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Bug 860965 - Part 1: Copy 1D ParallelArray operations to Array. (r=luke,nmatsakis)

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This commit is contained in:
Shu-yu Guo 2013-05-11 22:39:46 -07:00
parent 84f8af7a1f
commit 91b4c3d28c
3 changed files with 904 additions and 2 deletions
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890
js/src/builtin/Array.js
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@ -411,7 +411,7 @@ function ArrayFind(predicate/*, thisArg*/) {
/* Steps 8-9. */
/* Steps a (implicit), and e. */
/* Note: this will hang in some corner-case situations, because of IEEE-754 numbers'
/* Note: this will hang in some corner-case situations, because of IEEE-754 numbers'
* imprecision for large values. Example:
* var obj = { 18014398509481984: true, length: 18014398509481988 };
* Array.prototype.find.call(obj, () => true);
@ -449,7 +449,7 @@ function ArrayFindIndex(predicate/*, thisArg*/) {
/* Steps 8-9. */
/* Steps a (implicit), and e. */
/* Note: this will hang in some corner-case situations, because of IEEE-754 numbers'
/* Note: this will hang in some corner-case situations, because of IEEE-754 numbers'
* imprecision for large values. Example:
* var obj = { 18014398509481984: true, length: 18014398509481988 };
* Array.prototype.find.call(obj, () => true);
@ -466,3 +466,889 @@ function ArrayFindIndex(predicate/*, thisArg*/) {
/* Step 10. */
return -1;
}
#ifdef ENABLE_PARALLEL_JS
/*
* Strawman spec:
* http://wiki.ecmascript.org/doku.php?id=strawman:data_parallelism
*/
/* The mode asserts options object. */
#define TRY_PARALLEL(MODE) \
((!MODE || MODE.mode !== "seq"))
#define ASSERT_SEQUENTIAL_IS_OK(MODE) \
do { if (MODE) AssertSequentialIsOK(MODE) } while(false)
/* Slice array: see ComputeAllSliceBounds() */
#define SLICE_INFO(START, END) START, END, START, 0
#define SLICE_START(ID) ((ID << 2) + 0)
#define SLICE_END(ID) ((ID << 2) + 1)
#define SLICE_POS(ID) ((ID << 2) + 2)
/*
* How many items at a time do we do recomp. for parallel execution.
* Note that filter currently assumes that this is no greater than 32
* in order to make use of a bitset.
*/
#define CHUNK_SHIFT 5
#define CHUNK_SIZE 32
/* Safe versions of ARRAY.push(ELEMENT) */
#define ARRAY_PUSH(ARRAY, ELEMENT) \
callFunction(std_Array_push, ARRAY, ELEMENT);
#define ARRAY_SLICE(ARRAY, ELEMENT) \
callFunction(std_Array_slice, ARRAY, ELEMENT);
/**
* The ParallelSpew intrinsic is only defined in debug mode, so define a dummy
* if debug is not on.
*/
#ifndef DEBUG
#define ParallelSpew(args)
#endif
/**
* Determine the number of chunks of size CHUNK_SIZE;
* note that the final chunk may be smaller than CHUNK_SIZE.
*/
function ComputeNumChunks(length) {
var chunks = length >>> CHUNK_SHIFT;
if (chunks << CHUNK_SHIFT === length)
return chunks;
return chunks + 1;
}
/**
* Computes the bounds for slice |sliceIndex| of |numItems| items,
* assuming |numSlices| total slices. If numItems is not evenly
* divisible by numSlices, then the final thread may have a bit of
* extra work.
*/
function ComputeSliceBounds(numItems, sliceIndex, numSlices) {
var sliceWidth = (numItems / numSlices) | 0;
var startIndex = sliceWidth * sliceIndex;
var endIndex = sliceIndex === numSlices - 1 ? numItems : sliceWidth * (sliceIndex + 1);
return [startIndex, endIndex];
}
/**
* Divides |numItems| items amongst |numSlices| slices. The result
* is an array containing multiple values per slice: the start
* index, end index, current position, and some padding. The
* current position is initially the same as the start index. To
* access the values for a particular slice, use the macros
* SLICE_START() and so forth.
