1998 Free Software Foundation, Inc. + +This file is part of GDB. + +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +/* $Id$ */ + +/* Despite what the above comment says about this file being part of + GDB, we would like to keep these functions free of GDB + dependencies, since we want to be able to use them in contexts + outside of GDB (test suites, the stub, etc.) */ + +#include "defs.h" +#include "ax.h" + + +/* Functions for building expressions. */ + +/* Allocate a new, empty agent expression. */ +struct agent_expr * +new_agent_expr (scope) + CORE_ADDR scope; +{ + struct agent_expr *x = xmalloc (sizeof (*x)); + x->len = 0; + x->size = 1; /* Change this to a larger value once + reallocation code is tested. */ + x->buf = xmalloc (x->size); + x->scope = scope; + + return x; +} + +/* Free a agent expression. */ +void +free_agent_expr (x) + struct agent_expr *x; +{ + free (x->buf); + free (x); +} + + +/* Make sure that X has room for at least N more bytes. This doesn't + affect the length, just the allocated size. */ +static void +grow_expr (x, n) + struct agent_expr *x; + int n; +{ + if (x->len + n > x->size) + { + x->size *= 2; + if (x->size < x->len + n) + x->size = x->len + n + 10; + x->buf = xrealloc (x->buf, x->size); + } +} + + +/* Append the low N bytes of VAL as an N-byte integer to the + expression X, in big-endian order. */ +static void +append_const (x, val, n) + struct agent_expr *x; + LONGEST val; + int n; +{ + int i; + + grow_expr (x, n); + for (i = n - 1; i >= 0; i--) + { + x->buf[x->len + i] = val & 0xff; + val >>= 8; + } + x->len += n; +} + + +/* Extract an N-byte big-endian unsigned integer from expression X at + offset O. */ +static LONGEST +read_const (x, o, n) + struct agent_expr *x; + int o, n; +{ + int i; + LONGEST accum = 0; + + /* Make sure we're not reading off the end of the expression. */ + if (o + n > x->len) + error ("GDB bug: ax-general.c (read_const): incomplete constant"); + + for (i = 0; i < n; i++) + accum = (accum << 8) | x->buf[o + i]; + + return accum; +} + + +/* Append a simple operator OP to EXPR. */ +void +ax_simple (x, op) + struct agent_expr *x; + enum agent_op op; +{ + grow_expr (x, 1); + x->buf[x->len++] = op; +} + + +/* Append a sign-extension or zero-extension instruction to EXPR, to + extend an N-bit value. */ +static void +generic_ext (x, op, n) + struct agent_expr *x; + enum agent_op op; + int n; +{ + /* N must fit in a byte. */ + if (n < 0 || n > 255) + error ("GDB bug: ax-general.c (generic_ext): bit count out of range"); + /* That had better be enough range. */ + if (sizeof (LONGEST) * 8 > 255) + error ("GDB bug: ax-general.c (generic_ext): opcode has inadequate range"); + + grow_expr (x, 2); + x->buf[x->len++] = op; + x->buf[x->len++] = n; +} + + +/* Append a sign-extension instruction to EXPR, to extend an N-bit value. */ +void +ax_ext (x, n) + struct agent_expr *x; + int n; +{ + generic_ext (x, aop_ext, n); +} + + +/* Append a zero-extension instruction to EXPR, to extend an N-bit value. */ +void +ax_zero_ext (x, n) + struct agent_expr *x; + int n; +{ + generic_ext (x, aop_zero_ext, n); +} + + +/* Append a trace_quick instruction to EXPR, to record N bytes. */ +void +ax_trace_quick (x, n) + struct agent_expr *x; + int n; +{ + /* N must fit in a byte. */ + if (n < 0 || n > 255) + error ("GDB bug: ax-general.c (ax_trace_quick): size out of range for