llvm tutorial

7/25/2019 llvm tutorial

1/61

The LLVM CompilerThe LLVM Compiler

Framework and InfrastructureFramework and Infrastructure

Vikram AdveVikram [email protected]@cs.uiuc.e

dudu

Chris LattnerChris [email protected]@cs.uiuc.e

dudu

http://llvm.cs.uiuc.edu/http://llvm.cs.uiuc.edu/

LCPC Tutorial: September 22, 2004LCPC Tutorial: September 22, 2004


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A!kno$led%ementsA!kno$led%ementsUIUC Contributors:UIUC Contributors:

Tan&a 'rethourTan&a 'rethour

(isha 'rukman(isha 'rukman

Cameron 'us!hardtCameron 'us!hardt

)ohn Cris$ell)ohn Cris$ell

Alkis *vlo%imenosAlkis *vlo%imenos

'rian +aeke'rian +aeke u!hira Sasankau!hira Sasanka

Anand ShuklaAnand Shukla

'ill -endlin%'ill -endlin%

External Contributors:External Contributors:

.enrik 'a!h.enrik 'a!h

/ate 'e%eman/ate 'e%eman

)e Cohen)e Cohen

Paolo 1nverniiPaolo 1nvernii

'rad )ones'rad )ones

Vladimir (erliakovVladimir (erliakov Vladimir PrusVladimir Prus

eid Spen!ereid Spen!er

Funding:Funding:

This $ork is sponsored b& the /S3 /et +eneration Sot$are pro%ram throu%h %rantsThis $ork is sponsored b& the /S3 /et +eneration Sot$are pro%ram throu%h %rants*1A50067428 9an /S3 CA** a$ard and *1A50;07peratin% S&stems and Compilers pro%ram 9%rant ?CC566@@4@2, theb& the /S3 >peratin% S&stems and Compilers pro%ram 9%rant ?CC566@@4@2, the

/S3 *mbedded S&stems pro%ram 9%rant ?CC50206202, the (AC>#APA/S3 *mbedded S&stems pro%ram 9%rant ?CC50206202, the (AC>#APA

+i%as!ale S&stems esear!h Center 9+SC, 1'( throu%h the APA5unded+i%as!ale S&stems esear!h Center 9+SC, 1'( throu%h the APA5unded

P*CS proBe!t, and the (otorola niversit& Partnerships in esear!h pro%ram"P*CS proBe!t, and the (otorola niversit& Partnerships in esear!h pro%ram"


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LLV( Compiler S&stemLLV( Compiler S&stem

The LLVM Compiler InfrastructureThe LLVM Compiler InfrastructureProvides reusable !omponents or buildin% !ompilersProvides reusable !omponents or buildin% !ompilers

edu!e the time#!ost to build a ne$ !ompileredu!e the time#!ost to build a ne$ !ompiler

'uild stati! !ompilers, )1Ts, tra!e5based optimiers, """'uild stati! !ompilers, )1Ts, tra!e5based optimiers, """

The LLVM Compiler FrameworThe LLVM Compiler Framewor*nd5to5end !ompilers usin% the LLV( inrastru!ture*nd5to5end !ompilers usin% the LLV( inrastru!ture

C and CDD are robust and a%%ressive:C and CDD are robust and a%%ressive: )ava, S!heme and others are in development)ava, S!heme and others are in development

*mit C !ode or native !ode or E@8, Spar!, Po$erPC*mit C !ode or native !ode or E@8, Spar!, Po$erPC


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Three primar& LLV( !omponentsThree primar& LLV( !omponents

The LLVMThe LLVM Virtual Instruction SetVirtual Instruction SetThe !ommon lan%ua%e5 and tar%et5independent 1The !ommon lan%ua%e5 and tar%et5independent 1

1nternal 91 and eternal 9persistent representation1nternal 91 and eternal 9persistent representation

! collection of well"integrated libraries! collection of well"integrated librariesAnal&ses, optimiations, !ode %enerators, )1TAnal&ses, optimiations, !ode %enerators, )1T

!ompiler, %arba%e !olle!tion support, proilin%, F!ompiler, %arba%e !olle!tion support, proilin%, F

! collection of tools built from the libraries! collection of tools built from the librariesAssemblers, automati! debu%%er, linker, !odeAssemblers, automati! debu%%er, linker, !ode

%enerator, !ompiler driver, modular optimier, F%enerator, !ompiler driver, modular optimier, F


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Tutorial >vervie$Tutorial >vervie$

Introduction to the running exampleIntroduction to the running example LLVM C#C$$ Compiler %&er&iewLLVM C#C$$ Compiler %&er&iew.i%h5level vie$ o an eample LLV( !ompiler.i%h5level vie$ o an eample LLV( !ompiler

The LLVM Virtual Instruction 'etThe LLVM Virtual Instruction 'et 1 overvie$ and t&pe5s&stem1 overvie$ and t&pe5s&stem

LLVM C$$ I( and important !)I*sLLVM C$$ I( and important !)I*s'asi!s, Pass(ana%er, datalo$, Ar%Promotion'asi!s, Pass(ana%er, datalo$, Ar%Promotion

Important LLVM ToolsImportant LLVM Toolsopt, !ode %enerator, )1T, test suite, bu%pointopt, !ode %enerator, )1T, test suite, bu%point

Example applications of LLVMExample applications of LLVM


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unnin% eample: ar% promotionunnin% eample: ar% promotion

Consider use of b+"reference parameters:Consider use of b+"reference parameters:int callee,const int -./ 0int callee,const int -./ 0

return .$12return .$12

33

int caller,/ 0int caller,/ 0

return callee,4/2return callee,4/2

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int callee,const int 5./ 0int callee,const int 5./ 0

return 5.$12return 5.$12 // memory load// memory load

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int tmp2int tmp2 // stack object// stack object

tmp 6 42tmp 6 42 // memory store// memory store

return callee,-tmp/2return callee,-tmp/2

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compiles to

Eliminated load in callee

Eliminated store in caller

Eliminated stac slot for 7tmp*

int callee,int ./ 0int callee,int ./ 0 return .$12return .$12

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return callee,4/2return callee,4/2

33

8e want:8e want:


7/61Chris Lattner

-h& is this hardG-h& is this hardG

(e9uires interprocedural anal+sis:(e9uires interprocedural anal+sis:(ust !han%e the protot&pe o the !allee(ust !han%e the protot&pe o the !allee

(ust update all !all sites(ust update all !all sites $e must$e must nownowall !allersall !allers

-hat about !allers outside the translation unitG-hat about !allers outside the translation unitG

(e9uires alias anal+sis:(e9uires alias anal+sis:eeren!e !ould alias other pointers in !alleeeeren!e !ould alias other pointers in !allee

(ust kno$ that loaded value doesnHt !han%e rom(ust kno$ that loaded value doesnHt !han%e rom

un!tion entr& to the loadun!tion entr& to the load(ust kno$ the pointer is not bein% stored throu%h(ust kno$ the pointer is not bein% stored throu%h

(eference might not be to a stac obect;(eference might not be to a stac obect;


