vm.object.spur.js

"use strict";
/*
 * Copyright (c) 2013-2025 Vanessa Freudenberg
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

Squeak.Object.subclass('Squeak.ObjectSpur',
'initialization',
{
    initInstanceOf: function(aClass, indexableSize, hash, nilObj) {
        this.sqClass = aClass;
        this.hash = hash;
        var instSpec = aClass.pointers[Squeak.Class_format],
            instSize = instSpec & 0xFFFF,
            format = (instSpec>>16) & 0x1F
        this._format = format;
        if (format < 12) {
            if (format < 10) {
                if (instSize + indexableSize > 0)
                    this.pointers = this.fillArray(instSize + indexableSize, nilObj);
            } else // Words
                if (indexableSize > 0)
                    if (aClass.isFloatClass) {
                        this.isFloat = true;
                        this.float = 0.0;
                    } else
                        this.words = new Uint32Array(indexableSize);
        } else // Bytes
            if (indexableSize > 0) {
                // this._format |= -indexableSize & 3;       //deferred to writeTo()
                this.bytes = new Uint8Array(indexableSize);  //Methods require further init of pointers
            }
//      Definition of Spur's format code...
//
//     0 = 0 sized objects (UndefinedObject True False et al)
//     1 = non-indexable objects with inst vars (Point et al)
//     2 = indexable objects with no inst vars (Array et al)
//     3 = indexable objects with inst vars (MethodContext AdditionalMethodState et al)
//     4 = weak indexable objects with inst vars (WeakArray et al)
//     5 = weak non-indexable objects with inst vars (ephemerons) (Ephemeron)
//     6 = unused
//     7 = immediates (SmallInteger, Character)
//     8 = unused
//     9 = 64-bit indexable
// 10-11 = 32-bit indexable (Bitmap)          (plus one odd bit, unused in 32-bits)
// 12-15 = 16-bit indexable                   (plus two odd bits, one unused in 32-bits)
// 16-23 = 8-bit indexable                    (plus three odd bits, one unused in 32-bits)
// 24-31 = compiled methods (CompiledMethod)  (plus three odd bits, one unused in 32-bits)
    },
    installFromImage: function(oopMap, rawBits, classTable, floatClass, littleEndian, getCharacter, is64Bit) {
        //Install this object by decoding format, and rectifying pointers
        var classID = this.sqClass;
        if (classID < 32) throw Error("Invalid class ID: " + classID);
        this.sqClass = classTable[classID];
        if (!this.sqClass) throw Error("Class ID not in class table: " + classID);
        var bits = rawBits.get(this.oop),
            nWords = bits.length;
        switch (this._format) {
            case 0: // zero sized object
              // Pharo bug: Pharo 6.0 still has format 0 objects that actually do have inst vars
              // https://pharo.fogbugz.com/f/cases/19010/ImmediateLayout-and-EphemeronLayout-have-wrong-object-format
              // so we pretend these are regular objects and rely on nWords
            case 1: // only inst vars
            case 2: // only indexed vars
            case 3: // inst vars and indexed vars
            case 4: // only indexed vars (weak)
            case 5: // only inst vars (weak)
                if (nWords > 0) {
                    var oops = bits; // endian conversion was already done
                    this.pointers = this.decodePointers(nWords, oops, oopMap, getCharacter, is64Bit);
                }
                break;
            case 11: // 32 bit array (odd length in 64 bits)
                nWords--;
                this._format = 10;
            case 10: // 32 bit array
                if (this.sqClass === floatClass) {
                    //These words are actually a Float
                    this.isFloat = true;
                    this.float = this.decodeFloat(bits, littleEndian, true);
                } else if (nWords > 0) {
                    this.words = this.decodeWords(nWords, bits, littleEndian);
                }
                break;
            case 12: // 16 bit array
            case 13: // 16 bit array (odd length)
                throw Error("16 bit arrays not supported yet");
            case 20: // 8 bit array, length-4 (64 bit image)
            case 21: // ... length-5
            case 22: // ... length-6
            case 23: // ... length-7
                nWords--;
                this._format -= 4;
                // fall through
            case 16: // 8 bit array
            case 17: // ... length-1
            case 18: // ... length-2
            case 19: // ... length-3
                if (nWords > 0)
                    this.bytes = this.decodeBytes(nWords, bits, 0, this._format & 3);
                break;
            case 28: // CompiledMethod, length-4 (64 bit image)
            case 29: // ... length-5
            case 30: // ... length-6
            case 31: // ... length-7
                nWords--;
                this._format -= 4;
                // fall through
            case 24: // CompiledMethod