*/
function ComputeAllSliceBounds(numItems, numSlices) {
// FIXME(bug 844890): Use typed arrays here.
var info = [];
for (var i = 0; i < numSlices; i++) {
var [start, end] = ComputeSliceBounds(numItems, i, numSlices);
ARRAY_PUSH(info, SLICE_INFO(start, end));
}
return info;
}
/**
* Creates a new array by applying |func(e, i, self)| for each element |e|
* with index |i|.
*/
function ArrayMapPar(func, mode) {
if (!IsCallable(func))
ThrowError(JSMSG_NOT_FUNCTION, DecompileArg(0, func));
var self = ToObject(this);
var length = self.length;
var buffer = NewDenseArray(length);
parallel: for (;;) {
// Avoid parallel compilation if we are already nested in another
// parallel section or the user told us not to parallelize. The
// use of a for (;;) loop is working around some ion limitations:
//
// - Breaking out of named blocks does not currently work (bug 684384);
// - Unreachable Code Elim. can't properly handle if (a && b) (bug 669796)
if (ShouldForceSequential())
break parallel;
if (!TRY_PARALLEL(mode))
break parallel;
var chunks = ComputeNumChunks(length);
var numSlices = ForkJoinSlices();
var info = ComputeAllSliceBounds(chunks, numSlices);
ForkJoin(mapSlice, ForkJoinMode(mode));
return buffer;
}
// Sequential fallback:
ASSERT_SEQUENTIAL_IS_OK(mode);
for (var i = 0; i < length; i++) {
// Note: Unlike JS arrays, parallel arrays cannot have holes.
var v = func(self[i], i, self);
UnsafePutElements(buffer, i, v);
}
return buffer;
function mapSlice(sliceId, numSlices, warmup) {
var chunkPos = info[SLICE_POS(sliceId)];
var chunkEnd = info[SLICE_END(sliceId)];
if (warmup && chunkEnd > chunkPos + 1)
chunkEnd = chunkPos + 1;
while (chunkPos < chunkEnd) {
var indexStart = chunkPos << CHUNK_SHIFT;
var indexEnd = std_Math_min(indexStart + CHUNK_SIZE, length);
for (var i = indexStart; i < indexEnd; i++)
UnsafePutElements(buffer, i, func(self[i], i, self));
UnsafePutElements(info, SLICE_POS(sliceId), ++chunkPos);
}
return chunkEnd === info[SLICE_END(sliceId)];
}
}
/**
* Reduces the elements in an array in parallel. Order is not fixed and |func|
* is assumed to be associative.
*/
function ArrayReducePar(func, mode) {
if (!IsCallable(func))
ThrowError(JSMSG_NOT_FUNCTION, DecompileArg(0, func));
var self = ToObject(this);
var length = self.length;
if (length === 0)
ThrowError(JSMSG_EMPTY_ARRAY_REDUCE);
parallel: for (;;) { // see ArrayMapPar() to explain why for(;;) etc
if (ShouldForceSequential())
break parallel;
if (!TRY_PARALLEL(mode))
break parallel;
var chunks = ComputeNumChunks(length);
var numSlices = ForkJoinSlices();
if (chunks < numSlices)
break parallel;
var info = ComputeAllSliceBounds(chunks, numSlices);
var subreductions = NewDenseArray(numSlices);
ForkJoin(reduceSlice, ForkJoinMode(mode));
var accumulator = subreductions[0];
for (var i = 1; i < numSlices; i++)
accumulator = func(accumulator, subreductions[i]);
return accumulator;
}
// Sequential fallback:
ASSERT_SEQUENTIAL_IS_OK(mode);
var accumulator = self[0];
for (var i = 1; i < length; i++)
accumulator = func(accumulator, self[i]);
return accumulator;
function reduceSlice(sliceId, numSlices, warmup) {
var chunkStart = info[SLICE_START(sliceId)];
var chunkPos = info[SLICE_POS(sliceId)];
var chunkEnd = info[SLICE_END(sliceId)];
// (*) This function is carefully designed so that the warmup
// (which executes with chunkStart === chunkPos) will execute all
// potential loads and stores. In particular, the warmup run
// processes two chunks rather than one. Moreover, it stores
// accumulator into subreductions and then loads it again to
// ensure that the load is executed during the warmup, as it will
// certainly be executed during subsequent runs.
