1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>Getting Started with LLVM System</title>
<link rel="stylesheet" href="llvm.css" type="text/css">
</head>
<body>
<div class="doc_title">
Getting Started with the LLVM System
</div>
<ul>
<li><a href="#overview">Overview</a>
<li><a href="#quickstart">Getting Started Quickly (A Summary)</a>
<li><a href="#requirements">Requirements</a>
<ol>
<li><a href="#hardware">Hardware</a>
<li><a href="#software">Software</a>
</ol></li>
<li><a href="#starting">Getting Started with LLVM</a>
<ol>
<li><a href="#terminology">Terminology and Notation</a>
<li><a href="#environment">Setting Up Your Environment</a>
<li><a href="#unpack">Unpacking the LLVM Archives</a>
<li><a href="#checkout">Checkout LLVM from CVS</a>
<li><a href="#installcf">Install the GCC Front End</a>
<li><a href="#config">Local LLVM Configuration</a>
<li><a href="#compile">Compiling the LLVM Suite Source Code</a>
<li><a href="#objfiles">The Location of LLVM Object Files</a>
</ol></li>
<li><a href="#layout">Program layout</a>
<ol>
<li><a href="#cvsdir"><tt>CVS</tt> directories</a>
<li><a href="#include"><tt>llvm/include</tt></a>
<li><a href="#lib"><tt>llvm/lib</tt></a>
<li><a href="#runtime"><tt>llvm/runtime</tt></a>
<li><a href="#test"><tt>llvm/test</tt></a>
<li><a href="#tools"><tt>llvm/tools</tt></a>
<li><a href="#utils"><tt>llvm/utils</tt></a>
</ol></li>
<li><a href="#tutorial">An Example Using the LLVM Tool Chain</a>
<li><a href="#problems">Common Problems</a>
<li><a href="#links">Links</a>
</ul>
<p>By:
<a href="mailto:gshi1@uiuc.edu">Guochun Shi</a>,
<a href="mailto:sabre@nondot.org">Chris Lattner</a>,
<a href="mailto:criswell@uiuc.edu">John Criswell</a>,
<a href="http://misha.brukman.net">Misha Brukman</a>, and
<a href="http://www.cs.uiuc.edu/~vadve">Vikram Adve</a>.</p>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="overview"><b>Overview</b></a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>Welcome to LLVM! In order to get started, you first need to know some
basic information.</p>
<p>First, LLVM comes in two pieces. The first piece is the LLVM suite. This
contains all of the tools, libraries, and header files needed to use the low
level virtual machine. It contains an assembler, disassembler, bytecode
analyzer, and bytecode optimizer. It also contains a test suite that can be
used to test the LLVM tools and the GCC front end.</p>
<p>The second piece is the GCC front end. This component provides a version of
GCC that compiles C and C++ code into LLVM bytecode. Currently, the GCC front
end is a modified version of GCC 3.4 (we track the GCC 3.4 development). Once
compiled into LLVM bytecode, a program can be manipulated with the LLVM tools
from the LLVM suite.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="quickstart"><b>Getting Started Quickly (A Summary)</b></a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>Here's the short story for getting up and running quickly with LLVM:</p>
<ol>
<li>Install the GCC front end:
<ol>
<li><tt>cd <i>where-you-want-the-C-front-end-to-live</i></tt>
<li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf -</tt>
<li><b>Sparc Only:</b><br>
<tt>cd cfrontend/sparc<br>
./fixheaders</tt>
</ol></li>
<li>Get the Source Code
<ul>
<li>With the distributed files:
<ol>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
<li><tt>gunzip --stdout llvm.tar.gz | tar -xvf -</tt>
<li><tt>cd llvm</tt>
</ol></li>
<li>With anonymous CVS access:
<ol>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt></li>
<li><tt>cvs -d
:pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login</tt></li>
<li>Hit the return key when prompted for the password.
<li><tt>cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm
co llvm</tt></li>
<li><tt>cd llvm</tt></li>
</ol></li>
</ul></li>
<li>Configure the LLVM Build Environment
<ol>
<li>Change directory to where you want to store the LLVM object
files and run <tt>configure</tt> to configure the Makefiles and
header files for the default platform. Useful options include:
<ul>
<li><tt>--with-llvmgccdir=<i>directory</i></tt>
<p>Specify where the LLVM GCC frontend is installed.</p></li>
<li><tt>--enable-spec2000=<i>directory</i></tt>
<p>Enable the SPEC2000 benchmarks for testing. The SPEC2000
benchmarks should be available in
<tt><i>directory</i></tt>.</p></li>
</ul>
</ol></li>
<li>Build the LLVM Suite:
<ol>
<li>Set your LLVM_LIB_SEARCH_PATH environment variable.
