<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On Apr 12, 2012, at 7:44 AM, Daniel D. Daugherty wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Times; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="font-family: monospace; "><blockquote type="cite"><br class="Apple-interchange-newline">Why do we need to change compiler flags besides symbol generation ?<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">e.g. for gcc -O3 -g3 is perfectly valid combination.<br></blockquote><br>You'd have to dig into the history of why a FASTDEBUG flavor build<br>chose the options that it did. All I'm doing is using their research.<br></span></span></blockquote></div><br><div>Historically, the hotspot C++ code has sometimes stressed the C++ compilers we have used</div><div>over the years, and in addition the dynamic code generated by Hotspot at runtime can sometimes</div><div>conflict with the C++ compiler, both use various optimization tactics and sometimes they collide.</div><div>I haven't heard of that happening recently, usually it happens when we switch to newer compilers</div><div>on Windows and Solaris, but I'm sure it has happened with gcc too.</div><div><br></div><div>Adding -g to an optimized build can complicate matters further.</div><div>And it's not just the optimization level but all the various compiler options we use.</div><div>Sometimes we just have to gear back due to size or time issues compiling one particular file.</div><div><br></div><div>So with each 'build flavor' you create unique situations that need to be tweaked because of that unique flavor.</div><div><br></div><div>I had tried to make sure that at least with Solaris, when the a compiler bug caused us to add or</div><div>adjust the compiler options on a file, that a comment (with CR#) was placed around this area and the makefile</div><div>logic would do an 'if compiler version is N.N or less', assuming the bug was fixed in N.N+1.</div><div><br></div><div>This is all just a consequence of living in an imperfect world, and walking on the edge of the cliff,</div><div>which Hotspot code often does. Be careful out there.</div><div><br></div><div>-kto</div><div><br></div></body></html>