| /* Functions for manipulating expressions designed to be executed on the agent |
| Copyright 1998, 1999, 2000 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. */ |
| |
| /* 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" |
| |
| #include "value.h" |
| |
| static void grow_expr (struct agent_expr *x, int n); |
| |
| static void append_const (struct agent_expr *x, LONGEST val, int n); |
| |
| static LONGEST read_const (struct agent_expr *x, int o, int n); |
| |
| static void generic_ext (struct agent_expr *x, enum agent_op op, int n); |
| |
| /* Functions for building expressions. */ |
| |
| /* Allocate a new, empty agent expression. */ |
| struct agent_expr * |
| new_agent_expr (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 (struct agent_expr *x) |
| { |
| xfree (x->buf); |
| xfree (x); |
| } |
| |
| static void |
| do_free_agent_expr_cleanup (void *x) |
| { |
| free_agent_expr (x); |
| } |
| |
| struct cleanup * |
| make_cleanup_free_agent_expr (struct agent_expr *x) |
| { |
| return make_cleanup (do_free_agent_expr_cleanup, 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 (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 (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 (struct agent_expr *x, int o, int 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 (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 (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 (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 (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 (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 (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 (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 (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 (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 (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 (struct ui_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 (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; |
| xfree (reg_mask); |
| return; |
| } |
| |
| op = &aop_map[ax->buf[i]]; |
| |
| if (!op->name) |
| { |
| reqs->flaw = agent_flaw_bad_instruction; |
| xfree (reg_mask); |
| return; |
| } |
| |
| if (i + 1 + op->op_size > ax->len) |
| { |
| reqs->flaw = agent_flaw_incomplete_instruction; |
| xfree (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; |
| xfree (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; |
| xfree (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; |
| xfree (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; |
| xfree (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; |
| xfree (reg_mask); |
| return; |
| } |
| |
| reqs->final_height = height; |
| reqs->reg_mask_len = reg_mask_len; |
| reqs->reg_mask = reg_mask; |
| } |