0005919: ocamlopt generates bad executable

Notes
(0008839) zhihan (reporter) 2013-02-13 15:57	I did a little bit further investigation myself. I used readelf to disassemble the two files. Among the differences, this one might be related. In the 'bad' file produced from ocamlopt, the relocation address of 'strcmp' and 'strcpy' are placed in the '.rela.dyn' section, while in the 'good' file these relocations are placed in the '.rela.plt' section. According to resources on the internet, '.rela.plt' should hold relocation addresses for C functions and '.rela.dyn' should hold for data. In this regard, the relocation addresses of 'strcpy' is placed in the wrong section. Might it be the cause the seg fault?

(0008840) meyer (developer) 2013-02-13 20:55	The reason for that is that ocamlbuild might pick the wrong compiler. Ocamlbuild tries to use not the compiler on path but the one it's being rooted. Therefore: if /usr/local/bin/ocamlbuild.native is present it will always pick the /usr/local/ocamlc and not the one pointed by PATH. Please double check if you didn't hit that problem, perhaps you have several incompatible ocaml installations. What will happen if you compile the program manually?

(0008841) meyer (developer) 2013-02-13 20:56	the tarball you've attached cannot be opened. Please re-attach a right tarball.

(0008842) zhihan (reporter) 2013-02-13 21:00	So I should use the '-ocamlopt' option to make sure the right compiler is invoked?

(0008843) meyer (developer) 2013-02-13 21:53	Unfortunately yes, that's the only way you can change it. The trunk of the toolchain, if you wish to try dev version, contains also -which flag which will tell you what's being picked up. You can also use -verbose 100 which will show you the commands being invoked. Please make sure if you swap a compiler to use -clean flag before. If you are not forced to use 3.12.1 compiler, I'd strongly advise to try 4.00.1. The easiest way to get the system working is via OPAM.

(0009004) xleroy (administrator) 2013-03-24 12:02	So, do we have enough info on this PR to see if something needs to be done? W. Meyer wisely suggests to use a clean 4.00.1 installation. If this is enough to solve the problem, I move to close this PR.

Issue History
Date Modified	Username	Field	Change
2013-02-12 22:13	zhihan	New Issue
2013-02-12 22:13	zhihan	File Added: ocamlbug.tar.gz
2013-02-13 15:57	zhihan	Note Added: 0008839
2013-02-13 20:55	meyer	Note Added: 0008840
2013-02-13 20:56	meyer	Note Added: 0008841
2013-02-13 20:59	zhihan	File Added: ocamltest.tar.gz
2013-02-13 21:00	zhihan	Note Added: 0008842
2013-02-13 21:53	meyer	Note Added: 0008843
2013-03-24 12:02	xleroy	Note Added: 0009004
2013-03-24 12:02	xleroy	Status	new => feedback
2013-04-15 12:22	xleroy	Status	feedback => resolved
2013-04-15 12:22	xleroy	Resolution	open => unable to reproduce

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