jsemit.c

java script test programing source code

        for (sd = sdbase; sd < sdlimit; sd++) {
            JS_ASSERT(JT_HAS_TAG(sd->target));
            sd->offset += delta;

            if (sd->top != top) {
                sdtop = sd;
                top = sd->top;
                JS_ASSERT(top == sd->before);
                pivot = sd->offset;
                pc = base + top;
                op = (JSOp) *pc;
                type = (js_CodeSpec[op].format & JOF_TYPEMASK);
                if (JOF_TYPE_IS_EXTENDED_JUMP(type)) {
                    /*
                     * We already extended all the jump offset operands for
                     * the opcode at sd->top.  Jumps and branches have only
                     * one jump offset operand, but switches have many, all
                     * of which are adjacent in cg->spanDeps.
                     */
                    continue;
                }

                JS_ASSERT(type == JOF_JUMP ||
                          type == JOF_TABLESWITCH ||
                          type == JOF_LOOKUPSWITCH);
            }

            if (!JOF_TYPE_IS_EXTENDED_JUMP(type)) {
                span = SD_SPAN(sd, pivot);
                if (span < JUMP_OFFSET_MIN || JUMP_OFFSET_MAX < span) {
                    ptrdiff_t deltaFromTop = 0;

                    done = JS_FALSE;

                    switch (op) {
                      case JSOP_GOTO:         op = JSOP_GOTOX; break;
                      case JSOP_IFEQ:         op = JSOP_IFEQX; break;
                      case JSOP_IFNE:         op = JSOP_IFNEX; break;
                      case JSOP_OR:           op = JSOP_ORX; break;
                      case JSOP_AND:          op = JSOP_ANDX; break;
                      case JSOP_GOSUB:        op = JSOP_GOSUBX; break;
                      case JSOP_CASE:         op = JSOP_CASEX; break;
                      case JSOP_DEFAULT:      op = JSOP_DEFAULTX; break;
                      case JSOP_TABLESWITCH:  op = JSOP_TABLESWITCHX; break;
                      case JSOP_LOOKUPSWITCH: op = JSOP_LOOKUPSWITCHX; break;
                      default:
                        ReportStatementTooLarge(cx, cg);
                        return JS_FALSE;
                    }
                    *pc = (jsbytecode) op;

                    for (sd2 = sdtop; sd2 < sdlimit && sd2->top == top; sd2++) {
                        if (sd2 <= sd) {
                            /*
                             * sd2->offset already includes delta as it stood
                             * before we entered this loop, but it must also
                             * include the delta relative to top due to all the
                             * extended jump offset immediates for the opcode
                             * starting at top, which we extend in this loop.
                             *
                             * If there is only one extended jump offset, then
                             * sd2->offset won't change and this for loop will
                             * iterate once only.
                             */
                            sd2->offset += deltaFromTop;
                            deltaFromTop += JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN;
                        } else {
                            /*
                             * sd2 comes after sd, and won't be revisited by
                             * the outer for loop, so we have to increase its
                             * offset by delta, not merely by deltaFromTop.
                             */
                            sd2->offset += delta;
                        }

                        delta += JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN;
                        UpdateJumpTargets(cg->jumpTargets, sd2->offset,
                                          JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN);
                    }
                    sd = sd2 - 1;
                }
            }
        }

        growth += delta;
    } while (!done);

    if (growth) {
#ifdef DEBUG_brendan
        printf("%s:%u: %u/%u jumps extended in %d passes (%d=%d+%d)\n",
               cg->filename ? cg->filename : "stdin", cg->firstLine,
               growth / (JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN), cg->numSpanDeps,
               passes, offset + growth, offset, growth);
#endif

        /*
         * Ensure that we have room for the extended jumps, but don't round up
         * to a power of two -- we're done generating code, so we cut to fit.
         */
        limit = CG_LIMIT(cg);
        length = offset + growth;
        next = base + length;
        if (next > limit) {
            JS_ASSERT(length > BYTECODE_CHUNK);
            size = BYTECODE_SIZE(PTRDIFF(limit, base, jsbytecode));
            incr = BYTECODE_SIZE(length) - size;
            JS_ARENA_GROW_CAST(base, jsbytecode *, cg->codePool, size, incr);
            if (!base) {
                JS_ReportOutOfMemory(cx);
                return JS_FALSE;
            }
            CG_BASE(cg) = base;
            CG_LIMIT(cg) = next = base + length;
        }
        CG_NEXT(cg) = next;

        /*
         * Set up a fake span dependency record to guard the end of the code
         * being generated.  This guard record is returned as a fencepost by
         * FindNearestSpanDep if there is no real spandep at or above a given
         * unextended code offset.
         */
        guard.top = -1;
        guard.offset = offset + growth;
        guard.before = offset;
        guard.target = NULL;
    }