<li><tt>gmake -k |& tee gnumake.out
# this is csh or tcsh syntax</tt>
</ol>
</ol>
<p>Consult the <a href="starting">Getting Started with LLVM</a> section for
detailed information on configuring and compiling LLVM. See <a
href="#environment">Setting Up Your Environment</a> for tips that simplify
working with the GCC front end and LLVM tools. Go to <a href="#layout">Program
Layout</a> to learn about the layout of the source code tree.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="requirements"><b>Requirements</b></a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>Before you begin to use the LLVM system, review the requirements given below.
This may save you some trouble by knowing ahead of time what hardware and
software you will need.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="hardware"><b>Hardware</b></a>
</div>
<div class="doc_text">
<p>LLVM is known to work on the following platforms:</p>
<ul>
<li>Linux on x86 (Pentium and above)
<ul>
<li>Approximately 760 MB of Free Disk Space
<ul>
<li>Source code: 30 MB</li>
<li>Object code: 670 MB</li>
<li>GCC front end: 60 MB</li>
</ul></li>
</ul></li>
<li>Solaris on SparcV9 (Ultrasparc)
<ul>
<li>Approximately 1.24 GB of Free Disk Space
<ul>
<li>Source code: 30 MB</li>
<li>Object code: 1000 MB</li>
<li>GCC front end: 210 MB</li>
</ul></li>
</ul></li>
</ul>
<p>The LLVM suite <i>may</i> compile on other platforms, but it is not
guaranteed to do so. If compilation is successful, the LLVM utilities should be
able to assemble, disassemble, analyze, and optimize LLVM bytecode. Code
generation should work as well, although the generated native code may not work
on your platform.</p>
<p>The GCC front end is not very portable at the moment. If you want to get it
to work on another platform, you can download a copy of the source and try to
compile it on your platform.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="software"><b>Software</b></a>
</div>
<div class="doc_text">
<p>Compiling LLVM requires that you have several software packages
installed:</p>
<ul>
<li><a href="http://gcc.gnu.org">GCC 3.x with C and C++ language
support</a></li>
<li><a href="http://savannah.gnu.org/projects/make">GNU Make</a></li>
<li><a href="http://www.gnu.org/software/flex">Flex</a></li>
<li><a href="http://www.gnu.org/software/bison/bison.html">Bison</a></li>
</ul>
<p>There are some additional tools that you may want to have when working with
LLVM:</p>
<ul>
<li><A href="http://www.gnu.org/software/autoconf">GNU Autoconf</A>
<li><A href="http://savannah.gnu.org/projects/m4">GNU M4</A>
<p>If you want to make changes to the configure scripts, you will need GNU
autoconf (2.57 or higher), and consequently, GNU M4 (version 1.4 or
higher).</p></li>
<li><A href="http://www.codesourcery.com/qm/qmtest">QMTest</A></li>
<li><A href="http://www.python.org">Python</A>
<p>These are needed to use the LLVM test suite.</p></li>
</ul>
<p>The remainder of this guide is meant to get you up and running with
LLVM and to give you some basic information about the LLVM environment.
A <a href="#starting">complete guide to installation</a> is provided in the
next section.</p>
<p>The later sections of this guide describe the <a
href="#layout">general layout</a> of the the LLVM source tree, a <a
href="#tutorial">simple example</a> using the LLVM tool chain, and <a
href="#links">links</a> to find more information about LLVM or to get
help via e-mail.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="starting"><b>Getting Started with LLVM</b></a>
</div>
<!-- *********************************************************************** -->
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="terminology">Terminology and Notation</a>
</div>
<div class="doc_text">
<p>Throughout this manual, the following names are used to denote paths
specific to the local system and working environment. <i>These are not
environment variables you need to set but just strings used in the rest
of this document below</i>. In any of the examples below, simply replace
each of these names with the appropriate pathname on your local system.
All these paths are absolute:</p>
<dl compact>
<dt>SRC_ROOT
<dd>
This is the top level directory of the LLVM source tree.