if (warmup && chunkEnd > chunkPos + 2)
chunkEnd = chunkPos + 2;
if (chunkStart === chunkPos) {
var indexPos = chunkStart << CHUNK_SHIFT;
var accumulator = reduceChunk(self[indexPos], indexPos + 1, indexPos + CHUNK_SIZE);
UnsafePutElements(subreductions, sliceId, accumulator, // see (*) above
info, SLICE_POS(sliceId), ++chunkPos);
}
var accumulator = subreductions[sliceId]; // see (*) above
while (chunkPos < chunkEnd) {
var indexPos = chunkPos << CHUNK_SHIFT;
accumulator = reduceChunk(accumulator, indexPos, indexPos + CHUNK_SIZE);
UnsafePutElements(subreductions, sliceId, accumulator, info, SLICE_POS(sliceId), ++chunkPos);
}
return chunkEnd === info[SLICE_END(sliceId)];
}
function reduceChunk(accumulator, from, to) {
to = std_Math_min(to, length);
for (var i = from; i < to; i++)
accumulator = func(accumulator, self[i]);
return accumulator;
}
}
/**
* Returns an array [s_0, ..., s_N] where |s_i| is equal to the reduction (as
* per |reduce()|) of elements |0..i|. This is the generalization of partial
* sum.
*/
function ArrayScanPar(func, mode) {
if (!IsCallable(func))
ThrowError(JSMSG_NOT_FUNCTION, DecompileArg(0, func));
var self = ToObject(this);
var length = self.length;
if (length === 0)
ThrowError(JSMSG_EMPTY_ARRAY_REDUCE);
var buffer = NewDenseArray(length);
parallel: for (;;) { // see ArrayMapPar() to explain why for(;;) etc
if (ShouldForceSequential())
break parallel;
if (!TRY_PARALLEL(mode))
break parallel;
var chunks = ComputeNumChunks(length);
var numSlices = ForkJoinSlices();
if (chunks < numSlices)
break parallel;
var info = ComputeAllSliceBounds(chunks, numSlices);
// Scan slices individually (see comment on phase1()).
ForkJoin(phase1, ForkJoinMode(mode));
// Compute intermediates array (see comment on phase2()).
var intermediates = [];
var accumulator = buffer[finalElement(0)];
ARRAY_PUSH(intermediates, accumulator);
for (var i = 1; i < numSlices - 1; i++) {
accumulator = func(accumulator, buffer[finalElement(i)]);
ARRAY_PUSH(intermediates, accumulator);
}
// Reset the current position information for each slice, but
// convert from chunks to indices (see comment on phase2()).
for (var i = 0; i < numSlices; i++) {
info[SLICE_POS(i)] = info[SLICE_START(i)] << CHUNK_SHIFT;
info[SLICE_END(i)] = info[SLICE_END(i)] << CHUNK_SHIFT;
}
info[SLICE_END(numSlices - 1)] = std_Math_min(info[SLICE_END(numSlices - 1)], length);
// Complete each slice using intermediates array (see comment on phase2()).
ForkJoin(phase2, ForkJoinMode(mode));
return buffer;
}
// Sequential fallback:
ASSERT_SEQUENTIAL_IS_OK(mode);
scan(self[0], 0, length);
return buffer;
function scan(accumulator, start, end) {
UnsafePutElements(buffer, start, accumulator);
for (var i = start + 1; i < end; i++) {
accumulator = func(accumulator, self[i]);
UnsafePutElements(buffer, i, accumulator);
}
return accumulator;
}
/**
* In phase 1, we divide the source array into |numSlices| slices and
* compute scan on each slice sequentially as if it were the entire
* array. This function is responsible for computing one of those
* slices.
*
* So, if we have an array [A,B,C,D,E,F,G,H,I], |numSlices === 3|,
* and our function |func| is sum, then we would wind up computing a
* result array like:
*
* [A, A+B, A+B+C, D, D+E, D+E+F, G, G+H, G+H+I]
* ^~~~~~~~~~~~^ ^~~~~~~~~~~~^ ^~~~~~~~~~~~~^
* Slice 0 Slice 1 Slice 2
*
* Read on in phase2 to see what we do next!
