When configuring libxml-1.8.15 or libxml2-2.4.3 with

  CFLAGS='-O2 -march=athlon' ./configure

using gcc 3.01, the regression test fails:

##
## XML regression tests
##
Testing att1
...
Testing ent2
./test/ent2:4: error: Invalid URI: title.xml
<!ENTITY title PUBLIC "-//MY-TITLE//FR" "title.xml">
                                                   ^
./test/ent2:5: error: Invalid URI: img.gif
<!ENTITY image SYSTEM "img.gif" NDATA GIF>
                               ^
warning: failed to load external entity "-//MY-TITLE//FR"
1,10d0
< <?xml version="1.0"?>
< <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
< <!ENTITY xml "Extensible Markup Language">
< <!ENTITY title PUBLIC "-//MY-TITLE//FR" "title.xml">
< <!ENTITY image SYSTEM "img.gif" NDATA GIF>
< ]>
< <EXAMPLE>
<   &title;
<   This text is about XML, the &xml; and this is an embedded <IMG
src="image"/>
< </EXAMPLE>
result.ent2:1: error: Document is empty

^
result.ent2:1: error: Start tag expected, '<' not found

^
Testing ent3
...

Lots of other failures are reported in the following tests.

Since this problem does not occur when libxml is compiled with gcc 2.95.2
(otherwise same environment), this might well be a bug in gcc 3.0.1.