<p>
<dt>OBJ_ROOT
<dd>
This is the top level directory of the LLVM object tree (i.e. the
tree where object files and compiled programs will be placed. It
can be the same as SRC_ROOT).
<p>
<dt>LLVMGCCDIR
<dd>
This is the where the LLVM GCC Front End is installed.
<p>
For the pre-built GCC front end binaries, the LLVMGCCDIR is
<tt>cfrontend/<i>platform</i>/llvm-gcc</tt>.
</dl>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="environment">Setting Up Your Environment</a>
</div>
<div class="doc_text">
<p>
In order to compile and use LLVM, you will need to set some environment
variables. There are also some shell aliases which you may find useful.
You can set these on the command line, or better yet, set them in your
<tt>.cshrc</tt> or <tt>.profile</tt>.
<dl compact>
<dt><tt>LLVM_LIB_SEARCH_PATH</tt>=<tt><i>LLVMGCCDIR</i>/bytecode-libs</tt>
<dd>
This environment variable helps the LLVM GCC front end find bytecode
libraries that it will need for compilation.
<p>
<dt>alias llvmgcc <i>LLVMGCCDIR</i><tt>/bin/gcc</tt>
<dt>alias llvmg++ <i>LLVMGCCDIR</i><tt>/bin/g++</tt>
<dd>
This alias allows you to use the LLVM C and C++ front ends without putting
them in your <tt>PATH</tt> or typing in their complete pathnames.
</dl>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="unpack">Unpacking the LLVM Archives</a></h3>
</div>
<div class="doc_text">
<p>
If you have the LLVM distribution, you will need to unpack it before you
can begin to compile it. LLVM is distributed as a set of three files. Each
file is a TAR archive that is compressed with the gzip program.
</p>
<p> The three files are as follows:
<dl compact>
<dt>llvm.tar.gz
<dd>This is the source code to the LLVM suite.
<p>
<dt>cfrontend.sparc.tar.gz
<dd>This is the binary release of the GCC front end for Solaris/Sparc.
<p>
<dt>cfrontend.x86.tar.gz
<dd>This is the binary release of the GCC front end for Linux/x86.
</dl>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="checkout">Checkout LLVM from CVS</a></h3>
</div>
<div class="doc_text">
<p>If you have access to our CVS repository, you can get a fresh copy of
the entire source code. All you need to do is check it out from CVS as
follows:</p>
<ul>
<li><tt>cd <i>where-you-want-llvm-to-live</i></tt>
<li><tt>cvs -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login</tt>
<li>Hit the return key when prompted for the password.
<li><tt>cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co
llvm</tt>
</ul>
<p>This will create an '<tt>llvm</tt>' directory in the current
directory and fully populate it with the LLVM source code, Makefiles,
test directories, and local copies of documentation files.</p>
<p>Note that the GCC front end is not included in the CVS repository. You
should have downloaded the binary distribution for your platform.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="installcf">Install the GCC Front End</a></h3>
</div>
<div class="doc_text">
<p>Before configuring and compiling the LLVM suite, you need to extract the LLVM
GCC front end from the binary distribution. It is used for building the
bytecode libraries later used by the GCC front end for linking programs, and its
location must be specified when the LLVM suite is configured.</p>
<p>To install the GCC front end, do the following:</p>
<ol>
<li><tt>cd <i>where-you-want-the-front-end-to-live</i></tt></li>
<li><tt>gunzip --stdout cfrontend.<i>platform</i>.tar.gz | tar -xvf
-</tt></li>
</ol>
<p>If you are on a Sparc/Solaris machine, you will need to fix the header
files:</p>
<p><tt>cd cfrontend/sparc<br>
./fixheaders</tt></p>
<p>The binary versions of the GCC front end may not suit all of your needs. For
example, the binary distribution may include an old version of a system header
file, not "fix" a header file that needs to be fixed for GCC, or it may be
linked with libraries not available on your system.</p>
<p>In cases like these, you may want to try <a
href="CFEBuildInstrs.html">building the GCC front end from source.</a> This is
not for the faint of heart, so be forewarned.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="config">Local LLVM Configuration</a>
</div>
<div class="doc_text">
<p>Once checked out from the CVS repository, the LLVM suite source code must be
configured via the <tt>configure</tt> script. This script sets variables in
<tt>llvm/Makefile.config</tt> and <tt>llvm/include/Config/config.h</tt>. It
also populates <i>OBJ_ROOT</i> with the Makefiles needed to build LLVM.</p>
<p>The following environment variables are used by the <tt>configure</tt>
script to configure the build system:</p>
<table border=1>
<tr>
<th>Variable</th>
<th>Purpose</th>
</tr>
<tr>
<td>CC</td>
<td>Tells <tt>configure</tt> which C compiler to use. By default,
<tt>configure</tt> will look for the first GCC C compiler in
<tt>PATH</tt>. Use this variable to override
<tt>configure</tt>'s default behavior.</td>
</tr>
<tr>
<td>CXX</td>
<td>Tells <tt>configure</tt> which C++ compiler to use. By default,
<tt>configure</tt> will look for the first GCC C++ compiler in
<tt>PATH</tt>. Use this variable to override
<tt>configure</tt>'s default behavior.</td>
</tr>
</table>
<p>The following options can be used to set or enable LLVM specific options:</p>
<dl compact>
<dt><i>--with-llvmgccdir=LLVMGCCDIR</i>
<dd>
Path to the location where the LLVM C front end binaries and
associated libraries will be installed.