*/
function phase1(sliceId, numSlices, warmup) {
var chunkStart = info[SLICE_START(sliceId)];
var chunkPos = info[SLICE_POS(sliceId)];
var chunkEnd = info[SLICE_END(sliceId)];
if (warmup && chunkEnd > chunkPos + 2)
chunkEnd = chunkPos + 2;
if (chunkPos === chunkStart) {
// For the first chunk, the accumulator begins as the value in
// the input at the start of the chunk.
var indexStart = chunkPos << CHUNK_SHIFT;
var indexEnd = std_Math_min(indexStart + CHUNK_SIZE, length);
scan(self[indexStart], indexStart, indexEnd);
UnsafePutElements(info, SLICE_POS(sliceId), ++chunkPos);
}
while (chunkPos < chunkEnd) {
// For each subsequent chunk, the accumulator begins as the
// combination of the final value of prev chunk and the value in
// the input at the start of this chunk. Note that this loop is
// written as simple as possible, at the cost of an extra read
// from the buffer per iteration.
var indexStart = chunkPos << CHUNK_SHIFT;
var indexEnd = std_Math_min(indexStart + CHUNK_SIZE, length);
var accumulator = func(buffer[indexStart - 1], self[indexStart]);
scan(accumulator, indexStart, indexEnd);
UnsafePutElements(info, SLICE_POS(sliceId), ++chunkPos);
}
return chunkEnd === info[SLICE_END(sliceId)];
}
/**
* Computes the index of the final element computed by the slice |sliceId|.
*/
function finalElement(sliceId) {
var chunkEnd = info[SLICE_END(sliceId)]; // last chunk written by |sliceId| is endChunk - 1
var indexStart = std_Math_min(chunkEnd << CHUNK_SHIFT, length);
return indexStart - 1;
}
/**
* After computing the phase1 results, we compute an
* |intermediates| array. |intermediates[i]| contains the result
* of reducing the final value from each preceding slice j<i with
* the final value of slice i. So, to continue our previous
* example, the intermediates array would contain:
*
* [A+B+C, (A+B+C)+(D+E+F), ((A+B+C)+(D+E+F))+(G+H+I)]
*
* Here I have used parenthesization to make clear the order of
* evaluation in each case.
*
* An aside: currently the intermediates array is computed
* sequentially. In principle, we could compute it in parallel,
* at the cost of doing duplicate work. This did not seem
* particularly advantageous to me, particularly as the number
* of slices is typically quite small (one per core), so I opted
* to just compute it sequentially.
*
* Phase 2 combines the results of phase1 with the intermediates
* array to produce the final scan results. The idea is to
* reiterate over each element S[i] in the slice |sliceId|, which
* currently contains the result of reducing with S[0]...S[i]
* (where S0 is the first thing in the slice), and combine that
* with |intermediate[sliceId-1]|, which represents the result of
* reducing everything in the input array prior to the slice.
*
* To continue with our example, in phase 1 we computed slice 1 to
* be [D, D+E, D+E+F]. We will combine those results with
* |intermediates[1-1]|, which is |A+B+C|, so that the final
* result is [(A+B+C)+D, (A+B+C)+(D+E), (A+B+C)+(D+E+F)]. Again I
* am using parentheses to clarify how these results were reduced.
*
* SUBTLE: Because we are mutating |buffer| in place, we have to
* be very careful about bailouts! We cannot checkpoint a chunk
* at a time as we do elsewhere because that assumes it is safe to
* replay the portion of a chunk which was already processed.
* Therefore, in this phase, we track the current position at an
* index granularity, although this requires two memory writes per
* index.
*/
function phase2(sliceId, numSlices, warmup) {
if (sliceId === 0)
return true; // No work to do for the 0th slice.
var indexPos = info[SLICE_POS(sliceId)];
var indexEnd = info[SLICE_END(sliceId)];
if (warmup)
indexEnd = std_Math_min(indexEnd, indexPos + CHUNK_SIZE);
var intermediate = intermediates[sliceId - 1];
for (; indexPos < indexEnd; indexPos++) {
UnsafePutElements(buffer, indexPos, func(intermediate, buffer[indexPos]),
info, SLICE_POS(sliceId), indexPos + 1);
}
return indexEnd === info[SLICE_END(sliceId)];
}
}
/**
* |scatter()| redistributes the elements in the array into a new array.
*
* - targets: The index targets[i] indicates where the ith element
* should appear in the result.
*
* - defaultValue: what value to use for indices in the output array that
* are never targeted.
*
* - conflictFunc: The conflict function. Used to resolve what
* happens if two indices i and j in the source array are targeted
* as the same destination (i.e., targets[i] === targets[j]), then
* the final result is determined by applying func(targets[i],
* targets[j]). If no conflict function is provided, it is an error
* if targets[i] === targets[j].