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9/61Chris Lattner

The LLV( C#CDD CompilerThe LLV( C#CDD Compiler

From the high le&el< it is a standard compiler:From the high le&el< it is a standard compiler:Compatible $ith standard makeilesCompatible $ith standard makeiles

ses +CC 7"4 C and CDD parserses +CC 7"4 C and CDD parser

=istinguishing features:=istinguishing features:ses LLV( optimiers, not +CC optimiersses LLV( optimiers, not +CC optimiers

"o iles !ontain LLV( 1#b&te!ode, not ma!hine !ode"o iles !ontain LLV( 1#b&te!ode, not ma!hine !ode

*e!utable !an be b&te!ode 9)1THd or ma!hine !ode*e!utable !an be b&te!ode 9)1THd or ma!hine !ode

llvm%DD

llvm%!!C ile

CDD ile

"o ile

"o ilellvm linker ee!utable

Compile Time Link Time


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Lookin% into events at !ompile5timeLookin% into events at !ompile5time

llvm%!!C ile "o ile llvm%DDCDD ile "o ile

(odiied version o +DD

*mits LLV( 1 as tet ile

Lo$ers CDD AST to LLV(

(odiied version o +CC

*mits LLV( 1 as tet ile

Lo$ers C AST to LLV(

LLV( 1

Parser

LLV(

Veriier

40 LLV( Anal&sis I

>ptimiation Passes

LLV( "b!

3ile -riter

C to LLV(

3rontend

Compile5time

>ptimier

CDD to LLV(

3rontend

Compile5time

>ptimier

J!!;K J!!;plusK J%!!asKJ%!!asK

ead +lobal *limination, 1P Constant Propa%ation, ead

Ar%ument *limination, 1nlinin%, easso!iation, L1C(, Loop

>pts, (emor& Promotion, ead Store *limination, AC*, F


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Chris Lattner

Lookin% into events at link5timeLookin% into events at link5time"o ile

"o ilellvm linker ee!utable

/ative Code

'a!kend/ative ee!utable

Jll!K

C Code

'a!kend

C Compiler/ative

ee!utableJll! mar!h!K

J%!!K

Link in native "o iles

and libraries here

LLV(

Linker

Link5time

>ptimier

"b! ile or LLV( )1T

"o ile

"o ile

20 LLV( Anal&sis I

>ptimiation Passes

>ptionall& JinternaliesK:

marks most un!tions as

internal, to improve 1P>

Pere!t pla!e or ar%ument

promotion optimiationM


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+oals o the !ompiler desi%n+oals o the !ompiler desi%n

!nal+>e and optimi>e as earl+ as possible:!nal+>e and optimi>e as earl+ as possible:Compile5time opts redu!e modi&5rebuild5ee!ute !&!leCompile5time opts redu!e modi&5rebuild5ee!ute !&!le

Compile5time optimiations redu!e $ork at link5time 9b&Compile5time optimiations redu!e $ork at link5time 9b&

shrinkin% the pro%ramshrinkin% the pro%ram

!ll I)!#I)% mae an open"world assumption!ll I)!#I)% mae an open"world assumptionThus, the& all $ork on libraries and at !ompile5timeThus, the& all $ork on libraries and at !ompile5time

JJ1nternalieK pass enables J$hole pro%ramK optn1nternalieK pass enables J$hole pro%ramK optn

%ne I( ,without lowering/ for anal+sis - opt>n%ne I( ,without lowering/ for anal+sis - opt>nCompile5time optns !an be run at link5time tooMCompile5time optns !an be run at link5time tooMThe same 1 is used as input to the )1TThe same 1 is used as input to the )1T

IR design is the key to these goals!IR design is the key to these goals!


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+oals o LLV( 1+oals o LLV( 1

Eas+ to produce< understand< and define;Eas+ to produce< understand< and define; Language" and Target"IndependentLanguage" and Target"IndependentAST5level 1 9e"%" A/3, /C>L is not ver& easibleAST5level 1 9e"%" A/3, /C>L is not ver& easible

*ver& anal&sis#orm must kno$ about NallH lan%ua%es*ver& anal&sis#orm must kno$ about NallH lan%ua%es

%ne I( for anal+sis and optimi>ation%ne I( for anal+sis and optimi>ation 1 must be able to support a%%ressive 1P>, loop opts,1 must be able to support a%%ressive 1P>, loop opts,

s!alar opts, F hi%h5s!alar opts, F hi%h5 andandlo$5level optimiationMlo$5level optimiationM

%ptimi>e as much as earl+ as possible%ptimi>e as much as earl+ as possibleCanHt postpone ever&thin% until link or runtimeCanHt postpone ever&thin% until link or runtime

/o lo$erin% in the 1M/o lo$erin% in the 1M


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LLV( 1nstru!tion Set >vervie$ ?;LLV( 1nstru!tion Set >vervie$ ?;

Low"le&el and target"independent semanticsLow"le&el and target"independent semantics1SC5like three address !ode1SC5like three address !ode

1ninite virtual re%ister set in SSA orm1ninite virtual re%ister set in SSA orm

Simple, lo$5level !ontrol lo$ !onstru!tsSimple, lo$5level !ontrol lo$ !onstru!ts

Load#store instru!tions $ith t&ped5pointersLoad#store instru!tions $ith t&ped5pointers

I( has text< binar+< and in"memor+ formsI( has text< binar+< and in"memor+ forms

for (i = 0; i < N;for (i = 0; i < N;

++i)++i)

Sum(&A[i], &P);Sum(&A[i], &P);

loop:loop:

%i.1 =%i.1 =phiphiintint[ 0, %0 ], [ %i.!, %loop ][ 0, %0 ], [ %i.!, %loop ] %AiA""r =%AiA""r = #$t$l$m$ntptr#$t$l$m$ntptrflotflot%A,%A, intint%i.1%i.1

'll'lloi"oi"%Sum(%Sum(flotflot%AiA""r,%AiA""r, %pir%pir%P)%P)

%i.! =%i.! = """"intint%i.1, 1%i.1, 1

%tmp. =%tmp. = *$tlt*$tltintint%i.1, %N%i.1, %N

rroolool%tmp.,%tmp., l$ll$l%loop,%loop, l$ll$l%outloop%outloop


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LLV( 1nstru!tion Set >vervie$ ?2LLV( 1nstru!tion Set >vervie$ ?2

?igh"le&el information exposed in the code?igh"le&el information exposed in the code*pli!it datalo$ throu%h SSA orm*pli!it datalo$ throu%h SSA orm

*pli!it !ontrol5lo$ %raph 9even or e!eptions*pli!it !ontrol5lo$ %raph 9even or e!eptions

*pli!it lan%ua%e5independent t&pe5inormation*pli!it lan%ua%e5independent t&pe5inormation

*pli!it t&ped pointer arithmeti!*pli!it t&ped pointer arithmeti! Preserve arra& subs!ript and stru!ture indein%Preserve arra& subs!ript and stru!ture indein%

for (i = 0; i < N;for (i = 0; i < N;

++i)++i)