<p>
<dt><i>--enable-optimized</i>
<dd>
Enables optimized compilation by default (debugging symbols are removed
and GCC optimization flags are enabled). The default is to use an
unoptimized build (also known as a debug build).
<p>
<dt><i>--enable-jit</i>
<dd>
Compile the Just In Time (JIT) functionality. This is not available
on all platforms. The default is dependent on platform, so it is best
to explicitly enable it if you want it.
<p>
<dt><i>--enable-spec2000</i>
<dt><i>--enable-spec2000=<<tt>directory</tt>></i>
<dd>
Enable the use of SPEC2000 when testing LLVM. This is disabled by default
(unless <tt>configure</tt> finds SPEC2000 installed). By specifying
<tt>directory</tt>, you can tell configure where to find the SPEC2000
benchmarks. If <tt>directory</tt> is left unspecified, <tt>configure</tt>
uses the default value
<tt>/home/vadve/shared/benchmarks/speccpu2000/benchspec</tt>.
</dl>
<p>To configure LLVM, follow these steps:</p>
<ol>
<li>Change directory into the object root directory:
<br>
<tt>cd <i>OBJ_ROOT</i></tt>
<p>
<li>Run the <tt>configure</tt> script located in the LLVM source tree:
<br>
<tt><i>SRC_ROOT</i>/configure</tt>
<p>
</ol>
<p>In addition to running <tt>configure</tt>, you must set the
<tt>LLVM_LIB_SEARCH_PATH</tt> environment variable in your startup scripts.
This environment variable is used to locate "system" libraries like
"<tt>-lc</tt>" and "<tt>-lm</tt>" when linking. This variable should be set to
the absolute path for the bytecode-libs subdirectory of the GCC front end
install, or <i>LLVMGCCDIR</i>/bytecode-libs. For example, one might set
<tt>LLVM_LIB_SEARCH_PATH</tt> to
<tt>/home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs</tt> for the X86
version of the GCC front end on our research machines.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="compile">Compiling the LLVM Suite Source Code</a>
</div>
<div class="doc_text">
<p>Once you have configured LLVM, you can build it. There are three types of
builds:</p>
<dl compact>
<dt>Debug Builds
<dd>
These builds are the default when one types <tt>gmake</tt> (unless the
<tt>--enable-optimized</tt> option was used during configuration). The
build system will compile the tools and libraries with debugging
information.
<p>
<dt>Release (Optimized) Builds
<dd>
These builds are enabled with the <tt>--enable-optimized</tt> option to
<tt>configure</tt> or by specifying <tt>ENABLE_OPTIMIZED=1</tt> on the
<tt>gmake</tt> command line. For these builds, the build system will
compile the tools and libraries with GCC optimizations enabled and strip
debugging information from the libraries and executables it generates.
<p>
<dt>Profile Builds
<dd>
These builds are for use with profiling. They compile profiling
information into the code for use with programs like <tt>gprof</tt>.
Profile builds must be started by specifying <tt>ENABLE_PROFILING=1</tt>
on the <tt>gmake</tt> command line.
