On Fri, 21 Feb 2014, Richard Biener wrote:
>
> This improves compile-time of PR60291 at -O1 from 210s to 85s,
> getting remove unused locals out of the profile. There walking
> DECL_INITIAL of globals is quadratic when that is refered to from
> multiple functions. We've had the same issue with
> add_referenced_vars when that still existed.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, ok for trunk
> and branch?
>
> I've verified that I can still properly debug
>
> int **
> foo (void)
> {
> static int a = 0;
> static int *b = &a;
> static int **c = &b;
> return c;
> }
> int main()
> {
> return **foo();
> }
>
> (step into foo and print a, b and c). Note that even with 4.8
> right now
>
> int **
> foo (void)
> {
> int **q;
> {
> static int a = 0;
> static int *b = &a;
> static int **c = &b;
> q = c;
> }
> return q;
> }
> int main()
> {
> return **foo();
> }
>
> is broken (with -O1 -fno-inline, with inlining both cases are
> broken). But that all doesn't regress with the following and
> if we fix it then we should fix it another way, not by walking
> global initializers.
So I checked if this all is a regression and this particular
piece is a regression from 4.7 where we only walk global
initializers for VAR_DECLs with DECL_CONTEXT == current_function_decl.
So at this point it's easiest and least intrusive to re-instantiate
this restriction which was removed by r187800 (that was me - the
change looks accidential).
Re-bootstrapping / testing on x86_64-unknown-linux-gnu and will
commit afterwards to trunk and to the branch a bit later.
Thanks,
Richard.
2014-02-21 Richard Biener <[email protected]>
PR middle-end/60291
* tree-ssa-live.c (mark_all_vars_used_1): Do not walk
DECL_INITIAL for globals not in the current function context.
Index: gcc/tree-ssa-live.c
===================================================================
*** gcc/tree-ssa-live.c (revision 207960)
--- gcc/tree-ssa-live.c (working copy)
*************** mark_all_vars_used_1 (tree *tp, int *wal
*** 435,441 ****
{
/* When a global var becomes used for the first time also walk its
initializer (non global ones don't have any). */
! if (set_is_used (t) && is_global_var (t))
mark_all_vars_used (&DECL_INITIAL (t));
}
/* remove_unused_scope_block_p requires information about labels
--- 435,442 ----
{
/* When a global var becomes used for the first time also walk its
initializer (non global ones don't have any). */
! if (set_is_used (t) && is_global_var (t)
! && DECL_CONTEXT (t) == current_function_decl)
mark_all_vars_used (&DECL_INITIAL (t));
}
/* remove_unused_scope_block_p requires information about labels
