Attachment 369315 Details for Bug 197265 – Patch

[patch] Patch

patch197265 (text/plain), 9.30 KB, created by Robin Morisset on 2019-05-07 12:38:47 PDT

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Creator: Robin Morisset

Created: 2019-05-07 12:38:47 PDT

Size: 9.30 KB

patch

obsolete

>diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
>index da788495030..5eb2f8abe3d 100644
>--- a/Source/JavaScriptCore/ChangeLog
>+++ b/Source/JavaScriptCore/ChangeLog
>@@ -1,3 +1,37 @@
>+2019-05-07  Robin Morisset  <rmorisset@apple.com>
>+
>+        [B3] Constants should be hoisted to the root block
>+        https://bugs.webkit.org/show_bug.cgi?id=197265
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        This patch does the following:
>+        - B3ReduceStrength now hoists all constants to the root BB, and de-duplicates them along the way
>+        - B3PureCSE no longer bothers with constants, since they are already de-duplicated by the time it gets to see them
>+        - We now run eliminateDeadCode just after moveConstants, so that the Nops that moveConstants generates are freed instead of staying live throughout Air compilation.
>+        - I also took the opportunity to fix typos in comments in various parts of the code base.
>+
>+        Here are a few numbers to justify this patch:
>+        - In JetStream2, about 27% of values at the beginning of B3 are constants
>+        - In JetStream2, about 11% of values at the end of B3 are Nops
>+        - In JetStream2, this patch increases the number of times that tail duplication happens from a bit less than 24k to a bit more than 25k (hoisting constants makes blocks smaller).
>+
>+        When I tried measuring the total effect on JetStream2 I got a tiny and almost certainly non-significant progression.
>+
>+        * b3/B3Generate.cpp:
>+        (JSC::B3::generateToAir):
>+        * b3/B3MoveConstants.cpp:
>+        * b3/B3PureCSE.cpp:
>+        (JSC::B3::PureCSE::process):
>+        * b3/B3PureCSE.h:
>+        * b3/B3ReduceStrength.cpp:
>+        * bytecode/GetByIdStatus.cpp:
>+        (JSC::GetByIdStatus::computeForStubInfoWithoutExitSiteFeedback):
>+        * dfg/DFGCSEPhase.cpp:
>+        * dfg/DFGOSRAvailabilityAnalysisPhase.h:
>+        * dfg/DFGOSRExit.cpp:
>+        (JSC::DFG::OSRExit::executeOSRExit):
>+
> 2019-05-07  Tadeu Zagallo  <tzagallo@apple.com>
> 
>         tryCachePutByID should not crash if target offset changes
>diff --git a/Source/JavaScriptCore/b3/B3Generate.cpp b/Source/JavaScriptCore/b3/B3Generate.cpp
>index e370e215894..ba2fa08482e 100644
>--- a/Source/JavaScriptCore/b3/B3Generate.cpp
>+++ b/Source/JavaScriptCore/b3/B3Generate.cpp
>@@ -116,6 +116,7 @@ void generateToAir(Procedure& procedure)
>     lowerMacrosAfterOptimizations(procedure);
>     legalizeMemoryOffsets(procedure);
>     moveConstants(procedure);
>+    eliminateDeadCode(procedure);
> 
>     // FIXME: We should run pureCSE here to clean up some platform specific changes from the previous phases.
>     // https://bugs.webkit.org/show_bug.cgi?id=164873
>diff --git a/Source/JavaScriptCore/b3/B3MoveConstants.cpp b/Source/JavaScriptCore/b3/B3MoveConstants.cpp
>index 7acba1e525d..bbd781df40d 100644
>--- a/Source/JavaScriptCore/b3/B3MoveConstants.cpp
>+++ b/Source/JavaScriptCore/b3/B3MoveConstants.cpp
>@@ -154,7 +154,7 @@ private:
>                 };
>                 
>                 // We call this when we have found a constant that we'd like to use. It's possible that
>-                // we have computed that the constant should be meterialized in this block, but we
>+                // we have computed that the constant should be materialized in this block, but we
>                 // haven't inserted it yet. This inserts the constant if necessary.
>                 auto materialize = [&] (Value* child) {
>                     ValueKey key = child->key();
>diff --git a/Source/JavaScriptCore/b3/B3PureCSE.cpp b/Source/JavaScriptCore/b3/B3PureCSE.cpp
>index eb9c46b1740..e4e9ccd3efa 100644
>--- a/Source/JavaScriptCore/b3/B3PureCSE.cpp
>+++ b/Source/JavaScriptCore/b3/B3PureCSE.cpp
>@@ -68,7 +68,7 @@ Value* PureCSE::findMatch(const ValueKey& key, BasicBlock* block, Dominators& do
> 
> bool PureCSE::process(Value* value, Dominators& dominators)
> {
>-    if (value->opcode() == Identity)
>+    if (value->opcode() == Identity || value->isConstant())
>         return false;
> 
>     ValueKey key = value->key();
>diff --git a/Source/JavaScriptCore/b3/B3PureCSE.h b/Source/JavaScriptCore/b3/B3PureCSE.h
>index d26e4117f15..66857be1617 100644
>--- a/Source/JavaScriptCore/b3/B3PureCSE.h
>+++ b/Source/JavaScriptCore/b3/B3PureCSE.h
>@@ -40,7 +40,7 @@ class Value;
> typedef Vector<Value*, 1> Matches;
> 
> // This is a reusable utility for doing pure CSE. You can use it to do pure CSE on a program by just
>-// proceeding in order an calling process().
>+// proceeding in order and calling process().
> class PureCSE {
> public:
>     PureCSE();
>diff --git a/Source/JavaScriptCore/b3/B3ReduceStrength.cpp b/Source/JavaScriptCore/b3/B3ReduceStrength.cpp
>index 7e22c29d6d4..2f34efdc820 100644
