On Mon, Nov 02, 2015 at 02:38:33PM +0000, Alan Lawrence wrote: > On 23/09/15 23:06, Segher Boessenkool wrote: > >This adds an -freorder-blocks-algorithm=[simple|stc] flag, with "simple" > >as default. For -O2 and up (except -Os) it is switched to "stc" instead. > >Targets that never want STC can override this. This changes > >-freorder-blocks > >to be on at -O1 and up (was -O2 and up). > > > >In effect, the changes are for -O1 (which now gets "simple" instead of > >nothing), -Os (which now gets "simple" instead of "stc", since STC results > >in much bigger code), and for targets that wish to never use STC (not in > >this patch though). > > > > > >2015-09-23 Segher Boessenkool <seg...@kernel.crashing.org> > > > > * bb-reorder.c (reorder_basic_blocks): Use the algorithm selected > > with flag_reorder_blocks_algorithm. > > * common.opt (freorder-blocks-algorithm=): New flag. > > (reorder_blocks_algorithm): New enum. > > * flag-types.h (reorder_blocks_algorithm): New enum. > > * opts.c (default_options_table): Use -freorder-blocks at -O1 and up, > > and -freorder-blocks-algorithm=stc at -O2 and up (not at -Os). > > I'm a bit puzzled as to why nobody else has been seeing this, as it's been > happening to me as part of building gcc on x86_64, but since this patch > I've been seeing an ICE in vec::operator[] in reorder_basic_blocks_simple, > building libitm/beginend.cc. Preprocessed source attached, command line > reduced to: > > $ /work/alalaw01/build/./gcc/xg++ -B/work/alalaw01/build/./gcc/ -mrtm -O1 > -g -m32 -c temp.ii > /work/alalaw01/src/gcc/libitm/beginend.cc: In static member function > ‘static uint32_t GTM::gtm_thread::begin_transaction(uint32_t, const > gtm_jmpbuf*)’: > /work/alalaw01/src/gcc/libitm/beginend.cc:400:1: internal compiler error: > in operator[], at vec.h:714 > } > ^ > 0x1310783 vec<edge_def*, va_gc, vl_embed>::operator[](unsigned int) > /work/alalaw01/src/gcc/gcc/vec.h:714 > 0x1310783 reorder_basic_blocks_simple > /work/alalaw01/src/gcc/gcc/bb-reorder.c:2322
That seems to be happening in the FOR_EACH_BB_FN then? Or one of the EDGE_SUCCs? I cannot match up that line # with anything. Both cases suggest things are broken before already. > 0x1310783 reorder_basic_blocks > /work/alalaw01/src/gcc/gcc/bb-reorder.c:2450 > 0x1310783 execute > /work/alalaw01/src/gcc/gcc/bb-reorder.c:2551 > > Compilation succeeds at -O2 (instead of -O1). reorder_basic_blocks_simple isn't used at -O2 (it uses STC instead). I'll have a look at this wednesday. Segher