            case 25: // ... length-1
            case 26: // ... length-2
            case 27: // ... length-3
                var rawHeader = this.decodeWords(1, bits, littleEndian)[0];
                var intHeader = rawHeader >> (is64Bit ? 3 : 1);
                var numLits = intHeader & 0x7FFF,
                    oops = is64Bit
                      ? this.decodeWords64(numLits+1, bits, littleEndian)
                      : this.decodeWords(numLits+1, bits, littleEndian),
                    ptrWords = is64Bit ? (numLits + 1) * 2 : numLits + 1;
                this.pointers = this.decodePointers(numLits+1, oops, oopMap, getCharacter, is64Bit); //header+lits
                this.bytes = this.decodeBytes(nWords-ptrWords, bits, ptrWords, this._format & 3);
                if (is64Bit) this.pointers[0] = (bits[1] & 0x80000000) | intHeader; // fix header
                break;
            default:
                throw Error("Unknown object format: " + this._format);

        }
        this.mark = false; // for GC
    },
    decodeWords64: function(nWords, theBits, littleEndian) {
        // we assume littleEndian for now
        var words = new Array(nWords);
        for (var i = 0; i < nWords; i++) {
            var lo = theBits[i*2],
                hi = theBits[i*2+1];
            words[i] = Squeak.word64FromUint32(hi, lo);
        }
        return words;
    },
    decodePointers: function(nWords, theBits, oopMap, getCharacter, is64Bit) {
        //Convert immediate objects and look up object pointers in oopMap
        var ptrs = new Array(nWords);
        for (var i = 0; i < nWords; i++) {
            var oop = theBits[i];
            // in 64 bits, oops > 53 bits are read as [hi, lo]
            if (typeof oop !== "number") {
                if ((oop[1] & 7) === 4) {
                    ptrs[i] = this.decodeSmallFloat(oop[0], oop[1], is64Bit);
                } else if ((oop[1] & 7) === 1) {
                    ptrs[i] = is64Bit.makeLargeFromSmall(oop[0], oop[1]);
                } else if ((oop[1] & 7) === 2) {
                    throw Error("Large Immediate Characters not implemented yet");
                } else {
                    throw Error("Large OOPs not implemented yet");
                }
            } else if ((oop & 1) === 1) {          // SmallInteger
                if (is64Bit) {
                    // if it fits in a 31 bit SmallInt ...
                    ptrs[i] = (oop >= 0 ? oop <= 0x1FFFFFFFF : oop >= -0x200000000)
                        ? oop / 4 >> 1  // ... then convert directly, otherwise make large
                        : is64Bit.makeLargeFromSmall((oop - (oop >>> 0)) / 0x100000000 >>> 0, oop >>> 0);
                } else ptrs[i] = oop >> 1;
            } else if ((oop & 3) === 2) {   // Character
                if (oop < 0 || oop > 0x1FFFFFFFF) throw Error("Large Immediate Characters not implemented yet");
                ptrs[i] = getCharacter(oop >>> (is64Bit ? 3 : 2));
            } else if (is64Bit && (oop & 7) === 4) {   // SmallFloat
                ptrs[i] = this.decodeSmallFloat((oop - (oop >>> 0)) / 0x100000000 >>> 0, oop >>> 0, is64Bit);
            } else {                        // Object
                ptrs[i] = oopMap.get(oop) || 42424242;
                // when loading a context from image segment, there is
                // garbage beyond its stack pointer, resulting in the oop
                // not being found in oopMap. We just fill in an arbitrary
                // SmallInteger - it's never accessed anyway

                // until 64 bit is working correctly, leave this here as a check ...
                if (ptrs[i] === 42424242) debugger;
            }
        }
        return ptrs;
    },
    decodeSmallFloat: function(hi, lo, is64Bit) {
        // SmallFloats are stored with full 52 bit mantissa, but shortened exponent.
        // The lowest 3 bits are tags, the next is the sign bit
        var newHi = 0,
            newLo = 0,
            sign = (lo & 8) << (32-4),               // shift sign bit to msb
            isZero = (hi | (lo & 0xFFFFFFF0)) === 0; // ignore sign and tag bits
        if (isZero) {
            // zero is special - can be positive or negative
            newHi = sign;
        } else {
            // shift everything right by 4, fix exponent, add sign
            newHi = (hi >>> 4) + 0x38000000 | sign;
            newLo = (lo >>> 4) | (hi & 0xF) << (32-4);
            // 1023 is the bias of the 11-bit exponent in an IEEE 754 64-bit float,
            // and 127 is the bias of our 8-bit exponent. 1023-127 == 0x380
        }
        return is64Bit.makeFloat(new Uint32Array([newLo, newHi]));
    },
    overhead64: function(bits) {
        // the number of bytes this object is larger in 64 bits than in 32 bits
        // (due to 8-byte alignment even in 32 bits this only affects pointer objects)
        var overhead = 0;
        var words32 = 0;
        var words64 = 0;
        if (this._format <= 5) {
            // pointer objects
            overhead = bits.length & ~1; // each oop occupied 2 words instead of 1 ...
