[lldb-dev] Difficulty in using target.source-map to map source files
karnajit wangkhem via lldb-dev
lldb-dev at lists.llvm.org
Thu Aug 24 10:06:32 PDT 2017
Hi Jim,
Thanks for the valuable reply. Please find my comments inline.
Regards,
Karan
On Wed, Aug 23, 2017 at 12:32 AM, Jim Ingham <jingham at apple.com> wrote:
>
> > On Aug 21, 2017, at 12:02 PM, karnajit wangkhem via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
> >
> > Hi All,
> >
> > Below is a sample example, where target.source-map seems to have a
> limitation. The limitation seems to be because
> > 1. lldb does not have an equivalent command like directory in gdb
>
> The gdb "dir" command seemed always to be more annoying than useful in
> real situations. If your project had any complexity in the directory
> structure you ended up having to add dir commands for all the
> subdirectories, which got tedious quickly. Since you pretty much always
> move your sources around rigidly, "source maps" are a more natural way to
> specify this.
>
> Note, we could add a recursive "dir" command, but you can't do the
> simpleminded recursive search or you'll mess up when the sources have same
> named files in different directories. Because of this, again the source
> maps seem more suited.
>
>
-- Really a good info to know. Thanks!
> > 2. target.source-map does not accept multiple mapping entries. I checked
> this only with freebsd.
> >
> > (lldb) settings show target.source-map
> > target.source-map (path-map) =
> > [0] "/home/karnajitw/lldb_test_execs/test_source_line1" ->
> "/u/test/test_source_line1"
>
> That is not correct:
>
> (lldb) settings set target.source-map /some/source/path /tmp
> /some/other/source/path /tmp
> (lldb) settings show target.source-map
> target.source-map (path-map) =
> [0] "/some/source/path" -> "/tmp"
> [1] "/some/other/source/path" -> "/tmp"
>
> or
>
> (lldb) set set target.source-map /some/source/path /tmp
> (lldb) set append target.source-map /some/other/source/path /tmp
> (lldb) set show target.source-map
> target.source-map (path-map) =
> [0] "/some/source/path" -> "/tmp"
> [1] "/some/other/source/path" -> "/tmp"
>
- Thanks! This helped.
> >
> > 3. Haven't checked in the code yet, but if we see the mappings of
> scenario 1, they all point to a single real path
> /home/karnajitw/lldb_test_execs/test_source_line1. But looks like the
> mapping logic only considers strings into account. But, at the same time, I
> am not claiming that they should be interpreted as path from a different
> machine during the mapping.
> >
>
> I'm not sure what you mean here. lldb does what it can to unwind the
> source path, but it doesn't assume that those paths actually exist locally,
> so the most it can do is remove redundant "/"-s and "/./"-s and unwind
> ".."-s. We do this before most source path comparisons (it's part of the
> FileSpec Equals method). We've been tinkering with this over time so make
> sure you are using a recent version of lldb. If there are places where we
> don't do this, then that's easily fixed.
>
>
- Your answer is in line with what I wanted to know. My lldb should be
quite recent. But I used it only for freebsd currently.
% ./lldb --version
lldb version 5.0.0 (http://llvm.org/svn/llvm-project/lldb/trunk revision
305778)
clang revision 305546
llvm revision 305548
>
> > I want to check on this issue in-depth. But before that, want to confirm
> if this is real issue or there are other ways to deal these scenarios which
> I am not aware of?
> >
> > I am referring below link for the lldb commands.
> > https://lldb.llvm.org/lldb-gdb.html
> >
> > 1. First scenario: Different souce file path representation
> >
> > [/home/karnajitw/lldb_test_execs/test_source_line1] $ clang -O0 -g
> /home/karnajitw/lldb_test_execs///test_source_line1/main.c
> /home/karnajitw/lldb_test_execs/../lldb_test_execs/test_source_line1/a/ainc.c
> /home/karnajitw/lldb_test_execs/test_source_line1/a/b/binc.c
> >
> > Machine 1: /home/karnajitw/lldb_test_execs/test_source_line1 -> Machine
> 2: /u/test/test_source_line1
> >
> > test_source_line1
> > |-- a
> > | |-- ainc.c
> > | |-- ainc.h
> > | `-- b
> > | |-- binc.c
> > | `-- binc.h
> > |-- a.out
> > `-- main.c
> >
> > % ./lldb test_source_line1/a.out
> >
> > (lldb) target create "test_source_line1/a.out"
> > Current executable set to 'test_source_line1/a.out' (x86_64).
