2008-09-26 Gavin Barraclough <barraclough@apple.com>
Reviewed by Maciej Stachowiak & Oliver Hunt.
Add support for reusing temporary JSNumberCells. This change is based on the observation
that if the result of certain operations is a JSNumberCell and is consumed by a subsequent
operation that would produce a JSNumberCell, we can reuse the object rather than allocating
a fresh one. E.g. given the expression ((a * b) * c), we can statically determine that
(a * b) will have a numeric result (or else it will have thrown an exception), so the result
will either be a JSNumberCell or a JSImmediate.
This patch changes three areas of JSC:
* The AST now tracks type information about the result of each node.
* This information is consumed in bytecode compilation, and certain bytecode operations
now carry the statically determined type information about their operands.
* CTI uses the information in a number of fashions:
* Where an operand to certain arithmetic operations is reusable, it will plant code
to try to perform the operation in JIT code & reuse the cell, where appropriate.
* Where it can be statically determined that an operand can only be numeric (typically
the result of another arithmetic operation) the code will not redundantly check that
the JSCell is a JSNumberCell.
* Where either of the operands to an add are non-numeric do not plant an optimized
arithmetic code path, just call straight out to the C function.
+6% Sunspider (10% progression on 3D, 16% progression on math, 60% progression on access-nbody),
+1% v8-tests (improvements in raytrace & crypto)
* VM/CTI.cpp: Add optimized code generation with reuse of temporary JSNumberCells.
* VM/CTI.h:
* kjs/JSNumberCell.h:
* masm/X86Assembler.h:
* VM/CodeBlock.cpp: Add type information to specific bytecodes.
* VM/CodeGenerator.cpp:
* VM/CodeGenerator.h:
* VM/Machine.cpp:
* kjs/nodes.cpp: Track static type information for nodes.
* kjs/nodes.h:
* kjs/ResultDescriptor.h: (Added)
* JavaScriptCore.xcodeproj/project.pbxproj:
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@36976 268f45cc-cd09-0410-ab3c-d52691b4dbfc
13 files changed
