Title: [226426] trunk/Source/_javascript_Core
- Revision
- 226426
- Author
- sbar...@apple.com
- Date
- 2018-01-04 16:01:32 -0800 (Thu, 04 Jan 2018)
Log Message
Add a new pattern matching rule to Graph::methodOfGettingAValueProfileFor for SetLocal(@nodeWithHeapPrediction)
https://bugs.webkit.org/show_bug.cgi?id=181296
Reviewed by Filip Pizlo.
Inside Speedometer's Ember test, there is a recompile loop like:
a: GetByVal(..., semanticOriginX)
b: SetLocal(Cell:@a, semanticOriginX)
where the cell check always fails. For reasons I didn't investigate, the
baseline JIT's value profiling doesn't accurately capture the GetByVal's
result.
However, when compiling this cell speculation check in the DFG, we get a null
MethodOfGettingAValueProfile inside Graph::methodOfGettingAValueProfileFor for
this IR pattern because both @a and @b have the same semantic origin. We
should not follow the same semantic origin heuristic when dealing with
SetLocal since SetLocal(@nodeWithHeapPrediction) is such a common IR pattern.
For patterns like this, we introduce a new heuristic: @NodeThatDoesNotProduceAValue(@nodeWithHeapPrediction).
For this IR pattern, we will update the value profile for the semantic origin
for @nodeWithHeapPrediction. So, for the Speedometer example above, we
will correctly update the GetByVal's value profile, which will prevent
an OSR exit loop.
* dfg/DFGGraph.cpp:
(JSC::DFG::Graph::methodOfGettingAValueProfileFor):
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (226425 => 226426)
--- trunk/Source/_javascript_Core/ChangeLog 2018-01-05 00:00:25 UTC (rev 226425)
+++ trunk/Source/_javascript_Core/ChangeLog 2018-01-05 00:01:32 UTC (rev 226426)
@@ -1,3 +1,32 @@
+2018-01-04 Saam Barati <sbar...@apple.com>
+
+ Add a new pattern matching rule to Graph::methodOfGettingAValueProfileFor for SetLocal(@nodeWithHeapPrediction)
+ https://bugs.webkit.org/show_bug.cgi?id=181296
+
+ Reviewed by Filip Pizlo.
+
+ Inside Speedometer's Ember test, there is a recompile loop like:
+ a: GetByVal(..., semanticOriginX)
+ b: SetLocal(Cell:@a, semanticOriginX)
+
+ where the cell check always fails. For reasons I didn't investigate, the
+ baseline JIT's value profiling doesn't accurately capture the GetByVal's
+ result.
+
+ However, when compiling this cell speculation check in the DFG, we get a null
+ MethodOfGettingAValueProfile inside Graph::methodOfGettingAValueProfileFor for
+ this IR pattern because both @a and @b have the same semantic origin. We
+ should not follow the same semantic origin heuristic when dealing with
+ SetLocal since SetLocal(@nodeWithHeapPrediction) is such a common IR pattern.
+ For patterns like this, we introduce a new heuristic: @NodeThatDoesNotProduceAValue(@nodeWithHeapPrediction).
+ For this IR pattern, we will update the value profile for the semantic origin
+ for @nodeWithHeapPrediction. So, for the Speedometer example above, we
+ will correctly update the GetByVal's value profile, which will prevent
+ an OSR exit loop.
+
+ * dfg/DFGGraph.cpp:
+ (JSC::DFG::Graph::methodOfGettingAValueProfileFor):
+
2018-01-04 Keith Miller <keith_mil...@apple.com>
Array Storage operations sometimes did not update the indexing mask correctly.
Modified: trunk/Source/_javascript_Core/dfg/DFGGraph.cpp (226425 => 226426)
--- trunk/Source/_javascript_Core/dfg/DFGGraph.cpp 2018-01-05 00:00:25 UTC (rev 226425)
+++ trunk/Source/_javascript_Core/dfg/DFGGraph.cpp 2018-01-05 00:01:32 UTC (rev 226426)
@@ -1617,9 +1617,11 @@
MethodOfGettingAValueProfile Graph::methodOfGettingAValueProfileFor(Node* currentNode, Node* operandNode)
{
+ // This represents IR like `CurrentNode(@operandNode)`. For example: `GetByVal(..., Int32:@GetLocal)`.
+
for (Node* node = operandNode; node;) {
// currentNode is null when we're doing speculation checks for checkArgumentTypes().
- if (!currentNode || node->origin.semantic != currentNode->origin.semantic) {
+ if (!currentNode || node->origin.semantic != currentNode->origin.semantic || !currentNode->hasResult()) {
CodeBlock* profiledBlock = baselineCodeBlockFor(node->origin.semantic);
if (node->accessesStack(*this)) {
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