trace_quick"); + + grow_expr (x, 2); + x->buf[x->len++] = aop_trace_quick; + x->buf[x->len++] = n; +} + + +/* Append a goto op to EXPR. OP is the actual op (must be aop_goto or + aop_if_goto). We assume we don't know the target offset yet, + because it's probably a forward branch, so we leave space in EXPR + for the target, and return the offset in EXPR of that space, so we + can backpatch it once we do know the target offset. Use ax_label + to do the backpatching. */ +int ax_goto (x, op) + struct agent_expr *x; + enum agent_op op; +{ + grow_expr (x, 3); + x->buf[x->len + 0] = op; + x->buf[x->len + 1] = 0xff; + x->buf[x->len + 2] = 0xff; + x->len += 3; + return x->len - 2; +} + +/* Suppose a given call to ax_goto returns some value PATCH. When you + know the offset TARGET that goto should jump to, call + ax_label (EXPR, PATCH, TARGET) + to patch TARGET into the ax_goto instruction. */ +void +ax_label (x, patch, target) + struct agent_expr *x; + int patch; + int target; +{ + /* Make sure the value is in range. Don't accept 0xffff as an + offset; that's our magic sentinel value for unpatched branches. */ + if (target < 0 || target >= 0xffff) + error ("GDB bug: ax-general.c (ax_label): label target out of range"); + + x->buf[patch] = (target >> 8) & 0xff; + x->buf[patch + 1] = target & 0xff; +} + + +/* Assemble code to push a constant on the stack. */ +void +ax_const_l (x, l) + struct agent_expr *x; + LONGEST l; +{ + static enum agent_op ops[] + = { aop_const8, aop_const16, aop_const32, aop_const64 }; + int size; + int op; + + /* How big is the number? 'op' keeps track of which opcode to use. + Notice that we don't really care whether the original number was + signed or unsigned; we always reproduce the value exactly, and + use the shortest representation. */ + for (op = 0, size = 8; size < 64; size *= 2, op++) + if (-((LONGEST) 1 << size) <= l && l < ((LONGEST) 1 << size)) + break; + + /* Emit the right opcode... */ + ax_simple (x, ops[op]); + + /* Emit the low SIZE bytes as an unsigned number. We know that + sign-extending this will yield l. */ + append_const (x, l, size / 8); + + /* Now, if it was negative, and not full-sized, sign-extend it. */ + if (l < 0 && size < 64) + ax_ext (x, size); +} + + +void +ax_const_d (x, d) + struct agent_expr *x; + LONGEST d; +{ + /* FIXME: floating-point support not present yet. */ + error ("GDB bug: ax-general.c (ax_const_d): floating point not supported yet"); +} + + +/* Assemble code to push the value of register number REG on the + stack. */ +void ax_reg (x, reg) + struct agent_expr *x; + int reg; +{ + /* Make sure the register number is in range. */ + if (reg < 0 || reg > 0xffff) + error ("GDB bug: ax-general.c (ax_reg): register number out of range"); + grow_expr (x, 3); + x->buf[x->len ] = aop_reg; + x->buf[x->len + 1] = (reg >> 8) & 0xff; + x->buf[x->len + 2] = (reg ) & 0xff; + x->len += 3; +} + + + +/* Functions for disassembling agent expressions, and otherwise + debugging the expression compiler. */ + +struct aop_map aop_map[] = { + { 0, 0, 0, 0, 0 }, + { "float", 0, 0, 0, 0 }, /* 0x01 */ + { "add", 0, 0, 2, 1 }, /* 0x02 */ + { "sub", 0, 0, 2, 1 }, /* 0x03 */ + { "mul", 0, 0, 2, 1 }, /* 0x04 */ + { "div_signed", 0, 0, 2, 1 }, /* 0x05 */ + { "div_unsigned", 0, 0, 2, 1 }, /* 0x06 */ + { "rem_signed", 0, 0, 2, 1 }, /* 0x07 */ + { "rem_unsigned", 0, 0, 2, 1 }, /* 0x08 */ + { "lsh", 0, 0, 2, 1 }, /* 0x09 */ + { "rsh_signed", 0, 0, 2, 1 }, /* 0x0a */ + { "rsh_unsigned", 0, 0, 2, 1 }, /* 0x0b */ + { "trace", 0, 0, 2, 0 }, /* 0x0c */ + { "trace_quick", 1, 0, 1, 1 }, /* 0x0d */ + { "log_not", 0, 0, 1, 1 }, /* 0x0e */ + { "bit_and", 0, 0, 2, 1 }, /* 0x0f */ + { "bit_or", 0, 0, 2, 1 }, /* 0x10 */ + { "bit_xor", 0, 0, 2, 1 }, /* 0x11 */ + { "bit_not", 0, 0, 1, 1 }, /* 0x12 */ + { "equal", 0, 0, 2, 1 }, /* 0x13 */ + { "less_signed", 0, 0, 2, 1 }, /* 0x14 */ + { "less_unsigned", 0, 0, 2, 1 }, /* 0x15 */ + { "ext", 1, 0, 1, 1 }, /* 0x16 */ + { "ref8", 0, 8, 1, 1 }, /* 0x17 */ + { "ref16", 0, 16, 1, 1 }, /* 0x18 */ + { "ref32", 0, 32, 1, 1 }, /* 0x19 */ + { "ref64", 0, 64, 1, 1 }, /* 0x1a */ + { "ref_float", 0, 0, 1, 1 }, /* 0x1b */ + { "ref_double", 0, 0, 1, 1 }, /* 0x1c */ + { "ref_long_double", 0, 0, 1, 1 }, /* 0x1d */ + { "l_to_d", 0, 0, 1, 1 }, /* 0x1e */ + { "d_to_l", 0, 0, 1, 1 }, /* 0x1f */ + { "if_goto", 2, 0, 1, 0 }, /* 0x20 */ + { "goto", 2, 0, 0, 0 }, /* 0x21 */ + { "const8", 1, 8, 0, 1 }, /* 0x22 */ + { "const16", 2, 16, 0, 1 }, /* 0x23 */ + { "const32", 4, 32, 0, 1 }, /* 0x24 */ + { "const64", 8, 64, 0, 1 }, /* 0x25 */ + { "reg", 2, 0, 0, 1 }, /* 0x26 */ + { "end", 0, 0, 0, 0 }, /* 0x27 */ + { "dup", 0, 0, 1, 2 }, /* 0x28 */ + { "pop", 0, 0, 1, 0 }, /* 0x29 */ + { "zero_ext", 1, 0, 1, 1 }, /* 0x2a */ + { "swap", 0, 0, 2, 2 }, /* 0x2b */ + { 0, 0, 0, 0, 0 }, /* 0x2c */ + { 0, 0, 0, 0, 0 }, /* 0x2d */ + { 0, 0, 0, 0, 0 }, /* 0x2e */ + { 0, 0, 0, 0, 0 }, /* 0x2f */ + { "trace16", 2, 0, 1, 1 }, /* 0x30 */ +}; + + +/* Disassemble the expression EXPR, writing to F. */ +void +ax_print (f, x) + GDB_FILE *f; + struct agent_expr *x; +{ + int i; + int is_float = 0; + + /* Check the size of the name array against the number of entries in + the enum, to catch additions that people didn't sync. */ + if ((sizeof (aop_map) / sizeof (aop_map[0])) + != aop_last) + error ("GDB bug: ax-general.c (ax_print): opcode map out of sync"); + + for (i = 0; i < x->len; ) + { + enum agent_op op = x->buf[i]; + + if (op >= (sizeof (aop_map) / sizeof (aop_map[0])) + || ! aop_map[op].name) + { + fprintf_filtered (f, "%3d <bad opcode %02x>\n", i, op); + i++; + continue; + } + if (i + 1 + aop_map[op].op_size > x->len) + { + fprintf_filtered (f, "%3d <incomplete opcode %s>\n", + i, aop_map[op].name); + break; + } + + fprintf_filtered (f, "%3d %s", i, aop_map[op].name); + if (aop_map[op].op_size > 0) + { + fputs_filtered (" ", f); + + print_longest (f, 'd', 0, + read_const (x, i + 1, aop_map[op].op_size)); + } + fprintf_filtered (f, "\n"); + i += 1 + aop_map[op].op_size; + + is_float = (op == aop_float); + } +} + + +/* Given an agent expression AX, fill in an agent_reqs structure REQS + describing it. */ +void +ax_reqs (ax, reqs) + struct agent_expr *ax; + struct agent_reqs *reqs; +{ + int i; + int height; + + /* Bit vector for registers used. */ + int reg_mask_len = 1; + unsigned char *reg_mask = xmalloc (reg_mask_len * sizeof (reg_mask[0])); + + /* Jump target table. targets[i] is non-zero iff there is a jump to + offset i. */ + char *targets = (char *) alloca (ax->len * sizeof (targets[0])); + + /* Instruction boundary table. boundary[i] is non-zero iff an + instruction starts at offset i. */ + char *boundary = (char *) alloca (ax->len * sizeof (boundary[0])); + + /* Stack height record. iff either targets[i] or boundary[i] is + non-zero, heights[i] is