1

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

0

50

100

150

200

250

300

350

400

450

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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10

20

30

40

50

60

70

164.gzip

175.vpr

176.gcc

188.am

mp

300.twolf

MB

Heap Size(Byte) to Source Size(Byte)

0

2

4

6

8

10

12

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

0

10

20

30

40

50

60

168.wupwise

171.swim

172.mgrid

173.applu

301.apsi

MB

Heap Size(Byte) to Source Size(Byte)

0

100

200

300

400

500

600

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