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cosmopolitan/third_party/duktape/duk_hobject_pc2line.c

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/*
* Helpers for creating and querying pc2line debug data, which
* converts a bytecode program counter to a source line number.
*
* The run-time pc2line data is bit-packed, and documented in:
*
* doc/function-objects.rst
*/
#include "third_party/duktape/duk_internal.h"
#if defined(DUK_USE_PC2LINE)
/* Generate pc2line data for an instruction sequence, leaving a buffer on stack top. */
DUK_INTERNAL void duk_hobject_pc2line_pack(duk_hthread *thr, duk_compiler_instr *instrs, duk_uint_fast32_t length) {
duk_hbuffer_dynamic *h_buf;
duk_bitencoder_ctx be_ctx_alloc;
duk_bitencoder_ctx *be_ctx = &be_ctx_alloc;
duk_uint32_t *hdr;
duk_size_t new_size;
duk_uint_fast32_t num_header_entries;
duk_uint_fast32_t curr_offset;
duk_int_fast32_t curr_line, next_line, diff_line;
duk_uint_fast32_t curr_pc;
duk_uint_fast32_t hdr_index;
DUK_ASSERT(length <= DUK_COMPILER_MAX_BYTECODE_LENGTH);
num_header_entries = (length + DUK_PC2LINE_SKIP - 1) / DUK_PC2LINE_SKIP;
curr_offset = (duk_uint_fast32_t) (sizeof(duk_uint32_t) + num_header_entries * sizeof(duk_uint32_t) * 2);
duk_push_dynamic_buffer(thr, (duk_size_t) curr_offset);
h_buf = (duk_hbuffer_dynamic *) duk_known_hbuffer(thr, -1);
DUK_ASSERT(DUK_HBUFFER_HAS_DYNAMIC(h_buf) && !DUK_HBUFFER_HAS_EXTERNAL(h_buf));
hdr = (duk_uint32_t *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(thr->heap, h_buf);
DUK_ASSERT(hdr != NULL);
hdr[0] = (duk_uint32_t) length; /* valid pc range is [0, length[ */
curr_pc = 0U;
while (curr_pc < length) {
new_size = (duk_size_t) (curr_offset + DUK_PC2LINE_MAX_DIFF_LENGTH);
duk_hbuffer_resize(thr, h_buf, new_size);
hdr = (duk_uint32_t *) DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(thr->heap, h_buf);
DUK_ASSERT(hdr != NULL);
DUK_ASSERT(curr_pc < length);
hdr_index = 1 + (curr_pc / DUK_PC2LINE_SKIP) * 2;
curr_line = (duk_int_fast32_t) instrs[curr_pc].line;
hdr[hdr_index + 0] = (duk_uint32_t) curr_line;
hdr[hdr_index + 1] = (duk_uint32_t) curr_offset;
#if 0
DUK_DDD(DUK_DDDPRINT("hdr[%ld]: pc=%ld line=%ld offset=%ld",
(long) (curr_pc / DUK_PC2LINE_SKIP),
(long) curr_pc,
(long) hdr[hdr_index + 0],
(long) hdr[hdr_index + 1]));
#endif
duk_memzero(be_ctx, sizeof(*be_ctx));
be_ctx->data = ((duk_uint8_t *) hdr) + curr_offset;
be_ctx->length = (duk_size_t) DUK_PC2LINE_MAX_DIFF_LENGTH;
for (;;) {
curr_pc++;
if ( ((curr_pc % DUK_PC2LINE_SKIP) == 0) || /* end of diff run */
(curr_pc >= length) ) { /* end of bytecode */
break;
}
DUK_ASSERT(curr_pc < length);
next_line = (duk_int32_t) instrs[curr_pc].line;
diff_line = next_line - curr_line;
#if 0
DUK_DDD(DUK_DDDPRINT("curr_line=%ld, next_line=%ld -> diff_line=%ld",
(long) curr_line, (long) next_line, (long) diff_line));
#endif
if (diff_line == 0) {
/* 0 */
duk_be_encode(be_ctx, 0, 1);
} else if (diff_line >= 1 && diff_line <= 4) {
/* 1 0 <2 bits> */
duk_be_encode(be_ctx, (duk_uint32_t) ((0x02 << 2) + (diff_line - 1)), 4);
} else if (diff_line >= -0x80 && diff_line <= 0x7f) {
/* 1 1 0 <8 bits> */
DUK_ASSERT(diff_line + 0x80 >= 0 && diff_line + 0x80 <= 0xff);
duk_be_encode(be_ctx, (duk_uint32_t) ((0x06 << 8) + (diff_line + 0x80)), 11);
} else {
/* 1 1 1 <32 bits>
* Encode in two parts to avoid bitencode 24-bit limitation
*/
duk_be_encode(be_ctx, (duk_uint32_t) ((0x07 << 16) + ((next_line >> 16) & 0xffff)), 19);
duk_be_encode(be_ctx, (duk_uint32_t) (next_line & 0xffff), 16);
}
curr_line = next_line;
}
duk_be_finish(be_ctx);
DUK_ASSERT(!be_ctx->truncated);
/* be_ctx->offset == length of encoded bitstream */
curr_offset += (duk_uint_fast32_t) be_ctx->offset;
}
/* compact */
new_size = (duk_size_t) curr_offset;
duk_hbuffer_resize(thr, h_buf, new_size);
(void) duk_to_fixed_buffer(thr, -1, NULL);
DUK_DDD(DUK_DDDPRINT("final pc2line data: pc_limit=%ld, length=%ld, %lf bits/opcode --> %!ixT",
(long) length, (long) new_size, (double) new_size * 8.0 / (double) length,
(duk_tval *) duk_get_tval(thr, -1)));
}
/* PC is unsigned. If caller does PC arithmetic and gets a negative result,
* it will map to a large PC which is out of bounds and causes a zero to be
* returned.