Sum(&A[i], &P);Sum(&A[i], &P);

loop:loop:

%i.1 =%i.1 =phiphiintint[ 0, %0 ], [ %i.!, %loop ][ 0, %0 ], [ %i.!, %loop ] %AiA""r =%AiA""r = #$t$l$m$ntptr#$t$l$m$ntptrflotflot%A,%A, intint%i.1%i.1

'll'lloi"oi"%Sum(%Sum(flotflot%AiA""r,%AiA""r, %pir%pir%P)%P)

%i.! =%i.! = """"intint%i.1, 1%i.1, 1

%tmp. =%tmp. = *$tlt*$tltintint%i.1, %N%i.1, %N

rroolool%tmp.,%tmp., l$ll$l%loop,%loop, l$ll$l%outloop%outloop


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LLV( T&pe S&stem etailsLLV( T&pe S&stem etails

The entire t+pe s+stem consists of:The entire t+pe s+stem consists of:Primitives: void, bool, loat, ushort, opaOue, FPrimitives: void, bool, loat, ushort, opaOue, F

erived: pointer, arra&, stru!ture, un!tionerived: pointer, arra&, stru!ture, un!tion

/o hi%h5level t&pes: t&pe5s&stem is lan%ua%e neutralM/o hi%h5level t&pes: t&pe5s&stem is lan%ua%e neutralM

T+pe s+stem allows arbitrar+ casts:T+pe s+stem allows arbitrar+ casts:Allo$s epressin% $eakl&5t&ped lan%ua%es, like CAllo$s epressin% $eakl&5t&ped lan%ua%es, like C

Front-ends canFront-ends can implementimplementsafe languagessafe languagesAlso easy to define a type-safe subset of LLVMAlso easy to define a type-safe subset of LLVM

'ee also:'ee also:"o'*n#-$f.html"o'*n#-$f.html


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Lo$erin% sour!e5level t&pes to LLV(Lo$erin% sour!e5level t&pes to LLV(

'ource language t+pes are lowered:'ource language t+pes are lowered:i!h t&pe s&stems epanded to simple t&pe s&stemi!h t&pe s&stems epanded to simple t&pe s&stem

1mpli!it I abstra!t t&pes are made epli!it I !on!rete1mpli!it I abstra!t t&pes are made epli!it I !on!rete

Examples of lowering:Examples of lowering:eeren!es turn into pointers:eeren!es turn into pointers: && Comple numbers:Comple numbers: 'ompl$/ flot'ompl$/ flot flot, flot flot, flot

'itields:'itields: *tru't 2 int 3:; int 4:!; *tru't 2 int 3:; int 4:!; int int

1nheritan!e:1nheritan!e: 'l** : S int 2; 'l** : S int 2; S, int S, int

(ethods:(ethods: 'l** oi" foo(); 'l** oi" foo(); oi" foo()oi" foo()

'ame idea as lowering to machine code'ame idea as lowering to machine code


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LLV( Pro%ram Stru!tureLLV( Pro%ram Stru!ture

Module contains Functions#@lobalVariablesModule contains Functions#@lobalVariables(odule is unit o !ompilation#anal&sis#optimiation(odule is unit o !ompilation#anal&sis#optimiation

Function contains AasicAlocs#!rgumentsFunction contains AasicAlocs#!rguments

3un!tions rou%hl& !orrespond to un!tions in C3un!tions rou%hl& !orrespond to un!tions in C AasicAloc contains list of instructionsAasicAloc contains list of instructions*a!h blo!k ends in a !ontrol lo$ instru!tion*a!h blo!k ends in a !ontrol lo$ instru!tion

Instruction is opcode $ &ector of operandsInstruction is opcode $ &ector of operandsAll operands have t&pesAll operands have t&pes

1nstru!tion result is t&ped1nstru!tion result is t&ped


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>ur eample, !ompiled to LLV(>ur eample, !ompiled to LLV(

int callee,const int 5./ 0int callee,const int 5./ 0 return 5.$12return 5.$12 // load// load

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int T2int T2 // on stack// on stack

T 6 42T 6 42 // store// store return callee,-T/2return callee,-T/2

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internal int Bcallee,int5 B./ 0internal int Bcallee,int5 B./ 0 Btmp1 6 load int5 B.Btmp1 6 load int5 B.

BtmpD 6 add int Btmp1< 1BtmpD 6 add int Btmp1< 1

ret int BtmpDret int BtmpD

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int Bcaller,/ 0int Bcaller,/ 0 BT 6 alloca intBT 6 alloca int

store int 4< int5 BTstore int 4< int5 BT

Btmp 6 call int Bcallee,int5 BT/Btmp 6 call int Bcallee,int5 BT/

ret int Btmpret int Btmp

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Sta!k allo!ation is

epli!it in LLV(

All loads#stores are

epli!it in the LLV(

representation

Linker JinternaliesK

most un!tions in most

!ases


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>ur eample, desired transormation>ur eample, desired transormation

internal int Bcallee,int B.&al/ 0internal int Bcallee,int B.&al/ 0 BtmpD 6 add int B.&al< 1BtmpD 6 add int B.&al< 1


33

int Bcaller,/ 0int Bcaller,/ 0

BT 6 alloca intBT 6 alloca int store int 4< int5 BTstore int 4< int5 BT

Btmp1 6 load int5 BTBtmp1 6 load int5 BT

Btmp 6 call int Bcallee,Btmp1/Btmp 6 call int Bcallee,Btmp1/


33

internal int Bcallee,int5 B./ 0internal int Bcallee,int5 B./ 0 Btmp1 6 load int5 B.Btmp1 6 load int5 B.

BtmpD 6 add int Btmp1< 1BtmpD 6 add int Btmp1< 1


33

int Bcaller,/ 0int Bcaller,/ 0 BT 6 alloca intBT 6 alloca int

store int 4< int5 BTstore int 4< int5 BT

Btmp 6 call int Bcallee,int5 BT/Btmp 6 call int Bcallee,int5 BT/


33

Chan%e the protot&pe

or the un!tion

1nsert load instru!tions

into all !allers

pdate all !all sites o

N!alleeH

>ther transormation

95mem2re% !leans up

the rest

int Bcaller,/ 0int Bcaller,/ 0

Btmp 6 call int Bcallee,int 4/Btmp 6 call int Bcallee,int 4/


33


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Chris Lattner

LLV( Codin% 'asi!sLLV( Codin% 'asi!s

8ritten in modern C$$< uses the 'TL:8ritten in modern C$$< uses the 'TL:Parti!ularl& the ve!tor, set, and map !lassesParti!ularl& the ve!tor, set, and map !lasses

LLVM I( is almost all doubl+"lined lists:LLVM I( is almost all doubl+"lined lists:

(odule !ontains lists o 3un!tions I +lobalVariables(odule !ontains lists o 3un!tions I +lobalVariables3un!tion !ontains lists o 'asi!'lo!ks I Ar%uments3un!tion !ontains lists o 'asi!'lo!ks I Ar%uments

'asi!'lo!k !ontains list o 1nstru!tions'asi!'lo!k !ontains list o 1nstru!tions

Lined lists are tra&ersed with iterators:Lined lists are tra&ersed with iterators:5un'tion 6 = 75un'tion 6 = 7

for (5un'tion::it$rtor 8 = 69$#in(); 8 = 69$n"(); ++8) for (5un'tion::it$rtor 8 = 69$#in(); 8 = 69$n"(); ++8)

*i'lo' & = 8;*i'lo' & = 8;

......

