[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493 Andrew Pinski changed: What|Removed |Added Status|NEW |RESOLVED Resolution|--- |FIXED --- Comment #13 from Andrew Pinski --- Fixed for GCC 8: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=32b3df079a3af3933c2b137cb1f772e96ca9499d
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493 Andrew Pinski pinskia at gcc dot gnu.org changed: What|Removed |Added CC||a...@cloudius-systems.com --- Comment #8 from Andrew Pinski pinskia at gcc dot gnu.org --- *** Bug 59639 has been marked as a duplicate of this bug. ***
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493 --- Comment #9 from Kristis Makris mkgnu at mkgnu dot net --- I won't see, open or read your email. I won't even know you emailed me. If there's something you want me to do you have to use this: https://aimelia.com/res?id=CZPr9mKgQTQfD3dYqy00b5qg This is an automated response.
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493 --- Comment #10 from Kristis Makris mkgnu at mkgnu dot net --- I won't see, open or read your email. I won't even know you emailed me. If there's something you want me to do you have to use this: https://aimelia.com/res?id=BJ6WQBHg1LEYvkwLH6Hn02hK This is an automated response.
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493 --- Comment #11 from Kristis Makris mkgnu at mkgnu dot net --- I won't see, open or read your email. I won't even know you emailed me. If there's something you want me to do you have to use this: https://aimelia.com/res?id=wnVviP0qSkNXW1mtSIOKtdq5 This is an automated response.
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493 --- Comment #12 from Kristis Makris mkgnu at mkgnu dot net --- Please revise and resubmit. I can't tell clearly why whatever it is you are asking is important.
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
--- Comment #6 from mkgnu at mkgnu dot net 2007-04-30 23:42 --- It seems that when I use -freorder-blocks-and-partition along with -fprofile-use (after I have already run once an executable compiled with -freorder-blocks-and-partition -fprofile-generate) I can produce an object file that contains a .text.unlikely section, as expected. But when I try to further link this object file with other object files to produce an executable, the .text.unlikely section is missing from the final executable. I've tried this with gcc4.1.2/ld2.15 and then again with gcc4.1.1/ld2.17 with the same results. Is this another bug related to -freorder-blocks-and-partition ? Should I file a separate bug report for it ? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
--- Comment #7 from pinskia at gcc dot gnu dot org 2007-04-30 23:48 --- (In reply to comment #6) But when I try to further link this object file with other object files to produce an executable, the .text.unlikely section is missing from the final executable. I've tried this with gcc4.1.2/ld2.15 and then again with gcc4.1.1/ld2.17 with the same results. What do you mean by missing? The default linker scripts combines .text.* into .text (but puts together those sections first). -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
--- Comment #4 from pinskia at gcc dot gnu dot org 2007-04-24 20:27 --- *** Bug 31689 has been marked as a duplicate of this bug. *** -- pinskia at gcc dot gnu dot org changed: What|Removed |Added CC||mkgnu at mkgnu dot net http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
--- Comment #5 from mkgnu at mkgnu dot net 2007-04-25 02:12 --- (In reply to comment #3) I've tried a couple of different ways to use branch predictions for partitioning, but it never leads to meaningful results. Either everything is hot or everything is cold. I don't know what else to do about this. Steven, perhaps you could elaborate what you mean by saying it never leads to meaningful results ? I'm actually tempted to claim this is a WONTFIX because hot and cold are not meaningful without profile information. Thoughts, anyone? I'm working on a research prototype in which I produce code that should be cold for a considerable amount of time when a program runs. After some time (or perhaps never), when a flag is raised, we'd like to use the cold code just once, and then revert the program back to it's original behavior of running only hot code. Apparently, as bug 31689 shows, I need this feature. In this research prototype I am 100% certain that a piece of code will be cold -- there's no need to gather profiling information, and I absolutely need this code to be out of the .text section. Using this research prototype, I ran experiments that demonstrate a slowdown in computation-bound applications in the range of 4%-300% on the i386 and PowerPC architectures depending on the size of the processor i-cache. I believe that moving the cold code sections out of .text will bring the overhead down to less than 4%, constantly. I absolutely, positively, definitely find value in this feature. In fact, my research progress depends on it and I am actively looking for a way to have this implemented. Can you help ? I've tried using __builtin_expect() and -freorder-blocks-and-partition with gcc 4.1.2 and it doesn't seem to work. If there's a patch laying around that implements this feature without gathering profiling information I would love to try it out immediately. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493
[Bug rtl-optimization/26493] -freorder-blocks-and-partition is a dud without generated profiling data
--- Comment #3 from steven at gcc dot gnu dot org 2007-04-13 22:41 --- I've tried a couple of different ways to use branch predictions for partitioning, but it never leads to meaningful results. Either everything is hot or everything is cold. I don't know what else to do about this. I'm actually tempted to claim this is a WONTFIX because hot and cold are not meaningful without profile information. Thoughts, anyone? -- steven at gcc dot gnu dot org changed: What|Removed |Added AssignedTo|steven at gcc dot gnu dot |unassigned at gcc dot gnu |org |dot org Status|ASSIGNED|NEW http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26493