*/
DUK_LOCAL duk_uint_fast32_t duk__hobject_pc2line_query_raw(duk_hthread *thr, duk_hbuffer_fixed *buf, duk_uint_fast32_t pc) {
duk_bitdecoder_ctx bd_ctx_alloc;
duk_bitdecoder_ctx *bd_ctx = &bd_ctx_alloc;
duk_uint32_t *hdr;
duk_uint_fast32_t start_offset;
duk_uint_fast32_t pc_limit;
duk_uint_fast32_t hdr_index;
duk_uint_fast32_t pc_base;
duk_uint_fast32_t n;
duk_uint_fast32_t curr_line;
DUK_ASSERT(buf != NULL);
DUK_ASSERT(!DUK_HBUFFER_HAS_DYNAMIC((duk_hbuffer *) buf) && !DUK_HBUFFER_HAS_EXTERNAL((duk_hbuffer *) buf));
DUK_UNREF(thr);
/*
* Use the index in the header to find the right starting point
*/
hdr_index = pc / DUK_PC2LINE_SKIP;
pc_base = hdr_index * DUK_PC2LINE_SKIP;
n = pc - pc_base;
if (DUK_HBUFFER_FIXED_GET_SIZE(buf) <= sizeof(duk_uint32_t)) {
DUK_DD(DUK_DDPRINT("pc2line lookup failed: buffer is smaller than minimal header"));
goto pc2line_error;
}
hdr = (duk_uint32_t *) (void *) DUK_HBUFFER_FIXED_GET_DATA_PTR(thr->heap, buf);
pc_limit = hdr[0];
if (pc >= pc_limit) {
/* Note: pc is unsigned and cannot be negative */
DUK_DD(DUK_DDPRINT("pc2line lookup failed: pc out of bounds (pc=%ld, limit=%ld)",
(long) pc, (long) pc_limit));
goto pc2line_error;
}
curr_line = hdr[1 + hdr_index * 2];
start_offset = hdr[1 + hdr_index * 2 + 1];
if ((duk_size_t) start_offset > DUK_HBUFFER_FIXED_GET_SIZE(buf)) {
DUK_DD(DUK_DDPRINT("pc2line lookup failed: start_offset out of bounds (start_offset=%ld, buffer_size=%ld)",
(long) start_offset, (long) DUK_HBUFFER_GET_SIZE((duk_hbuffer *) buf)));
goto pc2line_error;
}
/*
* Iterate the bitstream (line diffs) until PC is reached
*/
duk_memzero(bd_ctx, sizeof(*bd_ctx));
bd_ctx->data = ((duk_uint8_t *) hdr) + start_offset;
bd_ctx->length = (duk_size_t) (DUK_HBUFFER_FIXED_GET_SIZE(buf) - start_offset);
#if 0
DUK_DDD(DUK_DDDPRINT("pc2line lookup: pc=%ld -> hdr_index=%ld, pc_base=%ld, n=%ld, start_offset=%ld",
(long) pc, (long) hdr_index, (long) pc_base, (long) n, (long) start_offset));
#endif
while (n > 0) {
#if 0
DUK_DDD(DUK_DDDPRINT("lookup: n=%ld, curr_line=%ld", (long) n, (long) curr_line));
#endif
if (duk_bd_decode_flag(bd_ctx)) {
if (duk_bd_decode_flag(bd_ctx)) {
if (duk_bd_decode_flag(bd_ctx)) {
/* 1 1 1 <32 bits> */
duk_uint_fast32_t t;
t = duk_bd_decode(bd_ctx, 16); /* workaround: max nbits = 24 now */
t = (t << 16) + duk_bd_decode(bd_ctx, 16);
curr_line = t;
} else {
/* 1 1 0 <8 bits> */
duk_uint_fast32_t t;
t = duk_bd_decode(bd_ctx, 8);
curr_line = curr_line + t - 0x80;
}
} else {
/* 1 0 <2 bits> */
duk_uint_fast32_t t;
t = duk_bd_decode(bd_ctx, 2);
curr_line = curr_line + t + 1;
}
} else {
/* 0: no change */
}
n--;
}
DUK_DDD(DUK_DDDPRINT("pc2line lookup result: pc %ld -> line %ld", (long) pc, (long) curr_line));
return curr_line;
pc2line_error:
DUK_D(DUK_DPRINT("pc2line conversion failed for pc=%ld", (long) pc));
return 0;
}
DUK_INTERNAL duk_uint_fast32_t duk_hobject_pc2line_query(duk_hthread *thr, duk_idx_t idx_func, duk_uint_fast32_t pc) {
duk_hbuffer_fixed *pc2line;
duk_uint_fast32_t line;
/* XXX: now that pc2line is used by the debugger quite heavily in
* checked execution, this should be optimized to avoid value stack
* and perhaps also implement some form of pc2line caching (see
* future work in debugger.rst).
*/
duk_xget_owndataprop_stridx_short(thr, idx_func, DUK_STRIDX_INT_PC2LINE);
pc2line = (duk_hbuffer_fixed *) (void *) duk_get_hbuffer(thr, -1);
if (pc2line != NULL) {
DUK_ASSERT(!DUK_HBUFFER_HAS_DYNAMIC((duk_hbuffer *) pc2line) && !DUK_HBUFFER_HAS_EXTERNAL((duk_hbuffer *) pc2line));
line = duk__hobject_pc2line_query_raw(thr, pc2line, (duk_uint_fast32_t) pc);
} else {
line = 0;
}
duk_pop(thr);
return line;
}
#endif /* DUK_USE_PC2LINE */
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