'ee also:'ee also:docs#)rogrammersManualhtmldocs#)rogrammersManualhtml


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LLV( Pass (ana%erLLV( Pass (ana%er

Compiler is organi>ed as a series of 7passes*:Compiler is organi>ed as a series of 7passes*:*a!h pass is one anal&sis or transormation*a!h pass is one anal&sis or transormation

Four t+pes of )ass:Four t+pes of )ass:

(odulePass(odulePass

: %eneral interpro!edural pass: %eneral interpro!edural pass

Call+raphSCCPassCall+raphSCCPass: bottom5up on the !all %raph: bottom5up on the !all %raph

3un!tionPass3un!tionPass: pro!ess a un!tion at a time: pro!ess a un!tion at a time

'asi!'lo!kPass'asi!'lo!kPass: pro!ess a basi! blo!k at a time: pro!ess a basi! blo!k at a time

Constraints imposed ,eg Function)ass/:Constraints imposed ,eg Function)ass/:3un!tionPass !an onl& look at J!urrent un!tionK3un!tionPass !an onl& look at J!urrent un!tionK

Cannot maintain state a!ross un!tionsCannot maintain state a!ross un!tions

'ee also:'ee also:"o'*>ritin#An?6P**.html"o'*>ritin#An?6P**.html


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Servi!es provided b& Pass(ana%erServi!es provided b& Pass(ana%er

%ptimi>ation of pass execution:%ptimi>ation of pass execution:Pro!ess a un!tion at a time instead o a pass at a timePro!ess a un!tion at a time instead o a pass at a time

*ample: 1 3, +, . are three un!tions in input p%m:*ample: 1 3, +, . are three un!tions in input p%m:

J3333++++....K not J3+.3+.3+.3+.KJ3333++++....K not J3+.3+.3+.3+.K

Pro!ess un!tions in parallel on an S(P 9uture $orkPro!ess un!tions in parallel on an S(P 9uture $ork

=eclarati&e dependenc+ management:=eclarati&e dependenc+ management:Automati!all& ulill and mana%e anal&sis pass lietimesAutomati!all& ulill and mana%e anal&sis pass lietimes

Share anal&ses bet$een passes $hen sae:Share anal&ses bet$een passes $hen sae: e"%" JominatorSet live unless pass modiies C3+Ke"%" JominatorSet live unless pass modiies C3+K

!&oid boilerplate for tra&ersal of program!&oid boilerplate for tra&ersal of program

'ee also:'ee also:"o'*>ritin#An?6P**.html"o'*>ritin#An?6P**.html


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Pass (ana%er D Ar% Promotion ?;#2Pass (ana%er D Ar% Promotion ?;#2

!rg )romotion is a Call@raph'CC)ass:!rg )romotion is a Call@raph'CC)ass:/aturall& operates bottom5up on the Call+raph/aturall& operates bottom5up on the Call+raph

'ubble pointers rom !allees out to !allers'ubble pointers rom !allees out to !allers

!: @in'lu"$ llmBllCrphSBBP**.h

D:*tru'tSimpl$Ar#Promotion : puli' BllCrphSBBP**

!rg )romotion re9uires !lias!nal+sis info!rg )romotion re9uires !lias!nal+sis infoTo prove saet& o transormationTo prove saet& o transormation

-orks $ith an& alias anal&sis al%orithm thou%h-orks $ith an& alias anal&sis al%orithm thou%hE:E: irtul oi" #$tAnlF*i*G*#$(AnlF*i*G*#$ &AG) 'on*t irtul oi" #$tAnlF*i*G*#$(AnlF*i*G*#$ &AG) 'on*t

AG.""-$Huir$"


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Finall+< implementFinall+< implement runJnSBBrunJnSBB,line G/:,line G/:ool Simpl$Ar#Promotion::ool Simpl$Ar#Promotion::runJnSBB('on*t *t"::$'tor


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LLV( atalo$ Anal&sisLLV( atalo$ Anal&sis

LLVM I( is in ''! form:LLVM I( is in ''! form:use5de and de5use !hains are al$a&s availableuse5de and de5use !hains are al$a&s available

All obBe!ts have user#use ino, even un!tionsAll obBe!ts have user#use ino, even un!tions

Control Flow @raph is alwa+s a&ailable:Control Flow @raph is alwa+s a&ailable:*posed as 'asi!'lo!k prede!essor#su!!essor lists*posed as 'asi!'lo!k prede!essor#su!!essor lists

(an& %eneri! %raph al%orithms usable $ith the C3+(an& %eneri! %raph al%orithms usable $ith the C3+

?igher"le&el info implemented as passes:?igher"le&el info implemented as passes:ominators, Call+raph, indu!tion vars, aliasin%, +V/, Fominators, Call+raph, indu!tion vars, aliasin%, +V/, F

'ee also:'ee also:"o'*Pro#rmm$r*6nul.html"o'*Pro#rmm$r*6nul.html


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Ar% Promotion: saet& !he!k ?;#4Ar% Promotion: saet& !he!k ?;#4

1: Function must be JinternalK ,aa JstaticK/1: Function must be JinternalK ,aa JstaticK/ EE:EE:if (5 LL 59h*8nt$rnlin#$()) r$turn fl*$;if (5 LL 59h*8nt$rnlin#$()) r$turn fl*$;

D: Mae sure address of F is not taenD: Mae sure address of F is not taen

1n LLV(, !he!k that there are onl& dire!t !alls usin% 31n LLV(, !he!k that there are onl& dire!t !alls usin% 3

::for (?lu$::u*$Oit$rtor G8 = 59u*$O$#in();for (?lu$::u*$Oit$rtor G8 = 59u*$O$#in(); G8 = 59u*$O$n"(); ++G8) G8 = 59u*$O$n"(); ++G8) BllSit$ BS = BllSit$::#$t(G8);BllSit$ BS = BllSit$::#$t(G8); if (BS.#$t8n*tru'tion()) if (BS.#$t8n*tru'tion()) "#aking the address" of $."#aking the address" of $. r$turn fl*$;r$turn fl*$;

: Chec to see if an+ args are promotable:: Chec to see if an+ args are promotable: 11:11:for (un*i#n$" i = 0; i = Point$rAr#*.*iK$(); ++i)for (un*i#n$" i = 0; i = Point$rAr#*.*iK$(); ++i) if (i*Sf$oPromot$Ar#um$nt(Point$rAr#*[i]))if (i*Sf$oPromot$Ar#um$nt(Point$rAr#*[i])) Point$rAr#*.$r*$(Point$rAr#*.$#in()+i);Point$rAr#*.$r*$(Point$rAr#*.$#in()+i); if (Point$rAr#*.$mptF()) r$turn fl*$; if (Point$rAr#*.$mptF()) r$turn fl*$; no args promotableno args promotable


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Chris Lattner

Ar% Promotion: saet& !he!k ?2#4Ar% Promotion: saet& !he!k ?2#4

4: !rgument pointer can onl+ be loaded from:4: !rgument pointer can onl+ be loaded from:/o stores throu%h ar%ument pointer allo$edM/o stores throu%h ar%ument pointer allo$edM

%oop o&er all uses of the argument 'use(def chains).%oop o&er all uses of the argument 'use(def chains).

