On 1/14/20 12:18 PM, Jan Hubicka wrote:
PING^1
On 1/3/20 12:23 PM, Martin Liška wrote:
Hi.
I'm not fully sure about the change, but -momit-leaf-frame-pointer
probably should not globally omit frame pointers?
Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
Ready to be installed?
Thanks,
Martin
gcc/ChangeLog:
2020-01-03 Martin Liska <mli...@suse.cz>
PR tree-optimization/92860
* config/i386/i386-options.c (ix86_option_override_internal):
Do not enable -fomit-frame-pointer with -momit-leaf-frame-pointer
as it will globally omit pointers (like in ira.c).
Does gcc omit frame pointer of leaf functions after your change?
My recollection how this code works is that flag_omit_frame_pointer is
needed for regalloc to consider omitting at first plce and then it
queries frame_pointer_required hook wihch if only
-momit-leaf-frame-pointer is used will return true for all non-leaf
functions so effectivly only leaf ones are omitted.
I've got it.
If you stop setting the flag I think IRA will not consider omitting at
all and whole flag will become noop.
Yes, then patch is then incorrect. We would needs something like:
diff --git a/gcc/config/i386/i386-options.c b/gcc/config/i386/i386-options.c
index 2acc9fb0cfe..ec538724581 100644
--- a/gcc/config/i386/i386-options.c
+++ b/gcc/config/i386/i386-options.c
@@ -1671,6 +1671,9 @@ ix86_recompute_optlev_based_flags (struct gcc_options
*opts,
opts->x_flag_pcc_struct_return = DEFAULT_PCC_STRUCT_RETURN;
}
}
+
+ if (TARGET_OMIT_LEAF_FRAME_POINTER_P (opts->x_target_flags))
+ opts->x_flag_omit_frame_pointer = 1;
}
/* Implement TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE hook. */
@@ -2437,8 +2440,6 @@ ix86_option_override_internal (bool main_args_p,
/* Keep nonleaf frame pointers. */
if (opts->x_flag_omit_frame_pointer)
opts->x_target_flags &= ~MASK_OMIT_LEAF_FRAME_POINTER;
- else if (TARGET_OMIT_LEAF_FRAME_POINTER_P (opts->x_target_flags))
- opts->x_flag_omit_frame_pointer = 1;
/* If we're doing fast math, we don't care about comparison order
wrt NaNs. This lets us use a shorter comparison sequence. */
But it does not work as opts->x_target_flags is changed for some reason
for a per-function opts.
Martin
Honza