</dl>
<p>Once you have LLVM configured, you can build it by entering the
<i>OBJ_ROOT</i> directory and issuing the following command:</p>
<p><tt>gmake</tt></p>
<p>If you have multiple processors in your machine, you may wish to use some of
the parallel build options provided by GNU Make. For example, you could use the
command:</p>
<p><tt>gmake -j2</tt></p>
<p>There are several special targets which are useful when working with the LLVM
source code:</p>
<dl compact>
<dt><tt>gmake clean</tt>
<dd>
Removes all files generated by the build. This includes object files,
generated C/C++ files, libraries, and executables.
<p>
<dt><tt>gmake distclean</tt>
<dd>
Removes everything that <tt>gmake clean</tt> does, but also removes
files generated by <tt>configure</tt>. It attempts to return the
source tree to the original state in which it was shipped.
<p>
<dt><tt>gmake install</tt>
<dd>
Installs LLVM files into the proper location. For the most part,
this does nothing, but it does install bytecode libraries into the
GCC front end's bytecode library directory. If you need to update
your bytecode libraries, this is the target to use once you've built
them.
<p>
</dl>
<p>It is also possible to override default values from <tt>configure</tt> by
declaring variables on the command line. The following are some examples:</p>
<dl compact>
<dt><tt>gmake ENABLE_OPTIMIZED=1</tt>
<dd>
Perform a Release (Optimized) build.
<p>
<dt><tt>gmake ENABLE_PROFILING=1</tt>
<dd>
Perform a Profiling build.
<p>
<dt><tt>gmake VERBOSE=1</tt>
<dd>
Print what <tt>gmake</tt> is doing on standard output.
<p>
</dl>
<p>Every directory in the LLVM object tree includes a <tt>Makefile</tt> to build
it and any subdirectories that it contains. Entering any directory inside the
LLVM object tree and typing <tt>gmake</tt> should rebuild anything in or below
that directory that is out of date.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="objfiles">The Location of LLVM Object Files</a>
</div>
<div class="doc_text">
<p>The LLVM build system is capable of sharing a single LLVM source tree among
several LLVM builds. Hence, it is possible to build LLVM for several different
platforms or configurations using the same source tree.</p>
<p>This is accomplished in the typical autoconf manner:</p>
<ul>
<li><p>Change directory to where the LLVM object files should live:</p>
<p><tt>cd <i>OBJ_ROOT</i></tt></p></li>
<li><p>Run the <tt>configure</tt> script found in the LLVM source
directory:</p>
<p><tt><i>SRC_ROOT</i>/configure</tt></p></li>
</ul>
<p>The LLVM build will place files underneath <i>OBJ_ROOT</i> in directories
named after the build type:</p>
<dl compact>
<dt>Debug Builds
<dd>
<dl compact>
<dt>Tools
<dd><tt><i>OBJ_ROOT</i>/tools/Debug</tt>
<dt>Libraries
<dd><tt><i>OBJ_ROOT</i>/lib/Debug</tt>
</dl>
<p>
<dt>Release Builds
<dd>
<dl compact>
<dt>Tools
<dd><tt><i>OBJ_ROOT</i>/tools/Release</tt>
<dt>Libraries
<dd><tt><i>OBJ_ROOT</i>/lib/Release</tt>
</dl>
<p>
<dt>Profile Builds
<dd>
<dl compact>
<dt>Tools
<dd><tt><i>OBJ_ROOT</i>/tools/Profile</tt>
<dt>Libraries
<dd><tt><i>OBJ_ROOT</i>/lib/Profile</tt>
</dl>
</dl>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="layout"><b>Program Layout</b></a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>One useful source of information about the LLVM source base is the LLVM <a
href="http://www.doxygen.org">doxygen</a> documentation, available at <tt><a
href="http://llvm.cs.uiuc.edu/doxygen/">http://llvm.cs.uiuc.edu/doxygen/</a></tt>.
The following is a brief introduction to code layout:</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="cvsdir"><tt>CVS</tt> directories</a>
</div>
<div class="doc_text">
<p>Every directory checked out of CVS will contain a <tt>CVS</tt> directory; for
the most part these can just be ignored.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="include"><tt>llvm/include</tt></a>
</div>
<div class="doc_text">
<p>This directory contains public header files exported from the LLVM
library. The three main subdirectories of this directory are:</p>
<ol>
<li><tt>llvm/include/llvm</tt> - This directory contains all of the LLVM
specific header files. This directory also has subdirectories for
different portions of LLVM: <tt>Analysis</tt>, <tt>CodeGen</tt>,
<tt>Target</tt>, <tt>Transforms</tt>, etc...</li>
<li><tt>llvm/include/Support</tt> - This directory contains generic
support libraries that are independent of LLVM, but are used by LLVM.
