Dominance information problem
I'm trying to do performance qualification for my structure
reorganization optimization.
I'm doing pretty straightforward stuff and I haven't at this point in
time (qualifying the optimization,) modified the program. So I'm a
little surprised this is failing. Here is the code that's failing on
the first iteration of the for loops:
struct cgraph_node *node;
FOR_EACH_FUNCTION_WITH_GIMPLE_BODY ( node) {
struct function *func = DECL_STRUCT_FUNCTION ( node->decl);
push_cfun ( func);
class loop *loop;
FOR_EACH_LOOP_FN ( func, loop, LI_ONLY_INNERMOST )
{
size_t num_bbs = loop->num_nodes;
basic_block *bbs = get_loop_body ( loop); // FAILS HERE!!!
:
stuff never reached
How it's failing (in code from dominance.c) I'm guessing tells me the
dominance information is messed up (unlikely) or needs to be
recomputed. If I'm not wrong, how do I go about doing the later
/* Return TRUE in case BB1 is dominated by BB2. */
bool
dominated_by_p (enum cdi_direction dir, const_basic_block bb1,
const_basic_block bb2)
{
unsigned int dir_index = dom_convert_dir_to_idx (dir);
struct et_node *n1 = bb1->dom[dir_index], *n2 = bb2->dom[dir_index];
gcc_checking_assert (dom_computed[dir_index]); // <=== BOOM!
if (dom_computed[dir_index] == DOM_OK)
return (n1->dfs_num_in >= n2->dfs_num_in
&& n1->dfs_num_out <= n2->dfs_num_out);
return et_below (n1, n2);
}
Thanks,
Gary Oblock
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Re: Lowest i386 CPU Model with proper C++ atomics
On Fri, Sep 11, 2020, 5:02 PM Joel Sherrill wrote: > > > On Fri, Sep 11, 2020 at 4:36 PM Janne Blomqvist > wrote: > >> On Fri, Sep 11, 2020 at 6:52 PM Joel Sherrill wrote: >> > >> > Hi >> > >> > Over at RTEMS, we ran into a case where the C++ atomics may not be right >> > for one of the lower level x86 models. We will investigate whether it >> can >> > be made right but this has led to the discussion of dropping older >> models >> > and setting a new minimum model. Right now, our base is a i386 w/FPU. >> The >> > best rationale we have for selecting a new floor is GCC atomics support. >> > >> > With that in mind, what's the lowest/oldest i386 CPU model we >> > should consider as the new base model? >> >> We sort-of discussed this issue back when the Linux kernel dropped >> support for i386. See thread starting at >> https://gcc.gnu.org/legacy-ml/gcc/2012-12/msg00079.html (a thread >> where you participated as well) >> > > Wow time flies! That was eight years ago and Dr Dewar was still alive. :( > > I guess the embedded x86 side has started to hit the wall also. Looks > like we should move to at least the i486 has a baseline. > I think I tripped across a mistake in i386/t-rtems. It is old enough that it was written to use -mcpu but currently uses -mtune. Shouldn't that -march? As written, I think it is getting default model code tuned for a higher model when we want code compatible with the higher model like other multilibs. Thoughts? Thanks --joel > Thanks. > > --joel > >> >> >> >> -- >> Janne Blomqvist >> >
gcc-10-20200912 is now available
Snapshot gcc-10-20200912 is now available on https://gcc.gnu.org/pub/gcc/snapshots/10-20200912/ and on various mirrors, see http://gcc.gnu.org/mirrors.html for details. This snapshot has been generated from the GCC 10 git branch with the following options: git://gcc.gnu.org/git/gcc.git branch releases/gcc-10 revision 08a0f33a1b0922386cf84aecccb0bc014646c609 You'll find: gcc-10-20200912.tar.xz Complete GCC SHA256=c178df2d7a40deb730e5d999205fc29a2df9bf3bbace7d31484052a296376e6c SHA1=3cbaab4ae9cc90dcbac388835e22d2f979cf0114 Diffs from 10-20200905 are available in the diffs/ subdirectory. When a particular snapshot is ready for public consumption the LATEST-10 link is updated and a message is sent to the gcc list. Please do not use a snapshot before it has been announced that way.
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