gcc 4.7 and gdb 6.3 problem

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competentcompton
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gcc 4.7 and gdb 6.3 problem

Unread postby competentcompton » Sat May 04, 2013 1:47 am

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?

Cheers

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foetz
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Re: gcc 4.7 and gdb 6.3 problem

Unread postby foetz » Sat May 04, 2013 2:55 am

did you set a breakpoint? if yes how?
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competentcompton
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Re: gcc 4.7 and gdb 6.3 problem

Unread postby competentcompton » Sat May 04, 2013 3:20 am

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.

Cheers

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canavan
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Re: gcc 4.7 and gdb 6.3 problem

Unread postby canavan » Sun May 05, 2013 8:56 am

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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Re: gcc 4.7 and gdb 6.3 problem

Unread postby foetz » Sun May 05, 2013 1:07 pm

alternatively you could just use "disas" on main and set an explicit breakpoint
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competentcompton
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Re: gcc 4.7 and gdb 6.3 problem

Unread postby competentcompton » Mon May 06, 2013 2:21 am

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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competentcompton
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Re: gcc 4.7 and gdb 6.3 problem

Unread postby competentcompton » Mon May 06, 2013 2:30 am

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.

Cheers

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Re: gcc 4.7 and gdb 6.3 problem

Unread postby foetz » Mon May 06, 2013 4:27 am

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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Re: gcc 4.7 and gdb 6.3 problem

Unread postby ShadeOfBlue » Mon May 06, 2013 4:59 am

Try a newer GDB, there have been some changes to the debugging format in gcc 4.something.

competentcompton
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Re: gcc 4.7 and gdb 6.3 problem

Unread postby competentcompton » Mon May 06, 2013 2:56 pm

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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Re: gcc 4.7 and gdb 6.3 problem

Unread postby hamei » Mon May 06, 2013 6:36 pm

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.
Folks say that if you listen real close at the height of the full moon, when the wind is blowin' off Nantucket Sound from the nor' east and the dogs are howlin' for no earthly reason, you can hear the awful screams of the crew of the "Ellie May," a sturdy whaler captained by John McTavish; for it was on just such a night when the rum was flowin' and, Davey Jones be damned, big John brought his men on deck for the first of several screaming contests.

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Re: gcc 4.7 and gdb 6.3 problem

Unread postby competentcompton » Thu May 09, 2013 3:59 am

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.

Cheers

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Re: gcc 4.7 and gdb 6.3 problem

Unread postby vishnu » Thu May 09, 2013 12:35 pm

Presumably you don't have the cvd debugger that comes with Prodev Workshop?
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competentcompton
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Re: gcc 4.7 and gdb 6.3 problem

Unread postby competentcompton » Thu May 09, 2013 3:02 pm

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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Re: gcc 4.7 and gdb 6.3 problem

Unread postby vishnu » Thu May 09, 2013 3:52 pm

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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