    /*
     * Now work backwards through the span dependencies, copying chunks of
     * bytecode between each extended jump toward the end of the grown code
     * space, and restoring immediate offset operands for all jump bytecodes.
     * The first chunk of bytecodes, starting at base and ending at the first
     * extended jump offset (NB: this chunk includes the operation bytecode
     * just before that immediate jump offset), doesn't need to be copied.
     */
    JS_ASSERT(sd == sdlimit);
    top = -1;
    while (--sd >= sdbase) {
        if (sd->top != top) {
            top = sd->top;
            op = (JSOp) base[top];
            type = (js_CodeSpec[op].format & JOF_TYPEMASK);

            for (sd2 = sd - 1; sd2 >= sdbase && sd2->top == top; sd2--)
                continue;
            sd2++;
            pivot = sd2->offset;
            JS_ASSERT(top == sd2->before);
        }

        oldpc = base + sd->before;
        span = SD_SPAN(sd, pivot);

        /*
         * If this jump didn't need to be extended, restore its span immediate
         * offset operand now, overwriting the index of sd within cg->spanDeps
         * that was stored temporarily after *pc when BuildSpanDepTable ran.
         *
         * Note that span might fit in 16 bits even for an extended jump op,
         * if the op has multiple span operands, not all of which overflowed
         * (e.g. JSOP_LOOKUPSWITCH or JSOP_TABLESWITCH where some cases are in
         * range for a short jump, but others are not).
         */
        if (!JOF_TYPE_IS_EXTENDED_JUMP(type)) {
            JS_ASSERT(JUMP_OFFSET_MIN <= span && span <= JUMP_OFFSET_MAX);
            SET_JUMP_OFFSET(oldpc, span);
            continue;
        }

        /*
         * Set up parameters needed to copy the next run of bytecode starting
         * at offset (which is a cursor into the unextended, original bytecode
         * vector), down to sd->before (a cursor of the same scale as offset,
         * it's the index of the original jump pc).  Reuse delta to count the
         * nominal number of bytes to copy.
         */
        pc = base + sd->offset;
        delta = offset - sd->before;
        JS_ASSERT(delta >= 1 + JUMP_OFFSET_LEN);

        /*
         * Don't bother copying the jump offset we're about to reset, but do
         * copy the bytecode at oldpc (which comes just before its immediate
         * jump offset operand), on the next iteration through the loop, by
         * including it in offset's new value.
         */
        offset = sd->before + 1;
        size = BYTECODE_SIZE(delta - (1 + JUMP_OFFSET_LEN));
        if (size) {
            memmove(pc + 1 + JUMPX_OFFSET_LEN,
                    oldpc + 1 + JUMP_OFFSET_LEN,
                    size);
        }

        SET_JUMPX_OFFSET(pc, span);
    }

    if (growth) {
        /*
         * Fix source note deltas.  Don't hardwire the delta fixup adjustment,
         * even though currently it must be JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN
         * at each sd that moved.  The future may bring different offset sizes
         * for span-dependent instruction operands.  However, we fix only main
         * notes here, not prolog notes -- we know that prolog opcodes are not
         * span-dependent, and aren't likely ever to be.
         */
        offset = growth = 0;
        sd = sdbase;
        for (sn = cg->main.notes, snlimit = sn + cg->main.noteCount;
             sn < snlimit;
             sn = SN_NEXT(sn)) {
            /*
             * Recall that the offset of a given note includes its delta, and
             * tells the offset of the annotated bytecode from the main entry
             * point of the script.
             */
            offset += SN_DELTA(sn);
            while (sd < sdlimit && sd->before < offset) {
                /*
                 * To compute the delta to add to sn, we need to look at the
                 * spandep after sd, whose offset - (before + growth) tells by
                 * how many bytes sd's instruction grew.
                 */
                sd2 = sd + 1;
                if (sd2 == sdlimit)
                    sd2 = &guard;
                delta = sd2->offset - (sd2->before + growth);
                if (delta > 0) {
                    JS_ASSERT(delta == JUMPX_OFFSET_LEN - JUMP_OFFSET_LEN);
                    sn = js_AddToSrcNoteDelta(cx, cg, sn, delta);
                    if (!sn)
                        return JS_FALSE;
                    snlimit = cg->main.notes + cg->main.noteCount;
                    growth += delta;
                }
                sd++;
            }

            /*
             * If sn has span-dependent offset operands, check whether each
             * covers further span-dependencies, and increase those operands
             * accordingly.  Some source notes measure offset not from the
             * annotated pc, but from that pc plus some small bias.  NB: we
             * assume that spec->offsetBias can't itself span span-dependent
             * instructions!
             */
            spec = &js_SrcNoteSpec[SN_TYPE(sn)];
            if (spec->isSpanDep) {
                pivot = offset + spec->offsetBias;
                n = spec->arity;
                for (i = 0; i < n; i++) {
                    span = js_GetSrcNoteOffset(sn, i);
                    if (span == 0)
                        continue;
                    target = pivot + span * spec->isSpanDep;
                    sd2 = FindNearestSpanDep(cg, target,
                                             (target >= pivot)
                                             ? sd - sdbase
                                             : 0,
                                             &guard);