1E:1E:for (?lu$::u*$Oit$rtor G8 = Ar#9u*$O$#in();for (?lu$::u*$Oit$rtor G8 = Ar#9u*$O$#in();

G8 = Ar#9u*$O$n"(); ++G8) G8 = Ar#9u*$O$n"(); ++G8)

If the user is a load*If the user is a load*

if (o"8n*t 8 = "FnO'*t


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Chris Lattner

G: Value of J5)K must not change in the AAG: Value of J5)K must not change in the AA-e move load out to the !aller, value !annot !han%eM-e move load out to the !aller, value !annot !han%eM

Get AliasAnalysis implementation from the pass manager.Get AliasAnalysis implementation from the pass manager.

1QR:1QR:Ali*AnlF*i* &AA = #$tAnlF*i*


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Chris Lattner

: J5)K cannot change from Fn entr+ to AA: J5)K cannot change from Fn entr+ to AA

1DQ:1DQ:for (pr$"Oit$rtor P8 = pr$"O$#in(), = pr$"O$n"();for (pr$"Oit$rtor P8 = pr$"O$#in(), = pr$"O$n"();

P8 = ; ++P8) P8 = ; ++P8) %oop o&er predecessors of .%oop o&er predecessors of .

Check each block from to entry '+$ search on in&erse graph).Check each block from to entry '+$ search on in&erse graph).

for (i"fOit$rtor


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Chris Lattner

Ar% Promotion: orm outline ?;#4Ar% Promotion: orm outline ?;#4

1: Mae protot+pe with new arg t+pes: 11: Mae protot+pe with new arg t+pes: 1'asi!all& Bust repla!es NintH $ith NintH in protot&pe'asi!all& Bust repla!es NintH $ith NintH in protot&pe

D: Create function with new protot+pe:D: Create function with new protot+pe:

!1:!1:5un'tion N5 = n$M 5un'tion(N5F, 59#$tin#$(),5un'tion N5 = n$M 5un'tion(N5F, 59#$tin#$(), 59#$tNm$());59#$tNm$());

59#$tPr$nt()9#$t5un'tioni*t().in*$rt(5, N5);59#$tPr$nt()9#$t5un'tioni*t().in*$rt(5, N5);

: Change all callers of F to call NF:: Change all callers of F to call NF:

If there are uses of $2 then calls to it remain.If there are uses of $2 then calls to it remain.

!!1:!!1:Mhil$ (59u*$O$mptF()) Mhil$ (59u*$O$mptF())

Get a caller of F.Get a caller of F.

BllSit$ BS = BllSit$::#$t(59u*$O'());BllSit$ BS = BllSit$::#$t(59u*$O'());


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Chris Lattner

Ar% Promotion: orm outline ?2#4Ar% Promotion: orm outline ?2#4

4: For each caller< add loads< determine args4: For each caller< add loads< determine argsLoop over the ar%s, insertin% the loads in the !allerLoop over the ar%s, insertin% the loads in the !aller

!!0:!!0:*t"::$'tor


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Chris Lattner


G: (eplace the call site of F with call of NFG: (eplace the call site of F with call of NF Create the call to -$ with the adjusted arguments.Create the call to -$ with the adjusted arguments.!!:!!:8n*tru'tion N$M = n$M Bll8n*t(N5, Ar#*, , Bll);8n*tru'tion N$M = n$M Bll8n*t(N5, Ar#*, , Bll);

If the return &alue of the old call was used2 use the ret&al of the new call.If the return &alue of the old call was used2 use the ret&al of the new call.

if (Bll9u*$O$mptF())if (Bll9u*$O$mptF()) Bll9r$pl'$AllG*$*>ith(N$M);Bll9r$pl'$AllG*$*>ith(N$M);

$inally2 remo&e the old call from the program2 reducing the use(count of $.$inally2 remo&e the old call from the program2 reducing the use(count of $. Bll9#$tPr$nt()9#$t8n*ti*t().$r*$(Bll);Bll9#$tPr$nt()9#$t8n*ti*t().$r*$(Bll);

: Mo&e code from old function to new Fn: Mo&e code from old function to new Fn

!Q:!Q:N59#$t*i'lo'i*t().*pli'$(N59$#in(),N59#$t*i'lo'i*t().*pli'$(N59$#in(), 59#$t*i'lo'i*t());59#$t*i'lo'i*t());


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Chris Lattner


: Change users of F*s arguments to use NF*s: Change users of F*s arguments to use NF*s

!R:!R: for (5un'tion::it$rtor 8 = 59$#in(), 8! = N59$#in();for (5un'tion::it$rtor 8 = 59$#in(), 8! = N59$#in();

8 = 59$n"(); ++8, ++8!)8 = 59$n"(); ++8, ++8!)

if (Ar#*oPromot$.'ount(8)) if (Ar#*oPromot$.'ount(8)) -ot promoting this arg1-ot promoting this arg1

89r$pl'$AllG*$*>ith(8!); 89r$pl'$AllG*$*>ith(8!); 3se new arg2 not old arg.3se new arg2 not old arg.

$l*$ $l*$

Mhil$ (89u*$O$mptF()) Mhil$ (89u*$O$mptF()) 4nly users can be loads.4nly users can be loads.

o"8n*t 8 = '*tith(8!);

89#$tPr$nt()9#$t8n*ti*t().$r*$(8);89#$tPr$nt()9#$t8n*ti*t().$r*$(8);

O: =elete old function:O: =elete old function:

!ER:!ER:59#$tPr$nt()9#$t5un'tioni*t().$r*$(5);59#$tPr$nt()9#$t5un'tioni*t().$r*$(5);


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Chris Lattner

LLV( tools: t$o lavorsLLV( tools: t$o lavors

JJ)rimiti&eK tools: do a single ob)rimiti&eK tools: do a single ob llvm5as: Convert rom "ll 9tet to "b! 9binar&llvm5as: Convert rom "ll 9tet to "b! 9binar&

llvm5dis: Convert rom "b! 9binar& to "ll 9tetllvm5dis: Convert rom "b! 9binar& to "ll 9tet

llvm5link: Link multiple "b! iles to%etherllvm5link: Link multiple "b! iles to%ether

llvm5pro: Print proile output to human readersllvm5pro: Print proile output to human readers

llvm!: Coni%urable !ompiler driverllvm!: Coni%urable !ompiler driver

!ggregate tools: pull in multiple features!ggregate tools: pull in multiple features

