Attachment 224721 Details for Bug 129085 – the patch

[patch] the patch

blah.patch (text/plain), 3.25 KB, created by Filip Pizlo on 2014-02-19 23:45:59 PST

(hide)

Description:

Filename:

MIME Type:

Creator: Filip Pizlo

Created: 2014-02-19 23:45:59 PST

Size: 3.25 KB

patch

obsolete

>Index: Source/JavaScriptCore/ChangeLog
>===================================================================
>--- Source/JavaScriptCore/ChangeLog	(revision 164416)
>+++ Source/JavaScriptCore/ChangeLog	(working copy)
>@@ -1,3 +1,16 @@
>+2014-02-19  Filip Pizlo  <fpizlo@apple.com>
>+
>+        FTL should not emit stack overflow checks in leaf functions
>+        https://bugs.webkit.org/show_bug.cgi?id=129085
>+
>+        Reviewed by NOBODY (OOPS!).
>+        
>+        Miniscule (0.5%) speed-up on V8v7.
>+
>+        * ftl/FTLLowerDFGToLLVM.cpp:
>+        (JSC::FTL::LowerDFGToLLVM::lower):
>+        (JSC::FTL::LowerDFGToLLVM::didOverflowStack):
>+
> 2014-02-19  ChangSeok Oh  <changseok.oh@collabora.com>
> 
>         Unreviewed build fix after r164396
>Index: Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp
>===================================================================
>--- Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp	(revision 164415)
>+++ Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp	(working copy)
>@@ -136,9 +136,9 @@ public:
>         m_tagMask = m_out.constInt64(TagMask);
>         
>         m_out.storePtr(m_out.constIntPtr(codeBlock()), addressFor(JSStack::CodeBlock));
>+        
>         m_out.branch(
>-            m_out.below(m_callFrame, m_out.loadPtr(m_out.absolute(vm().addressOfFTLStackLimit()))),
>-            rarely(stackOverflow), usually(lowBlock(m_graph.block(0))));
>+            didOverflowStack(), rarely(stackOverflow), usually(lowBlock(m_graph.block(0))));
>         
>         m_out.appendTo(stackOverflow, m_handleExceptions);
>         vmCall(m_out.operation(operationThrowStackOverflowError), m_callFrame, m_out.constIntPtr(codeBlock()), NoExceptions);
>@@ -3700,6 +3700,42 @@ private:
>         m_out.store64(m_out.add(m_out.load64(counter), m_out.constInt64(1)), counter);
>     }
>     
>+    LValue didOverflowStack()
>+    {
>+        // This does a very simple leaf function analysis. The invariant of FTL call
>+        // frames is that the caller had already done enough of a stack check to
>+        // prove that this call frame has enough stack to run, and also enough stack
>+        // to make runtime calls. So, we only need to stack check when making calls
>+        // to other JS functions. If we don't find such calls then we don't need to
>+        // do any stack checks.
>+        
>+        for (BlockIndex blockIndex = 0; blockIndex < m_graph.numBlocks(); ++blockIndex) {
>+            BasicBlock* block = m_graph.block(blockIndex);
>+            if (!block)
>+                continue;
>+            
>+            for (unsigned nodeIndex = block->size(); nodeIndex--;) {
>+                Node* node = block->at(nodeIndex);
>+                
>+                switch (node->op()) {
>+                case GetById:
>+                case PutById:
>+                case Call:
>+                case Construct:
>+                    return m_out.below(
>+                        m_callFrame,
>+                        m_out.loadPtr(
>+                            m_out.absolute(vm().addressOfFTLStackLimit())));
>+                    
>+                default:
>+                    break;
>+                }
>+            }
>+        }
>+        
>+        return m_out.booleanFalse;
>+    }
>+    
>     LValue getById(LValue base)
>     {
>         StringImpl* uid = m_graph.identifiers()[m_node->identifierNumber()];

Flags:

msaboff: review+

Actions: View | Formatted Diff | Diff

Attachments on bug 129085: 224721