*
* - length: length of the output array (if not specified, uses the
* length of the input).
*
* - mode: internal debugging specification.
*/
function ArrayScatterPar(targets, defaultValue, conflictFunc, length, mode) {
if (conflictFunc && !IsCallable(conflictFunc))
ThrowError(JSMSG_NOT_FUNCTION, DecompileArg(2, conflictFunc));
var self = ToObject(this);
if (length === undefined)
length = self.length;
// The Divide-Scatter-Vector strategy:
// 1. Slice |targets| array of indices ("scatter-vector") into N
// parts.
// 2. Each of the N threads prepares an output buffer and a
// write-log.
// 3. Each thread scatters according to one of the N parts into its
// own output buffer, tracking written indices in the write-log
// and resolving any resulting local collisions in parallel.
// 4. Merge the parts (either in parallel or sequentially), using
// the write-logs as both the basis for finding merge-inputs and
// for detecting collisions.
// The Divide-Output-Range strategy:
// 1. Slice the range of indices [0..|length|-1] into N parts.
// Allocate a single shared output buffer of length |length|.
// 2. Each of the N threads scans (the entirety of) the |targets|
// array, seeking occurrences of indices from that thread's part
// of the range, and writing the results into the shared output
// buffer.
// 3. Since each thread has its own portion of the output range,
// every collision that occurs can be handled thread-locally.
// SO:
//
// If |targets.length| >> |length|, Divide-Scatter-Vector seems like
// a clear win over Divide-Output-Range, since for the latter, the
// expense of redundantly scanning the |targets| will diminish the
// gain from processing |length| in parallel, while for the former,
// the total expense of building separate output buffers and the
// merging post-process is small compared to the gain from
// processing |targets| in parallel.
//
// If |targets.length| << |length|, then Divide-Output-Range seems
// like it *could* win over Divide-Scatter-Vector. (But when is
// |targets.length| << |length| or even |targets.length| < |length|?
// Seems like an odd situation and an uncommon case at best.)
//
// The unanswered question is which strategy performs better when
// |targets.length| approximately equals |length|, especially for
// special cases like collision-free scatters and permutations.
var targetsLength = std_Math_min(targets.length, self.length);
if (!IS_UINT32(targetsLength) || !IS_UINT32(length))
ThrowError(JSMSG_BAD_ARRAY_LENGTH);
parallel: for (;;) { // see ArrayMapPar() to explain why for(;;) etc
if (ShouldForceSequential())
break parallel;
if (!TRY_PARALLEL(mode))
break parallel;
if (forceDivideScatterVector())
return parDivideScatterVector();
else if (forceDivideOutputRange())
return parDivideOutputRange();
else if (conflictFunc === undefined && targetsLength < length)
return parDivideOutputRange();
return parDivideScatterVector();
}
// Sequential fallback:
ASSERT_SEQUENTIAL_IS_OK(mode);
return seq();
function forceDivideScatterVector() {
return mode && mode.strategy && mode.strategy === "divide-scatter-vector";
}
function forceDivideOutputRange() {
return mode && mode.strategy && mode.strategy === "divide-output-range";
}
function collide(elem1, elem2) {
if (conflictFunc === undefined)
ThrowError(JSMSG_PAR_ARRAY_SCATTER_CONFLICT);
return conflictFunc(elem1, elem2);
}
function parDivideOutputRange() {
var chunks = ComputeNumChunks(targetsLength);
var numSlices = ForkJoinSlices();
var checkpoints = NewDenseArray(numSlices);
for (var i = 0; i < numSlices; i++)
UnsafePutElements(checkpoints, i, 0);
var buffer = NewDenseArray(length);
var conflicts = NewDenseArray(length);
for (var i = 0; i < length; i++) {
UnsafePutElements(buffer, i, defaultValue);
UnsafePutElements(conflicts, i, false);
}
ForkJoin(fill, ForkJoinMode(mode));
return buffer;
function fill(sliceId, numSlices, warmup) {
var indexPos = checkpoints[sliceId];
var indexEnd = targetsLength;
if (warmup)
indexEnd = std_Math_min(indexEnd, indexPos + CHUNK_SIZE);
// Range in the output for which we are responsible:
var [outputStart, outputEnd] = ComputeSliceBounds(length, sliceId, numSlices);
for (; indexPos < indexEnd; indexPos++) {
var x = self[indexPos];
var t = checkTarget(indexPos, targets[indexPos]);
if (t < outputStart || t >= outputEnd)
continue;
if (conflicts[t])
x = collide(x, buffer[t]);
UnsafePutElements(buffer, t, x, conflicts, t, true, checkpoints, sliceId, indexPos + 1);
}
return indexEnd === targetsLength;
}
}
function parDivideScatterVector() {
// Subtle: because we will be mutating the localBuffers and
// conflict arrays in place, we can never replay an entry in the
// target array for fear of inducing a conflict where none existed
// before. Therefore, we must proceed not by chunks but rather by
// individual indices.
