1 /*
2 * Helpers for creating and querying pc2line debug data, which
3 * converts a bytecode program counter to a source line number.
4 *
5 * The run-time pc2line data is bit-packed, and documented in:
6 *
7 * doc/function-objects.rst
8 */
9
10 #include "duk_internal.h"
11
12 #if defined(DUK_USE_PC2LINE)
13
14 /* Generate pc2line data for an instruction sequence, leaving a buffer on stack top. */
duk_hobject_pc2line_pack(duk_hthread * thr,duk_compiler_instr * instrs,duk_uint_fast32_t length)15 DUK_INTERNAL void duk_hobject_pc2line_pack(duk_hthread *thr, duk_compiler_instr *instrs, duk_uint_fast32_t length) {
16 duk_context *ctx = (duk_context *) thr;
17 duk_hbuffer_dynamic *h_buf;
18 duk_bitencoder_ctx be_ctx_alloc;
19 duk_bitencoder_ctx *be_ctx = &be_ctx_alloc;
20 duk_uint32_t *hdr;
21 duk_size_t new_size;
22 duk_uint_fast32_t num_header_entries;
23 duk_uint_fast32_t curr_offset;
24 duk_int_fast32_t curr_line, next_line, diff_line;
25 duk_uint_fast32_t curr_pc;
26 duk_uint_fast32_t hdr_index;
27
28 DUK_ASSERT(length <= DUK_COMPILER_MAX_BYTECODE_LENGTH);
29
30 /* XXX: add proper spare handling to dynamic buffer, to minimize
31 * reallocs; currently there is no spare at all.
32 */
33
34 num_header_entries = (length + DUK_PC2LINE_SKIP - 1) / DUK_PC2LINE_SKIP;
35 curr_offset = (duk_uint_fast32_t) (sizeof(duk_uint32_t) + num_header_entries * sizeof(duk_uint32_t) * 2);
36
37 duk_push_dynamic_buffer(ctx, (duk_size_t) curr_offset);
38 h_buf = (duk_hbuffer_dynamic *) duk_get_hbuffer(ctx, -1);
39 DUK_ASSERT(h_buf != NULL);
40 DUK_ASSERT(DUK_HBUFFER_HAS_DYNAMIC(h_buf) && !DUK_HBUFFER_HAS_EXTERNAL(h_buf));
41
42 hdr = (duk_uint32_t *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(thr->heap, h_buf);
43 DUK_ASSERT(hdr != NULL);
44 hdr[0] = (duk_uint32_t) length; /* valid pc range is [0, length[ */
45
46 curr_pc = 0U;
47 while (curr_pc < length) {
48 new_size = (duk_size_t) (curr_offset + DUK_PC2LINE_MAX_DIFF_LENGTH);
49 duk_hbuffer_resize(thr, h_buf, new_size);
50
51 hdr = (duk_uint32_t *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(thr->heap, h_buf);
52 DUK_ASSERT(hdr != NULL);
53 DUK_ASSERT(curr_pc < length);
54 hdr_index = 1 + (curr_pc / DUK_PC2LINE_SKIP) * 2;
55 curr_line = (duk_int_fast32_t) instrs[curr_pc].line;
56 hdr[hdr_index + 0] = (duk_uint32_t) curr_line;
57 hdr[hdr_index + 1] = (duk_uint32_t) curr_offset;
58
59 #if 0
60 DUK_DDD(DUK_DDDPRINT("hdr[%ld]: pc=%ld line=%ld offset=%ld",
61 (long) (curr_pc / DUK_PC2LINE_SKIP),
62 (long) curr_pc,
63 (long) hdr[hdr_index + 0],
64 (long) hdr[hdr_index + 1]));
65 #endif
66
67 DUK_MEMZERO(be_ctx, sizeof(*be_ctx));
68 be_ctx->data = ((duk_uint8_t *) hdr) + curr_offset;
69 be_ctx->length = (duk_size_t) DUK_PC2LINE_MAX_DIFF_LENGTH;
70
71 for (;;) {
72 curr_pc++;
73 if ( ((curr_pc % DUK_PC2LINE_SKIP) == 0) || /* end of diff run */
74 (curr_pc >= length) ) { /* end of bytecode */
75 break;
76 }
77 DUK_ASSERT(curr_pc < length);
78 next_line = (duk_int32_t) instrs[curr_pc].line;
