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From: oleg@okmij.org
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Subject: Re: [Caml-list] Re: ocaml 3.12.1 and delimcc


Many thanks to Christophe Raffalli for investigating the problem. It
turns out, the problem lies in GCC, which is used to compile a small
bit of C code in delimcc. As Christophe Raffalli reports, GCC versions
4.4 and 4.6 (and, I add, 4.2.1 -- the version used in FreeBSD) are not
problematic. However, when GCC 4.7 compiles the C portion of delimcc,
testd0opt gives a segfault. 

The stacks-native.c file in delimcc does rely on alloca and depends on
the absence of tail-call optimization. One function is written in a
way to defeat the optimization; alas, GCC may be to clever to optimize
the counter-measure away. Well, C only roughly fits the role of the
portable assembler. I don't have GCC 4.7 readily available and can't
offer an immediate fix. It is worth playing with optimization flags,
and set -O0, for instance, when compiling stacks-native.c. I'll see if
I could find a pragma or other way to disable undesirable
optimizations.