var numSlices = ForkJoinSlices();
var info = ComputeAllSliceBounds(targetsLength, numSlices);
// FIXME(bug 844890): Use typed arrays here.
var localBuffers = NewDenseArray(numSlices);
for (var i = 0; i < numSlices; i++)
UnsafePutElements(localBuffers, i, NewDenseArray(length));
var localConflicts = NewDenseArray(numSlices);
for (var i = 0; i < numSlices; i++) {
var conflicts_i = NewDenseArray(length);
for (var j = 0; j < length; j++)
UnsafePutElements(conflicts_i, j, false);
UnsafePutElements(localConflicts, i, conflicts_i);
}
// Initialize the 0th buffer, which will become the output. For
// the other buffers, we track which parts have been written to
// using the conflict buffer so they do not need to be
// initialized.
var outputBuffer = localBuffers[0];
for (var i = 0; i < length; i++)
UnsafePutElements(outputBuffer, i, defaultValue);
ForkJoin(fill, ForkJoinMode(mode));
mergeBuffers();
return outputBuffer;
function fill(sliceId, numSlices, warmup) {
var indexPos = info[SLICE_POS(sliceId)];
var indexEnd = info[SLICE_END(sliceId)];
if (warmup)
indexEnd = std_Math_min(indexEnd, indexPos + CHUNK_SIZE);
var localbuffer = localBuffers[sliceId];
var conflicts = localConflicts[sliceId];
while (indexPos < indexEnd) {
var x = self[indexPos];
var t = checkTarget(indexPos, targets[indexPos]);
if (conflicts[t])
x = collide(x, localbuffer[t]);
UnsafePutElements(localbuffer, t, x, conflicts, t, true,
info, SLICE_POS(sliceId), ++indexPos);
}
return indexEnd === info[SLICE_END(sliceId)];
}
/**
* Merge buffers 1..NUMSLICES into buffer 0. In principle, we could
* parallelize the merge work as well. But for this first cut,
* just do the merge sequentially.
*/
function mergeBuffers() {
var buffer = localBuffers[0];
var conflicts = localConflicts[0];
for (var i = 1; i < numSlices; i++) {
var otherbuffer = localBuffers[i];
var otherconflicts = localConflicts[i];
for (var j = 0; j < length; j++) {
if (otherconflicts[j]) {
if (conflicts[j]) {
buffer[j] = collide(otherbuffer[j], buffer[j]);
} else {
buffer[j] = otherbuffer[j];
conflicts[j] = true;
}
}
}
}
}
}
function seq() {
var buffer = NewDenseArray(length);
var conflicts = NewDenseArray(length);
for (var i = 0; i < length; i++) {
UnsafePutElements(buffer, i, defaultValue);
UnsafePutElements(conflicts, i, false);
}
for (var i = 0; i < targetsLength; i++) {
var x = self[i];
var t = checkTarget(i, targets[i]);
if (conflicts[t])
x = collide(x, buffer[t]);
UnsafePutElements(buffer, t, x, conflicts, t, true);
}
return buffer;
}
function checkTarget(i, t) {
if (TO_INT32(t) !== t)
ThrowError(JSMSG_PAR_ARRAY_SCATTER_BAD_TARGET, i);
if (t < 0 || t >= length)
ThrowError(JSMSG_PAR_ARRAY_SCATTER_BOUNDS);
// It's not enough to return t, as -0 | 0 === -0.
return TO_INT32(t);
}
}
/**
* The filter operation applied in parallel.