> > (lldb) l main
> > File: /home/karnajitw/lldb_test_execs///test_source_line1/main.c
> > (lldb) l afn
> > File: /home/karnajitw/lldb_test_execs/../lldb_test_execs/test_sour
> ce_line1/a/ainc.c
> > (lldb) l bfn
> > File: /home/karnajitw/lldb_test_execs/test_source_line1/a/b/binc.c
> >
> > (lldb) settings set target.source-map /home/karnajitw/lldb_test_execs///test_source_line1
> /u/test/test_source_line1
> >
> > (lldb) l main
> > File: /home/karnajitw/lldb_test_execs///test_source_line1/main.c
> > 1 #include "a/ainc.h"
> > 2
> > 3 int main()
> > 4 {
> > 5 afn();
> > 6
> > 7 bfn();
> > 8
> > 9 return 0;
> > 10 }
> > (lldb) l afn
> > File: /home/karnajitw/lldb_test_execs/../lldb_test_execs/test_sour
> ce_line1/a/ainc.c
> > (lldb) l bfn
> > File: /home/karnajitw/lldb_test_execs/test_source_line1/a/b/binc.c
> >
> > (lldb) settings set target.source-map /home/karnajitw/lldb_test_exec
> s/../lldb_test_execs/test_source_line1 /u/test/test_source_line1
> >
> > (lldb) l main
> > File: /home/karnajitw/lldb_test_execs///test_source_line1/main.c
> > (lldb) l afn
> > File: /home/karnajitw/lldb_test_execs/../lldb_test_execs/test_sour
> ce_line1/a/ainc.c
> > 1 #include <stdio.h>
> > 2 #include "ainc.h"
> > 3
> > 4 void afn()
> > 5 {
> > 6 printf("Hello this is afn...\n");
> > 7 }
> > (lldb) l bfn
> > File: /home/karnajitw/lldb_test_execs/test_source_line1/a/b/binc.c
> >
> > (lldb) settings set target.source-map /home/karnajitw/lldb_test_execs/test_source_line1
> /u/test/test_source_line1
> >
> > (lldb) l main
> > File: /home/karnajitw/lldb_test_execs///test_source_line1/main.c
> > (lldb) l afn
> > File: /home/karnajitw/lldb_test_execs/../lldb_test_execs/test_sour
> ce_line1/a/ainc.c
> > (lldb) l bfn
> > File: /home/karnajitw/lldb_test_execs/test_source_line1/a/b/binc.c
> > 1 #include <stdio.h>
> > 2 #include "binc.h"
> > 3
> > 4 void bfn()
> > 5 {
> > 6 printf("Hello this is bfn...\n");
> > 7 }
>
> I can't test the "///" part of this, clang seems to always collapse these
> for me. But with a recent lldb, I see:
>
> $ clang -g -O0 -c '/tmp/sources/build/../files/hello.c'
> $ dwarfdump hello.o
> ...
> 0x0000000b: TAG_compile_unit [1] *
> AT_producer( "Apple LLVM version 9.0.0 (clang-900.0.31)" )
> AT_language( DW_LANG_C99 )
> AT_name( "/tmp/sources/build/../files/hello.c" )
>
> So we did get a compile unit name with .. in it, but:
>
> lldbrulez:/tmp/sources/build > clang -g -O0 -o hello hello.o
> lldbrulez:/tmp/sources/build > lldb
> (lldb) file hello
> Current executable set to 'hello' (x86_64).
> (lldb) source list -n main
> File: /tmp/sources/build/../files/hello.c
> 1 #include <stdio.h>
> 2
> 3 int
> 4 main()
> 5 {
> 6 printf ("Hello there.\n");
> 7 return 0;
> 8 }
>
> So we do unwind the ..'s in this case. This example doesn't have
> source-maps, but the same thing works if I move the sources and add just a
> <build-top> -> <debug-top> mapping. As I say, we have been working these
> ".." aware comparisons through all the file compares recently, so you may
> just need to get a newer lldb.