For example, some C++ STL utilities and a Command Line option processing
library store their header files here.</li>
<li><tt>llvm/include/Config</tt> - This directory contains header files
configured by the <tt>configure</tt> script. They wrap "standard" UNIX
and C header files. Source code can include these header files which
automatically take care of the conditional #includes that the
<tt>configure</tt> script generates.</li>
</ol>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="lib"><tt>llvm/lib</tt></a>
</div>
<div class="doc_text">
<p>This directory contains most of the source files of the LLVM system. In LLVM,
almost all code exists in libraries, making it very easy to share code among the
different <a href="#tools">tools</a>.</p>
<dl compact>
<dt><tt>llvm/lib/VMCore/</tt><dd> This directory holds the core LLVM
source files that implement core classes like Instruction and BasicBlock.
<dt><tt>llvm/lib/AsmParser/</tt><dd> This directory holds the source code
for the LLVM assembly language parser library.
<dt><tt>llvm/lib/ByteCode/</tt><dd> This directory holds code for reading
and write LLVM bytecode.
<dt><tt>llvm/lib/CWriter/</tt><dd> This directory implements the LLVM to C
converter.
<dt><tt>llvm/lib/Analysis/</tt><dd> This directory contains a variety of
different program analyses, such as Dominator Information, Call Graphs,
Induction Variables, Interval Identification, Natural Loop Identification,
etc...
<dt><tt>llvm/lib/Transforms/</tt><dd> This directory contains the source
code for the LLVM to LLVM program transformations, such as Aggressive Dead
Code Elimination, Sparse Conditional Constant Propagation, Inlining, Loop
Invariant Code Motion, Dead Global Elimination, and many others...
<dt><tt>llvm/lib/Target/</tt><dd> This directory contains files that
describe various target architectures for code generation. For example,
the llvm/lib/Target/Sparc directory holds the Sparc machine
description.<br>
<dt><tt>llvm/lib/CodeGen/</tt><dd> This directory contains the major parts
of the code generator: Instruction Selector, Instruction Scheduling, and
Register Allocation.
<dt><tt>llvm/lib/Support/</tt><dd> This directory contains the source code
that corresponds to the header files located in
<tt>llvm/include/Support/</tt>.
</dl>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="runtime"><tt>llvm/runtime</tt></a>
</div>
<div class="doc_text">
<p>This directory contains libraries which are compiled into LLVM bytecode and
used when linking programs with the GCC front end. Most of these libraries are
skeleton versions of real libraries; for example, libc is a stripped down
version of glibc.</p>
<p>Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front
end to compile.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="test"><tt>llvm/test</tt></a>
</div>
<div class="doc_text">
<p>This directory contains regression tests and source code that is used to test
the LLVM infrastructure.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="tools"><tt>llvm/tools</tt></a>
</div>
<div class="doc_text">
<p>The <b>tools</b> directory contains the executables built out of the
libraries above, which form the main part of the user interface. You can
always get help for a tool by typing <tt>tool_name --help</tt>. The
following is a brief introduction to the most important tools.</p>
<dl compact>
<dt>
<dt><tt><b>analyze</b></tt><dd> <tt>analyze</tt> is used to run a specific
analysis on an input LLVM bytecode file and print out the results. It is
primarily useful for debugging analyses, or familiarizing yourself with
what an analysis does.<p>
<dt><tt><b>bugpoint</b></tt><dd> <tt>bugpoint</tt> is used to debug
optimization passes or code generation backends by narrowing down the
given test case to the minimum number of passes and/or instructions that
still cause a problem, whether it is a crash or miscompilation. See <a
href="HowToSubmitABug.html">HowToSubmitABug.html</a> for more information
on using <tt>bugpoint</tt>.<p>
<dt><tt><b>llvm-ar</b></tt><dd>The archiver produces an archive containing
the given LLVM bytecode files, optionally with an index for faster
lookup.<p>
<dt><tt><b>llvm-as</b></tt><dd>The assembler transforms the human readable
LLVM assembly to LLVM bytecode.<p>
<dt><tt><b>llvm-dis</b></tt><dd>The disassembler transforms the LLVM
bytecode to human readable LLVM assembly. Additionally, it can convert