*/
function ArrayFilterPar(func, mode) {
if (!IsCallable(func))
ThrowError(JSMSG_NOT_FUNCTION, DecompileArg(0, func));
var self = ToObject(this);
var length = self.length;
parallel: for (;;) { // see ArrayMapPar() to explain why for(;;) etc
if (ShouldForceSequential())
break parallel;
if (!TRY_PARALLEL(mode))
break parallel;
var chunks = ComputeNumChunks(length);
var numSlices = ForkJoinSlices();
if (chunks < numSlices * 2)
break parallel;
var info = ComputeAllSliceBounds(chunks, numSlices);
// Step 1. Compute which items from each slice of the result
// buffer should be preserved. When we're done, we have an array
// |survivors| containing a bitset for each chunk, indicating
// which members of the chunk survived. We also keep an array
// |counts| containing the total number of items that are being
// preserved from within one slice.
//
// FIXME(bug 844890): Use typed arrays here.
var counts = NewDenseArray(numSlices);
for (var i = 0; i < numSlices; i++)
UnsafePutElements(counts, i, 0);
var survivors = NewDenseArray(chunks);
ForkJoin(findSurvivorsInSlice, ForkJoinMode(mode));
// Step 2. Compress the slices into one contiguous set.
var count = 0;
for (var i = 0; i < numSlices; i++)
count += counts[i];
var buffer = NewDenseArray(count);
if (count > 0)
ForkJoin(copySurvivorsInSlice, ForkJoinMode(mode));
return buffer;
}
// Sequential fallback:
ASSERT_SEQUENTIAL_IS_OK(mode);
var buffer = [];
for (var i = 0; i < length; i++) {
var elem = self[i];
if (func(elem, i, self))
ARRAY_PUSH(buffer, elem);
}
return buffer;
/**
* As described above, our goal is to determine which items we
* will preserve from a given slice. We do this one chunk at a
* time. When we finish a chunk, we record our current count and
* the next chunk sliceId, lest we should bail.
*/
function findSurvivorsInSlice(sliceId, numSlices, warmup) {
var chunkPos = info[SLICE_POS(sliceId)];
var chunkEnd = info[SLICE_END(sliceId)];
if (warmup && chunkEnd > chunkPos)
chunkEnd = chunkPos + 1;
var count = counts[sliceId];
while (chunkPos < chunkEnd) {
var indexStart = chunkPos << CHUNK_SHIFT;
var indexEnd = std_Math_min(indexStart + CHUNK_SIZE, length);
var chunkBits = 0;
for (var bit = 0; indexStart + bit < indexEnd; bit++) {
var keep = !!func(self[indexStart + bit], indexStart + bit, self);
chunkBits |= keep << bit;
count += keep;
}
UnsafePutElements(survivors, chunkPos, chunkBits,
counts, sliceId, count,
info, SLICE_POS(sliceId), ++chunkPos);
}
return chunkEnd === info[SLICE_END(sliceId)];
}
function copySurvivorsInSlice(sliceId, numSlices, warmup) {
// Copies the survivors from this slice into the correct position.
// Note that this is an idempotent operation that does not invoke
// user code. Therefore, we don't expect bailouts and make an
// effort to proceed chunk by chunk or avoid duplicating work.
// Total up the items preserved by previous slices.
var count = 0;
if (sliceId > 0) { // FIXME(#819219)---work around a bug in Ion's range checks
for (var i = 0; i < sliceId; i++)
count += counts[i];
}
// Compute the final index we expect to write.
var total = count + counts[sliceId];
if (count === total)
return true;
// Iterate over the chunks assigned to us. Read the bitset for
// each chunk. Copy values where a 1 appears until we have
// written all the values that we expect to. We can just iterate
// from 0...CHUNK_SIZE without fear of a truncated final chunk
// because we are already checking for when count==total.
var chunkStart = info[SLICE_START(sliceId)];
var chunkEnd = info[SLICE_END(sliceId)];
for (var chunk = chunkStart; chunk < chunkEnd; chunk++) {
var chunkBits = survivors[chunk];
if (!chunkBits)
continue;
var indexStart = chunk << CHUNK_SHIFT;
for (var i = 0; i < CHUNK_SIZE; i++) {
if (chunkBits & (1 << i)) {
UnsafePutElements(buffer, count++, self[indexStart + i]);
if (count === total)
break;
}
}
}
return true;
}
}
/**
* "Comprehension form": This is the function invoked for |Array.buildPar(len,
* fn)| It creates a new array with length |len| where index |i| is equal to
* |fn(i)|.
