| Message ID | 20110121075453.GD2724@tyan-ft48-01.lab.bos.redhat.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Jan 21, 2011 at 8:54 AM, Jakub Jelinek <jakub@redhat.com> wrote: > Hi! > > On testcases like: > integer :: i > i = 6 > print *, i > print *, i > ! 98 times more print *, i > end > (and any other Fortran procedures that have lots of IO statements) > we allocate ~48000 bytes on the stack instead of ~500, because > none of the __dt_parm.N etc. variables share the stack slots. > > The expansion stack sharing algorithm uses BLOCK_VARS to determine > what can and what can't be shared, but remove_unused_scope_block_p > considers solely debuginfo reasons and removes such vars as unused > because debug info is not emitted for them. > > Fixed by only ignoring small vars like that, but not larger ones. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? Ok. Thanks, Richard. > 2011-01-20 Jakub Jelinek <jakub@redhat.com> > > * tree-ssa-live.c (remove_unused_scope_block_p): Don't remove > DECL_IGNORED_P non-reg vars if they are used. > > --- gcc/tree-ssa-live.c.jj 2010-12-02 11:51:31.000000000 +0100 > +++ gcc/tree-ssa-live.c 2011-01-20 17:51:55.000000000 +0100 > @@ -453,8 +453,11 @@ remove_unused_scope_block_p (tree scope) > else if (TREE_CODE (*t) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*t)) > unused = false; > > - /* Remove everything we don't generate debug info for. */ > - else if (DECL_IGNORED_P (*t)) > + /* Remove everything we don't generate debug info for. > + Don't remove larger vars though, because BLOCK_VARS are > + used also during expansion to determine which variables > + might share stack space. */ > + else if (DECL_IGNORED_P (*t) && is_gimple_reg (*t)) > { > *t = DECL_CHAIN (*t); > next = t; > > Jakub >
--- gcc/tree-ssa-live.c.jj 2010-12-02 11:51:31.000000000 +0100 +++ gcc/tree-ssa-live.c 2011-01-20 17:51:55.000000000 +0100 @@ -453,8 +453,11 @@ remove_unused_scope_block_p (tree scope) else if (TREE_CODE (*t) == VAR_DECL && DECL_HAS_VALUE_EXPR_P (*t)) unused = false; - /* Remove everything we don't generate debug info for. */ - else if (DECL_IGNORED_P (*t)) + /* Remove everything we don't generate debug info for. + Don't remove larger vars though, because BLOCK_VARS are + used also during expansion to determine which variables + might share stack space. */ + else if (DECL_IGNORED_P (*t) && is_gimple_reg (*t)) { *t = DECL_CHAIN (*t); next = t;