the height the stack should have before + executing the bytecode at that point. */ + int *heights = (int *) alloca (ax->len * sizeof (heights[0])); + + /* Pointer to a description of the present op. */ + struct aop_map *op; + + memset (reg_mask, 0, reg_mask_len * sizeof (reg_mask[0])); + memset (targets, 0, ax->len * sizeof (targets[0])); + memset (boundary, 0, ax->len * sizeof (boundary[0])); + + reqs->max_height = reqs->min_height = height = 0; + reqs->flaw = agent_flaw_none; + reqs->max_data_size = 0; + + for (i = 0; i < ax->len; i += 1 + op->op_size) + { + if (ax->buf[i] > (sizeof (aop_map) / sizeof (aop_map[0]))) + { + reqs->flaw = agent_flaw_bad_instruction; + free (reg_mask); + return; + } + + op = &aop_map[ax->buf[i]]; + + if (! op->name) + { + reqs->flaw = agent_flaw_bad_instruction; + free (reg_mask); + return; + } + + if (i + 1 + op->op_size > ax->len) + { + reqs->flaw = agent_flaw_incomplete_instruction; + free (reg_mask); + return; + } + + /* If this instruction is a jump target, does the current stack + height match the stack height at the jump source? */ + if (targets[i] && (heights[i] != height)) + { + reqs->flaw = agent_flaw_height_mismatch; + free (reg_mask); + return; + } + + boundary[i] = 1; + heights[i] = height; + + height -= op->consumed; + if (height < reqs->min_height) + reqs->min_height = height; + height += op->produced; + if (height > reqs->max_height) + reqs->max_height = height; + + if (op->data_size > reqs->max_data_size) + reqs->max_data_size = op->data_size; + + /* For jump instructions, check that the target is a valid + offset. If it is, record the fact that that location is a + jump target, and record the height we expect there. */ + if (aop_goto == op - aop_map + || aop_if_goto == op - aop_map) + { + int target = read_const (ax, i + 1, 2); + if (target < 0 || target >= ax->len) + { + reqs->flaw = agent_flaw_bad_jump; + free (reg_mask); + return; + } + /* Have we already found other jumps to the same location? */ + else if (targets[target]) + { + if (heights[i] != height) + { + reqs->flaw = agent_flaw_height_mismatch; + free (reg_mask); + return; + } + } + else + { + targets[target] = 1; + heights[target] = height; + } + } + + /* For unconditional jumps with a successor, check that the + successor is a target, and pick up its stack height. */ + if (aop_goto == op - aop_map + && i + 3 < ax->len) + { + if (! targets[i + 3]) + { + reqs->flaw = agent_flaw_hole; + free (reg_mask); + return; + } + + height = heights[i + 3]; + } + + /* For reg instructions, record the register in the bit mask. */ + if (aop_reg == op - aop_map) + { + int reg = read_const (ax, i + 1, 2); + int byte = reg / 8; + + /* Grow the bit mask if necessary. */ + if (byte >= reg_mask_len) + { + /* It's not appropriate to double here. This isn't a + string buffer. */ + int new_len = byte + 1; + reg_mask = xrealloc (reg_mask, + new_len * sizeof (reg_mask[0])); + memset (reg_mask + reg_mask_len, 0, + (new_len - reg_mask_len) * sizeof (reg_mask[0])); + reg_mask_len = new_len; + } + + reg_mask[byte] |= 1 << (reg % 8); + } + } + + /* Check that all the targets are on boundaries. */ + for (i = 0; i < ax->len; i++) + if (targets[i] && !boundary[i]) + { + reqs->flaw = agent_flaw_bad_jump; + free (reg_mask); + return; + } + + reqs->final_height = height; + reqs->reg_mask_len = reg_mask_len; + reqs->reg_mask = reg_mask; +} |