Attachment 368998 Details for Bug 197305 – Patch

[patch] Patch

patch197305 (text/plain), 8.74 KB, created by Robin Morisset on 2019-05-03 14:58:38 PDT

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Creator: Robin Morisset

Created: 2019-05-03 14:58:38 PDT

Size: 8.74 KB

patch

obsolete

>diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
>index bde32b8c253..0d7122ad023 100644
>--- a/Source/JavaScriptCore/ChangeLog
>+++ b/Source/JavaScriptCore/ChangeLog
>@@ -1,3 +1,23 @@
>+2019-05-03  Robin Morisset  <rmorisset@apple.com>
>+
>+        [Air] highOrderAdjacents in AbstractColoringAllocator::conservativeHeuristic should be some kind of array
>+        https://bugs.webkit.org/show_bug.cgi?id=197305
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        Currently it is a HashSet, but it only ever holds at most registerCount() items. And linear search tends to be faster on such a small collection than hashing + searching in a HashSet.
>+        Further benefits include avoiding the allocation of the HashSet, not actually adding the nodes adjacent to V (since there are no duplicates in the adjacency lists).
>+
>+        This patch also contains a trivial optimization: if the remaining number of nodes to consider + the number of highOrderAdjacents already seen is smaller than registerCount() we can return true directly.
>+        Apart from that, the patch got some trivial cleanup of GraphColoringRegisterAllocation::allocateOnBank() (that for example was only logging the number of iterations for FP registers, and not the more interesting number for GP registers).
>+
>+        The time spent in the register allocator throughout JetStream2 on this MacBook Pro moves from 3767 / 3710 / 3785 ms to 3551 / 3454 / 3503 ms.
>+        So about a 6% speedup for that phase, and between 1 and 1.5% speedup for FTL/OMG compilation overall.
>+
>+        No new tests as there is no intended change to the code being generated, and this was already tested by running testb3 + JetStream2.
>+
>+        * b3/air/AirAllocateRegistersByGraphColoring.cpp:
>+
> 2019-05-03  Devin Rousso  <drousso@apple.com>
> 
>         Web Inspector: Record actions performed on WebGL2RenderingContext
>diff --git a/Source/JavaScriptCore/b3/air/AirAllocateRegistersByGraphColoring.cpp b/Source/JavaScriptCore/b3/air/AirAllocateRegistersByGraphColoring.cpp
>index 8f497650acb..a98176b986d 100644
>--- a/Source/JavaScriptCore/b3/air/AirAllocateRegistersByGraphColoring.cpp
>+++ b/Source/JavaScriptCore/b3/air/AirAllocateRegistersByGraphColoring.cpp
>@@ -192,32 +192,45 @@ protected:
>         const auto& adjacentsOfU = m_adjacencyList[u];
>         const auto& adjacentsOfV = m_adjacencyList[v];
> 
>-        if (adjacentsOfU.size() + adjacentsOfV.size() < registerCount()) {
>+        Vector<IndexType, 100> highOrderAdjacents;
>+        RELEASE_ASSERT(registerCount() < 100);
>+        unsigned numCandidates = adjacentsOfU.size() + adjacentsOfV.size();
>+        if (numCandidates < registerCount()) {
>             // Shortcut: if the total number of adjacents is less than the number of register, the condition is always met.
>             return true;
>         }
> 
>-        HashSet<IndexType> highOrderAdjacents;
>-
>         for (IndexType adjacentTmpIndex : adjacentsOfU) {
>             ASSERT(adjacentTmpIndex != v);
>             ASSERT(adjacentTmpIndex != u);
>+            numCandidates--;
>             if (!hasBeenSimplified(adjacentTmpIndex) && m_degrees[adjacentTmpIndex] >= registerCount()) {
>-                auto addResult = highOrderAdjacents.add(adjacentTmpIndex);
>-                if (addResult.isNewEntry && highOrderAdjacents.size() >= registerCount())
>+                ASSERT(std::find(highOrderAdjacents.begin(), highOrderAdjacents.end(), adjacentTmpIndex) == highOrderAdjacents.end());
>+                highOrderAdjacents.uncheckedAppend(adjacentTmpIndex);
>+                if (highOrderAdjacents.size() >= registerCount())
>                     return false;
>-            }
>+            } else if (highOrderAdjacents.size() + numCandidates < registerCount())
>+                return true;
>         }
>+        ASSERT(numCandidates == adjacentsOfV.size());
>+
>+        auto iteratorEndHighOrderAdjacentsOfU = highOrderAdjacents.end();
>         for (IndexType adjacentTmpIndex : adjacentsOfV) {
>             ASSERT(adjacentTmpIndex != u);
>             ASSERT(adjacentTmpIndex != v);
>-            if (!hasBeenSimplified(adjacentTmpIndex) && m_degrees[adjacentTmpIndex] >= registerCount()) {
>-                auto addResult = highOrderAdjacents.add(adjacentTmpIndex);
>-                if (addResult.isNewEntry && highOrderAdjacents.size() >= registerCount())
>+            numCandidates--;
>+            if (!hasBeenSimplified(adjacentTmpIndex)