79 diff_line = next_line - curr_line;
80
81 #if 0
82 DUK_DDD(DUK_DDDPRINT("curr_line=%ld, next_line=%ld -> diff_line=%ld",
83 (long) curr_line, (long) next_line, (long) diff_line));
84 #endif
85
86 if (diff_line == 0) {
87 /* 0 */
88 duk_be_encode(be_ctx, 0, 1);
89 } else if (diff_line >= 1 && diff_line <= 4) {
90 /* 1 0 <2 bits> */
91 duk_be_encode(be_ctx, (0x02 << 2) + (diff_line - 1), 4);
92 } else if (diff_line >= -0x80 && diff_line <= 0x7f) {
93 /* 1 1 0 <8 bits> */
94 DUK_ASSERT(diff_line + 0x80 >= 0 && diff_line + 0x80 <= 0xff);
95 duk_be_encode(be_ctx, (0x06 << 8) + (diff_line + 0x80), 11);
96 } else {
97 /* 1 1 1 <32 bits>
98 * Encode in two parts to avoid bitencode 24-bit limitation
99 */
100 duk_be_encode(be_ctx, (0x07 << 16) + ((next_line >> 16) & 0xffffU), 19);
101 duk_be_encode(be_ctx, next_line & 0xffffU, 16);
102 }
103
104 curr_line = next_line;
105 }
106
107 duk_be_finish(be_ctx);
108 DUK_ASSERT(!be_ctx->truncated);
109
110 /* be_ctx->offset == length of encoded bitstream */
111 curr_offset += (duk_uint_fast32_t) be_ctx->offset;
112 }
113
114 /* compact */
115 new_size = (duk_size_t) curr_offset;
116 duk_hbuffer_resize(thr, h_buf, new_size);
117
118 (void) duk_to_fixed_buffer(ctx, -1, NULL);
119
120 DUK_DDD(DUK_DDDPRINT("final pc2line data: pc_limit=%ld, length=%ld, %lf bits/opcode --> %!ixT",
121 (long) length, (long) new_size, (double) new_size * 8.0 / (double) length,
122 (duk_tval *) duk_get_tval(ctx, -1)));
123 }
124
125 /* PC is unsigned. If caller does PC arithmetic and gets a negative result,
126 * it will map to a large PC which is out of bounds and causes a zero to be
127 * returned.
128 */
duk__hobject_pc2line_query_raw(duk_hthread * thr,duk_hbuffer_fixed * buf,duk_uint_fast32_t pc)129 DUK_LOCAL duk_uint_fast32_t duk__hobject_pc2line_query_raw(duk_hthread *thr, duk_hbuffer_fixed *buf, duk_uint_fast32_t pc) {
130 duk_bitdecoder_ctx bd_ctx_alloc;
131 duk_bitdecoder_ctx *bd_ctx = &bd_ctx_alloc;
132 duk_uint32_t *hdr;
133 duk_uint_fast32_t start_offset;
134 duk_uint_fast32_t pc_limit;
135 duk_uint_fast32_t hdr_index;
136 duk_uint_fast32_t pc_base;
137 duk_uint_fast32_t n;
138 duk_uint_fast32_t curr_line;
139
140 DUK_ASSERT(buf != NULL);
141 DUK_ASSERT(!DUK_HBUFFER_HAS_DYNAMIC((duk_hbuffer *) buf) && !DUK_HBUFFER_HAS_EXTERNAL((duk_hbuffer *) buf));
142 DUK_UNREF(thr);
143
144 /*
145 * Use the index in the header to find the right starting point
146 */
147
148 hdr_index = pc / DUK_PC2LINE_SKIP;
149 pc_base = hdr_index * DUK_PC2LINE_SKIP;
150 n = pc - pc_base;
151
152 if (DUK_HBUFFER_FIXED_GET_SIZE(buf) <= sizeof(duk_uint32_t)) {
153 DUK_DD(DUK_DDPRINT("pc2line lookup failed: buffer is smaller than minimal header"));
154 goto error;
155 }
156
157 hdr = (duk_uint32_t *) (void *) DUK_HBUFFER_FIXED_GET_DATA_PTR(thr->heap, buf);
158 pc_limit = hdr[0];
159 if (pc >= pc_limit) {
160 /* Note: pc is unsigned and cannot be negative */
161 DUK_DD(DUK_DDPRINT("pc2line lookup failed: pc out of bounds (pc=%ld, limit=%ld)",