*
* The final |mode| argument is an internal argument used only during our
* unit-testing.
*/
function ArrayStaticBuildPar(length, func, mode) {
if (!IS_UINT32(length))
ThrowError(JSMSG_BAD_ARRAY_LENGTH);
if (!IsCallable(func))
ThrowError(JSMSG_NOT_FUNCTION, DecompileArg(1, func));
var buffer = NewDenseArray(length);
parallel: for (;;) {
if (ShouldForceSequential())
break parallel;
if (!TRY_PARALLEL(mode))
break parallel;
var chunks = ComputeNumChunks(length);
var numSlices = ForkJoinSlices();
var info = ComputeAllSliceBounds(chunks, numSlices);
ForkJoin(constructSlice, ForkJoinMode(mode));
return buffer;
}
// Sequential fallback:
ASSERT_SEQUENTIAL_IS_OK(mode);
fill(0, length);
return buffer;
function constructSlice(sliceId, numSlices, warmup) {
var chunkPos = info[SLICE_POS(sliceId)];
var chunkEnd = info[SLICE_END(sliceId)];
if (warmup && chunkEnd > chunkPos)
chunkEnd = chunkPos + 1;
while (chunkPos < chunkEnd) {
var indexStart = chunkPos << CHUNK_SHIFT;
var indexEnd = std_Math_min(indexStart + CHUNK_SIZE, length);
fill(indexStart, indexEnd);
UnsafePutElements(info, SLICE_POS(sliceId), ++chunkPos);
}
return chunkEnd === info[SLICE_END(sliceId)];
}
function fill(indexStart, indexEnd) {
for (var i = indexStart; i < indexEnd; i++)
UnsafePutElements(buffer, i, func(i));
}
}
/*
* Mark the main operations as clone-at-callsite for better precision.
* This is slightly overkill, as all that we really need is to
* specialize to the receiver and the elemental function, but in
* practice this is likely not so different, since element functions
* are often used in exactly one place.
*/
SetScriptHints(ArrayMapPar, { cloneAtCallsite: true });
SetScriptHints(ArrayReducePar, { cloneAtCallsite: true });
SetScriptHints(ArrayScanPar, { cloneAtCallsite: true });
SetScriptHints(ArrayScatterPar, { cloneAtCallsite: true });
SetScriptHints(ArrayFilterPar, { cloneAtCallsite: true });
SetScriptHints(ArrayStaticBuildPar, { cloneAtCallsite: true });
#endif /* ENABLE_PARALLEL_JS */

1
js/src/builtin/Utilities.js
View File

@ -26,6 +26,7 @@
/* Utility macros */
#define TO_INT32(x) (x | 0)
#define TO_UINT32(x) (x >>> 0)
#define IS_UINT32(x) (x >>> 0 === x)
/* Assertions */
#ifdef DEBUG

15
js/src/jsarray.cpp
View File

@ -2807,6 +2807,15 @@ static const JSFunctionSpec array_methods[] = {
{"some", {NULL, NULL}, 1,0, "ArraySome"},
{"every", {NULL, NULL}, 1,0, "ArrayEvery"},
#ifdef ENABLE_PARALLEL_JS
/* Parallelizable and pure methods. */
{"mapPar", {NULL, NULL}, 2,0, "ArrayMapPar"},
{"reducePar", {NULL, NULL}, 2,0, "ArrayReducePar"},
{"scanPar", {NULL, NULL}, 2,0, "ArrayScanPar"},
{"scatterPar", {NULL, NULL}, 5,0, "ArrayScatterPar"},
{"filterPar", {NULL, NULL}, 2,0, "ArrayFilterPar"},
#endif
/* ES6 additions */
{"find", {NULL, NULL}, 1,0, "ArrayFind"},
{"findIndex", {NULL, NULL}, 1,0, "ArrayFindIndex"},
@ -2825,6 +2834,12 @@ static const JSFunctionSpec array_static_methods[] = {
{"reduce", {NULL, NULL}, 2,0, "ArrayStaticReduce"},
{"reduceRight", {NULL, NULL}, 2,0, "ArrayStaticReduceRight"},
JS_FN("of", array_of, 0,0),
#ifdef ENABLE_PARALLEL_JS
/* Parallelizable and pure static methods. */
{"buildPar", {NULL, NULL}, 3,0, "ArrayStaticBuildPar"},
#endif
JS_FS_END
};