                    /*
                     * Increase target by sd2's before-vs-after offset delta,
                     * which is absolute (i.e., relative to start of script,
                     * as is target).  Recompute the span by subtracting its
                     * adjusted pivot from target.
                     */
                    target += sd2->offset - sd2->before;
                    span = target - (pivot + growth);
                    span *= spec->isSpanDep;
                    noteIndex = sn - cg->main.notes;
                    if (!js_SetSrcNoteOffset(cx, cg, noteIndex, i, span))
                        return JS_FALSE;
                    sn = cg->main.notes + noteIndex;
                    snlimit = cg->main.notes + cg->main.noteCount;
                }
            }
        }
        cg->main.lastNoteOffset += growth;

        /*
         * Fix try/catch notes (O(numTryNotes * log2(numSpanDeps)), but it's
         * not clear how we can beat that).
         */
        for (tn = cg->tryBase, tnlimit = cg->tryNext; tn < tnlimit; tn++) {
            /*
             * First, look for the nearest span dependency at/above tn->start.
             * There may not be any such spandep, in which case the guard will
             * be returned.
             */
            offset = tn->start;
            sd = FindNearestSpanDep(cg, offset, 0, &guard);
            delta = sd->offset - sd->before;
            tn->start = offset + delta;

            /*
             * Next, find the nearest spandep at/above tn->start + tn->length.
             * Use its delta minus tn->start's delta to increase tn->length.
             */
            length = tn->length;
            sd2 = FindNearestSpanDep(cg, offset + length, sd - sdbase, &guard);
            if (sd2 != sd)
                tn->length = length + sd2->offset - sd2->before - delta;

            /*
             * Finally, adjust tn->catchStart upward only if it is non-zero,
             * and provided there are spandeps below it that grew.
             */
            offset = tn->catchStart;
            if (offset != 0) {
                sd = FindNearestSpanDep(cg, offset, sd2 - sdbase, &guard);
                tn->catchStart = offset + sd->offset - sd->before;
            }
        }
    }

#ifdef DEBUG_brendan
  {
    uintN bigspans = 0;
    top = -1;
    for (sd = sdbase; sd < sdlimit; sd++) {
        offset = sd->offset;

        /* NB: sd->top cursors into the original, unextended bytecode vector. */
        if (sd->top != top) {
            JS_ASSERT(top == -1 ||
                      !JOF_TYPE_IS_EXTENDED_JUMP(type) ||
                      bigspans != 0);
            bigspans = 0;
            top = sd->top;
            JS_ASSERT(top == sd->before);
            op = (JSOp) base[offset];
            type = (js_CodeSpec[op].format & JOF_TYPEMASK);
            JS_ASSERT(type == JOF_JUMP ||
                      type == JOF_JUMPX ||
                      type == JOF_TABLESWITCH ||
                      type == JOF_TABLESWITCHX ||
                      type == JOF_LOOKUPSWITCH ||
                      type == JOF_LOOKUPSWITCHX);
            pivot = offset;
        }

        pc = base + offset;
        if (JOF_TYPE_IS_EXTENDED_JUMP(type)) {
            span = GET_JUMPX_OFFSET(pc);
            if (span < JUMP_OFFSET_MIN || JUMP_OFFSET_MAX < span) {
                bigspans++;
            } else {
                JS_ASSERT(type == JOF_TABLESWITCHX ||
                          type == JOF_LOOKUPSWITCHX);
            }
        } else {
            span = GET_JUMP_OFFSET(pc);
        }
        JS_ASSERT(SD_SPAN(sd, pivot) == span);
    }
    JS_ASSERT(!JOF_TYPE_IS_EXTENDED_JUMP(type) || bigspans != 0);
  }
#endif

    /*
     * Reset so we optimize at most once -- cg may be used for further code
     * generation of successive, independent, top-level statements.  No jump
     * can span top-level statements, because JS lacks goto.
     */
    size = SPANDEPS_SIZE(JS_BIT(JS_CeilingLog2(cg->numSpanDeps)));
    JS_ArenaFreeAllocation(&cx->tempPool, cg->spanDeps,
                           JS_MAX(size, SPANDEPS_SIZE_MIN));
    cg->spanDeps = NULL;
    FreeJumpTargets(cg, cg->jumpTargets);
    cg->jumpTargets = NULL;
    cg->numSpanDeps = cg->numJumpTargets = 0;
    cg->spanDepTodo = CG_OFFSET(cg);
    return JS_TRUE;
}

static JSBool
EmitJump(JSContext *cx, JSCodeGenerator *cg, JSOp op, ptrdiff_t off)
{
    JSBool extend;