- Lets say in my above example, the function is this way
main -> afn -> bfn
Now, I breakpoint on bfn, now to get source list on all the 3 frames, I
will need this below mapping
(lldb)
target.source-map (path-map) =
[0] "/home/karnajitw/lldb_test_execs///test_source_line1" ->
"/u/test/test_source_line1"
[1] "/home/karnajitw/lldb_test_execs/../lldb_test_execs/test_source_line1"
-> "/u/test/test_source_line1"
[2] "/home/karnajitw/lldb_test_execs/test_source_line1" ->
"/u/test/test_source_line1"
Like the previous discussion, All the LHS and RHS actually refers to the
same path. So why we need 3 mappings here? But, as I have mentioned
previously the problem could be just in the freebsd version also.
>
>
> > 2. Scenario 2: Deep directory structure
> >
> > <top>/obj/a/b/c/d/e/app/sub/../../../../../../../../src/a/b/
> c/d/e/app/sub/file
> > <top>/obj/a/b/c/d/e/app/../../../../../../../src/a/b/c/d/e/app/file
> >
> > - If we carry the copy the source file to machine 2, we cannot easily
> map the source file without creating dummy <top>/obj/a/b/c/d/e/f/g.
> >
You should only need to map <top> to <top>. The only reason you would have
> to start specifying subdirectories is you have ones specified with ".."-s,
> but that problem is properly handled by making the file comparisons aware
> of backup operators. So if the comparisons are working right (again check
> a more recent lldb) you should not need to deal with all these dots.
>
>
- Checked with latest lldb build, its the same
(lldb) version
lldb version 6.0.0 (http://llvm.org/svn/llvm-project/lldb/trunk revision
311075)
clang revision 311072
llvm revision 311071
$ build/bin/lldb a.out
(lldb) target create "a.out"
Current executable set to 'a.out' (x86_64).
(lldb) settings set target.source-map
/home/karnajitw/lldbtest/obj/a/b/c/d/e/app/../../../../../../../src/a/b/c/d/e/app
/home/karnajitw/app
(lldb) l main
File:
/home/karnajitw/lldbtest/obj/a/b/c/d/e/app/../../../../../../../src/a/b/c/d/e/app/main.c
1 #include "sub/subfile.h"
2
3 int main()
4 {
5 subfn();
6
7 return 0;
8 }
9
(lldb) l subfn
File:
/home/karnajitw/lldbtest/obj/a/b/c/d/e/app/sub/../../../../../../../../src/a/b/c/d/e/app/sub/subfile.c
(lldb) settings append target.source-map
/home/karnajitw/lldbtest/obj/a/b/c/d/e/app/sub/../../../../../../../../src/a/b/c/d/e/app
/home/karnajitw/app
(lldb) l subfn
File:
/home/karnajitw/lldbtest/obj/a/b/c/d/e/app/sub/../../../../../../../../src/a/b/c/d/e/app/sub/subfile.c
1 #include <stdio.h>
2 #include "subfile.h"
3
4 void subfn()
5 {
6 printf("This is subfn...\n");
7 }
8
It still needs both the mappings
(lldb) settings show target.source-map
target.source-map (path-map) =
[0]
"/home/karnajitw/lldbtest/obj/a/b/c/d/e/app/../../../../../../../src/a/b/c/d/e/app"
-> "/home/karnajitw/app"
[1]
"/home/karnajitw/lldbtest/obj/a/b/c/d/e/app/sub/../../../../../../../../src/a/b/c/d/e/app"
-> "/home/karnajitw/app"
> 3. Scenario 3: External libraries
> > - I haven't exactly tested this yet. But I belive in scenario too we
> might need to change the source-map.
>
> External libraries should be no different from your project. I don't see
> anything different needed here.
>
>
- Agreed.
> Jim
>
>
> >
> > Please look into this and guide me for the same.
> >
> > Regards,
> > Karan
> > _______________________________________________
> > lldb-dev mailing list
> > lldb-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>
>
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