%!!as#%!!ld: Compile#link5time optimiers or C#CDD 3*%!!as#%!!ld: Compile#link5time optimiers or C#CDD 3*bu%point: automati! !ompiler debu%%erbu%point: automati! !ompiler debu%%er

llvm5%!!#llvm5%DD: C#CDD !ompilersllvm5%!!#llvm5%DD: C#CDD !ompilers

'ee also:'ee also:"o'*Bommn"Cui"$"o'*Bommn"Cui"$


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Chris Lattner

opt tool: LLV( modular optimieropt tool: LLV( modular optimier

In&oe arbitrar+ se9uence of passes:In&oe arbitrar+ se9uence of passes:Completel& !ontrol Pass(ana%er rom !ommand lineCompletel& !ontrol Pass(ana%er rom !ommand line

Supports loadin% passes as plu%ins rom "so ilesSupports loadin% passes as plu%ins rom "so iles

opt "load fooso "pass1 "passD "pass xbc "o +bcopt "load fooso "pass1 "passD "pass xbc "o +bc

)asses JregisterK themsel&es:)asses JregisterK themsel&es:R1:R1: -$#i*t$rJpt


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Chris Lattner

unnin% Ar% Promotion $ith optunnin% Ar% Promotion $ith opt

Aasic execution with 7opt*:Aasic execution with 7opt*: opt 9*impl$r#promotion in.' 9o out.'opt 9*impl$r#promotion in.' 9o out.'

Load "b! ile, run pass, $rite out resultsLoad "b! ile, run pass, $rite out results

se J5load ilename"soK i !ompiled into a librar&se J5load ilename"soK i !ompiled into a librar&

Pass(ana%er resolves all dependen!iesPass(ana%er resolves all dependen!ies

%ptionall+ choose an alias anal+sis to use:%ptionall+ choose an alias anal+sis to use: opt U*i' U*impl$r#promotionopt U*i' U*impl$r#promotion ,default/ ,default/

Alternativel&,Alternativel&, U*t$$n*9, Un"$r*9, U"*9, 7U*t$$n*9, Un"$r*9, U"*9, 7

%ther useful options a&ailable:%ther useful options a&ailable: 9*tt*9*tt*: )rint statistics collected from the passes: )rint statistics collected from the passes

9tim$9p**$*9tim$9p**$*: Time each pass being run< print output: Time each pass being run< print output


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Chris Lattner

*ample 5stats output 9%!!as ;


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Chris Lattner

*ample 5time5passes 9%!!as ;


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Chris Lattner

Anal&e tool: Visualie anal&sis resultsAnal&e tool: Visualie anal&sis results

)rint most LLVM data structures)rint most LLVM data structuresominators, loops, alias sets, C3+, !all %raph, Fominators, loops, alias sets, C3+, !all %raph, F

Converts most LLV( data stru!tures to NdotH %raphsConverts most LLV( data stru!tures to NdotH %raphs


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Chris Lattner

LLC Tool: Stati! !ode %eneratorLLC Tool: Stati! !ode %enerator

Compiles LLVMCompiles LLVM nati&e assembl+ languagenati&e assembl+ languageCurrentl& or E@8, Spar!, Po$erPC 9others in alphaCurrentl& or E@8, Spar!, Po$erPC 9others in alpha ll' fil$.' 9o fil$.* 9mr'h=/ERll' fil$.' 9o fil$.* 9mr'h=/ER

* fil$.* Uo fil$.o* fil$.* Uo fil$.o

Compiles LLVMCompiles LLVM portable C codeportable C code ll' fil$.' 9o fil$.' 9mr'h='ll' fil$.' 9o fil$.' 9mr'h='

#'' U' fil$.' Uo fil$.o#'' U' fil$.' Uo fil$.o

Targets are modular - d+namicall+ loadable:Targets are modular - d+namicall+ loadable: ll' Ulo" lirm.*o fil$.' 9mr'h=rmll' Ulo" lirm.*o fil$.' 9mr'h=rm


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Chris Lattner

The LLV( Code +eneratorThe LLV( Code +enerator

Target independent:Target independent:riven b& an al%orithm independent tar%et des!riptionriven b& an al%orithm independent tar%et des!ription

ata la&out, e%ister, 1nstru!tion, S!hedulin%, Fata la&out, e%ister, 1nstru!tion, S!hedulin%, F

Aasic code generator la+out:Aasic code generator la+out:

!ll passes are replaceable!ll passes are replaceable

e"%" Trivial to !han%e and add re%ister allo!atorse"%" Trivial to !han%e and add re%ister allo!ators

Targets can add custom passesTargets can add custom passese"%" E@8 has spe!ial support or 3P sta!ke"%" E@8 has spe!ial support or 3P sta!k

'ee also:'ee also:docs#Code@eneratorhtmldocs#Code@eneratorhtml

1nstru!tion

Sele!tionLLV( "s ile

(a!hine

SSA >pts

e%ister

Allo!ator

1nstr

S!hed

Code

*mission

*poses all tar%et5spe!ii!

details about a un!tion

9!allin% !onventions, et!

S!hedulin%, Peephole, G

Tar%et 1ndependentTar%et Spe!ii!

9%enerated

Tar%et Spe!ii! 9b&

hand or no$ 4 al%orithmsavailable toda&

ll! 5re%allo!oo


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Chris Lattner

Portin% LLV( to a ne$ tar%etPortin% LLV( to a ne$ tar%et

LLVM targets are &er+ eas+ to write:LLVM targets are &er+ eas+ to write:Ane!dotal eviden!e su%%ests ; $eek or a basi! portAne!dotal eviden!e su%%ests ; $eek or a basi! port

FF or someone amiliar $ith the tar%et ma!hine andor someone amiliar $ith the tar%et ma!hine and

!ompilers in %eneral, but not $ith LLV(!ompilers in %eneral, but not $ith LLV(

LLVM targets are written with JtablegenK toolLLVM targets are written with JtablegenK toolSimple de!larative s&ntaSimple de!larative s&nta

esi%ned to a!tor out redundan!& in tar%et des!esi%ned to a!tor out redundan!& in tar%et des!

'ome C$$ code is still re9uired'ome C$$ code is still re9uiredPrimaril& in the instru!tion sele!torPrimaril& in the instru!tion sele!tor

Continuin% $ork to improve thisContinuin% $ork to improve this

'ee also:'ee also:docs#Table@enFundamentalshtmldocs#Table@enFundamentalshtmlandand 8riting!nLLVMAacendhtml8riting!nLLVMAacendhtml


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LLI allows direct execution of bc filesLLI allows direct execution of bc filesEg:Eg: lli #r$p.' 9i foo .'lli #r$p.' 9i foo .'

