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Cetus – An Extensible Compiler Infrastructure
Sang Ik LeeTroy Johnson
Rudolf EigenmannECE, Purdue University
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Introduction
Source-to-source compiler infrastructure
Goals Extensible internal representation (IR) Easy to Use IR-API Debugging aid Multi-platform support
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Design Rationales Why write something new ? Polaris
Targets only Fortran 77 Suif
No major release since 2001 Only C is supported
GCC Not designed for source to source
passes
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Cetus Implementation
Implemented in Java C parser written using “Antlr”
parser generator Uses external preprocessor
Works with several preprocessors including GNU “cpp”
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Internal Representation
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Internal Representation cont.
Statement IR Expressions: Actual operations Statements: Flow of expressions, statements Hierarchical: Some statements have inner
blocks of statements Symbol Table
Distributed : Each scope has a separate table Scope : Block with local symbols
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Ongoing Work
Extending Cetus to handle C++ Parser is hard to write
Needs context sensitive information to guide parsing
Also true for C but could be easily resolved Solution
Use generalized LR parser Resolve ambiguity after parsing and
during IR construction
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Cetus Features
Debugging support Java
Assertions, exceptions, runtime stack trace + source information
Cetus API has internal assertions
Pretty printing Keep close to source
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Cetus Features cont.
Expression simplifier Expression substitution can create very long
expressions Change expression into a canonical form Canonical form enables some compiler
passes Parallel parsing
Parses one file per thread Speed up of 2.9 using 4 threads for 176.gcc
on 4 processor UltraSparc 480Mhz system
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IR Construction Time
Parsing + IR Construction Time
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164.gzip
175.vpr
176.gcc
188.am
mp
300.twolf
Sec
on
ds
SUN
AMD
176.gcc on AMD includes non standard C constructs from header file after preprocessing
SUN: 480Mhz UltraSparc+Solaris
AMD: 1.6Ghz AMD AthlonXP+Linux
164.gzip : 34000 lines
175.vpr : 52000 lines
176.gcc : 571000 lines
188.ammp : 47000 lines
300.twolf : 106000 lines
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Cetus Memory UsageHeap Size
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164.gzip
175.vpr
176.gcc
188.am
mp
300.twolf
MB
Heap Size(Byte) to Source Size(Byte)
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164.gzip
175.vpr
176.gcc
188.am
mp
300.twolf
Rat
io
•5 benchmarks from Spec CPU2000 representing different source size
•Complete IR kept in memory for inter-procedural analysis
•Measured on SUN Platform
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Polaris Memory UsageHeap Size
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168.wupwise
171.swim
172.mgrid
173.applu
301.apsi
MB
Heap Size(Byte) to Source Size(Byte)
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168.wupwise
171.swim
172.mgrid
173.applu
301.apsi
Rat
io
•5 benchmarks from Spec CPU2000 representing different source size
•Complete IR kept in memory for inter-procedural analysis
•Measured on SUN Platform
•301.apsi : 7500 lines
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Example Cetus Pass:OpenMP Translator Source-to-source translation Work sharing construct
Micro-tasking helper functions Data clause
Modify symbol table entries Modify expressions
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/* * Get name of private variables from priv_list * add a new Symbol for each private variable and * replace all references to older Symbol * “stmt” is a CompoundStatement */ for (i = 0; i < priv_list.size(); i++) { name = (String) priv_list.get(i); // get the variable name orig_var = stmt.get(name); // get older(existing) Symbol // add a new Symbol for Private variable priv_var = stmt.add(original_var.getTypeList(), name); // replace all reference to Symbol orig_var with reference to Symbol priv_var stmt.replace(new IdExpression(orig_var),new IdExpression(priv_var)); }
Example Cetus Pass cont.
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Conclusions
Source-to-source compiler infrastructure
C support Fully implemented Works with SPEC CPU2000
C++ support GLR parser implemented
