On Mon, Nov 15, 2010 at 07:30:35PM +0100, Jim Bos wrote: > On 11/15/2010 07:08 PM, Linus Torvalds wrote: > > On Mon, Nov 15, 2010 at 9:40 AM, Jim Bos <jim...@xs4all.nl> wrote: > >> > >> Hmm, that doesn't work. > >> > >> [ Not sure if you read to whole thread but initial workaround was to > >> change the asm(..) to asm volatile(..) which did work. ] > > > > Since I have a different gcc than yours (and I'm not going to compile > > my own), have you posted your broken .s file anywhere? In fact, with > > the noinline (and the removal of the "+m" thing - iow just the patch > > you tried), what does just the "i8k_smm" function assembly look like > > for you after you've done a "make drivers/char/i8k.s"? > > > > If the asm just doesn't exist AT ALL, that's just odd. Because every > > single call-site of i8k_smm() clearly looks at the return value. So > > the volatile really shouldn't make any difference from that > > standpoint. Odd. > > > > Linus > > > > Attached version with plain 2.6.36 source and version with the committed > patch, i.e with the '"+m" (*regs)'
Thanks, this actually helped to see the problem. The problem is not inside of i8k_smm, which is not inlined, but in the callers. ipa-pure-const.c pass thinks i8k_smm is a pure function, thus regs = {}; regs.eax = 166; x = i8k_smm (®s); if (!x) x = regs.eax; in the callers is optimized into regs = {} regs.eax = 166; x = i8k_smm (®s); if (!x) x = 166; Now, not sure why this happens, as there is case GIMPLE_ASM: for (i = 0; i < gimple_asm_nclobbers (stmt); i++) { tree op = gimple_asm_clobber_op (stmt, i); if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 1) { if (dump_file) fprintf (dump_file, " memory asm clobber is not const/pure"); /* Abandon all hope, ye who enter here. */ local->pure_const_state = IPA_NEITHER; } } Debugging... Jakub