LLI uses a Rust"In"Time compiler if a&ailable:LLI uses a Rust"In"Time compiler if a&ailable:ses same !ode %enerator as LLCses same !ode %enerator as LLC

>ptionall& uses aster !omponents than LLC>ptionall& uses aster !omponents than LLC

*mits ma!hine !ode to memor& instead o J"sK ile*mits ma!hine !ode to memor& instead o J"sK ile

)1T is a librar& that !an be embedded in other tools)1T is a librar& that !an be embedded in other tools

%therwise< it uses the LLVM interpreter:%therwise< it uses the LLVM interpreter: 1nterpreter is etremel& simple and ver& slo$1nterpreter is etremel& simple and ver& slo$

1nterpreter is portable thou%hM1nterpreter is portable thou%hM

LL1 Tool: LLV( *e!ution *n%ineLL1 Tool: LLV( *e!ution *n%ine


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Chris Lattner

C and CDD Pro%ram Test SuiteC and CDD Pro%ram Test Suite

Large collection of programs and benchmars:Large collection of programs and benchmars:Standard suites 9e"%" SP*C 6=#2000, >lden, Ptrdist,Standard suites 9e"%" SP*C 6=#2000, >lden, Ptrdist,

(!Cat, Stanord, 3reeben!h, ShootoutF(!Cat, Stanord, 3reeben!h, ShootoutF

1ndividual pro%rams: s%ea, siod, sim, pi, povra&, F1ndividual pro%rams: s%ea, siod, sim, pi, povra&, F

Proprietar& suites 9e"%" SP*C reOuire suite sour!eProprietar& suites 9e"%" SP*C reOuire suite sour!e

Consistent build en&ironment:Consistent build en&ironment:*as& add hooks to build or proilin%#instrumentation*as& add hooks to build or proilin%#instrumentation

*as& to %et perorman!e numbers rom entire test suite*as& to %et perorman!e numbers rom entire test suite Entire test suite is checed e&er+ night:Entire test suite is checed e&er+ night:.osted on Linu,Solaris,3ree'S on E@8,Spar! I PPC.osted on Linu,Solaris,3ree'S on E@8,Spar! I PPC

'ee also:'ee also:"o'*$*tin#Cui"$.html"o'*$*tin#Cui"$.html


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Chris Lattner

1nte%rated ebu%%in% Tools1nte%rated ebu%%in% Tools

Extensi&e assertions throughout codeExtensi&e assertions throughout code3ind problems as earl& as possible 9!lose to sour!e3ind problems as earl& as possible 9!lose to sour!e

LLVM I( Verifier: Checs modules for &alidit+LLVM I( Verifier: Checs modules for &alidit+Che!ks t&pe properties, dominan!e properties, et!"Che!ks t&pe properties, dominan!e properties, et!"

Automati!all& run b& optAutomati!all& run b& opt

Problem oundG: print an error messa%e and abortProblem oundG: print an error messa%e and abort

LLVM I( Lea =etectorLLVM I( Lea =etector

*i!ient and simple J%arba%e !olle!torK or 1 obBe!ts*i!ient and simple J%arba%e !olle!torK or 1 obBe!ts*nsure 1 obBe!ts are deallo!ated appropriatel&*nsure 1 obBe!ts are deallo!ated appropriatel&


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Chris Lattner

The 'u%point automated bu% inderThe 'u%point automated bu% inder

'imple idea: automate 7binar+* search for bug'imple idea: automate 7binar+* search for bug'u% isolation: $hi!h passes intera!t to produ!e bu%'u% isolation: $hi!h passes intera!t to produ!e bu%

Test case reductionTest case reduction: redu!e input pro%ram: redu!e input pro%ram

%ptimi>er#Codegen crashes:%ptimi>er#Codegen crashes:Thro$ portion o test !ase a$a&, !he!k or !rashThro$ portion o test !ase a$a&, !he!k or !rash

1 so, keep %oin%1 so, keep %oin%

>ther$ise, revert and tr& somethin% else>ther$ise, revert and tr& somethin% else

*tremel& ee!tive in pra!ti!e*tremel& ee!tive in pra!ti!e 'imple greed+ algorithms for test reduction'imple greed+ algorithms for test reduction

Completel+ blac"box approachCompletel+ blac"box approach

'ee also:'ee also:"o'*u#point.html"o'*u#point.html


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Chris Lattner

ebu%%in% (is!ompilationsebu%%in% (is!ompilations

%ptimi>er miscompilation:%ptimi>er miscompilation:Split test!ase in t$o, optimie one" Still brokenGSplit test!ase in t$o, optimie one" Still brokenG

Qeep shrinkin% the portion bein% optimiedQeep shrinkin% the portion bein% optimied

Codegen miscompilation:Codegen miscompilation:Split test!ase in t$o, !ompile one $ith C'*, brokenGSplit test!ase in t$o, !ompile one $ith C'*, brokenG

Shrink portion bein% !ompiled $ith non C'* !ode%enShrink portion bein% !ompiled $ith non C'* !ode%en

Code splitting granularities:Code splitting granularities:

Take out $hole un!tionsTake out $hole un!tionsTake out loop nestsTake out loop nests

Take out individual basi! blo!ksTake out individual basi! blo!ks


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Chris Lattner

.o$ $ell does this thin% $orkG.o$ $ell does this thin% $orkG

Extremel+ effecti&e:Extremel+ effecti&e:Can oten redu!e a ;00Q L>C pro%ram and 80 passesCan oten redu!e a ;00Q L>C pro%ram and 80 passes

to a e$ basi! blo!ks and ; pass in = minutesto a e$ basi! blo!ks and ; pass in = minutes

Crashes are ound mu!h aster than mis!ompilationsCrashes are ound mu!h aster than mis!ompilations

no need to run the pro%ram to test a redu!tionno need to run the pro%ram to test a redu!tion Interacts with integrated debugging toolsInteracts with integrated debugging toolsuntime errors are dete!ted asteruntime errors are dete!ted aster

Limitations:Limitations:Pro%ram must be deterministi!Pro%ram must be deterministi!

FF or modiied to be soor modiied to be so

3inds JaK bu%, not JtheK bu%3inds JaK bu%, not JtheK bu%


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Chris Lattner

se Case ;: *d%e or Path Proilin%se Case ;: *d%e or Path Proilin%

5oal*5oal* Profiling Research or PGOProfiling Research or PGO Implementation:Implementation:FunctionPassFunctionPass: LLV(5to5LLV( transormation: LLV(5to5LLV( transormation

1nstrumentation: se C3+, intervals, dominators1nstrumentation: se C3+, intervals, dominators

Code %eneration: se C or an& native ba!k endCode %eneration: se C or an& native ba!k end

Proile eedba!k: se proile Ouer& intera!eProile eedba!k: se proile Ouer& intera!e

Core extensions needed:Core extensions needed: nonenone

Maor LLVM AenefitsMaor LLVM AenefitsLan%ua%e5independen!e, C3+, ver& simple 1Lan%ua%e5independen!e, C3+, ver& simple 1


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Chris Lattner

se Case 2: Alias Anal&sisse Case 2: Alias Anal&sis

5oal*5oal* Research on ne alias analysis algorithmsResearch on ne alias analysis algorithms Implementation:Implementation:ModulePassModulePass: -hole5pro%ram anal&sis pass on LLV(: -hole5pro%ram anal&sis pass on LLV(

se t&pe inormationR SSAR heap#sta!k#%lobalsse t&pe inormationR SSAR heap#sta!k#%lobals