            // ... but odd lengths get padded so we subtract 1
            // words32 === words64 because same number of oops
        } else if (this._format >= 24) {
            // compiled methods
            var numLits = (bits[0] >> 3) & 0x7FFF; // assumes 64 bit little endian
            var overhead = numLits + 1;  // each oop occupied 2 words instead of 1 ...
            var oddOops = (overhead & 1) === 1;
            var oddBytes = this._format >= 28;
            // ... odd-word lengths would get padded so we subtract 1,
            // but if there is also odd-word bytecodes it cancels out so we save 1 word instead
            if (oddOops) overhead += oddBytes ? +1 : -1;
            words64 = bits.length / 2;
            words32 = bits.length - overhead;
        } else {
            // non-pointer objects have no oop overhead
            words32 = bits.length;
            words64 = words32 / 2;
        }
        // we need an extra header in 32 bits if we now use more words than before
        return {
            bytes: overhead * 4,
            sizeHeader: words32 >= 255 && words64 < 255,
        }
    },
    initInstanceOfChar: function(charClass, unicode) {
        this.oop = (unicode << 2) | 2;
        this.sqClass = charClass;
        this.hash = unicode;
        this._format = 7;
        this.mark = true;   // stays always marked so not traced by GC
    },
    initInstanceOfFloat: function(floatClass, bits) {
        this.sqClass = floatClass;
        this.hash = 0;
        this._format = 10;
        this.isFloat = true;
        this.float = this.decodeFloat(bits, true, true);
    },
    initInstanceOfLargeInt: function(largeIntClass, size) {
        this.sqClass = largeIntClass;
        this.hash = 0;
        this._format = 16;
        // this._format |= -indexableSize & 3;       //deferred to writeTo()
        this.bytes = new Uint8Array(size);
    },
    classNameFromImage: function(oopMap, rawBits) {
        var name = oopMap.get(rawBits.get(this.oop)[Squeak.Class_name]);
        if (name && name._format >= 16 && name._format < 24) {
            var bits = rawBits.get(name.oop),
                bytes = name.decodeBytes(bits.length, bits, 0, name._format & 7);
            return Squeak.bytesAsString(bytes);
        }
        return "Class";
    },
    renameFromImage: function(oopMap, rawBits, classTable) {
        var classObj = classTable[this.sqClass];
        if (!classObj) return this;
        var instProto = classObj.instProto || classObj.classInstProto(classObj.classNameFromImage(oopMap, rawBits));
        if (!instProto) return this;
        var renamedObj = new instProto; // Squeak.SpurObject
        renamedObj.oop = this.oop;
        renamedObj.sqClass = this.sqClass;
        renamedObj._format = this._format;
        renamedObj.hash = this.hash;
        return renamedObj;
    },
},
'accessing', {
    instSize: function() {//same as class.classInstSize, but faster from format
        if (this._format < 2) return this.pointersSize(); //fixed fields only
        return this.sqClass.classInstSize();
    },
    indexableSize: function(primHandler) {
        var fmt = this._format;
        if (fmt < 2) return -1; //not indexable
        if (fmt === 3 && primHandler.vm.isContext(this))
            return this.pointers[Squeak.Context_stackPointer]; // no access beyond top of stacks
        if (fmt < 6) return this.pointersSize() - this.instSize(); // pointers
        if (fmt < 12) return this.wordsSize(); // words
        if (fmt < 16) return this.shortsSize(); // shorts
        if (fmt < 24) return this.bytesSize(); // bytes
        return 4 * this.pointersSize() + this.bytesSize(); // methods
    },
    snapshotSize: function() {
        // words of extra object header and body this object would take up in image snapshot
        // body size includes header size that is always present
        var nWords =
            this.isFloat ? 2 :
            this.words ? this.words.length :
            this.pointers ? this.pointers.length : 0;
        // methods have both pointers and bytes
        if (this.bytes) nWords += (this.bytes.length + 3) >>> 2;
        var extraHeader = nWords >= 255 ? 2 : 0;
        nWords += nWords & 1; // align to 8 bytes
        nWords += 2; // one 64 bit header always present
        if (nWords < 4) nWords = 4; // minimum object size
        return {header: extraHeader, body: nWords};
    },
    writeTo: function(data, pos, littleEndian, objToOop) {
        var nWords =
            this.isFloat ? 2 :
            this.words ? this.words.length :
            this.pointers ? this.pointers.length : 0;
        if (this.bytes) {
            nWords += (this.bytes.length + 3) >>> 2;
            this._format |= -this.bytes.length & 3;
        }
        var beforePos = pos,
            formatAndClass = (this._format << 24) | (this.sqClass.hash & 0x003FFFFF),