LLVM bytecode to C, which is enabled with the <tt>-c</tt> option.<p>
<dt><tt><b>llvm-link</b></tt><dd> <tt>llvm-link</tt>, not surprisingly,
links multiple LLVM modules into a single program.<p>
<dt><tt><b>lli</b></tt><dd> <tt>lli</tt> is the LLVM interpreter, which
can directly execute LLVM bytecode (although very slowly...). In addition
to a simple interpreter, <tt>lli</tt> also has a tracing mode (entered by
specifying <tt>-trace</tt> on the command line). Finally, for
architectures that support it (currently only x86 and Sparc), by default,
<tt>lli</tt> will function as a Just-In-Time compiler (if the
functionality was compiled in), and will execute the code <i>much</i>
faster than the interpreter.<p>
<dt><tt><b>llc</b></tt><dd> <tt>llc</tt> is the LLVM backend compiler,
which translates LLVM bytecode to a SPARC or x86 assembly file.<p>
<dt><tt><b>llvmgcc</b></tt><dd> <tt>llvmgcc</tt> is a GCC-based C frontend
that has been retargeted to emit LLVM code as the machine code output. It
works just like any other GCC compiler, taking the typical <tt>-c, -S, -E,
-o</tt> options that are typically used. The source code for the
<tt>llvmgcc</tt> tool is currently not included in the LLVM CVS tree
because it is quite large and not very interesting.<p>
<ol>
<dt><tt><b>gccas</b></tt><dd> This tool is invoked by the
<tt>llvmgcc</tt> frontend as the "assembler" part of the compiler. This
tool actually assembles LLVM assembly to LLVM bytecode,
performs a variety of optimizations, and outputs LLVM bytecode. Thus
when you invoke <tt>llvmgcc -c x.c -o x.o</tt>, you are causing
<tt>gccas</tt> to be run, which writes the <tt>x.o</tt> file (which is
an LLVM bytecode file that can be disassembled or manipulated just like
any other bytecode file). The command line interface to <tt>gccas</tt>
is designed to be as close as possible to the <b>system</b>
`<tt>as</tt>' utility so that the gcc frontend itself did not have to be
modified to interface to a "weird" assembler.<p>
<dt><tt><b>gccld</b></tt><dd> <tt>gccld</tt> links together several LLVM
bytecode files into one bytecode file and does some optimization. It is
the linker invoked by the GCC frontend when multiple .o files need to be
linked together. Like <tt>gccas</tt>, the command line interface of
<tt>gccld</tt> is designed to match the system linker, to aid
interfacing with the GCC frontend.<p>
</ol>
<dt><tt><b>opt</b></tt><dd> <tt>opt</tt> reads LLVM bytecode, applies a
series of LLVM to LLVM transformations (which are specified on the command
line), and then outputs the resultant bytecode. The '<tt>opt --help</tt>'
command is a good way to get a list of the program transformations
available in LLVM.<p>
</dl>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="utils"><tt>llvm/utils</tt></a>
</div>
<div class="doc_text">
<p>This directory contains utilities for working with LLVM source code, and some
of the utilities are actually required as part of the build process because they
are code generators for parts of LLVM infrastructure.</p>
<dl compact>
<td><tt><b>Burg/</b></tt><dd> <tt>Burg</tt> is an instruction selector
generator -- it builds trees on which it then performs pattern-matching to
select instructions according to the patterns the user has specified. Burg
is currently used in the Sparc V9 backend.<p>
<dt><tt><b>codegen-diff</b></tt><dd> <tt>codegen-diff</tt> is a script
that finds differences between code that LLC generates and code that LLI
generates. This is a useful tool if you are debugging one of them,
assuming that the other generates correct output. For the full user
manual, run <tt>`perldoc codegen-diff'</tt>.<p>
<dt><tt><b>cvsupdate</b></tt><dd> <tt>cvsupdate</tt> is a script that will
update your CVS tree, but produce a much cleaner and more organized output
than simply running <tt>`cvs -z3 up -dP'</tt> will. For example, it will group
together all the new and updated files and modified files in separate
sections, so you can see at a glance what has changed. If you are at the
top of your LLVM CVS tree, running <tt>utils/cvsupdate</tt> is the
preferred way of updating the tree.<p>
<dt><tt><b>emacs/</b></tt><dd> The <tt>emacs</tt> directory contains
syntax-highlighting files which will work with Emacs and XEmacs editors,
providing syntax highlighting support for LLVM assembly files and TableGen
description files. For information on how to use the syntax files, consult
