Byte code size and serialized byte code size optimizations (15-20% serialized byte code size reduction) by curtisman · Pull Request #3594 · chakra-core/ChakraCore

curtisman · 2017-08-28T05:08:55Z

Byte code size reductions:

Variable slot index size in layout

Serialized byte code size reductions:

Move has loopHeaderArray and has asmJsInfo into the bit field (instead of a byte)
Don't emit field that has non-zero default value.
Use the defined fields to indicate existing of more field to reduce serialized byte code size
Use constant type to indicate whether it is property string or not instead of an extra boolean
Add int8 and int16 constant type for small int encoding in the constant table
Separate out the byte offset from the character offset in the LineOffsetCache so that we can omit them if the source is purely ASCII-7
-Reduce by half the memory used by the LineOffsetCache for ASCII-7 sources, and it reduces the serialized byte code size as well.
Remove unused sourceSpans from byte code serialization.
Serialize the bit flag with constant encoding (since the bit flag always as a large value)

Also:

Clean up unused Reg2WithICIndex and REg1Int2 layout
Move LineOffsetCache to Runtime/Base instead of Common/DataStructures, and de-templatize it as we only use Recycler as the allocator anyway.

dilijev · 2017-08-31T17:45:58Z

    }

-    inline void InterpreterStackFrame::OP_StModuleSlot(Var instance, int32 slotIndex1, int32 slotIndex2, Var value)
+    inline void InterpreterStackFrame::OP_StModuleSlot(Var instance, uint32 slotIndex1, uint32 slotIndex2, Var value)


Var instance [](start = 55, length = 12)

instance param unused?

Yeah.. it is borrowing the SET_ELEM_ENVSLOTNonVar in the interpreter dispatch, which to clean up will require more change. I will do that separately.

dilijev · 2017-08-31T17:48:15Z

-namespace JsUtil
-{
-    template <typename TAllocator>
-    class LineOffsetCache


LineOffsetCache [](start = 10, length = 15)

Any changes to this code besides splitting into .h and .cpp under lib/runtime/base and removing the JsUtil namespace?

Yes. Splitting the data from charOffset/byteOffset pair to separate list, so that the byteOffset don't need to be stored if it is ASCII-7 (which charOffset == byteOffset)

dilijev · 2017-08-31T17:50:56Z

#undef DECLARE_SERIALIZABLE_ACCESSOR_FIELD

Move #undef DECLARE_SERIALIZABLE_ACCESSOR_FIELD_NO_CHECK after this line?

Refers to: lib/Runtime/SerializableFunctionFields.h:112 in 31cc8d6. [](commit_id = 31cc8d6, deletion_comment = False)

dilijev · 2017-08-31T17:52:49Z

    const int magicEndOfPropIdsOfFormals = *(int*)"]pif";
    const int magicStartOfSlotIdToNestedIndexArray = *(int*)"sni[";
-    const int magicEndOfSlotIdToNestedIndexArray = *(int*)"]sni"
+    const int magicEndOfSlotIdToNestedIndexArray = *(int*)"]sni";


; [](start = 64, length = 1)

wait... how was this not an error?

The code is only enabled explicitly to debug issues. No official build has this code enabled.

dilijev · 2017-08-31T17:53:38Z

+    bool has_propertyIdOfFormals: 1;
    bool has_slotIdInCachedScopeToNestedIndexArray : 1;
+    bool has_debuggerScopeSlotArray : 1;
+


nit: blank line

dilijev · 2017-08-31T17:54:23Z

+    ctStringTemplateCallsite = 10,
+    ctPropertyString16 = 11,
+    ctInt16 = 12,
+    ctInt8 = 13,


why not group the three int size constant types?

I guess since the byte code is going to be updated already, I might as well?

Sigh... I will have to renumber them all

dilijev · 2017-08-31T17:57:09Z

    }

-    uint32 AddPropertyIdOfFormals(BufferBuilderList & builder, FunctionBody * function)
+    uint32 AddPropertyIdOfFormals(BufferBuilderList & builder, PropertyIdArray * propIds, FunctionBody * function)


propIds [](start = 81, length = 7)

Assert(propIds != nullptr) ?

Doesn't feel like the assert serves much value.....

dilijev · 2017-08-31T17:59:49Z


+    const byte * ReadConstantSizedUInt32(const byte * buffer, uint * value)
+    {
+        return ReadConstantSizedInt32(buffer, (int *)value);


Int32 [](start = 32, length = 5)

mismatch of ReadUInt32 (name) and ReadInt32 (returned)

The uint return is in out param.

tcare

…rialized byte code size reduction) Byte code size reductions: - Variable slot index size in layout Serialized byte code size reductions: - Move has loopHeaderArray and has asmJsInfo into the bit field (instead of a byte) - Don't emit field that has non-zero default value. - Use the defined fields to indicate existing of more field to reduce serialized byte code size - Use constant type to indicate whether it is property string or not instead of an extra boolean - Add int8 and int16 constant type for small int encoding in the constant table - Separate out the byte offset from the character offset in the LineOffsetCache so that we can omit them if the source is purely ASCII-7 -Reduce by half the memory used by the LineOffsetCache for ASCII-7 sources, and it reduces the serialized byte code size as well. - Remove unused sourceSpans from byte code serialization. - Serialize the bit flag with constant encoding (since the bit flag always as a large value) Also: - Clean up unused Reg2WithICIndex and REg1Int2 layout - Move LineOffsetCache to Runtime/Base instead of Common/DataStructures, and de-templatize it as we only use Recycler as the allocator anyway.

… optimizations (15-20% serialized byte code size reduction) Merge pull request #3594 from curtisman:bytecode Byte code size reductions: - Variable slot index size in layout Serialized byte code size reductions: - Move has loopHeaderArray and has asmJsInfo into the bit field (instead of a byte) - Don't emit field that has non-zero default value. - Use the defined fields to indicate existing of more field to reduce serialized byte code size - Use constant type to indicate whether it is property string or not instead of an extra boolean - Add int8 and int16 constant type for small int encoding in the constant table - Separate out the byte offset from the character offset in the LineOffsetCache so that we can omit them if the source is purely ASCII-7 -Reduce by half the memory used by the LineOffsetCache for ASCII-7 sources, and it reduces the serialized byte code size as well. - Remove unused sourceSpans from byte code serialization. - Serialize the bit flag with constant encoding (since the bit flag always as a large value) Also: - Clean up unused Reg2WithICIndex and REg1Int2 layout - Move LineOffsetCache to Runtime/Base instead of Common/DataStructures, and de-templatize it as we only use Recycler as the allocator anyway.

msftclas added the cla-not-required label Aug 28, 2017

curtisman force-pushed the bytecode branch 3 times, most recently from c45931a to 31cc8d6 Compare August 28, 2017 20:36

curtisman requested a review from pleath August 28, 2017 20:36

dilijev reviewed Aug 31, 2017

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pleath approved these changes Aug 31, 2017

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tcare approved these changes Aug 31, 2017

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curtisman force-pushed the bytecode branch from 31cc8d6 to 6eb4457 Compare August 31, 2017 22:16

chakrabot merged commit 6eb4457 into chakra-core:master Sep 1, 2017

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curtisman commented Aug 28, 2017

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dilijev Aug 31, 2017 •

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