>--- a/Source/JavaScriptCore/b3/B3ReduceStrength.cpp
>+++ b/Source/JavaScriptCore/b3/B3ReduceStrength.cpp
>@@ -402,6 +402,7 @@ public:
>         : m_proc(proc)
>         , m_insertionSet(proc)
>         , m_blockInsertionSet(proc)
>+        , m_root(proc.at(0))
>     {
>     }
> 
>@@ -442,6 +443,7 @@ public:
>             // keep @thing. That's better, since we usually want things to stay wherever the client
>             // put them. We're not actually smart enough to move things around at random.
>             m_changed |= eliminateDeadCodeImpl(m_proc);
>+            m_valueForConstant.clear();
>             
>             simplifySSA();
>             
>@@ -2145,7 +2147,29 @@ private:
>             }
>             break;
>         }
>-            
>+
>+        case Const32:
>+        case Const64:
>+        case ConstFloat:
>+        case ConstDouble: {
>+            ValueKey key = m_value->key();
>+            if (Value* constInRoot = m_valueForConstant.get(key)) {
>+                if (constInRoot != m_value) {
>+                    m_value->replaceWithIdentity(constInRoot);
>+                    m_changed = true;
>+                }
>+            } else if (m_block == m_root)
>+                m_valueForConstant.add(key, m_value);
>+            else {
>+                Value* constInRoot = m_proc.clone(m_value);
>+                m_root->appendNonTerminal(constInRoot);
>+                m_valueForConstant.add(key, constInRoot);
>+                m_value->replaceWithIdentity(constInRoot);
>+                m_changed = true;
>+            }
>+            break;
>+        }
>+
>         default:
>             break;
>         }
>@@ -2794,6 +2818,8 @@ private:
>     Procedure& m_proc;
>     InsertionSet m_insertionSet;
>     BlockInsertionSet m_blockInsertionSet;
>+    HashMap<ValueKey, Value*> m_valueForConstant;
>+    BasicBlock* m_root { nullptr };
>     BasicBlock* m_block { nullptr };
>     unsigned m_index { 0 };
>     Value* m_value { nullptr };
>diff --git a/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp b/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
>index 26bcd5ff763..6e4e8bfdbe1 100644
>--- a/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
>+++ b/Source/JavaScriptCore/bytecode/GetByIdStatus.cpp
>@@ -276,7 +276,7 @@ GetByIdStatus GetByIdStatus::computeForStubInfoWithoutExitSiteFeedback(
>                     return GetByIdStatus(JSC::slowVersion(summary));
> 
>                 if (domAttribute) {
>-                    // Give up when cutom accesses are not merged into one.
>+                    // Give up when custom accesses are not merged into one.
>                     if (result.numVariants() != 1)
>                         return GetByIdStatus(JSC::slowVersion(summary));
>                 } else {
>diff --git a/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp b/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp
>index 2ba59463fb1..e89daae4957 100644
>--- a/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp
>+++ b/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp
>@@ -257,7 +257,7 @@ private:
>         });
>     }
> 
>-    // The majority of Impure Stack Slotsare unique per value.
>+    // The majority of Impure Stack Slots are unique per value.
>     // This is very useful for fast clobber(), we can just remove the slot addressed by AbstractHeap
>     // in O(1).
>     //
>diff --git a/Source/JavaScriptCore/dfg/DFGOSRAvailabilityAnalysisPhase.h b/Source/JavaScriptCore/dfg/DFGOSRAvailabilityAnalysisPhase.h
>index 14de94da1d8..69e8b7550c8 100644
>--- a/Source/JavaScriptCore/dfg/DFGOSRAvailabilityAnalysisPhase.h
>+++ b/Source/JavaScriptCore/dfg/DFGOSRAvailabilityAnalysisPhase.h
>@@ -33,7 +33,7 @@ namespace JSC { namespace DFG {
> 
> class Graph;
> 
>-// Computes BasicBlock::ssa->availabiltiyAtHead/Tail. This is a forward flow type inference
>+// Computes BasicBlock::ssa->availabilityAtHead/Tail. This is a forward flow type inference
> // over MovHints and SetLocals. This analysis is run directly by the Plan for preparing for
> // lowering to B3 IR, but it can also be used as a utility. Note that if you run it before
> // stack layout, all of the flush availability will omit the virtual register - but it will
>diff --git a/Source/JavaScriptCore/dfg/DFGOSRExit.cpp b/Source/JavaScriptCore/dfg/DFGOSRExit.cpp
>index e185a100f20..09b30ba3cfc 100644
>--- a/Source/JavaScriptCore/dfg/DFGOSRExit.cpp
>+++ b/Source/JavaScriptCore/dfg/DFGOSRExit.cpp
>@@ -452,7 +452,7 @@ void OSRExit::executeOSRExit(Context& context)
> 
>     context.sp() = context.fp<uint8_t*>() + exitState.stackPointerOffset;
> 
>-    // The only reason for using this do while look is so we can break out midway when appropriate.
>+    // The only reason for using this do while loop is so we can break out midway when appropriate.
>     do {
>         auto extraInitializationLevel = static_cast<ExtraInitializationLevel>(exitState.extraInitializationLevel);
>

Flags:

saam: review+
rmorisset: commit-queue-

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Attachments on bug 197265: 368522 | 369315 | 369319