On Thu, Sep 19, 2013 at 8:36 AM, Taimoor Mirza <taimoor.m...@gmail.com> wrote:
Please use Reply-All to keep the CC list on your reply email. This way others on the mailing list can follow the discussion and participate. > O1 disassembly is at http://pastebin.com/yxWAmmmf > > O2 disassembly is at http://pastebin.com/v0uqHuYY I diffed them. The differences look reasonable, nothing obviously broken: * The broken -O2 version inlines qemu_coroutine_switch() into coroutine_trampoline(). * The broken -O2 version changes the ordering of basic blocks and switches a few instructions for shorter/cheaper equivalents. Taimoor: Can you try "make check" with the -O2 version? In particular, the test-coroutine tests may fail and that could help us figure out which operation is broken. Paolo: CCed you in case you want to diff the working -O1 against the broken -O2 disassembly. Perhaps Taimoor's gcc 4.6.2 -O2 subtly breaks around the Windows Fiber API calls. > On Wed, Sep 18, 2013 at 7:10 PM, Stefan Hajnoczi <stefa...@gmail.com> wrote: >> On Thu, Sep 05, 2013 at 04:02:43PM +0500, Taimoor Mirza wrote: >>> I am using released 1.5.0 version from http://wiki.qemu.org/Download. >>> I think it should be same as commit ID >>> "295d81c62414a63c625fa2e78175573d4b3f5ba4" >>> >>> I have observed some interesting behavior. This problem does not come >>> if I use MinGW with GCC version 4.7.2. I was originally using 4.6.2. I >>> spent some time looking at what can cause this problem and found out >>> an interesting thing. If I change optimization flag from O2 to O1 >>> while building coroutine-win32 then it works fine even with 4.6.2. >>> For this I first built QEMU binary with default O2 flag, remove >>> coroutine-win32.o, changed CFLAG in makefile to O1 and rerun make. >>> Generated binary works fine without any problem. >> >> Can you pastebin the output of "objdump -dr coroutine-win32.o" for both >> -O2 and -O1? >> >> Let's diff them and figure out why it breaks with -O2. >> >> Stefan