the <tt>README</tt> file in that directory.<p>
<dt><tt><b>getsrcs.sh</b></tt><dd> The <tt>getsrcs.sh</tt> script finds
and outputs all non-generated source files, which is useful if one wishes
to do a lot of development across directories and does not want to
individually find each file. One way to use it is to run, for example:
<tt>xemacs `utils/getsources.sh`</tt> from the top of your LLVM source
tree.<p>
<dt><tt><b>makellvm</b></tt><dd> The <tt>makellvm</tt> script compiles all
files in the current directory and then compiles and links the tool that
is the first argument. For example, assuming you are in the directory
<tt>llvm/lib/Target/Sparc</tt>, if <tt>makellvm</tt> is in your path,
simply running <tt>makellvm llc</tt> will make a build of the current
directory, switch to directory <tt>llvm/tools/llc</tt> and build it,
causing a re-linking of LLC.<p>
<dt><tt><b>NightlyTest.pl</b></tt> and
<tt><b>NightlyTestTemplate.html</b></tt><dd> These files are used in a
cron script to generate nightly status reports of the functionality of
tools, and the results can be seen by following the appropriate link on
the <a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a>.<p>
<dt><tt><b>TableGen/</b></tt><dd> The <tt>TableGen</tt> directory contains
the tool used to generate register descriptions, instruction set
descriptions, and even assemblers from common TableGen description
files.<p>
<dt><tt><b>vim/</b></tt><dd> The <tt>vim</tt> directory contains
syntax-highlighting files which will work with the VIM editor, providing
syntax highlighting support for LLVM assembly files and TableGen
description files. For information on how to use the syntax files, consult
the <tt>README</tt> file in that directory.<p>
</dl>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="tutorial">An Example Using the LLVM Tool Chain</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<ol>
<li>First, create a simple C file, name it 'hello.c':
<pre>
#include <stdio.h>
int main() {
printf("hello world\n");
return 0;
}
</pre></li>
<li><p>Next, compile the C file into a LLVM bytecode file:</p>
<p><tt>% llvmgcc hello.c -o hello</tt></p>
<p>This will create two result files: <tt>hello</tt> and
<tt>hello.bc</tt>. The <tt>hello.bc</tt> is the LLVM bytecode that
corresponds the the compiled program and the library facilities that it
required. <tt>hello</tt> is a simple shell script that runs the bytecode
file with <tt>lli</tt>, making the result directly executable.</p></li>
<li><p>Run the program. To make sure the program ran, execute one of the
following commands:</p>
<p><tt>% ./hello</tt></p>
<p>or</p>
<p><tt>% lli hello.bc</tt></p></li>
<li><p>Use the <tt>llvm-dis</tt> utility to take a look at the LLVM assembly
code:</p>
<p><tt>% llvm-dis < hello.bc | less</tt><p></li>
<li><p>Compile the program to native Sparc assembly using the code
generator (assuming you are currently on a Sparc system):</p>
<p><tt>% llc hello.bc -o hello.s</tt></p>
<li><p>Assemble the native sparc assemble file into a program:</p>
<p><tt>% /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc</tt></p>
<li><p>Execute the native sparc program:</p>
<p><tt>% ./hello.sparc</tt></p></li>
</ol>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="problems">Common Problems</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>If you are having problems building or using LLVM, or if you have any other
general questions about LLVM, please consult the <a href="FAQ.html">Frequently
Asked Questions</a> page.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="links">Links</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>This document is just an <b>introduction</b> to how to use LLVM to do
some simple things... there are many more interesting and complicated things
that you can do that aren't documented here (but we'll gladly accept a patch
if you want to write something up!). For more information about LLVM, check
out:</p>
<ul>
<li><a href="http://llvm.cs.uiuc.edu/">LLVM homepage</a></li>
<li><a href="http://llvm.cs.uiuc.edu/doxygen/">LLVM doxygen tree</a></li>
<li><a href="http://llvm.cs.uiuc.edu/docs/Projects.html">Starting a Project
that Uses LLVM</a></li>
</ul>
</div>
<!-- *********************************************************************** -->
<hr>
<div class="doc_footer">
<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
<br>
Last modified: $Date$
</div>
</body>
</html>
|