CompareCompare !impleAA!impleAA,, !teensgard"s!teensgard"s,,Andersen"sAndersen"s,, #!A#!A

*valuate man& !lients via*valuate man& !lients viaAliasAnalysisAliasAnalysis intera!eintera!e

Core extensions needed:Core extensions needed: nonenone

Maor LLVM AenefitsMaor LLVM AenefitsLan%ua%e5independen!e, t&pe ino, SSA, SA, 1P>Lan%ua%e5independen!e, t&pe ino, SSA, SA, 1P>

AliasAnalysisAliasAnalysis intera!e $ith man& pre5eistin% !lientsintera!e $ith man& pre5eistin% !lients


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Chris Lattner

se Case 7: LS Preet!hin%se Case 7: LS Preet!hin%

5oal*5oal* Prefetching lin$ed data structuresPrefetching lin$ed data structures Implementation:Implementation:ModulePassModulePass: Link5time LLV(5to5LLV( transormation: Link5time LLV(5to5LLV( transormation

%ode transformations%ode transformations: use t&pe ino, loop anal&sis,: use t&pe ino, loop anal&sis,

unrollin%, preet!h insertionunrollin%, preet!h insertion#ata transformations#ata transformations 9e"%," addin% histor& pointers:9e"%," addin% histor& pointers:

useuse strongstrongt&pe ino rom SA, 1P>t&pe ino rom SA, 1P>

Core extensions needed:Core extensions needed:

Preet!h operation: add asPreet!h operation: add as intrinsi!intrinsi!9in pro%ress9in pro%ress Maor LLVM AenefitsMaor LLVM Aenefits

Lan%ua%e5independen!e, t&pe ino, SA, 1P>Lan%ua%e5independen!e, t&pe ino, SA, 1P>


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Chris Lattner

se Case 4: Lan%ua%e 3ront endse Case 4: Lan%ua%e 3ront end

5oal*5oal* &se LLVM to implement a ne language&se LLVM to implement a ne language Implementation:Implementation:Parser 9sa& to AST, Semanti! !he!kin%Parser 9sa& to AST, Semanti! !he!kin%

AST5to5LLV( translatorAST5to5LLV( translator

Core extensions needed:Core extensions needed: dependsdepends.i%h5level t&pe s&stem is.i%h5level t&pe s&stem is omitted by designomitted by design

Maor LLVM AenefitsMaor LLVM AenefitsLo$5level, but po$erul t&pe s&stemLo$5level, but po$erul t&pe s&stem

Ver& simple 1 to %enerate 9e"%", !ompare +CC TLVer& simple 1 to %enerate 9e"%", !ompare +CC TL

*tensive %lobal and 1P optimiation rame$ork*tensive %lobal and 1P optimiation rame$ork

)1T en%ine, native ba!k5ends, C ba!k5end)1T en%ine, native ba!k5ends, C ba!k5end


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Chris Lattner

se Case =: )1T Compilerse Case =: )1T Compiler

5oal*5oal* 'rite ()T compiler for a bytecode language'rite ()T compiler for a bytecode language Implementation:Implementation:*tend the LLV( )1T rame$ork*tend the LLV( )1T rame$ork

!imple ()T!imple ()T: 3ast translation rom b&te!ode to LLV(: 3ast translation rom b&te!ode to LLV(

9then use LLV( )1T D +C9then use LLV( )1T D +COptimi*ing ()TOptimi*ing ()T: Lan%ua%e5spe!ii! optimiations D ast: Lan%ua%e5spe!ii! optimiations D ast

translation 9then use LLV( optimiations, )1T, +Ctranslation 9then use LLV( optimiations, )1T, +C

Core extensions needed:Core extensions needed: none in generalnone in general

Maor LLVM AenefitsMaor LLVM AenefitsCompa!t, t&ped, lan%ua%e5independent 1Compa!t, t&ped, lan%ua%e5independent 1

*istin% )1T rame$ork and +C*istin% )1T rame$ork and +C


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Chris Lattner

se Case 8: Ar!hite!ture esear!hse Case 8: Ar!hite!ture esear!h

5oal*5oal* %ompiler support for ne architectures%ompiler support for ne architectures Implementation:Implementation:Add ne$ ma!hine des!ription 9or modi& oneAdd ne$ ma!hine des!ription 9or modi& one

Add an& ne$ LLV(5to5LLV( transormationsAdd an& ne$ LLV(5to5LLV( transormations

Core extensions needed:Core extensions needed: depends on goalsdepends on goals 1mminent eatures:1mminent eatures:modulo sched6 &ector opsmodulo sched6 &ector ops

Maor LLVM AenefitsMaor LLVM AenefitsLo$5level, t&ped, ma!hine5independent 1Lo$5level, t&ped, ma!hine5independent 1

*pli!it re%ister#memor& ar!hite!ture*pli!it re%ister#memor& ar!hite!ture

A%%ressive mid5level and ba!k5end !ompiler rame$orkA%%ressive mid5level and ba!k5end !ompiler rame$ork

Full-system e+aluation,Full-system e+aluation, appli!ations, libraries, even >Sappli!ations, libraries, even >S


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Chris Lattner

3ive point LLV( evie$3ive point LLV( evie$

Extremel+ simple I( to learn and useExtremel+ simple I( to learn and use ;5to5; !orresponden!e bet$een "ll, "b!, and CDD 1;5to5; !orresponden!e bet$een "ll, "b!, and CDD 1

Ver& positive user rea!tionsVer& positive user rea!tions

)owerful and modular optimi>er)owerful and modular optimi>er

*as& to etend, or Bust use $hat is alread& there*as& to etend, or Bust use $hat is alread& there Clean and modular code generatorClean and modular code generator*as& to retar%et, eas& to repla!e#t$eak !omponents*as& to retar%et, eas& to repla!e#t$eak !omponents

Man+ Jproducti&it+ toolsK ,bugpoint< &erifier/Man+ Jproducti&it+ toolsK ,bugpoint< &erifier/

+et more done, Oui!kerM+et more done, Oui!kerM !cti&e de& communit+< good documentation!cti&e de& communit+< good documentation(ailin% lists, 1C, do&%en, etensive do!s(ailin% lists, 1C, do&%en, etensive do!s


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+et started $ith LLV(M+et started $ith LLV(M

=ownload latest release or CV':=ownload latest release or CV':http://llvm.cs.uiuc.edu/releases/http://llvm.cs.uiuc.edu/releases/

Follow the J@etting 'tarted @uideK:Follow the J@etting 'tarted @uideK:

http://llvm.cs.uiuc.edu/docs/GettingStarted.hthttp://llvm.cs.uiuc.edu/docs/GettingStarted.ht

mlml

-alks &ou throu%h install and setup-alks &ou throu%h install and setup

Lots o other do!s available in Jdo!sK dire!tor&Lots o other do!s available in Jdo!sK dire!tor&

)oin us on mailin% lists and 1C)oin us on mailin% lists and 1C

?app+ hacing;?app+ hacing;

Documents

llvm tutorial