            sizeAndHash = (nWords << 24) | (this.hash & 0x003FFFFF);
        // write extra header if needed
        if (nWords >= 255) {
            data.setUint32(pos, nWords, littleEndian); pos += 4;
            sizeAndHash = (255 << 24) | (this.hash & 0x003FFFFF);
            data.setUint32(pos, sizeAndHash, littleEndian); pos += 4;
        }
        // write regular header
        data.setUint32(pos, formatAndClass, littleEndian); pos += 4;
        data.setUint32(pos, sizeAndHash, littleEndian); pos += 4;
        // now write body, if any
        if (this.isFloat) {
            data.setFloat64(pos, this.float, littleEndian); pos += 8;
        } else if (this.words) {
            for (var i = 0; i < this.words.length; i++) {
                data.setUint32(pos, this.words[i], littleEndian); pos += 4;
            }
        } else if (this.pointers) {
            var startIndex = 0;
            if (this._format >= 24) {
                // preserve signFlag in method header
                var mask = this.methodSignFlag() ? 0x80000000 : 0;
                var taggedHeader = this.pointers[0] << 1 | 1 | mask;
                data.setUint32(pos, taggedHeader, littleEndian); pos += 4;
                startIndex = 1;
            }
            for (var i = startIndex; i < this.pointers.length; i++) {
                data.setUint32(pos, objToOop(this.pointers[i]), littleEndian); pos += 4;
            }
        }
        // no "else" because CompiledMethods have both pointers and bytes
        if (this.bytes) {
            for (var i = 0; i < this.bytes.length; i++)
                data.setUint8(pos++, this.bytes[i]);
            // skip to next word
            pos += -this.bytes.length & 3;
        }
        // minimum object size is 16, align to 8 bytes
        if (nWords === 0) pos += 8;
        else pos += (nWords & 1) * 4;
        // done
        if (pos !== beforePos + this.totalBytes()) throw Error("written size does not match");
        return pos;
    },
},
'testing', {
    isBytes: function() {
        var fmt = this._format;
        return fmt >= 16 && fmt <= 23;
    },
    isPointers: function() {
        return this._format <= 6;
    },
    isWords: function() {
        return this._format === 10;
    },
    isWordsOrBytes: function() {
        var fmt = this._format;
        return fmt === 10 || (fmt >= 16 && fmt <= 23);
    },
    isWeak: function() {
        return this._format === 4;
    },
    isMethod: function() {
        return this._format >= 24;
    },
    sameFormats: function(a, b) {
        return a < 16 ? a === b : (a & 0xF8) === (b & 0xF8);
    },
},
'as class', {
    defaultInst: function() {
        return Squeak.ObjectSpur;
    },
    classInstFormat: function() {
        return (this.pointers[Squeak.Class_format] >> 16) & 0x1F;
    },
    classInstSize: function() {
        // this is a class, answer number of named inst vars
        return this.pointers[Squeak.Class_format] & 0xFFFF;
    },
    classInstIsBytes: function() {
        var fmt = this.classInstFormat();
        return fmt >= 16 && fmt <= 23;
    },
    classInstIsPointers: function() {
        return this.classInstFormat() <= 6;
    },
    classByteSizeOfInstance: function(nElements) {
        var format = this.classInstFormat(),
            nWords = this.classInstSize();
        if (format < 9) nWords += nElements;                        // 32 bit
        else if (format >= 16) nWords += (nElements + 3) / 4 | 0;   //  8 bit
        else if (format >= 12) nWords += (nElements + 1) / 2 | 0;   // 16 bit
        else if (format >= 10) nWords += nElements;                 // 32 bit
        else nWords += nElements * 2;                               // 64 bit
        nWords += nWords & 1;                                       // align to 64 bits
        nWords += nWords >= 255 ? 4 : 2;                            // header words
        if (nWords < 4) nWords = 4;                                 // minimum object size
        return nWords * 4;
    },
},
'as compiled block', {
    blockOuterCode: function() {
        return this.pointers[this.pointers.length - 1];
    },
},
'as method', {
    methodSignFlag: function() {
        return this.pointers[0] < 0;
    },
    methodNumLits: function() {
        return this.pointers[0] & 0x7FFF;
    },
    methodPrimitiveIndex: function() {
        if ((this.pointers[0] & 0x10000) === 0) return 0;
        return this.bytes[1] + 256 * this.bytes[2];
    },
    methodAsString: function() {
        var cls = this.pointers[this.pointers.length - 1].pointers[Squeak.ClassBinding_value];
        var selector = this.pointers[this.pointers.length - 2];
        if (selector.pointers) selector = selector.pointers[Squeak.AdditionalMethodState_selector];
        return cls.className() + ">>" + selector.bytesAsString();
    },
});