162 (long) pc, (long) pc_limit));
163 goto error;
164 }
165
166 curr_line = hdr[1 + hdr_index * 2];
167 start_offset = hdr[1 + hdr_index * 2 + 1];
168 if ((duk_size_t) start_offset > DUK_HBUFFER_FIXED_GET_SIZE(buf)) {
169 DUK_DD(DUK_DDPRINT("pc2line lookup failed: start_offset out of bounds (start_offset=%ld, buffer_size=%ld)",
170 (long) start_offset, (long) DUK_HBUFFER_GET_SIZE((duk_hbuffer *) buf)));
171 goto error;
172 }
173
174 /*
175 * Iterate the bitstream (line diffs) until PC is reached
176 */
177
178 DUK_MEMZERO(bd_ctx, sizeof(*bd_ctx));
179 bd_ctx->data = ((duk_uint8_t *) hdr) + start_offset;
180 bd_ctx->length = (duk_size_t) (DUK_HBUFFER_FIXED_GET_SIZE(buf) - start_offset);
181
182 #if 0
183 DUK_DDD(DUK_DDDPRINT("pc2line lookup: pc=%ld -> hdr_index=%ld, pc_base=%ld, n=%ld, start_offset=%ld",
184 (long) pc, (long) hdr_index, (long) pc_base, (long) n, (long) start_offset));
185 #endif
186
187 while (n > 0) {
188 #if 0
189 DUK_DDD(DUK_DDDPRINT("lookup: n=%ld, curr_line=%ld", (long) n, (long) curr_line));
190 #endif
191
192 if (duk_bd_decode_flag(bd_ctx)) {
193 if (duk_bd_decode_flag(bd_ctx)) {
194 if (duk_bd_decode_flag(bd_ctx)) {
195 /* 1 1 1 <32 bits> */
196 duk_uint_fast32_t t;
197 t = duk_bd_decode(bd_ctx, 16); /* workaround: max nbits = 24 now */
198 t = (t << 16) + duk_bd_decode(bd_ctx, 16);
199 curr_line = t;
200 } else {
201 /* 1 1 0 <8 bits> */
202 duk_uint_fast32_t t;
203 t = duk_bd_decode(bd_ctx, 8);
204 curr_line = curr_line + t - 0x80;
205 }
206 } else {
207 /* 1 0 <2 bits> */
208 duk_uint_fast32_t t;
209 t = duk_bd_decode(bd_ctx, 2);
210 curr_line = curr_line + t + 1;
211 }
212 } else {
213 /* 0: no change */
214 }
215
216 n--;
217 }
218
219 DUK_DDD(DUK_DDDPRINT("pc2line lookup result: pc %ld -> line %ld", (long) pc, (long) curr_line));
220 return curr_line;
221
222 error:
223 DUK_D(DUK_DPRINT("pc2line conversion failed for pc=%ld", (long) pc));
224 return 0;
225 }
226
duk_hobject_pc2line_query(duk_context * ctx,duk_idx_t idx_func,duk_uint_fast32_t pc)227 DUK_INTERNAL duk_uint_fast32_t duk_hobject_pc2line_query(duk_context *ctx, duk_idx_t idx_func, duk_uint_fast32_t pc) {
228 duk_hbuffer_fixed *pc2line;
229 duk_uint_fast32_t line;
230
231 /* XXX: now that pc2line is used by the debugger quite heavily in
232 * checked execution, this should be optimized to avoid value stack
233 * and perhaps also implement some form of pc2line caching (see
234 * future work in debugger.rst).
235 */
236
237 duk_get_prop_stridx(ctx, idx_func, DUK_STRIDX_INT_PC2LINE);
238 pc2line = (duk_hbuffer_fixed *) duk_get_hbuffer(ctx, -1);
239 if (pc2line != NULL) {
240 DUK_ASSERT(!DUK_HBUFFER_HAS_DYNAMIC((duk_hbuffer *) pc2line) && !DUK_HBUFFER_HAS_EXTERNAL((duk_hbuffer *) pc2line));
241 line = duk__hobject_pc2line_query_raw((duk_hthread *) ctx, pc2line, (duk_uint_fast32_t) pc);
242 } else {
243 line = 0;
244 }
245 duk_pop(ctx);
246
247 return line;
248 }
249
250 #endif /* DUK_USE_PC2LINE */
251