>+                && m_degrees[adjacentTmpIndex] >= registerCount()
>+                && std::find(highOrderAdjacents.begin(), iteratorEndHighOrderAdjacentsOfU, adjacentTmpIndex) == iteratorEndHighOrderAdjacentsOfU) {
>+                ASSERT(std::find(iteratorEndHighOrderAdjacentsOfU, highOrderAdjacents.end(), adjacentTmpIndex) == highOrderAdjacents.end());
>+                highOrderAdjacents.uncheckedAppend(adjacentTmpIndex);
>+                if (highOrderAdjacents.size() >= registerCount())
>                     return false;
>-            }
>+            } else if (highOrderAdjacents.size() + numCandidates < registerCount())
>+                return true;
>         }
> 
>+        ASSERT(!numCandidates);
>         ASSERT(highOrderAdjacents.size() < registerCount());
>         return true;
>     }
>@@ -1021,7 +1034,7 @@ protected:
>     }
> 
>     // Low-degree vertex can always be colored: just pick any of the color taken by any
>-    // other adjacent verices.
>+    // other adjacent vertices.
>     // The "Simplify" phase takes a low-degree out of the interference graph to simplify it.
>     void simplify()
>     {
>@@ -1789,13 +1802,9 @@ public:
>         padInterference(m_code);
> 
>         allocateOnBank<GP>();
>-        m_numIterations = 0;
>         allocateOnBank<FP>();
> 
>         fixSpillsAfterTerminals(m_code);
>-
>-        if (reportStats)
>-            dataLog("Num iterations = ", m_numIterations, "\n");
>     }
> 
> private:
>@@ -1808,12 +1817,15 @@ private:
>         // we should add the Tmp to unspillableTmps. That will help avoid relooping only to turn the
>         // Tmp into an unspillable Tmp.
>         // https://bugs.webkit.org/show_bug.cgi?id=152699
>-        
>-        while (true) {
>-            ++m_numIterations;
>+
>+        unsigned numIterations = 0;
>+        bool done = false;
>+
>+        while (!done) {
>+            ++numIterations;
> 
>             if (traceDebug)
>-                dataLog("Code at iteration ", m_numIterations, ":\n", m_code);
>+                dataLog("Code at iteration ", numIterations, ":\n", m_code);
> 
>             // FIXME: One way to optimize this code is to remove the recomputation inside the fixpoint.
>             // We need to recompute because spilling adds tmps, but we could just update tmpWidth when we
>@@ -1822,7 +1834,7 @@ private:
>             // spill code we emit. Since we currently recompute TmpWidth after spilling, the newly
>             // created Tmps may get narrower use/def widths. On the other hand, the spiller already
>             // selects which move instruction to use based on the original Tmp's widths, so it may not
>-            // matter than a subsequent iteration sees a coservative width for the new Tmps. Also, the
>+            // matter than a subsequent iteration sees a conservative width for the new Tmps. Also, the
>             // recomputation may not actually be a performance problem; it's likely that a better way to
>             // improve performance of TmpWidth is to replace its HashMap with something else. It's
>             // possible that most of the TmpWidth overhead is from queries of TmpWidth rather than the
>@@ -1835,7 +1847,7 @@ private:
>                 if (!allocator.requiresSpilling()) {
>                     this->assignRegistersToTmp<bank>(allocator);
>                     if (traceDebug)
>-                        dataLog("Successfull allocation at iteration ", m_numIterations, ":\n", m_code);
>+                        dataLog("Successfull allocation at iteration ", numIterations, ":\n", m_code);
> 
>                     return true;
>                 }
>@@ -1843,8 +1855,7 @@ private:
>                 this->addSpillAndFill<bank>(allocator, unspillableTmps);
>                 return false;
>             };
>-            
>-            bool done;
>+
>             if (useIRC()) {
>                 ColoringAllocator<bank, IRC> allocator(m_code, m_tmpWidth, m_useCounts, unspillableTmps);
>                 done = doAllocation(allocator);
>@@ -1852,9 +1863,8 @@ private:
>                 ColoringAllocator<bank, Briggs> allocator(m_code, m_tmpWidth, m_useCounts, unspillableTmps);
>                 done = doAllocation(allocator);
>             }
>-            if (done)
>-                return;
>         }
>+        dataLogLnIf(reportStats, "Num iterations = ", numIterations, " for bank: ", bank);
>     }
> 
>     template<Bank bank>
>@@ -2187,7 +2197,6 @@ private:
>     Code& m_code;
>     TmpWidth m_tmpWidth;
>     UseCounts<Tmp>& m_useCounts;
>-    unsigned m_numIterations { 0 };
> };
> 
> } // anonymous namespace

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keith_miller: review+
ews-watchlist: commit-queue-

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Attachments on bug 197305: 368297 | 368334 | 368998 | 369031 | 378401