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Unread postPosted: Sat May 04, 2013 12:47 am 
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Hi,

I have a piece of code that I was trying to compile and debug with gcc 4.7 and gdb 6.3.

Maybe these two versions are not compatible?

The problem is that when debugging code compiled with the -g option the debugger does not stop in main.
Rather it stops at a line of code that is about 1/3 of the way through the source file.

Anyone else seen this?

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Unread postPosted: Sat May 04, 2013 1:55 am 
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did you set a breakpoint? if yes how?

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Unread postPosted: Sat May 04, 2013 2:20 am 
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yes I did

under gdb I used

break main

but also I ran it as

gdb -dbx

and used stop in main

both incorrectly stopped at the same line in the code.

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Unread postPosted: Sun May 05, 2013 7:56 am 
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If you compile with any kind of optimizations, there may be no 1:1 mapping between the lines of source code and the program code. Sometimes, if you single-step through the program, the execution will jump all over the place. Try recompiling with -O0.


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Unread postPosted: Sun May 05, 2013 12:07 pm 
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alternatively you could just use "disas" on main and set an explicit breakpoint

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Unread postPosted: Mon May 06, 2013 1:21 am 
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Compilation line is

gcc -g source.c


Also output the result of preprocessing and looking at the result of that it appears that the preprocess is keeping line numbers ok.

Looking at the output from gcc -S and comparing the code from it appears that

disas main show the correct code.

However

info line main

shows

Line 102 of "lg.c" starts at address 0x100026f8 <test_interior+80> amnd ends at <main+1088>

Clearly when I use

break main
run

I would hope that it would indicate that I am at start address 0x???? <main+offset>

Still scratching my head at this one.

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Unread postPosted: Mon May 06, 2013 1:30 am 
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one other thing I wanted to add. If I compile it with my mipspro 7.4.4m the gdb 6.3 gets the line numbers correct but I get some other issues which I was hoping that using a gcc/gdb combo would fix and not throw this problem up.

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Unread postPosted: Mon May 06, 2013 3:27 am 
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well gnu for everything but x86 is only the cheap alternative in most cases. having glitches like this is quite common

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Unread postPosted: Mon May 06, 2013 3:59 am 
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Try a newer GDB, there have been some changes to the debugging format in gcc 4.something.


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Unread postPosted: Mon May 06, 2013 1:56 pm 
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I thought that it might come down to using a newer version of gdb.

Anyone know who did the neko 6.3 compile. Just want to find out if there any special instructions?

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Unread postPosted: Mon May 06, 2013 5:36 pm 
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competentcompton wrote:
Anyone know who did the neko 6.3 compile. Just want to find out if there any special instructions?

Usually that's all in the release notes ... /usr/nekoware/relnotes

If you wanted to upgrade you can take the original spec and idb files that you'll find in /usr/nekoware/dist and make a tardist .... it's not difficult, just a little tedious.

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Unread postPosted: Thu May 09, 2013 2:59 am 
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well the release notes setings certainly do not work for a compile of gdb 7.6

I'll have to look into this one some more. Already getting compiler errors.

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Unread postPosted: Thu May 09, 2013 11:35 am 
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Presumably you don't have the cvd debugger that comes with Prodev Workshop?

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Unread postPosted: Thu May 09, 2013 2:02 pm 
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Sensitive topic

I have db which is version 7.1 (I think) and it was giving problems with debugging code from my 7.4.4m compiler.

I can't find it and may have lost the disk it is on (darn!)

I thought I would try using gdb 6.3 but it (pparently) has issues with mips C++ code.

Then I thought "sod it" I will try to use gcc 4.7 but presto it doesn't work either.

I have gone full round trip and am now left with compiling gdb myself and hoping that it works with gcc 4.7

:roll:


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Unread postPosted: Thu May 09, 2013 2:52 pm 
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Is that the version of cvd that comes with Prodev Workshop 2.9.1? Looks like they haven't updated the product information since MIPSPro 7.4 came out: http://techpubs.sgi.com/library/tpl/cgi-bin/summary.cgi?db=bks&docnumber=007-2582-006

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